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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 01/20] unwind_user: Add generic and arch-specific headers to MAINTAINERS Date: Wed, 20 May 2026 17:39:45 +0200 Message-ID: <20260520154004.3845823-2-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: YKvfFXI6TIxbisoowa3fG8e0_F0on43b X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0dd5dd cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=1XWaLZrsAAAA:8 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=HxY8WkbW6gBkmJkjgtEA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: hi_SJXSzHYSz7oiCOl1mI8qRHjox_iF9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfXyhBN7BRDhO4V fLT3CBvE35SKtEj/bGNwvGcyb80PUunwDw8MWIrpJDxnHfqOzZPLRSAbLjrpqOgA166QrqXlbXf +a/SDwN0ZCyoKUA9pdsHIVJGkx9wy/OzNBRAkMVt0AIVEn3D6Z2LiFaCCcWJ2dr7Rrr6/v7q4/N MET/5n7AzhxawpcaqYxAZk5mX6S883co5SuU8p8w0nS6TiDoDafGFkbpzNhr6y9xL9OWKY82pZE /9po9qQF21/u84dndhQ8jhmTPiXeyL7Wa9NYW0H1xjfJrHTJfKw4pgYLX+H09uXQdwkp6NAmqop kQ4jDz2pWlW0FeY9B9A4Vl2wD+DRvmq/M04w1L3HowEzyIPyQjezkC0EfCNUjA3wvOziGDq9BZa clBxs22wAyMm+1+D5TRXdWg2//wLH9uOnhdHuh5KsLRQYUjLXxe+XKJT/YJ3QHREXBIIqOufAmn 5ZKNCpsfzF+e6tHPtFQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" Commit 71753c6ed2bf ("unwind_user: Add user space unwinding API with frame pointer support") introduced include/asm-generic/unwind_user.h without adding it to MAINTAINERS, as well as any future arch-specific versions such as the one added by commit 49cf34c0815f ("unwind_user/x86: Enable frame pointer unwinding on x86") which introduced arch/x86/include/asm/unwind_user.h. Suggested-by: Dylan Hatch Signed-off-by: Jens Remus --- Notes (jremus): Changes in v14: - New patch. MAINTAINERS | 2 ++ 1 file changed, 2 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index c2c6d79275c6..7434e9d7b33f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27874,6 +27874,8 @@ USERSPACE STACK UNWINDING M: Josh Poimboeuf M: Steven Rostedt S: Maintained +F: arch/*/include/asm/unwind_user.h +F: include/asm-generic/unwind_user.h F: include/linux/unwind*.h F: kernel/unwind/ =20 --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 683973F23D5; Wed, 20 May 2026 15:40:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779291656; cv=none; b=Qo7u5gH2uZf1YsEB9EHK3mJu7B09cYe+ydCMBENJKlE6XkM6rulmGS8yhuWsGayyskf1I3Bv88GbrRavUtsIAOD8vQ69/WfC7ktUnHRKhZY4tNwtr9/F7zEt+8MISfLU3QdTeXTPmxX1gmRvdImYc50WT348gnfDNJc3B+LUdSA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779291656; c=relaxed/simple; bh=40eCuTAya7UOGfTpyAXI86nQufMPTC+FPH5MAZEmNXk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YImQUtPndRdkqMoAhiUbK4w5Y1giePCdwJpPVVovk0rZAT9kz403KEmfz7EozxsaBYUBeJTcy6JUDRYuuoH8VUSSFRkgrpN9p366nqIl8AjQJkov2+orMyVA6AG1rtkBMvy5fdVNMZGENyz0XSFsNyhqHBuXay0xVIFp9CVKw+Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=EdEukfR4; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="EdEukfR4" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 64K6Ehpp2818971; Wed, 20 May 2026 15:40:14 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=Q5n7SZa1kCJjW4GKz WdX9Nc0n7Hf175be+HBk4Nr0Ko=; b=EdEukfR4Hw++PC1z++DjT8XQ0ZHyAG3wU d4C3cPoa/+Gp0dzzBFQpHyCoZExuwwvun0WFBNI+1Su/2fKLjFCg+sljbPNGVZsh NPAxKTmYkKUaZrka7vB4+s4DWb5aavXH1RW4Qtdc10fG/0+n0Bauybpcd5ICAbey wip3OcZcE4otIJkVBpFgeN1piR/s7KI4J/LMyRKeklw9qMA35GnWDGcKlfVkCKtp WkkfUZVCm8mQuJeud9j+61hoCCiPfmVb+axDYY6XlXIqYxzMEFpKk8fc5MEwoxy+ txtZXZCo8p2I9pHFzbLceOUnjNyUeYXH3gH6xreX/UUfiIOmv0n2g== Received: from ppma13.dal12v.mail.ibm.com (dd.9e.1632.ip4.static.sl-reverse.com [50.22.158.221]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4e6h9y2vmb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 15:40:13 +0000 (GMT) Received: from pps.filterd (ppma13.dal12v.mail.ibm.com [127.0.0.1]) by ppma13.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 64KFdACX016266; Wed, 20 May 2026 15:40:12 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma13.dal12v.mail.ibm.com (PPS) with ESMTPS id 4e754gfrhe-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 15:40:12 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64KFe8A825690384 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 May 2026 15:40:08 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7DB912004B; Wed, 20 May 2026 15:40:08 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E4BA82004D; Wed, 20 May 2026 15:40:07 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 15:40:07 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Steven Rostedt , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Dylan Hatch , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 02/20] unwind_user/sframe: Add support for reading .sframe headers Date: Wed, 20 May 2026 17:39:46 +0200 Message-ID: <20260520154004.3845823-3-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX1XVSLcrG7H6f KurXm7LSnAs0DOR1a2UG55zr6bNdqa4Tb0Zi91y/NYgWTbQLBCz5SDCq0TZIwoRK0fBLjs02ZP2 kBQmUTYPssD1VsHcF7eHo7+OqAn1zMPKyB5S7l/pZhE1F6pCPS8GmofiElTj78DnExERr5csC+9 hEC9MaRLOCsDSXVqmWfbbECbMvpGiexqK9KhKXqm3yiO28HlltEjAYYBpLlZVKwVLFzguiR8/Kd SPJI94kqFkF/TR/ss0rPVS9jKFusiW94cj2mHJGdcPAUmectyUSbIXfZuVTyYs2njBxB+RvRMmQ /YYlSgyro7R25hLrd6tjrKji0ZhQexn/DxG+gRDgDV09NXvMXOhxYH/tJ/jtdyKsjB0VkiSYMa2 e047bWBfrxaoA+NV8XMx/j2vTAud0NuZDDv5WHhgNcCoaCoqGb8vTfwBJoa/s4Ufw9zNdGc0Gni WsAgv5KsUt//OJoNtNQ== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0dd5dd cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=CCpqsmhAAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=n2P1YqxNjAFD8MGDs80A:9 a=ul9cdbp4aOFLsgKbc677:22 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: wdhLLsLq9gws6Xxr31fVHQt-1N207Km2 X-Proofpoint-GUID: AbugIBAPnhPyOr4ahSt9w4Zc9eJrIAqj X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf In preparation for unwinding user space stacks with sframe, add basic sframe compile infrastructure and support for reading the .sframe section header. sframe_add_section() reads the header and unconditionally returns an error, so it's not very useful yet. A subsequent patch will improve that. Link: https://lore.kernel.org/all/f27e8463783febfa0dabb0432a3dd6be8ad98412.= 1737511963.git.jpoimboe@kernel.org/ [ Jens Remus: Add support for SFrame V3. Add support for PC-relative FDE function start offset. Cleanup includes and indentation. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Improve text/sframe section start/end validation. (Sashiko AI) - Use GFP_KERNEL_ACCOUNT instead of GFP_KERNEL (see memory-allocation.rst, section "Get Free Page flags"). (Sashiko AI) =20 Changes in v14: - Rename SFRAME_FDE_TYPE_REGULAR to SFRAME_FDE_TYPE_DEFAULT to match SFrame V3 specification. (Indu) - Correct SFRAME_V3_FDE_TYPE_MASK value. =20 Changes in v13: - Update to SFrame V3: - Add and use SFRAME_VERSION_3 definition. - Add helper macros to access SFrame V3 FDE type. - Rename SFRAME_FUNC_*() macros to SFRAME_FDE_*(). - Rename SFRAME_FDE_TYPE_PC* defines to SFRAME_FDE_PCTYPE_* and SFRAME_FUNC_FDE_TYPE() macro to SFRAME_V3_FDE_PCTYPE(). - Reword OFFSET to DATAWORD in SFRAME_FRE_OFFSET_{COUNT|SIZE}() macros. - Rename version-specific SFRAME_*() macros to SFRAME_V3_*(). - Update struct sframe_fde and rename to sframe_fde_v3: - Change field start_addr from s32 to s64 and rename to func_start_off. - Change field fres_num from u32 to u16. - New field u8 info2. - Remove u16 padding field. - Split FDE into function descriptor entry (struct sframe_fde_v3) and attributes (struct sframe_fde_v3). - Rename macro parameter "data" to "info" to hint at fde/fre info word and wrap it in parenthesis. - Group SFRAME_* definitions so that related ones are together. - Reword commit message (my changes). MAINTAINERS | 1 + arch/Kconfig | 3 + include/linux/sframe.h | 37 +++++++++++ kernel/unwind/Makefile | 3 +- kernel/unwind/sframe.c | 136 +++++++++++++++++++++++++++++++++++++++++ kernel/unwind/sframe.h | 81 ++++++++++++++++++++++++ 6 files changed, 260 insertions(+), 1 deletion(-) create mode 100644 include/linux/sframe.h create mode 100644 kernel/unwind/sframe.c create mode 100644 kernel/unwind/sframe.h diff --git a/MAINTAINERS b/MAINTAINERS index 7434e9d7b33f..a9b42b67a88d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27876,6 +27876,7 @@ M: Steven Rostedt S: Maintained F: arch/*/include/asm/unwind_user.h F: include/asm-generic/unwind_user.h +F: include/linux/sframe.h F: include/linux/unwind*.h F: kernel/unwind/ =20 diff --git a/arch/Kconfig b/arch/Kconfig index e86880045158..94b2d5e8e529 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -486,6 +486,9 @@ config HAVE_UNWIND_USER_FP bool select UNWIND_USER =20 +config HAVE_UNWIND_USER_SFRAME + bool + config HAVE_PERF_REGS bool help diff --git a/include/linux/sframe.h b/include/linux/sframe.h new file mode 100644 index 000000000000..0642595534f9 --- /dev/null +++ b/include/linux/sframe.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SFRAME_H +#define _LINUX_SFRAME_H + +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + +struct sframe_section { + unsigned long sframe_start; + unsigned long sframe_end; + unsigned long text_start; + unsigned long text_end; + + unsigned long fdes_start; + unsigned long fres_start; + unsigned long fres_end; + unsigned int num_fdes; + + signed char ra_off; + signed char fp_off; +}; + +extern int sframe_add_section(unsigned long sframe_start, unsigned long sf= rame_end, + unsigned long text_start, unsigned long text_end); +extern int sframe_remove_section(unsigned long sframe_addr); + +#else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */ + +static inline int sframe_add_section(unsigned long sframe_start, unsigned = long sframe_end, + unsigned long text_start, unsigned long text_end) +{ + return -ENOSYS; +} +static inline int sframe_remove_section(unsigned long sframe_addr) { retur= n -ENOSYS; } + +#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */ + +#endif /* _LINUX_SFRAME_H */ diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile index eae37bea54fd..146038165865 100644 --- a/kernel/unwind/Makefile +++ b/kernel/unwind/Makefile @@ -1 +1,2 @@ - obj-$(CONFIG_UNWIND_USER) +=3D user.o deferred.o + obj-$(CONFIG_UNWIND_USER) +=3D user.o deferred.o + obj-$(CONFIG_HAVE_UNWIND_USER_SFRAME) +=3D sframe.o diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c new file mode 100644 index 000000000000..d24e9d4f8bef --- /dev/null +++ b/kernel/unwind/sframe.c @@ -0,0 +1,136 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Userspace sframe access functions + */ + +#define pr_fmt(fmt) "sframe: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "sframe.h" + +#define dbg(fmt, ...) \ + pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + +static void free_section(struct sframe_section *sec) +{ + kfree(sec); +} + +static int sframe_read_header(struct sframe_section *sec) +{ + unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end; + struct sframe_header shdr; + unsigned int num_fdes; + + if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))= ) { + dbg("header usercopy failed\n"); + return -EFAULT; + } + + if (shdr.preamble.magic !=3D SFRAME_MAGIC || + shdr.preamble.version !=3D SFRAME_VERSION_3 || + !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) || + !(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) || + shdr.auxhdr_len) { + dbg("bad/unsupported sframe header\n"); + return -EINVAL; + } + + if (!shdr.num_fdes || !shdr.num_fres) { + dbg("no fde/fre entries\n"); + return -EINVAL; + } + + header_end =3D sec->sframe_start + SFRAME_HEADER_SIZE(shdr); + if (header_end >=3D sec->sframe_end) { + dbg("header doesn't fit in section\n"); + return -EINVAL; + } + + num_fdes =3D shdr.num_fdes; + fdes_start =3D header_end + shdr.fdes_off; + fdes_end =3D fdes_start + (num_fdes * sizeof(struct sframe_fde_v3)); + + fres_start =3D header_end + shdr.fres_off; + fres_end =3D fres_start + shdr.fre_len; + + if (fres_start < fdes_end || fres_end > sec->sframe_end) { + dbg("inconsistent fde/fre offsets\n"); + return -EINVAL; + } + + sec->num_fdes =3D num_fdes; + sec->fdes_start =3D fdes_start; + sec->fres_start =3D fres_start; + sec->fres_end =3D fres_end; + + sec->ra_off =3D shdr.cfa_fixed_ra_offset; + sec->fp_off =3D shdr.cfa_fixed_fp_offset; + + return 0; +} + +int sframe_add_section(unsigned long sframe_start, unsigned long sframe_en= d, + unsigned long text_start, unsigned long text_end) +{ + struct vm_area_struct *sframe_vma, *text_vma; + struct mm_struct *mm =3D current->mm; + struct sframe_section *sec; + int ret; + + if (sframe_start >=3D sframe_end || text_start >=3D text_end) { + dbg("invalid sframe/text address\n"); + return -EINVAL; + } + + scoped_guard(mmap_read_lock, mm) { + sframe_vma =3D vma_lookup(mm, sframe_start); + if (!sframe_vma || sframe_end > sframe_vma->vm_end) { + dbg("bad sframe address (0x%lx - 0x%lx)\n", + sframe_start, sframe_end); + return -EINVAL; + } + + text_vma =3D vma_lookup(mm, text_start); + if (!text_vma || + !(text_vma->vm_flags & VM_EXEC) || + text_end > text_vma->vm_end) { + dbg("bad text address (0x%lx - 0x%lx)\n", + text_start, text_end); + return -EINVAL; + } + } + + sec =3D kzalloc(sizeof(*sec), GFP_KERNEL_ACCOUNT); + if (!sec) + return -ENOMEM; + + sec->sframe_start =3D sframe_start; + sec->sframe_end =3D sframe_end; + sec->text_start =3D text_start; + sec->text_end =3D text_end; + + ret =3D sframe_read_header(sec); + if (ret) + goto err_free; + + /* TODO nowhere to store it yet - just free it and return an error */ + ret =3D -ENOSYS; + +err_free: + free_section(sec); + return ret; +} + +int sframe_remove_section(unsigned long sframe_start) +{ + return -ENOSYS; +} diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h new file mode 100644 index 000000000000..fc2908e92c7b --- /dev/null +++ b/kernel/unwind/sframe.h @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * From https://www.sourceware.org/binutils/docs/sframe-spec.html + */ +#ifndef _SFRAME_H +#define _SFRAME_H + +#include + +#define SFRAME_VERSION_1 1 +#define SFRAME_VERSION_2 2 +#define SFRAME_VERSION_3 3 +#define SFRAME_MAGIC 0xdee2 + +#define SFRAME_F_FDE_SORTED 0x1 +#define SFRAME_F_FRAME_POINTER 0x2 +#define SFRAME_F_FDE_FUNC_START_PCREL 0x4 + +#define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 +#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 +#define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 + +struct sframe_preamble { + u16 magic; + u8 version; + u8 flags; +} __packed; + +struct sframe_header { + struct sframe_preamble preamble; + u8 abi_arch; + s8 cfa_fixed_fp_offset; + s8 cfa_fixed_ra_offset; + u8 auxhdr_len; + u32 num_fdes; + u32 num_fres; + u32 fre_len; + u32 fdes_off; + u32 fres_off; +} __packed; + +#define SFRAME_HEADER_SIZE(header) \ + ((sizeof(struct sframe_header) + (header).auxhdr_len)) + +struct sframe_fde_v3 { + s64 func_start_off; + u32 func_size; + u32 fres_off; +} __packed; + +struct sframe_fda_v3 { + u16 fres_num; + u8 info; + u8 info2; + u8 rep_size; +} __packed; + +#define SFRAME_FDE_PCTYPE_INC 0 +#define SFRAME_FDE_PCTYPE_MASK 1 + +#define SFRAME_AARCH64_PAUTH_KEY_A 0 +#define SFRAME_AARCH64_PAUTH_KEY_B 1 + +#define SFRAME_V3_FDE_FRE_TYPE(info) ((info) & 0xf) +#define SFRAME_V3_FDE_PCTYPE(info) (((info) >> 4) & 0x1) +#define SFRAME_V3_AARCH64_FDE_PAUTH_KEY(info) (((info) >> 5) & 0x1) + +#define SFRAME_FDE_TYPE_DEFAULT 0 + +#define SFRAME_V3_FDE_TYPE_MASK 0x1f +#define SFRAME_V3_FDE_TYPE(info2) ((info2) & SFRAME_V3_FDE_TYPE_MASK) + +#define SFRAME_BASE_REG_FP 0 +#define SFRAME_BASE_REG_SP 1 + +#define SFRAME_V3_FRE_CFA_BASE_REG_ID(info) ((info) & 0x1) +#define SFRAME_V3_FRE_DATAWORD_COUNT(info) (((info) >> 1) & 0xf) +#define SFRAME_V3_FRE_DATAWORD_SIZE(info) (((info) >> 5) & 0x3) +#define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info) (((info) >> 7) & 0x1) + +#endif /* _SFRAME_H */ --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 755F33FCB00; 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 03/20] unwind_user/sframe: Store .sframe section data in per-mm maple tree Date: Wed, 20 May 2026 17:39:47 +0200 Message-ID: <20260520154004.3845823-4-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX5TrrRi1QbhaZ mtb+viY3ZVyPqp2/LdmIKm9Mj0K++oKuhi5wWxDdXVlBzno28IkX/FXd7d7OFBvQT2YuOG303Nd Eyk8pVQJdGmp0Knuk+YvarqeAunl9pRr5glnt0FoSEHepTMJiFZ2MTt4o1X2dJhBa4NOH682k55 5eQQlBaGORAU0EIpvHw05r8KWOF/7DDFi32sUlQcObU8rHqYm1hkF8JVnrUeo7cd6fzDqsPPEs4 OVtpgm19tgGdWbmetigQo/r5YVDmjcj+zE2DW1zLbA1WKqi89g9cTJpDew6vwFfK5N9bjB4vmyh R7wn4mtMww5x6QJmCHKGKVuS0r/9m3bqFEg686QBOrxGQzoglnvf3G5b94lDQYy/NN6aR4JaZHc 1HFFnyvoj815B2af8Rgmw8TiItxChY0ZaRTv2Od2ZfpnUyyk9Gh4/GR2OPg1Oq9Z7QJ41lLGpJX St1R0AUPHMMN1sWG4vw== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0dd5de cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=YdqKCSFLGneDM7Tu_fYA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: jFA2BCFLIDNy3DfJcvarB-LzGoKGWbPR X-Proofpoint-GUID: EXL2z-QuVSdgEqYVdBBkbCg6LsZjCogh X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf Associate an .sframe section with its mm by adding it to a per-mm maple tree which is indexed by the corresponding text address range. A single .sframe section can be associated with multiple text ranges. [ Jens Remus: Minor cleanups. Reword commit subject/message. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Fix text section end passed to mtree_insert_range() to be inclusive. (Sashiko AI) - sframe_remove_section(): Add guard(srcu) to guard access to sec->sframe_start. This also guards access to sec->filename in __sframe_remove_section(). (Sashiko AI) - Use GFP_KERNEL_ACCOUNT instead of GFP_KERNEL (see memory-allocation.rst, section "Get Free Page flags"). (Sashiko AI) arch/x86/include/asm/mmu.h | 2 +- include/linux/mm_types.h | 3 ++ include/linux/sframe.h | 15 ++++++++++ kernel/fork.c | 10 +++++++ kernel/unwind/sframe.c | 59 ++++++++++++++++++++++++++++++++++++-- mm/init-mm.c | 2 ++ 6 files changed, 87 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index 0fe9c569d171..227a32899a59 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -87,7 +87,7 @@ typedef struct { .context =3D { \ .ctx_id =3D 1, \ .lock =3D __MUTEX_INITIALIZER(mm.context.lock), \ - } + }, =20 void leave_mm(void); #define leave_mm leave_mm diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index a308e2c23b82..c1505356b6fc 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1424,6 +1424,9 @@ struct mm_struct { #ifdef CONFIG_MM_ID mm_id_t mm_id; #endif /* CONFIG_MM_ID */ +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + struct maple_tree sframe_mt; +#endif } __randomize_layout; =20 /* diff --git a/include/linux/sframe.h b/include/linux/sframe.h index 0642595534f9..7ea6a97ed8af 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -2,6 +2,8 @@ #ifndef _LINUX_SFRAME_H #define _LINUX_SFRAME_H =20 +#include + #ifdef CONFIG_HAVE_UNWIND_USER_SFRAME =20 struct sframe_section { @@ -19,18 +21,31 @@ struct sframe_section { signed char fp_off; }; =20 +#define INIT_MM_SFRAME .sframe_mt =3D MTREE_INIT(sframe_mt, 0), +extern void sframe_free_mm(struct mm_struct *mm); + extern int sframe_add_section(unsigned long sframe_start, unsigned long sf= rame_end, unsigned long text_start, unsigned long text_end); extern int sframe_remove_section(unsigned long sframe_addr); =20 +static inline bool current_has_sframe(void) +{ + struct mm_struct *mm =3D current->mm; + + return mm && !mtree_empty(&mm->sframe_mt); +} + #else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */ =20 +#define INIT_MM_SFRAME +static inline void sframe_free_mm(struct mm_struct *mm) {} static inline int sframe_add_section(unsigned long sframe_start, unsigned = long sframe_end, unsigned long text_start, unsigned long text_end) { return -ENOSYS; } static inline int sframe_remove_section(unsigned long sframe_addr) { retur= n -ENOSYS; } +static inline bool current_has_sframe(void) { return false; } =20 #endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */ =20 diff --git a/kernel/fork.c b/kernel/fork.c index 5f3fdfdb14c7..8d8195561c95 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -110,6 +110,7 @@ #include #include #include +#include #include =20 #include @@ -735,6 +736,7 @@ void __mmdrop(struct mm_struct *mm) mm_pasid_drop(mm); mm_destroy_cid(mm); percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS); + sframe_free_mm(mm); =20 free_mm(mm); } @@ -1072,6 +1074,13 @@ static void mmap_init_lock(struct mm_struct *mm) #endif } =20 +static void mm_init_sframe(struct mm_struct *mm) +{ +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + mt_init(&mm->sframe_mt); +#endif +} + static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct = *p, struct user_namespace *user_ns) { @@ -1100,6 +1109,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm= , struct task_struct *p, mm->pmd_huge_pte =3D NULL; #endif mm_init_uprobes_state(mm); + mm_init_sframe(mm); hugetlb_count_init(mm); =20 mm_flags_clear_all(mm); diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index d24e9d4f8bef..6b3ce3f8966d 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -81,6 +81,7 @@ static int sframe_read_header(struct sframe_section *sec) int sframe_add_section(unsigned long sframe_start, unsigned long sframe_en= d, unsigned long text_start, unsigned long text_end) { + struct maple_tree *sframe_mt =3D ¤t->mm->sframe_mt; struct vm_area_struct *sframe_vma, *text_vma; struct mm_struct *mm =3D current->mm; struct sframe_section *sec; @@ -122,15 +123,67 @@ int sframe_add_section(unsigned long sframe_start, un= signed long sframe_end, if (ret) goto err_free; =20 - /* TODO nowhere to store it yet - just free it and return an error */ - ret =3D -ENOSYS; + ret =3D mtree_insert_range(sframe_mt, sec->text_start, sec->text_end - 1, + sec, GFP_KERNEL_ACCOUNT); + if (ret) { + dbg("mtree_insert_range failed: text=3D%lx-%lx\n", + sec->text_start, sec->text_end); + goto err_free; + } + + return 0; =20 err_free: free_section(sec); return ret; } =20 +static int __sframe_remove_section(struct mm_struct *mm, + struct sframe_section *sec) +{ + if (!mtree_erase(&mm->sframe_mt, sec->text_start)) { + dbg("mtree_erase failed: text=3D%lx\n", sec->text_start); + return -EINVAL; + } + + free_section(sec); + + return 0; +} + int sframe_remove_section(unsigned long sframe_start) { - return -ENOSYS; + struct mm_struct *mm =3D current->mm; + struct sframe_section *sec; + unsigned long index =3D 0; + bool found =3D false; + int ret =3D 0; + + guard(srcu)(&sframe_srcu); + + mt_for_each(&mm->sframe_mt, sec, index, ULONG_MAX) { + if (sec->sframe_start =3D=3D sframe_start) { + found =3D true; + ret |=3D __sframe_remove_section(mm, sec); + } + } + + if (!found || ret) + return -EINVAL; + + return 0; +} + +void sframe_free_mm(struct mm_struct *mm) +{ + struct sframe_section *sec; + unsigned long index =3D 0; + + if (!mm) + return; + + mt_for_each(&mm->sframe_mt, sec, index, ULONG_MAX) + free_section(sec); 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 04/20] x86/uaccess: Add unsafe_copy_from_user() implementation Date: Wed, 20 May 2026 17:39:48 +0200 Message-ID: <20260520154004.3845823-5-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 3btCtYYv704e7QVRif3oIlL8SE6SlRb_ X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0dd5df cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=-G4kms3_kQfBhqX38bYA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: ZBNYzs-Kfe6qK0IRQ9H0uETwdsz5vRZr X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX7agdQ47zcZUK NxJf7mhM9Dq8WEgXsNveuBMroPimxAQZiVHAQLkYTpqMg6wu2nEJi9xjwC+iE3pA80Q+XlKkYMt moMXJCsM7Nwo3EpuooQJNvHQzB7RbsnccORBLvA/HgTpC6TuF6Qu5q85PWo5PU6FS1q/25UBH7n cY77XPXSParcwgdpuX1oJWgzJgx8FtbKzQzrGzjW68RUCCghe/a4/d5oG+iwf9i5ak/9OLgIaov PAywMX80ST6bvL85kIc7iCwIVGApyFN7K5n1wr0Hn855NGJcOIp0aA85qt0V7smykBErn8yx3dy 69CKNQ8euWtg3HsNEiCvg6KAhYjW+1HqaJFxXPd4Npw/DoI5gSPn52jnx0YrRJTRym58i6ofbMo L4ZOm3t7lzEAKMA6wtCv560LFFDiPx3LH0at8/dP0k7moj6g3+WeQK4LHm7Xi69n1V2+HxmGpa9 nJwtefS7kTWneJvRqYA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf Add an x86 implementation of unsafe_copy_from_user() similar to the existing unsafe_copy_to_user(). Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - unsafe_copy_from_user(): Use const void *__src. (Sashiko AI) arch/x86/include/asm/uaccess.h | 39 +++++++++++++++++++++++++--------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 3a0dd3c2b233..235886106f31 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -598,7 +598,7 @@ _label: \ * We want the unsafe accessors to always be inlined and use * the error labels - thus the macro games. */ -#define unsafe_copy_loop(dst, src, len, type, label) \ +#define unsafe_copy_to_user_loop(dst, src, len, type, label) \ while (len >=3D sizeof(type)) { \ unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ dst +=3D sizeof(type); \ @@ -606,15 +606,34 @@ _label: \ len -=3D sizeof(type); \ } =20 -#define unsafe_copy_to_user(_dst,_src,_len,label) \ -do { \ - char __user *__ucu_dst =3D (_dst); \ - const char *__ucu_src =3D (_src); \ - size_t __ucu_len =3D (_len); \ - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ - unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ +#define unsafe_copy_to_user(_dst, _src, _len, label) \ +do { \ + void __user *__dst =3D (_dst); \ + const void *__src =3D (_src); \ + size_t __len =3D (_len); \ + unsafe_copy_to_user_loop(__dst, __src, __len, u64, label); \ + unsafe_copy_to_user_loop(__dst, __src, __len, u32, label); \ + unsafe_copy_to_user_loop(__dst, __src, __len, u16, label); \ + unsafe_copy_to_user_loop(__dst, __src, __len, u8, label); \ +} while (0) + +#define unsafe_copy_from_user_loop(dst, src, len, type, label) \ + while (len >=3D sizeof(type)) { \ + unsafe_get_user(*(type *)(dst), (type __user *)(src), label); \ + dst +=3D sizeof(type); \ + src +=3D sizeof(type); \ + len -=3D sizeof(type); \ + } + +#define unsafe_copy_from_user(_dst, _src, _len, label) \ +do { \ + void *__dst =3D (_dst); \ + const void __user *__src =3D (_src); 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 05/20] unwind_user/sframe: Add support for reading .sframe contents Date: Wed, 20 May 2026 17:39:49 +0200 Message-ID: <20260520154004.3845823-6-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX+KyUcX1FG2vU n8gYHjVpZDoX3hXbA1c09LdtY+3olYXtvxLMx2wbiUveypGBroQNWzeM+30qN95rFLpZVVfN/lQ l84FLCFZbFFM6b4e5E7Z30sS5EZ6A26SmD/lL0usGtRZpQ3NbABFuv8uFlF7lHwX0U8UTzEMHcg 8t6J0kJi5XRbeNzAnq4sM+dFmIk7+6WtsT9PUr827ZCYc7c1IOI1RVXXv9R0QB4Gh3oNWpzrIGY XcAwUQfSniljRM70wNLxxLR9GxRuSHmil4KNyREBterUHgD/HBZSQtYSEFbe61oIJnDG7UQSJFf KFHTDsqqSLiuN+noxjy/PcDJl7CzCo6YHC7hfFyVYb5Eh4Lt8B9bRNBtGN+iVizG+ZDsF6IP9ko K/ExcVwhIQwVA/CoRrO4vY4bY4yEy5amM7Budpn0bC4t3BxFOdkXmRAaqM9eh9n9lpwVMjGMxcH aw4Ujg+6nr0yeAAE/bw== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0dd5df cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=YuDcBBqGAAAA:8 a=eEjjhumUK4yHDpHCs10A:9 a=2JgSa4NbpEOStq-L5dxp:22 a=V9_jqlfyBUA7Gw2gN5zN:22 X-Proofpoint-ORIG-GUID: Wmf40LnDvKx5JDnQDdqdgGtJQszDPoX9 X-Proofpoint-GUID: d6QHTcX7dCeHRcayAjAMHYNYHY7Jqtut X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf In preparation for using sframe to unwind user space stacks, add an sframe_find() interface for finding the sframe information associated with a given text address. For performance, use user_read_access_begin() and the corresponding unsafe_*() accessors. Note that use of pr_debug() in uaccess-enabled regions would break noinstr validation, so there aren't any debug messages yet. That will be added in a subsequent commit. Link: https://lore.kernel.org/all/77c0d1ec143bf2a53d66c4ecb190e7e0a576fbfd.= 1737511963.git.jpoimboe@kernel.org/ Link: https://lore.kernel.org/all/b35ca3a3-8de5-4d32-8d30-d4e562f6b0de@linu= x.ibm.com/ [ Jens Remus: Add initial support for SFrame V3 (limited to default FDEs). Add support for PC-relative FDE function start offset. Simplify logic by using an internal FDE representation. Rename struct sframe_fre to sframe_fre_internal to align with struct sframe_fde_internal. Cleanup includes. Fix checkpatch errors "spaces required around that ':'". ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - __read_fde(): - Validate FDE repetition size for PCTYPE_MASK FDEs to be non-zero to prevent division by zero. (Sashiko AI) - Validate FDE PC type for supported values (i.e. PCTYPE_INC or PCTYPE_MASK). - Validate FDE function end against text end. - Validate FDE's number of FREs to be less or equal to FDE's function size, as each FRE must cover at least one byte. (Indu) - __read_fre(): Validate FRE function offset against FDE repetition size for PCTYPE_MASK. - Change type of struct sframe_fde_internal field fres_num to the one of struct sframe_fda_v3 field fres_num. - Normalize error code usage (.sframe is removed for all but ENOENT): ENOENT: No sframe or no FDE for IP found (FDE found but no FRE found is EINVAL) EFAULT: Bad address EINVAL: Invalid input or sframe - Build-time checks for config options: - 64BIT: SFrame V3 only supports 64-bit architectures. - HAVE_EFFICIENT_UNALIGNED_ACCESS: Unaligned access to 16/32-bit SFrame FRE fields and datawords using unsafe_get_user(). (Steven) - Reword my changelog in commit message. =20 Changes in v14: - Fix FDE function start address check in __read_fde(). - Adjust to rename of SFRAME_FDE_TYPE_*. =20 Changes in v13: - Update to SFrame V3: - Adjust to SFRAME_V3_*() macros and macro/define renames. - Adjust to struct sframe_fde_v3 rename. - Adjust to s64 FDE function start offset. - Rename local variables fde_type to fde_pctype. - Add and maintain struct sframe_fde_internal field u8 info2. - Adjust to FDE split into function descriptor entry (struct sframe_fde_v3) and attributes (struct sframe_fde_v3). - Rename offset_count/offset_size to dataword_count/dataword_count. - Limit __read_fre() to SFrame V3 regular FDEs (FDE_TYPE_REGULAR). A subsequent patch will add support for flexible FDEs (FDE_TYPE_FLEX). - Rename struct sframe_fde_internal field func_start_addr to func_addr. - Add support u64/s64 in UNSAFE_GET_USER_INC() for s64 FDE function start offset. - Reduce indentation of assignments to fre. - Reword commit message (my changes). include/linux/sframe.h | 6 + kernel/unwind/sframe.c | 367 ++++++++++++++++++++++++++++++++++- kernel/unwind/sframe_debug.h | 35 ++++ 3 files changed, 404 insertions(+), 4 deletions(-) create mode 100644 kernel/unwind/sframe_debug.h diff --git a/include/linux/sframe.h b/include/linux/sframe.h index 7ea6a97ed8af..9a72209696f9 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -3,10 +3,14 @@ #define _LINUX_SFRAME_H =20 #include +#include +#include =20 #ifdef CONFIG_HAVE_UNWIND_USER_SFRAME =20 struct sframe_section { + struct rcu_head rcu; + unsigned long sframe_start; unsigned long sframe_end; unsigned long text_start; @@ -27,6 +31,7 @@ extern void sframe_free_mm(struct mm_struct *mm); extern int sframe_add_section(unsigned long sframe_start, unsigned long sf= rame_end, unsigned long text_start, unsigned long text_end); extern int sframe_remove_section(unsigned long sframe_addr); +extern int sframe_find(unsigned long ip, struct unwind_user_frame *frame); =20 static inline bool current_has_sframe(void) { @@ -45,6 +50,7 @@ static inline int sframe_add_section(unsigned long sframe= _start, unsigned long s return -ENOSYS; } static inline int sframe_remove_section(unsigned long sframe_addr) { retur= n -ENOSYS; } +static inline int sframe_find(unsigned long ip, struct unwind_user_frame *= frame) { return -ENOSYS; } static inline bool current_has_sframe(void) { return false; } =20 #endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */ diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 6b3ce3f8966d..a38f50a36363 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -15,9 +15,350 @@ #include =20 #include "sframe.h" +#include "sframe_debug.h" + +struct sframe_fde_internal { + unsigned long func_addr; + u32 func_size; + u32 fda_off; + u32 fres_off; + u16 fres_num; + u8 info; + u8 info2; + u8 rep_size; +}; + +struct sframe_fre_internal { + unsigned int size; + u32 ip_off; + s32 cfa_off; + s32 ra_off; + s32 fp_off; + u8 info; +}; + +DEFINE_STATIC_SRCU(sframe_srcu); + +static __always_inline unsigned char fre_type_to_size(unsigned char fre_ty= pe) +{ + if (fre_type > 2) + return 0; + return 1 << fre_type; +} + +static __always_inline unsigned char dataword_size_enum_to_size(unsigned c= har dataword_size) +{ + if (dataword_size > 2) + return 0; + return 1 << dataword_size; +} + +static __always_inline int __read_fde(struct sframe_section *sec, + unsigned int fde_num, + struct sframe_fde_internal *fde) +{ + unsigned long fde_addr, fda_addr, func_start, func_end; + struct sframe_fde_v3 _fde; + struct sframe_fda_v3 _fda; + unsigned char fde_pctype; + + fde_addr =3D sec->fdes_start + (fde_num * sizeof(struct sframe_fde_v3)); + unsafe_copy_from_user(&_fde, (void __user *)fde_addr, + sizeof(struct sframe_fde_v3), Efault); + + func_start =3D fde_addr + _fde.func_start_off; + func_end =3D func_start + _fde.func_size; + if (func_start < sec->text_start || func_end > sec->text_end) + return -EFAULT; + + fda_addr =3D sec->fres_start + _fde.fres_off; + if (fda_addr + sizeof(struct sframe_fda_v3) > sec->fres_end) + return -EFAULT; + unsafe_copy_from_user(&_fda, (void __user *)fda_addr, + sizeof(struct sframe_fda_v3), Efault); + + fde_pctype =3D SFRAME_V3_FDE_PCTYPE(_fda.info); + if (fde_pctype !=3D SFRAME_FDE_PCTYPE_INC && + fde_pctype !=3D SFRAME_FDE_PCTYPE_MASK) + return -EINVAL; + if (fde_pctype =3D=3D SFRAME_FDE_PCTYPE_MASK && !_fda.rep_size) + return -EINVAL; + if (_fda.fres_num > _fde.func_size) + return -EINVAL; + + fde->func_addr =3D func_start; + fde->func_size =3D _fde.func_size; + fde->fda_off =3D _fde.fres_off; + fde->fres_off =3D _fde.fres_off + sizeof(struct sframe_fda_v3); + fde->fres_num =3D _fda.fres_num; + fde->info =3D _fda.info; + fde->info2 =3D _fda.info2; + fde->rep_size =3D _fda.rep_size; =20 -#define dbg(fmt, ...) \ - pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + return 0; + +Efault: + return -EFAULT; +} + +static __always_inline int __find_fde(struct sframe_section *sec, + unsigned long ip, + struct sframe_fde_internal *fde) +{ + unsigned long func_addr_low =3D 0, func_addr_high =3D ULONG_MAX; + struct sframe_fde_v3 __user *first, *low, *high, *found =3D NULL; + int ret; + + first =3D (void __user *)sec->fdes_start; + low =3D first; + high =3D first + sec->num_fdes - 1; + + while (low <=3D high) { + struct sframe_fde_v3 __user *mid; + s64 func_off; + unsigned long func_addr; + + mid =3D low + ((high - low) / 2); + + unsafe_get_user(func_off, (s64 __user *)mid, Efault); + func_addr =3D (unsigned long)mid + func_off; + + if (ip >=3D func_addr) { + if (func_addr < func_addr_low) + return -EINVAL; + + func_addr_low =3D func_addr; + + found =3D mid; + low =3D mid + 1; + } else { + if (func_addr > func_addr_high) + return -EINVAL; + + func_addr_high =3D func_addr; + + high =3D mid - 1; + } + } + + if (!found) + return -ENOENT; + + ret =3D __read_fde(sec, found - first, fde); + if (ret) + return ret; + + /* make sure it's not in a gap */ + if (ip < fde->func_addr || ip >=3D fde->func_addr + fde->func_size) + return -ENOENT; + + return 0; + +Efault: + return -EFAULT; +} + +#define ____UNSAFE_GET_USER_INC(to, from, type, label) \ +({ \ + type __to; \ + unsafe_get_user(__to, (type __user *)from, label); \ + from +=3D sizeof(__to); \ + to =3D __to; \ +}) + +#define __UNSAFE_GET_USER_INC(to, from, size, label, u_or_s) \ +({ \ + switch (size) { \ + case 1: \ + ____UNSAFE_GET_USER_INC(to, from, u_or_s##8, label); \ + break; \ + case 2: \ + ____UNSAFE_GET_USER_INC(to, from, u_or_s##16, label); \ + break; \ + case 4: \ + ____UNSAFE_GET_USER_INC(to, from, u_or_s##32, label); \ + break; \ + default: \ + return -EFAULT; \ + } \ +}) + +#define UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label) \ + __UNSAFE_GET_USER_INC(to, from, size, label, u) + +#define UNSAFE_GET_USER_SIGNED_INC(to, from, size, label) \ + __UNSAFE_GET_USER_INC(to, from, size, label, s) + +#define UNSAFE_GET_USER_INC(to, from, size, label) \ + _Generic(to, \ + u8 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \ + u16 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \ + u32 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \ + u64 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \ + s8 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \ + s16 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \ + s32 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \ + s64 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label)) + +static __always_inline int __read_fre(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long fre_addr, + struct sframe_fre_internal *fre) +{ + unsigned char fde_type =3D SFRAME_V3_FDE_TYPE(fde->info2); + unsigned char fde_pctype =3D SFRAME_V3_FDE_PCTYPE(fde->info); + unsigned char fre_type =3D SFRAME_V3_FDE_FRE_TYPE(fde->info); + unsigned char dataword_count, dataword_size; + s32 cfa_off, ra_off, fp_off; + unsigned long cur =3D fre_addr; + unsigned char addr_size; + u32 ip_off; + u8 info; + + addr_size =3D fre_type_to_size(fre_type); + if (!addr_size) + return -EINVAL; + + if (fre_addr + addr_size + 1 > sec->fres_end) + return -EFAULT; + + UNSAFE_GET_USER_INC(ip_off, cur, addr_size, Efault); + if ((fde_pctype =3D=3D SFRAME_FDE_PCTYPE_INC && ip_off >=3D fde->func_siz= e) || + (fde_pctype =3D=3D SFRAME_FDE_PCTYPE_MASK && ip_off >=3D fde->rep_siz= e)) + return -EINVAL; + + UNSAFE_GET_USER_INC(info, cur, 1, Efault); + dataword_count =3D SFRAME_V3_FRE_DATAWORD_COUNT(info); + dataword_size =3D dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE= (info)); + if (!dataword_count || !dataword_size) + return -EINVAL; + + if (cur + (dataword_count * dataword_size) > sec->fres_end) + return -EFAULT; + + /* TODO: Support for flexible FDEs not implemented yet. */ + if (fde_type !=3D SFRAME_FDE_TYPE_DEFAULT) + return -EINVAL; + + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); + dataword_count--; + + ra_off =3D sec->ra_off; + if (!ra_off) { + if (!dataword_count--) + return -EINVAL; + + UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault); + } + + fp_off =3D sec->fp_off; + if (!fp_off && dataword_count) { + dataword_count--; + UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault); + } + + if (dataword_count) + return -EINVAL; + + fre->size =3D addr_size + 1 + (dataword_count * dataword_size); + fre->ip_off =3D ip_off; + fre->cfa_off =3D cfa_off; + fre->ra_off =3D ra_off; + fre->fp_off =3D fp_off; + fre->info =3D info; + + return 0; + +Efault: + return -EFAULT; +} + +static __always_inline int __find_fre(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long ip, + struct unwind_user_frame *frame) +{ + unsigned char fde_pctype =3D SFRAME_V3_FDE_PCTYPE(fde->info); + struct sframe_fre_internal *fre, *prev_fre =3D NULL; + struct sframe_fre_internal fres[2]; + unsigned long fre_addr; + bool which =3D false; + unsigned int i; + u32 ip_off; + + ip_off =3D ip - fde->func_addr; + + if (fde_pctype =3D=3D SFRAME_FDE_PCTYPE_MASK) + ip_off %=3D fde->rep_size; + + fre_addr =3D sec->fres_start + fde->fres_off; + + for (i =3D 0; i < fde->fres_num; i++) { + int ret; + + /* + * Alternate between the two fre_addr[] entries for 'fre' and + * 'prev_fre'. + */ + fre =3D which ? fres : fres + 1; + which =3D !which; + + ret =3D __read_fre(sec, fde, fre_addr, fre); + if (ret) + return ret; + + fre_addr +=3D fre->size; + + if (prev_fre && fre->ip_off <=3D prev_fre->ip_off) + return -EINVAL; + + if (fre->ip_off > ip_off) + break; + + prev_fre =3D fre; + } + + if (!prev_fre) + return -EINVAL; + fre =3D prev_fre; + + frame->cfa_off =3D fre->cfa_off; + frame->ra_off =3D fre->ra_off; + frame->fp_off =3D fre->fp_off; + frame->use_fp =3D SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME= _BASE_REG_FP; + + return 0; +} + +int sframe_find(unsigned long ip, struct unwind_user_frame *frame) +{ + struct mm_struct *mm =3D current->mm; + struct sframe_section *sec; + struct sframe_fde_internal fde; + int ret; + + if (!mm) + return -EINVAL; + + guard(srcu)(&sframe_srcu); + + sec =3D mtree_load(&mm->sframe_mt, ip); + if (!sec) + return -ENOENT; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + + ret =3D __find_fde(sec, ip, &fde); + if (ret) + goto end; + + ret =3D __find_fre(sec, &fde, ip, frame); +end: + user_read_access_end(); + return ret; +} =20 static void free_section(struct sframe_section *sec) { @@ -30,6 +371,15 @@ static int sframe_read_header(struct sframe_section *se= c) struct sframe_header shdr; unsigned int num_fdes; =20 + /* SFrame V3 is only supported on 64-bit architectures */ + BUILD_BUG_ON(!IS_ENABLED(CONFIG_64BIT)); + + /* + * Unaligned access to 16/32-bit SFrame FRE fields and datawords + * using unsafe_get_user() via UNSAFE_GET_USER_INC() + */ + BUILD_BUG_ON(!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)); + if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))= ) { dbg("header usercopy failed\n"); return -EFAULT; @@ -120,8 +470,10 @@ int sframe_add_section(unsigned long sframe_start, uns= igned long sframe_end, sec->text_end =3D text_end; =20 ret =3D sframe_read_header(sec); - if (ret) + if (ret) { + dbg_print_header(sec); goto err_free; + } =20 ret =3D mtree_insert_range(sframe_mt, sec->text_start, sec->text_end - 1, sec, GFP_KERNEL_ACCOUNT); @@ -138,6 +490,13 @@ int sframe_add_section(unsigned long sframe_start, uns= igned long sframe_end, return ret; } =20 +static void sframe_free_srcu(struct rcu_head *rcu) +{ + struct sframe_section *sec =3D container_of(rcu, struct sframe_section, r= cu); + + free_section(sec); +} + static int __sframe_remove_section(struct mm_struct *mm, struct sframe_section *sec) { @@ -146,7 +505,7 @@ static int __sframe_remove_section(struct mm_struct *mm, return -EINVAL; } =20 - free_section(sec); + call_srcu(&sframe_srcu, &sec->rcu, sframe_free_srcu); =20 return 0; } diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h new file mode 100644 index 000000000000..36352124cde8 --- /dev/null +++ b/kernel/unwind/sframe_debug.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _SFRAME_DEBUG_H +#define _SFRAME_DEBUG_H + +#include +#include "sframe.h" + +#ifdef CONFIG_DYNAMIC_DEBUG + +#define dbg(fmt, ...) \ + pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + +static __always_inline void dbg_print_header(struct sframe_section *sec) +{ + unsigned long fdes_end; + + fdes_end =3D sec->fdes_start + (sec->num_fdes * sizeof(struct sframe_fde_= v3)); + + dbg("SEC: sframe:0x%lx-0x%lx text:0x%lx-0x%lx " + "fdes:0x%lx-0x%lx fres:0x%lx-0x%lx " + "ra_off:%d fp_off:%d\n", + sec->sframe_start, sec->sframe_end, sec->text_start, sec->text_end, + sec->fdes_start, fdes_end, sec->fres_start, sec->fres_end, + sec->ra_off, sec->fp_off); +} + +#else /* !CONFIG_DYNAMIC_DEBUG */ + +#define dbg(args...) no_printk(args) + +static inline void dbg_print_header(struct sframe_section *sec) {} + +#endif /* !CONFIG_DYNAMIC_DEBUG */ + +#endif /* _SFRAME_DEBUG_H */ --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06A973EFD22; 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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 06/20] unwind_user/sframe: Detect .sframe sections in executables Date: Wed, 20 May 2026 17:39:50 +0200 Message-ID: <20260520154004.3845823-7-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2ISu0SHUttbv0n9vfydNFpwKXpKjlH2q X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX7PV/sJz2ww+P 3/f3BwtqiU3FT5DyPXz/orsUimp1undhsKdq310qkRgje6tdAsY2U4BkqnfSMhIEfWfuov+4rgR mo42nz8tcH/qemdVol+DHMPwvoE2yxYwZQqdVUUiQ0jyF4VmLrX8yIPILiNqjKnFPcnpoi836r1 C7KiJHgX0dhkCMbdGiKnUIYS+AdbqK/rnvOgjhvu4fCZflSXa/UZB8VAq27Vc4j8WsH6nkkgPCx VSa6i+/e6LVr/6ZNM2amsTvZDWLUiPJtu7wFw2/a6Hc/qYDrf6QMfLroerbfywNZSIhorssD7W8 FguGSisAkobDJ6ilrcRLEJ84WkXWPE9RfcH3HmlSBqmiKH6ATBzfN48AgW7/5E+CKQj1qamK3C6 4O28N/xY7eBGwku9QCDhG3AS6KOFt1puUzFLO3Qy4CPu3BZohjGpl9F0EyjGlq3jRSzj0Goqegi 0LV1b1g8mjUBWXNVPnw== X-Proofpoint-GUID: 2ISu0SHUttbv0n9vfydNFpwKXpKjlH2q X-Authority-Analysis: v=2.4 cv=apyCzyZV c=1 sm=1 tr=0 ts=6a0dd5df cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=eNuN5pRUQDBy6NUwPKcA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 phishscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf When loading an ELF executable, automatically detect an .sframe section and associate it with the mm_struct. [ Jens Remus: Fix checkpatch warning "braces {} are not necessary for single statement blocks". ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Only add sframe for text that is PT_LOAD in addition to PF_X. (Sashiko AI) fs/binfmt_elf.c | 48 +++++++++++++++++++++++++++++++++++++--- include/uapi/linux/elf.h | 1 + 2 files changed, 46 insertions(+), 3 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 16a56b6b3f6c..980a9f229cd1 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -48,6 +48,7 @@ #include #include #include +#include #include #include =20 @@ -637,6 +638,21 @@ static inline int make_prot(u32 p_flags, struct arch_e= lf_state *arch_state, return arch_elf_adjust_prot(prot, arch_state, has_interp, is_interp); } =20 +static void elf_add_sframe(struct elf_phdr *text, struct elf_phdr *sframe, + unsigned long base_addr) +{ + unsigned long sframe_start, sframe_end, text_start, text_end; + + sframe_start =3D base_addr + sframe->p_vaddr; + sframe_end =3D sframe_start + sframe->p_memsz; + + text_start =3D base_addr + text->p_vaddr; + text_end =3D text_start + text->p_memsz; + + /* Ignore return value, sframe section isn't critical */ + sframe_add_section(sframe_start, sframe_end, text_start, text_end); +} + /* This is much more generalized than the library routine read function, so we keep this separate. Technically the library read function is only provided so that we can read a.out libraries that have @@ -647,7 +663,7 @@ static unsigned long load_elf_interp(struct elfhdr *int= erp_elf_ex, unsigned long no_base, struct elf_phdr *interp_elf_phdata, struct arch_elf_state *arch_state) { - struct elf_phdr *eppnt; + struct elf_phdr *eppnt, *sframe_phdr =3D NULL; unsigned long load_addr =3D 0; int load_addr_set =3D 0; unsigned long error =3D ~0UL; @@ -673,7 +689,8 @@ static unsigned long load_elf_interp(struct elfhdr *int= erp_elf_ex, =20 eppnt =3D interp_elf_phdata; for (i =3D 0; i < interp_elf_ex->e_phnum; i++, eppnt++) { - if (eppnt->p_type =3D=3D PT_LOAD) { + switch (eppnt->p_type) { + case PT_LOAD: { int elf_type =3D MAP_PRIVATE; int elf_prot =3D make_prot(eppnt->p_flags, arch_state, true, true); @@ -712,6 +729,19 @@ static unsigned long load_elf_interp(struct elfhdr *in= terp_elf_ex, error =3D -ENOMEM; goto out; } + break; + } + case PT_GNU_SFRAME: + sframe_phdr =3D eppnt; + break; + } + } + + if (sframe_phdr) { + eppnt =3D interp_elf_phdata; + for (i =3D 0; i < interp_elf_ex->e_phnum; i++, eppnt++) { + if (eppnt->p_flags & PF_X && eppnt->p_type =3D=3D PT_LOAD) + elf_add_sframe(eppnt, sframe_phdr, load_addr); } } =20 @@ -836,7 +866,7 @@ static int load_elf_binary(struct linux_binprm *bprm) int first_pt_load =3D 1; unsigned long error; struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata =3D NULL; - struct elf_phdr *elf_property_phdata =3D NULL; + struct elf_phdr *elf_property_phdata =3D NULL, *sframe_phdr =3D NULL; unsigned long elf_brk; bool brk_moved =3D false; int retval, i; @@ -945,6 +975,10 @@ static int load_elf_binary(struct linux_binprm *bprm) executable_stack =3D EXSTACK_DISABLE_X; break; =20 + case PT_GNU_SFRAME: + sframe_phdr =3D elf_ppnt; + break; + case PT_LOPROC ... 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 07/20] unwind_user/sframe: Wire up unwind_user to sframe Date: Wed, 20 May 2026 17:39:51 +0200 Message-ID: <20260520154004.3845823-8-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX1/SYL7+2n3s7 aLSsXixcBHlsytcw5OQTh3jpKRlKfFSg/jpcGOoSFbT5WCNeZIcg6OZmPPWaj6ynOwGlCbSAPGM G7kEBRbez8PijWmEAZ8Yw8xzDHP0/KY+ZVyYf5tVsBUSqAxz1hVguRch08pJ308XuzkLv8Ygfd7 Bh+WwQb5r1iqsma8FF2P9uyc8WkdAh6x1BnWL0AXM4RJvrpPwg0676nz73fxvT3Y8nQXCJwj1ig tAf2or4g0gOB5WuZTISmc06Icmo2cUG64KTreuseZM0ySFKlxd+yXIaq9TDMeHmAGUhcOjK0X27 Dxxe6pqcqDqBXDblIWS/EVcVzVKnq81wDS1OB0dUQO7PIw8PparzGnsWy0vSlJtF0eoV1hEl9q3 P2i47GHpjKG+XRZlUnv87ZHXUSvIE70zcVctHnl7Kpzcqa52Eu5qCjvIb9TYmF6f9GgqwLqI/bj FTHFPHUHYd1v0gWWf3w== X-Proofpoint-GUID: JJRgHReXCbHr6ZJcTDCpGLa5yjE3ZG_H X-Proofpoint-ORIG-GUID: kwkMNcL2g_NLE0Oar4XAplhdwsm003rE X-Authority-Analysis: v=2.4 cv=aYBRWxot c=1 sm=1 tr=0 ts=6a0dd5e0 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=ItKwCHsCKAUqeRWvWoIA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf Now that the sframe infrastructure is fully in place, make it work by hooking it up to the unwind_user interface. [ Jens Remus: Remove unused pt_regs from unwind_user_next_common() and its callers. Simplify unwind_user_next_sframe(). ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- arch/Kconfig | 1 + include/linux/unwind_user_types.h | 4 +++- kernel/unwind/user.c | 23 +++++++++++++++++++++++ 3 files changed, 27 insertions(+), 1 deletion(-) diff --git a/arch/Kconfig b/arch/Kconfig index 94b2d5e8e529..37549832bd1f 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -488,6 +488,7 @@ config HAVE_UNWIND_USER_FP =20 config HAVE_UNWIND_USER_SFRAME bool + select UNWIND_USER =20 config HAVE_PERF_REGS bool diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_= types.h index 412729a269bc..43e4b160883f 100644 --- a/include/linux/unwind_user_types.h +++ b/include/linux/unwind_user_types.h @@ -9,7 +9,8 @@ * available. */ enum unwind_user_type_bits { - UNWIND_USER_TYPE_FP_BIT =3D 0, + UNWIND_USER_TYPE_SFRAME_BIT =3D 0, + UNWIND_USER_TYPE_FP_BIT =3D 1, =20 NR_UNWIND_USER_TYPE_BITS, }; @@ -17,6 +18,7 @@ enum unwind_user_type_bits { enum unwind_user_type { /* Type "none" for the start of stack walk iteration. */ UNWIND_USER_TYPE_NONE =3D 0, + UNWIND_USER_TYPE_SFRAME =3D BIT(UNWIND_USER_TYPE_SFRAME_BIT), UNWIND_USER_TYPE_FP =3D BIT(UNWIND_USER_TYPE_FP_BIT), }; =20 diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index 90ab3c1a205e..1fb272419733 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -7,6 +7,7 @@ #include #include #include +#include =20 #define for_each_user_frame(state) \ for (unwind_user_start(state); !(state)->done; unwind_user_next(state)) @@ -82,6 +83,16 @@ static int unwind_user_next_fp(struct unwind_user_state = *state) return unwind_user_next_common(state, &fp_frame); } =20 +static int unwind_user_next_sframe(struct unwind_user_state *state) +{ + struct unwind_user_frame frame; + + /* sframe expects the frame to be local storage */ + if (sframe_find(state->ip, &frame)) + return -ENOENT; + return unwind_user_next_common(state, &frame); +} + static int unwind_user_next(struct unwind_user_state *state) { unsigned long iter_mask =3D state->available_types; @@ -95,6 +106,16 @@ static int unwind_user_next(struct unwind_user_state *s= tate) =20 state->current_type =3D type; switch (type) { + case UNWIND_USER_TYPE_SFRAME: + switch (unwind_user_next_sframe(state)) { + case 0: + return 0; 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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 08/20] unwind_user: Stop when reaching an outermost frame Date: Wed, 20 May 2026 17:39:52 +0200 Message-ID: <20260520154004.3845823-9-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX5tXd5a79RShz qd9w4gNTPiiJY7CMhk85NzHnBFXOqudYX4kmjm6u56Q6DwYTCwd1UuzIZxagLdGTDMpMeMAZ8/x 9BhfFPSYyWqEY2cyeseDt+7cmLOcQ7Waf8lHW0uDwUUdghM5sl0Qz8/Q1gLxk+GDmJxxDyzyT1I lLfBs3cnXWTlPx3oMF11QJ8TkXId1G1M6UBVOmj7vgI2ozMvB7qi5qaR+xxkT1Bb3sIEqwypXIO +nECMOeDW+04DheSJ/Y12vLekS8UWt34Z5EvFtankilNLyfElwfcnlKrzlqy1e6d4lUJs6w5O4m GCK5XBCb32B3qaTURrIGCT9YFj725eJbPsjFzQRIs0ZlI182S2QlqtYH7pT3dREJaklq2tG8Sa8 d6/JgchSpyfADmKgda4f99BuELQmkrTF8F5+eP2jiyTW2vgVGzgiqMuxqPXfQJmvIKTg/vaCHZR GJfyhoEcuLrjGJR2B8g== X-Proofpoint-GUID: wvBUGDyFlzpAOgjPw_K_8hx9qpGk4_yW X-Proofpoint-ORIG-GUID: 9bbppHG8EDr34JUJC_qg9IOyE4sI_bx3 X-Authority-Analysis: v=2.4 cv=aYBRWxot c=1 sm=1 tr=0 ts=6a0dd5e1 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=_1qlYuAciRtwIPuEvDgA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" Add an indication for an outermost frame to the unwind user frame structure and stop unwinding when reaching an outermost frame. This will be used by unwind user sframe, as SFrame may represent an undefined return address as indication for an outermost frame. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- arch/x86/include/asm/unwind_user.h | 6 ++++-- include/linux/unwind_user_types.h | 1 + kernel/unwind/user.c | 6 ++++++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwi= nd_user.h index 6e469044e4de..2dfb5ef11e36 100644 --- a/arch/x86/include/asm/unwind_user.h +++ b/arch/x86/include/asm/unwind_user.h @@ -23,13 +23,15 @@ static inline int unwind_user_word_size(struct pt_regs = *regs) .cfa_off =3D 2*(ws), \ .ra_off =3D -1*(ws), \ .fp_off =3D -2*(ws), \ - .use_fp =3D true, + .use_fp =3D true, \ + .outermost =3D false, =20 #define ARCH_INIT_USER_FP_ENTRY_FRAME(ws) \ .cfa_off =3D 1*(ws), \ .ra_off =3D -1*(ws), \ .fp_off =3D 0, \ - .use_fp =3D false, + .use_fp =3D false, \ + .outermost =3D false, =20 static inline bool unwind_user_at_function_start(struct pt_regs *regs) { diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_= types.h index 43e4b160883f..616cc5ee4586 100644 --- a/include/linux/unwind_user_types.h +++ b/include/linux/unwind_user_types.h @@ -32,6 +32,7 @@ struct unwind_user_frame { s32 ra_off; 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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 09/20] unwind_user/sframe: Add support for outermost frame indication Date: Wed, 20 May 2026 17:39:53 +0200 Message-ID: <20260520154004.3845823-10-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e1 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=U72JrVpwKSe1qDC-WCIA:9 X-Proofpoint-ORIG-GUID: RutorrHK_Yh961JRGNUS1hvnwjZkw88C X-Proofpoint-GUID: XnZrEE4_Iky6X02Y2pC9TJ5PPqyzpqIn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX1OqTSBjg6JuQ 3CYMiUWNmccKjjzBUq2FHOZJTDO7VV9RUQtDZ/UosD6cXC4wirTJjKWlbMgrl57yNKjZx4nqukq CUEyyWpoI+g96MdSRvblOL3fNjCPUGmjXY8swPhuIFkQLVXheAquLoSsWfWMx3R6TTOvnx3HXEi gTK2ZGHp2EO4VVybVguhAvAOyiXxbjjRblupu5eGISleIYUFA8D+1pMybPtQ7IOkPP/lVSPpBJ+ KdgYqWAWsxR62CmXaPjcU7qj0KlR791ABFSU5jlans+thlIpN2KGruDpNnwhNS4C5i4fU2fxluh hmge4nC/w4oV7pFW7faXGslWKLCMvhTmSL8q5nnhRvinUilCZYfHgBCDucTfgEKIMiDgejCKPP7 njDNzY36T8g9hnYZU71eXoCzez16WpGBrTeb5i8io6vVApLmm8HCKExgY84mMF4IT50TmosB2E/ C5c1EoJcDHhQugNIg7w== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" SFrame may represent an undefined return address (RA) as SFrame FRE without any offsets as indication for an outermost frame. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- kernel/unwind/sframe.c | 15 ++++++++++++++- kernel/unwind/sframe.h | 1 + 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index a38f50a36363..f723c1a32f90 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -230,7 +230,7 @@ static __always_inline int __read_fre(struct sframe_sec= tion *sec, UNSAFE_GET_USER_INC(info, cur, 1, Efault); dataword_count =3D SFRAME_V3_FRE_DATAWORD_COUNT(info); dataword_size =3D dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE= (info)); - if (!dataword_count || !dataword_size) + if (!dataword_size) return -EINVAL; =20 if (cur + (dataword_count * dataword_size) > sec->fres_end) @@ -240,6 +240,17 @@ static __always_inline int __read_fre(struct sframe_se= ction *sec, if (fde_type !=3D SFRAME_FDE_TYPE_DEFAULT) return -EINVAL; =20 + if (!dataword_count) { + /* + * A FRE without data words indicates RA undefined / + * outermost frame. + */ + cfa_off =3D 0; + ra_off =3D 0; + fp_off =3D 0; + goto done; + } + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); dataword_count--; =20 @@ -260,6 +271,7 @@ static __always_inline int __read_fre(struct sframe_sec= tion *sec, if (dataword_count) return -EINVAL; =20 +done: fre->size =3D addr_size + 1 + (dataword_count * dataword_size); fre->ip_off =3D ip_off; fre->cfa_off =3D cfa_off; @@ -326,6 +338,7 @@ static __always_inline int __find_fre(struct sframe_sec= tion *sec, frame->ra_off =3D fre->ra_off; frame->fp_off =3D fre->fp_off; frame->use_fp =3D SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME= _BASE_REG_FP; + frame->outermost =3D SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); =20 return 0; } diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h index fc2908e92c7b..ed111fd0d702 100644 --- a/kernel/unwind/sframe.h +++ b/kernel/unwind/sframe.h @@ -77,5 +77,6 @@ struct sframe_fda_v3 { #define SFRAME_V3_FRE_DATAWORD_COUNT(info) (((info) >> 1) & 0xf) #define SFRAME_V3_FRE_DATAWORD_SIZE(info) (((info) >> 5) & 0x3) #define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info) (((info) >> 7) & 0x1) +#define SFRAME_V3_FRE_RA_UNDEFINED_P(info) (SFRAME_V3_FRE_DATAWORD_COUNT(= info) =3D=3D 0) =20 #endif /* _SFRAME_H */ --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BB6953F39C7; 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 10/20] unwind_user/sframe: Remove .sframe section on detected corruption Date: Wed, 20 May 2026 17:39:54 +0200 Message-ID: <20260520154004.3845823-11-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e3 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=yLRsOmMQGpVHI0ogWx0A:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: veXC281t-x8pUsd_KRr4ocx8fXCOmcCb X-Proofpoint-GUID: BXFZlkLxsxRGpSJbt-MqdCy5geQBe9y1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfXztA7Qa75XLln /qY82xY+uZY2Bjg++7j2TKASy9G0ehTabDtfHznKosfWTSvoO9G+li0TpDK0/LMEmNHqdpvt19g 0HqHY1yTq7HzbVRGQQ2pcLO5E9MgnNkoXq5e5vIXWupvSv4yfvWtjKPociHnYrSlE1eLfskkB9W 9fEDDRZYq+4ZQMeGNkauL1op/J++0j60etavTCjHQOIbFArWSOlWzykN3d9xpCCbqqFkhvHTYfJ peRPAei9Kh86Dh3xnCSQInumGvYZSxZKVI/5E6dwDQzYW0USAV1Yv63dHOV5RsJ/lm5koXtpiSF xyx8D01OWEfeWpLWGdngDEXiGdtkBf6RJ1mB+eB7Z0h4lOiRCF9ood4IC69pUpuP8GuJE+IhuYk vwaNj78I4i95mRuPiPxfgxHbtyLvAKNk83JuJ5jqYVhv5DjzJF6hqe9vsD7bRWICuq+OYNxCbQq cdKoJ+U7jP9JShLOw3A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf To avoid continued attempted use of a bad .sframe section, remove it on demand when the first sign of corruption is detected. Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - sframe_find(): Align to normalized error code usage and remove .sframe for all but ENOENT. Also remove if user_read_access_begin() fails. kernel/unwind/sframe.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index f723c1a32f90..02331956009a 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -360,16 +360,23 @@ int sframe_find(unsigned long ip, struct unwind_user_= frame *frame) return -ENOENT; =20 if (!user_read_access_begin((void __user *)sec->sframe_start, - sec->sframe_end - sec->sframe_start)) - return -EFAULT; + sec->sframe_end - sec->sframe_start)) { + ret =3D -EFAULT; + goto end; + } =20 ret =3D __find_fde(sec, ip, &fde); if (ret) - goto end; + goto end_uaccess; =20 ret =3D __find_fre(sec, &fde, ip, frame); -end: +end_uaccess: user_read_access_end(); + +end: + if (ret && ret !=3D -ENOENT) + WARN_ON_ONCE(sframe_remove_section(sec->sframe_start)); + return ret; } =20 --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 632A116DC28; 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 11/20] unwind_user/sframe: Show file name in debug output Date: Wed, 20 May 2026 17:39:55 +0200 Message-ID: <20260520154004.3845823-12-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: nOGEipXW_Vq4kLBKw8DEOnaegiLq7WTj X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0dd5e2 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=pfo6fe6KaiqNJ1UUovoA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: tAQjVecBoP-dCCoo7L_C0wBnG0GrfXMA X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfXxJNpDQlYKZnC TBYNRBK75HFL20RcXOaKHoMyEFWef7YDs42GyablNEycjMtQixsgLIYaiy8w4Erewww6HIkl/O7 hziswLCOT8RDnNEwpNUf5G1xqW0wXPwo6ffa8K3o/Qz37cnrTsvISx2EbS8ja4zzWmIWodJ/eG4 G23qcbbwZ1hLeaifW58Qfm7qfNAiTBxcX+iZ3b451kQVYxUpdCvLx3AvdTtN/dHgLtymDgvDMVN WPyD5BL50ruvn+Bkw2Qq5yNz/qK2D0rVv8yW8xvtdzpDRwKaUIdRY/JjbAq2E/71CuSVDnyKtdW 1+golc23P3PrSYt8eDcNA6al5nuW2XHq+Pw4OoQyViVYJlIvj11UD818J9XZVsBlozQ3DgzceUx v0miDnRbyMReg6kCkxOePDmntXRHIafDrVMpPcaXaIRb6JXYGVlf29l7n7Hi/w7LeC4SebJam/S xZCmMl4D0l6RB9tNraw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf When debugging sframe issues, the error messages aren't all that helpful without knowing what file a corresponding .sframe section belongs to. Prefix debug output strings with the file name. [ Jens Remus: Fix checkpatch error "space prohibited before that close parenthesis ')'". ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Use GFP_KERNEL_ACCOUNT instead of GFP_KERNEL (see memory-allocation.rst, section "Get Free Page flags"). (Sashiko AI) =20 Changes in v14: - Uppercase terms FDE and FRE in debug messages. include/linux/sframe.h | 4 +++- kernel/unwind/sframe.c | 23 ++++++++++-------- kernel/unwind/sframe_debug.h | 45 +++++++++++++++++++++++++++++++----- 3 files changed, 56 insertions(+), 16 deletions(-) diff --git a/include/linux/sframe.h b/include/linux/sframe.h index 9a72209696f9..b79c5ec09229 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -10,7 +10,9 @@ =20 struct sframe_section { struct rcu_head rcu; - +#ifdef CONFIG_DYNAMIC_DEBUG + const char *filename; +#endif unsigned long sframe_start; unsigned long sframe_end; unsigned long text_start; diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 02331956009a..f931932bd34a 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -374,14 +374,17 @@ int sframe_find(unsigned long ip, struct unwind_user_= frame *frame) user_read_access_end(); =20 end: - if (ret && ret !=3D -ENOENT) + if (ret && ret !=3D -ENOENT) { + dbg_sec("removing bad .sframe section\n"); WARN_ON_ONCE(sframe_remove_section(sec->sframe_start)); + } =20 return ret; } =20 static void free_section(struct sframe_section *sec) { + dbg_free(sec); kfree(sec); } =20 @@ -401,7 +404,7 @@ static int sframe_read_header(struct sframe_section *se= c) BUILD_BUG_ON(!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)); =20 if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))= ) { - dbg("header usercopy failed\n"); + dbg_sec("header usercopy failed\n"); return -EFAULT; } =20 @@ -410,18 +413,18 @@ static int sframe_read_header(struct sframe_section *= sec) !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) || !(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) || shdr.auxhdr_len) { - dbg("bad/unsupported sframe header\n"); + dbg_sec("bad/unsupported sframe header\n"); return -EINVAL; } =20 if (!shdr.num_fdes || !shdr.num_fres) { - dbg("no fde/fre entries\n"); + dbg_sec("no FDE/FRE entries\n"); return -EINVAL; } =20 header_end =3D sec->sframe_start + SFRAME_HEADER_SIZE(shdr); if (header_end >=3D sec->sframe_end) { - dbg("header doesn't fit in section\n"); + dbg_sec("header doesn't fit in section\n"); return -EINVAL; } =20 @@ -433,7 +436,7 @@ static int sframe_read_header(struct sframe_section *se= c) fres_end =3D fres_start + shdr.fre_len; =20 if (fres_start < fdes_end || fres_end > sec->sframe_end) { - dbg("inconsistent fde/fre offsets\n"); + dbg_sec("inconsistent FDE/FRE offsets\n"); return -EINVAL; } =20 @@ -489,6 +492,8 @@ int sframe_add_section(unsigned long sframe_start, unsi= gned long sframe_end, sec->text_start =3D text_start; sec->text_end =3D text_end; =20 + dbg_init(sec); + ret =3D sframe_read_header(sec); if (ret) { dbg_print_header(sec); @@ -498,8 +503,8 @@ int sframe_add_section(unsigned long sframe_start, unsi= gned long sframe_end, ret =3D mtree_insert_range(sframe_mt, sec->text_start, sec->text_end - 1, sec, GFP_KERNEL_ACCOUNT); if (ret) { - dbg("mtree_insert_range failed: text=3D%lx-%lx\n", - sec->text_start, sec->text_end); + dbg_sec("mtree_insert_range failed: text=3D%lx-%lx\n", + sec->text_start, sec->text_end); goto err_free; } =20 @@ -521,7 +526,7 @@ static int __sframe_remove_section(struct mm_struct *mm, struct sframe_section *sec) { if (!mtree_erase(&mm->sframe_mt, sec->text_start)) { - dbg("mtree_erase failed: text=3D%lx\n", sec->text_start); + dbg_sec("mtree_erase failed: text=3D%lx\n", sec->text_start); return -EINVAL; } =20 diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h index 36352124cde8..a63e75cccc70 100644 --- a/kernel/unwind/sframe_debug.h +++ b/kernel/unwind/sframe_debug.h @@ -10,26 +10,59 @@ #define dbg(fmt, ...) \ pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) =20 +#define dbg_sec(fmt, ...) \ + dbg("%s: " fmt, sec->filename, ##__VA_ARGS__) + static __always_inline void dbg_print_header(struct sframe_section *sec) { unsigned long fdes_end; =20 fdes_end =3D sec->fdes_start + (sec->num_fdes * sizeof(struct sframe_fde_= v3)); =20 - dbg("SEC: sframe:0x%lx-0x%lx text:0x%lx-0x%lx " - "fdes:0x%lx-0x%lx fres:0x%lx-0x%lx " - "ra_off:%d fp_off:%d\n", - sec->sframe_start, sec->sframe_end, sec->text_start, sec->text_end, - sec->fdes_start, fdes_end, sec->fres_start, sec->fres_end, - sec->ra_off, sec->fp_off); + dbg_sec("SEC: sframe:0x%lx-0x%lx text:0x%lx-0x%lx " + "fdes:0x%lx-0x%lx fres:0x%lx-0x%lx " + "ra_off:%d fp_off:%d\n", + sec->sframe_start, sec->sframe_end, sec->text_start, sec->text_end, + sec->fdes_start, fdes_end, sec->fres_start, sec->fres_end, + sec->ra_off, sec->fp_off); +} + +static inline void dbg_init(struct sframe_section *sec) +{ + struct mm_struct *mm =3D current->mm; + struct vm_area_struct *vma; + + guard(mmap_read_lock)(mm); + vma =3D vma_lookup(mm, sec->sframe_start); + if (!vma) + sec->filename =3D kstrdup("(vma gone???)", GFP_KERNEL_ACCOUNT); + else if (vma->vm_file) + sec->filename =3D kstrdup_quotable_file(vma->vm_file, GFP_KERNEL_ACCOUNT= ); + else if (vma->vm_ops && vma->vm_ops->name) + sec->filename =3D kstrdup(vma->vm_ops->name(vma), GFP_KERNEL_ACCOUNT); + else if (arch_vma_name(vma)) + sec->filename =3D kstrdup(arch_vma_name(vma), GFP_KERNEL_ACCOUNT); + else if (!vma->vm_mm) + sec->filename =3D kstrdup("(vdso)", GFP_KERNEL_ACCOUNT); + else + sec->filename =3D kstrdup("(anonymous)", GFP_KERNEL_ACCOUNT); 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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 12/20] unwind_user/sframe: Add .sframe validation option Date: Wed, 20 May 2026 17:39:56 +0200 Message-ID: <20260520154004.3845823-13-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e4 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=RXKZOtKmAAAA:8 a=iNKnMr3YqTL5pEm6fAYA:9 a=2JgSa4NbpEOStq-L5dxp:22 a=UFF3uGjEBZWolfm0k6KQ:22 X-Proofpoint-ORIG-GUID: -mkfSxAZrBitVU35z00n1maSPFGjEpyV X-Proofpoint-GUID: PcRSCFKq2nBAV8d8RsO-g8IszMq0jrZL X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX+4A6NmuzGWeG gmHkZhotg90f9w+n46VxxVYmpLojP/Pt/cjMxbc+bsVsKbKMK3nWoUaXSAZS7+c3S9+4IuyB69u Q3N9BqkINDt6at0tT1rsTSuhQZ0e4OGlWGjyjnhGCSe8a6QPxHKHkxZR5WmP9q2cH/rBdaHOMoW 185O2lPNMtCIlDj3X//0PqtRmPJ02kt8dhD1WK517q5fwGG6zRBOE9WtzjuQVlKHlV4Pb7DdFCk KIdf1PIMU0+Y/CgmbH5Aiz/kHFn0C1EvA8YH3ixcQCFRedYca5C0RDweYn0/B5IPfCzFD2nNFT/ yhnmKZnnSw+TFjiZHfbgd2MEAsA2aPVclD8l6QxCLkVdjYr/lgqi7W7wk8MRyetKECNyQSYLsvV bd0FdsDcOuU3GhXqKbonzTbO0F15lUJBy6pL/1Lkz6tO/yF8oVvYpzMbOaF8iGRnXIf12me2j3l PZE36FK2khAMfW/k9zQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf Add a debug feature to validate all .sframe sections when first loading the file rather than on demand. [ Jens Remus: Add support for SFrame V3. Add support for PC-relative FDE function start offset. Adjust to rename of struct sframe_fre to sframe_fre_internal. Use %#x/%#lx format specifiers. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - sframe_validate_section(): Fix format specifier for number of FREs in debug message. (Sashiko AI) - Normalize error code usage (.sframe is removed for all but ENOENT): ENOENT: No sframe or no FDE for IP found (FDE found but no FRE is EINVAL) EFAULT: Bad address EINVAL: Invalid input or sframe =20 Changes in v14: - Add debug message if safe_read_fde() fails. - Update function names in debug messages. - Uppercase terms FDE and FRE in debug messages. =20 Changes in v13: - Update to SFrame V3: - Print struct sframe_fde_internal fields fda_off and info2 in debug message. - Adjust to rename of struct sframe_fde_internal field func_start_addr to func_addr. - Use format strings "%#x" and "%#lx" instead of "0x%x" and "0x%lx". - Reword commit message (my changes). arch/Kconfig | 19 ++++++++ kernel/unwind/sframe.c | 101 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 120 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index 37549832bd1f..132249d342a3 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -490,6 +490,25 @@ config HAVE_UNWIND_USER_SFRAME bool select UNWIND_USER =20 +config SFRAME_VALIDATION + bool "Enable .sframe section debugging" + depends on HAVE_UNWIND_USER_SFRAME + depends on DYNAMIC_DEBUG + help + When adding an .sframe section for a task, validate the entire + section immediately rather than on demand. + + This is a debug feature which is helpful for rooting out .sframe + section issues. If the .sframe section is corrupt, it will fail to + load immediately, with more information provided in dynamic printks. + + This has a significant page cache footprint due to its reading of the + entire .sframe section for every loaded executable and shared + library. Also, it's done for all processes, even those which don't + get stack traced by the kernel. Not recommended for general use. + + If unsure, say N. + config HAVE_PERF_REGS bool help diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index f931932bd34a..b5f984fb2df2 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -382,6 +382,103 @@ int sframe_find(unsigned long ip, struct unwind_user_= frame *frame) return ret; } =20 +#ifdef CONFIG_SFRAME_VALIDATION + +static int safe_read_fde(struct sframe_section *sec, + unsigned int fde_num, struct sframe_fde_internal *fde) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret =3D __read_fde(sec, fde_num, fde); + user_read_access_end(); + return ret; +} + +static int safe_read_fre(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long fre_addr, + struct sframe_fre_internal *fre) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret =3D __read_fre(sec, fde, fre_addr, fre); + user_read_access_end(); + return ret; +} + +static int sframe_validate_section(struct sframe_section *sec) +{ + unsigned long prev_ip =3D 0; + unsigned int i; + + for (i =3D 0; i < sec->num_fdes; i++) { + struct sframe_fre_internal *fre, *prev_fre =3D NULL; + unsigned long ip, fre_addr; + struct sframe_fde_internal fde; + struct sframe_fre_internal fres[2]; + bool which =3D false; + unsigned int j; + int ret; + + ret =3D safe_read_fde(sec, i, &fde); + if (ret) { + dbg_sec("safe_read_fde(%u) failed\n", i); + return ret; + } + + ip =3D fde.func_addr; + if (ip <=3D prev_ip) { + dbg_sec("FDE %u not sorted\n", i); + return -EINVAL; + } + prev_ip =3D ip; + + fre_addr =3D sec->fres_start + fde.fres_off; + for (j =3D 0; j < fde.fres_num; j++) { + int ret; + + fre =3D which ? fres : fres + 1; + which =3D !which; + + ret =3D safe_read_fre(sec, &fde, fre_addr, fre); + if (ret) { + dbg_sec("FDE %u: safe_read_fre(%u) failed\n", i, j); + dbg_sec("FDE: func_addr:%#lx func_size:%#x fda_off:%#x fres_off:%#x fr= es_num:%u info:%u info2:%u rep_size:%u\n", + fde.func_addr, fde.func_size, + fde.fda_off, + fde.fres_off, fde.fres_num, + fde.info, fde.info2, + fde.rep_size); 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 13/20] unwind_user: Enable archs that pass RA in a register Date: Wed, 20 May 2026 17:39:57 +0200 Message-ID: <20260520154004.3845823-14-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX+ZJ+3qEpulp9 BPO8NYhXZzH0Ny3YLbhLv8U9s/DDBqHpZ1G2HzppTO2GEySYMNtom0KBol1DYSgNmEEJ/9TZIzE t/MKr0wyZVdq5HZD4HgwRj6irE66q0X9OOlPIb0J71I9MUJn/s6KXssb9DE0nbg4KrkRqZ5dTnl Qvop6V9bEx33jm1DRKnjeJCkQkBPkm32hdmY4+3XIrTHS5r5BcVVh4jx6jt2zeEIZvQUE9gzslX OVZLTyVrlksaoecaS23DoE5V7E3D9qRdgfEdIeed5cwMm6pebyZcOxaCE2Nx2GXGNT5oYUW3ZyY B6tR/EKDHvLQc3QmOI+tS/3qJFEsz6e9Vt30QJZkFZA/kRtiJAwLfnS8wji6l1b9nN+1RD7rYEV EVctAemmYp6SZb9GY1LyoGMNUdtZE9ZB//Kz6m5UTpHITxeGSEI6xE0jIP/Cxybj3GNAJYeiWq6 YwGyLK/iMXwireapCRA== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0dd5e4 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=c48flIb4C_QYATK_dV0A:9 X-Proofpoint-ORIG-GUID: dtAPcJIj4_HKjvCpdMenCV1ryW5p_1td X-Proofpoint-GUID: CcKY7XMm1KJQsZb35JSoWVF1glEn73FC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" Not all architectures/ABIs pass the return address (RA) on the stack on function entry, like x86-64 does due to its CALL instruction pushing the RA onto the stack. Architectures/ABIs, such as s390, also do not require the RA to be saved on the stack in the function prologue. In particular, the RA may never be saved to the stack at all, such as in leaf functions. Unwinding must therefore not assume the presence of a RA saved on stack for the topmost frame. Treat a RA offset from CFA of zero as indication that the RA is not saved (on the stack). For the topmost frame treat it as indication that the RA is in the link/RA register, such as on arm64 and s390, and obtain it from there. For non-topmost frames treat it as error, as the RA must be saved. Additionally allow the SP to be unchanged in the topmost frame, for architectures where SP at function entry =3D=3D SP at call site, such as arm64 and s390. Note that treating a RA offset from CFA of zero as indication that the RA is not saved on the stack additionally allows for architectures, such as s390, where the frame pointer (FP) may be saved without the RA being saved as well. Provided that such architectures represent this in SFrame by encoding the "missing" RA offset using a padding RA offset with a value of zero. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Define pr_fmt(). - unwind_user_get_ra_reg(): Use pr_debug_once() instead of WARN_ON_ONCE() to prevent user-triggered warning/panic. (Sashiko AI) - Reworded commit message. (Indu) include/linux/unwind_user.h | 10 ++++++++++ kernel/unwind/sframe.c | 6 ++---- kernel/unwind/user.c | 20 ++++++++++++++++---- 3 files changed, 28 insertions(+), 8 deletions(-) diff --git a/include/linux/unwind_user.h b/include/linux/unwind_user.h index 64618618febd..7bf58f23aa64 100644 --- a/include/linux/unwind_user.h +++ b/include/linux/unwind_user.h @@ -23,6 +23,16 @@ static inline bool unwind_user_at_function_start(struct = pt_regs *regs) #define unwind_user_at_function_start unwind_user_at_function_start #endif =20 +#ifndef unwind_user_get_ra_reg +static inline int unwind_user_get_ra_reg(unsigned long *val) +{ + pr_debug_once("%s (%d): unwind_user_get_ra_reg() not implemented\n", + current->comm, current->pid); + return -EINVAL; +} +#define unwind_user_get_ra_reg unwind_user_get_ra_reg +#endif + int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries); =20 #endif /* _LINUX_UNWIND_USER_H */ diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index b5f984fb2df2..4af533e9f980 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -255,10 +255,8 @@ static __always_inline int __read_fre(struct sframe_se= ction *sec, dataword_count--; =20 ra_off =3D sec->ra_off; - if (!ra_off) { - if (!dataword_count--) - return -EINVAL; - + if (!ra_off && dataword_count) { + dataword_count--; UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault); } =20 diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index fdb1001e3750..afa7c6f6d9b4 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -2,6 +2,9 @@ /* * Generic interfaces for unwinding user space */ + +#define pr_fmt(fmt) "unwind_user: " fmt + #include #include #include @@ -48,8 +51,12 @@ static int unwind_user_next_common(struct unwind_user_st= ate *state, } cfa +=3D frame->cfa_off; =20 - /* Make sure that stack is not going in wrong direction */ - if (cfa <=3D state->sp) + /* + * Make sure that stack is not going in wrong direction. Allow SP + * to be unchanged for the topmost frame, by subtracting topmost, + * which is either 0 or 1. + */ + if (cfa <=3D state->sp - state->topmost) return -EINVAL; =20 /* Make sure that the address is word aligned */ @@ -57,8 +64,13 @@ static int unwind_user_next_common(struct unwind_user_st= ate *state, return -EINVAL; =20 /* Get the Return Address (RA) */ - if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) - return -EINVAL; + if (frame->ra_off) { + if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) + return -EINVAL; + } else { + if (!state->topmost || unwind_user_get_ra_reg(&ra)) + return -EINVAL; + } =20 /* Get the Frame Pointer (FP) */ if (frame->fp_off && get_user_word(&fp, cfa, frame->fp_off, state->ws)) --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BA373F0A98; Wed, 20 May 2026 15:40:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779291653; cv=none; b=IuCm0yPFCTAOP3D1DDawJqLHVjKTV4JFOIBrXzSDi/KzZf/GWMWCxRqhGN2ODhp3v2oBXkfMKwoAHgrTf+f2mtUMQu84N6I9+gZXaD8Elj6iKtND7krN4GBYTryF2vkRtJZJZS+KS8/VZm/LVEiOxy6g65BGUwBuVqeuLciXK/Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779291653; c=relaxed/simple; bh=bT0zK5CoGmn3oLcHdtThNemcw4K7L3Ne1tvDn4cDHw0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=b+9suHtO64EVhmZZGFcM14qc+5fp5G2dDP3HwKNmSYG+PYwm4jBaeFMihYdqy2iNzST/txrtY38PglWyWmYWDVfZRVaewo927fhA1KiUIGb1JJkwHkAYfcGQI3HUaw8Y/d8St4IID8Tyuv2UOY+b2SHD3tnmBWXu6QzzsFt7PD4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=XKSutO62; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="XKSutO62" Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 64KDohNu3469512; Wed, 20 May 2026 15:40:21 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=NhEny1+IV3hVg/kbI p/lU5dvCc7jZRXTsSPWi4iKz4M=; b=XKSutO62orZcFI7NYLJDdtxPV0lEem7KM kRNuiUd07S7rN5+9E0kBglitMCXC+oLoSIvZdJTICgGPilVZCsJmvbB187/Cu18n jxGdgSxXPZhXj5cRXTOH+FOBGny2Wzq5TBQxDoUuM62hf+6ue1U82MB7OP/3GfKH qCbNIEbjjtXQ420ato8GJ5kAQhtgdZZZQUFAxIs8LKFbmqD2S7FZyOZT1fsXO9Jk Lf24wmoW8Gqoqv7hWQYPcLXRC2VcER2W2MgVLew7A2EGfk/yWcKEgEWqQzJL9Qzs f7j51kJHMe37Va8zYSlgXTCpud1TNUMWKrhvUrpe211mZhl/vxxjw== Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4e6h8mtsq5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 15:40:20 +0000 (GMT) Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 64KFd5l2031979; Wed, 20 May 2026 15:40:19 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4e73wk801r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 15:40:19 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64KFeFEq28836250 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 May 2026 15:40:15 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6CE6620040; Wed, 20 May 2026 15:40:15 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D9DB320043; Wed, 20 May 2026 15:40:14 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 15:40:14 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Steven Rostedt , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Dylan Hatch , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 14/20] unwind_user: Flexible FP/RA recovery rules Date: Wed, 20 May 2026 17:39:58 +0200 Message-ID: <20260520154004.3845823-15-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: bjb0sOXAnH3JU91njUgX4braTkmoUJrB X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0dd5e5 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=-jr7Rsxdtpxs5_a9E3IA:9 X-Proofpoint-ORIG-GUID: 1_L5HKBB9bos9ctA5fqW-NLNXeDxe97w X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX/CuZ9+mDDKtT f2ZnKPloOuEcfESTT5B7C2kP9j/vkmW+mGu/lXkfZA0JwAtKX0n17AJOLSdFDZ+82AVAUAaycvf ri8c/DdCG84hRhK0NuLSKt4Yn4wjZZAAGCGOp/76Oz069hwNR97x0z6F3sJYvg3Zpq01z/CCSL8 SsY0qT+RCjalTsTwwuLvkJN08NWvnX1nRGwBn6eNfg4wHBS8KqcHsitBbdFe/XQCdghgp/eYo2E mgQ9EJx/uKq60Ra/pAAY2/gDsqEmTdbzDKXftLWRD/U59KHlT/PLHFDMoPkStBfgr8zL94O5wYG M14jtEVvKggdLjWechuy+tw+9AU5mJb3ghneRPJspKWHCN+B1hoZlhnMiQH5AXODhdrMAL9ftS6 YUOnBQOQvMFIdwVUEN9lnsZZEEBe/Md+dKOuxGcndJAkU2wWIyyNFrdE51vDJHGNvbJ5yfs7Vn1 ni5dviHW6zu+Yr//m/w== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" To enable support for SFrame V3 flexible FDEs with a subsequent patch, add support for the following flexible frame pointer (FP) and return address (RA) recovery rules: FP/RA =3D *(CFA + offset) FP/RA =3D register + offset FP/RA =3D *(register + offset) Note that FP/RA recovery rules that use arbitrary register contents are only valid when in the topmost frame, as their contents are otherwise unknown. This also enables unwinding of user space for architectures, such as s390, that may save the frame pointer (FP) and/or return address (RA) in other registers, for instance when in a leaf function. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Define dbg_once(). - unwind_user_get_reg(): Use pr_debug_once() instead of WARN_ON_ONCE() to prevent user-triggered warning/panic. (Sashiko AI) - unwind_user_next_common(): Handle UNWIND_USER_RULE_CFA_OFFSET for RA and FP to use dbg_once() instead of WARN_ON_ONCE() to prevent user- triggered warning/panic. (Sashiko AI) =20 Changes in v14: - Improve comment on why UNWIND_USER_RULE_CFA_OFFSET is not implemented. (Mark Rutland) arch/x86/include/asm/unwind_user.h | 21 +++++++-- include/linux/unwind_user.h | 10 +++++ include/linux/unwind_user_types.h | 23 +++++++++- kernel/unwind/sframe.c | 16 ++++++- kernel/unwind/user.c | 70 +++++++++++++++++++++++++++--- 5 files changed, 125 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwi= nd_user.h index 2dfb5ef11e36..9c3417be4283 100644 --- a/arch/x86/include/asm/unwind_user.h +++ b/arch/x86/include/asm/unwind_user.h @@ -21,15 +21,26 @@ static inline int unwind_user_word_size(struct pt_regs = *regs) =20 #define ARCH_INIT_USER_FP_FRAME(ws) \ .cfa_off =3D 2*(ws), \ - .ra_off =3D -1*(ws), \ - .fp_off =3D -2*(ws), \ + .ra =3D { \ + .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ + .offset =3D -1*(ws), \ + }, \ + .fp =3D { \ + .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ + .offset =3D -2*(ws), \ + }, \ .use_fp =3D true, \ .outermost =3D false, =20 #define ARCH_INIT_USER_FP_ENTRY_FRAME(ws) \ .cfa_off =3D 1*(ws), \ - .ra_off =3D -1*(ws), \ - .fp_off =3D 0, \ + .ra =3D { \ + .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ + .offset =3D -1*(ws), \ + }, \ + .fp =3D { \ + .rule =3D UNWIND_USER_RULE_RETAIN,\ + }, \ .use_fp =3D false, \ .outermost =3D false, =20 @@ -41,4 +52,6 @@ static inline bool unwind_user_at_function_start(struct p= t_regs *regs) =20 #endif /* CONFIG_HAVE_UNWIND_USER_FP */ =20 +#include + #endif /* _ASM_X86_UNWIND_USER_H */ diff --git a/include/linux/unwind_user.h b/include/linux/unwind_user.h index 7bf58f23aa64..6aca38f89ddd 100644 --- a/include/linux/unwind_user.h +++ b/include/linux/unwind_user.h @@ -33,6 +33,16 @@ static inline int unwind_user_get_ra_reg(unsigned long *= val) #define unwind_user_get_ra_reg unwind_user_get_ra_reg #endif =20 +#ifndef unwind_user_get_reg +static inline int unwind_user_get_reg(unsigned long *val, unsigned int reg= num) +{ + pr_debug_once("%s (%d): unwind_user_get_reg(%u) not implemented\n", + current->comm, current->pid, regnum); + return -EINVAL; +} +#define unwind_user_get_reg unwind_user_get_reg +#endif + int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries); =20 #endif /* _LINUX_UNWIND_USER_H */ diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_= types.h index 616cc5ee4586..0d02714a1b5d 100644 --- a/include/linux/unwind_user_types.h +++ b/include/linux/unwind_user_types.h @@ -27,10 +27,29 @@ struct unwind_stacktrace { unsigned long *entries; }; =20 +#define UNWIND_USER_RULE_DEREF BIT(31) + +enum unwind_user_rule { + UNWIND_USER_RULE_RETAIN, /* entity =3D entity */ + UNWIND_USER_RULE_CFA_OFFSET, /* entity =3D CFA + offset */ + UNWIND_USER_RULE_REG_OFFSET, /* entity =3D register + offset */ + /* DEREF variants */ + UNWIND_USER_RULE_CFA_OFFSET_DEREF =3D /* entity =3D *(CFA + offset) */ + UNWIND_USER_RULE_CFA_OFFSET | UNWIND_USER_RULE_DEREF, + UNWIND_USER_RULE_REG_OFFSET_DEREF =3D /* entity =3D *(register + offset) = */ + UNWIND_USER_RULE_REG_OFFSET | UNWIND_USER_RULE_DEREF, +}; + +struct unwind_user_rule_data { + enum unwind_user_rule rule; + s32 offset; + unsigned int regnum; +}; + struct unwind_user_frame { s32 cfa_off; - s32 ra_off; - s32 fp_off; + struct unwind_user_rule_data ra; + struct unwind_user_rule_data fp; bool use_fp; bool outermost; }; diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 4af533e9f980..e82d1dcdd471 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -283,6 +283,18 @@ static __always_inline int __read_fre(struct sframe_se= ction *sec, return -EFAULT; } =20 +static __always_inline void +sframe_init_rule_data(struct unwind_user_rule_data *rule_data, + s32 offset) +{ + if (offset) { + rule_data->rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF; + rule_data->offset =3D offset; + } else { + rule_data->rule =3D UNWIND_USER_RULE_RETAIN; + } +} + static __always_inline int __find_fre(struct sframe_section *sec, struct sframe_fde_internal *fde, unsigned long ip, @@ -333,8 +345,8 @@ static __always_inline int __find_fre(struct sframe_sec= tion *sec, fre =3D prev_fre; =20 frame->cfa_off =3D fre->cfa_off; - frame->ra_off =3D fre->ra_off; - frame->fp_off =3D fre->fp_off; + sframe_init_rule_data(&frame->ra, fre->ra_off); + sframe_init_rule_data(&frame->fp, fre->fp_off); frame->use_fp =3D SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME= _BASE_REG_FP; frame->outermost =3D SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); =20 diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index afa7c6f6d9b4..c6a2abac78e0 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -12,6 +12,17 @@ #include #include =20 +#ifdef CONFIG_DYNAMIC_DEBUG + +#define dbg_once(fmt, ...) \ + pr_debug_once("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + +#else /* !CONFIG_DYNAMIC_DEBUG */ + +#define dbg_once(args...) no_printk(args) + +#endif /* !CONFIG_DYNAMIC_DEBUG */ + #define for_each_user_frame(state) \ for (unwind_user_start(state); !(state)->done; unwind_user_next(state)) =20 @@ -64,22 +75,67 @@ static int unwind_user_next_common(struct unwind_user_s= tate *state, return -EINVAL; =20 /* Get the Return Address (RA) */ - if (frame->ra_off) { - if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) - return -EINVAL; - } else { + switch (frame->ra.rule) { + case UNWIND_USER_RULE_RETAIN: if (!state->topmost || unwind_user_get_ra_reg(&ra)) return -EINVAL; + break; + case UNWIND_USER_RULE_CFA_OFFSET: + /* + * RA =3D CFA + offset does not make sense. + * A return address cannot legitimately be a stack address. + */ + dbg_once("UNWIND_USER_RULE_CFA_OFFSET invalid for RA\n"); + return -EINVAL; + case UNWIND_USER_RULE_CFA_OFFSET_DEREF: + ra =3D cfa + frame->ra.offset; + break; + case UNWIND_USER_RULE_REG_OFFSET: + case UNWIND_USER_RULE_REG_OFFSET_DEREF: + if (!state->topmost || unwind_user_get_reg(&ra, frame->ra.regnum)) + return -EINVAL; + ra +=3D frame->ra.offset; + break; + default: + WARN_ON_ONCE(1); + return -EINVAL; } + if (frame->ra.rule & UNWIND_USER_RULE_DEREF && + get_user_word(&ra, ra, 0, state->ws)) + return -EINVAL; =20 /* Get the Frame Pointer (FP) */ - if (frame->fp_off && get_user_word(&fp, cfa, frame->fp_off, state->ws)) + switch (frame->fp.rule) { + case UNWIND_USER_RULE_RETAIN: + fp =3D state->fp; 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Wed, 20 May 2026 15:40:15 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 15:40:15 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Steven Rostedt , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Dylan Hatch , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 15/20] unwind_user: Flexible CFA recovery rules Date: Wed, 20 May 2026 17:39:59 +0200 Message-ID: <20260520154004.3845823-16-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e6 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=BPVtMwLGy6aXIs-GLTYA:9 X-Proofpoint-ORIG-GUID: Et2AxjJa3Pj5hZ9P6YS9rixUG5u30Bxd X-Proofpoint-GUID: alsWMSSF3RoBq4pWCZzCaW2wyGxtsgZi X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfXwEAaGgncNazS K3O7aDPEFTy0urcJGZvRbU84B2qZOMrJeE0uANav4q0zbAtahuusOYIUnmql7Ripk/CitiGnEEM 3UpbIo3Hg5iScbuVyR0+hUDQ8SE1iWL8l33h5iHaX8KSGUDioLguxV+9ri0dti2JfItyKu6lvp1 BIsk6BJ6HZGHTg+/EPCdf7JFVl714WKiCR/pnIiHjE0agryiBfq3PEffwwSn1d5G87HJ3XW7IS3 CfCu9lAeKw3j6prRmLsH5+NZildLM2zEBlw1Es/faTPnDtfOjIgqU86UgNee/0xz14NAYUmvwEW VRhP3FqLyGwAgB2TirkkpeLHOEnnwAXfkzVmi5xmAuNnPLnXrwiq4xJz25OA/kkd1El9th4pRMB /9yE6zg6n9IeH+QxiSCex7KmPO6qcKvQUPPVEMnH799ThgIHqlQWw7nDuoHVBEsmKhbEIZi7qZW Sq8lKfRbgc50N1t718Q== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" To enable support for SFrame V3 flexible FDEs with a subsequent patch, add support for the following flexible Canonical Frame Address (CFA) recovery rules: CFA =3D SP + offset CFA =3D *(SP + offset) CFA =3D FP + offset CFA =3D *(FP + offset) CFA =3D register + offset CFA =3D *(register + offset) Note that CFA recovery rules that use arbitrary register contents are only valid when in the topmost frame, as their contents are otherwise unknown. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - enum unwind_user_cfa_rule, unwind_user_next_common(): Add support for SP/FP-based CFA recovery rules with dereferencing. (Sashiko AI) arch/x86/include/asm/unwind_user.h | 12 ++++++++---- include/linux/unwind_user_types.h | 22 ++++++++++++++++++++-- kernel/unwind/sframe.c | 15 +++++++++++++-- kernel/unwind/user.c | 24 ++++++++++++++++++++---- 4 files changed, 61 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwi= nd_user.h index 9c3417be4283..f38f7c5ff1de 100644 --- a/arch/x86/include/asm/unwind_user.h +++ b/arch/x86/include/asm/unwind_user.h @@ -20,7 +20,10 @@ static inline int unwind_user_word_size(struct pt_regs *= regs) #ifdef CONFIG_HAVE_UNWIND_USER_FP =20 #define ARCH_INIT_USER_FP_FRAME(ws) \ - .cfa_off =3D 2*(ws), \ + .cfa =3D { \ + .rule =3D UNWIND_USER_CFA_RULE_FP_OFFSET,\ + .offset =3D 2*(ws), \ + }, \ .ra =3D { \ .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ .offset =3D -1*(ws), \ @@ -29,11 +32,13 @@ static inline int unwind_user_word_size(struct pt_regs = *regs) .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ .offset =3D -2*(ws), \ }, \ - .use_fp =3D true, \ .outermost =3D false, =20 #define ARCH_INIT_USER_FP_ENTRY_FRAME(ws) \ - .cfa_off =3D 1*(ws), \ + .cfa =3D { \ + .rule =3D UNWIND_USER_CFA_RULE_SP_OFFSET,\ + .offset =3D 1*(ws), \ + }, \ .ra =3D { \ .rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF,\ .offset =3D -1*(ws), \ @@ -41,7 +46,6 @@ static inline int unwind_user_word_size(struct pt_regs *r= egs) .fp =3D { \ .rule =3D UNWIND_USER_RULE_RETAIN,\ }, \ - .use_fp =3D false, \ .outermost =3D false, =20 static inline bool unwind_user_at_function_start(struct pt_regs *regs) diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_= types.h index 0d02714a1b5d..c18be5b7d586 100644 --- a/include/linux/unwind_user_types.h +++ b/include/linux/unwind_user_types.h @@ -29,6 +29,25 @@ struct unwind_stacktrace { =20 #define UNWIND_USER_RULE_DEREF BIT(31) =20 +enum unwind_user_cfa_rule { + UNWIND_USER_CFA_RULE_SP_OFFSET, /* CFA =3D SP + offset */ + UNWIND_USER_CFA_RULE_FP_OFFSET, /* CFA =3D FP + offset */ + UNWIND_USER_CFA_RULE_REG_OFFSET, /* CFA =3D register + offset */ + /* DEREF variants */ + UNWIND_USER_CFA_RULE_SP_OFFSET_DEREF =3D /* CFA =3D *(SP + offset) */ + UNWIND_USER_CFA_RULE_SP_OFFSET | UNWIND_USER_RULE_DEREF, + UNWIND_USER_CFA_RULE_FP_OFFSET_DEREF =3D /* CFA =3D *(FP + offset) */ + UNWIND_USER_CFA_RULE_FP_OFFSET | UNWIND_USER_RULE_DEREF, + UNWIND_USER_CFA_RULE_REG_OFFSET_DEREF =3D /* CFA =3D *(register + offset)= */ + UNWIND_USER_CFA_RULE_REG_OFFSET | UNWIND_USER_RULE_DEREF, +}; + +struct unwind_user_cfa_rule_data { + enum unwind_user_cfa_rule rule; + s32 offset; + unsigned int regnum; +}; + enum unwind_user_rule { UNWIND_USER_RULE_RETAIN, /* entity =3D entity */ UNWIND_USER_RULE_CFA_OFFSET, /* entity =3D CFA + offset */ @@ -47,10 +66,9 @@ struct unwind_user_rule_data { }; =20 struct unwind_user_frame { - s32 cfa_off; + struct unwind_user_cfa_rule_data cfa; struct unwind_user_rule_data ra; struct unwind_user_rule_data fp; - bool use_fp; bool outermost; }; =20 diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index e82d1dcdd471..6187379750db 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -283,6 +283,18 @@ static __always_inline int __read_fre(struct sframe_se= ction *sec, return -EFAULT; } =20 +static __always_inline void +sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data, + unsigned char fre_info, + s32 offset) +{ + if (SFRAME_V3_FRE_CFA_BASE_REG_ID(fre_info) =3D=3D SFRAME_BASE_REG_FP) + cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_FP_OFFSET; + else + cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_SP_OFFSET; + cfa_rule_data->offset =3D offset; +} + static __always_inline void sframe_init_rule_data(struct unwind_user_rule_data *rule_data, s32 offset) @@ -344,10 +356,9 @@ static __always_inline int __find_fre(struct sframe_se= ction *sec, return -EINVAL; fre =3D prev_fre; =20 - frame->cfa_off =3D fre->cfa_off; + sframe_init_cfa_rule_data(&frame->cfa, fre->info, fre->cfa_off); sframe_init_rule_data(&frame->ra, fre->ra_off); sframe_init_rule_data(&frame->fp, fre->fp_off); - frame->use_fp =3D SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME= _BASE_REG_FP; frame->outermost =3D SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); =20 return 0; diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c index c6a2abac78e0..447061b10613 100644 --- a/kernel/unwind/user.c +++ b/kernel/unwind/user.c @@ -53,14 +53,30 @@ static int unwind_user_next_common(struct unwind_user_s= tate *state, } =20 /* Get the Canonical Frame Address (CFA) */ - if (frame->use_fp) { + switch (frame->cfa.rule) { + case UNWIND_USER_CFA_RULE_SP_OFFSET: + case UNWIND_USER_CFA_RULE_SP_OFFSET_DEREF: + cfa =3D state->sp; + break; + case UNWIND_USER_CFA_RULE_FP_OFFSET: + case UNWIND_USER_CFA_RULE_FP_OFFSET_DEREF: if (state->fp < state->sp) return -EINVAL; cfa =3D state->fp; - } else { - cfa =3D state->sp; + break; + case UNWIND_USER_CFA_RULE_REG_OFFSET: + case UNWIND_USER_CFA_RULE_REG_OFFSET_DEREF: + if (!state->topmost || unwind_user_get_reg(&cfa, frame->cfa.regnum)) + return -EINVAL; + break; + default: + WARN_ON_ONCE(1); + return -EINVAL; } - cfa +=3D frame->cfa_off; + cfa +=3D frame->cfa.offset; + if (frame->cfa.rule & UNWIND_USER_RULE_DEREF && + get_user_word(&cfa, cfa, 0, state->ws)) + return -EINVAL; =20 /* * Make sure that stack is not going in wrong direction. 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 16/20] unwind_user/sframe: Add support for SFrame V3 flexible FDEs Date: Wed, 20 May 2026 17:40:00 +0200 Message-ID: <20260520154004.3845823-17-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e6 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=8hFt8YRx_kKiWWpTwHgA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: 3j54Q3NE8Nkhuecuddh4AHyr2-jan06O X-Proofpoint-GUID: WIcYwToedsDCD7AnHrwCFaNbEA3to4Zc X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX9oMid8pXmCzt s6kc2eyQavKQgPVdi598y+e6PRSRSP5qIXGfQyZVu5k5XfJnmiLmLDmkbnZbbT6K1gdvfkF4gym k2tOtM4qFxuFsX1zZ+ZT0JBT6+RexbXbsHi1NsLzZW9gHy/IIRPupUB/ZxDcVC+KX58mrgMWHcr wkoQHgvUwK6b6LhPyowBpekyemDEls75YOD9D91dP10c2tTVMgCxmruTyblcZgHSuW8Kqco39E3 +z7HxdrXRWa0F+z5dEiT6oLcWI/lB8b6DRQS1Cqo/9O5wgJbtMbqU35hbPHgcPTHRWzgDnLXQU3 7k0PT6/0+xJQvvcW61gHrJ+BK3faZeJWqwea72hYsk33OJlCuUpprGLj551rgWIUhHMFENP0wIp AN5eM54yAPtg3SaNgvgB5lc/gUwPn3bKS1a4wYU9IyQYLEXnqEhGtByzSnYIA4OVE7p80s3Xj1N ptozTOia566RysEqkLw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" SFrame V3 introduces flexible FDEs in addition to the regular FDEs. The key difference is that flexible FDEs encode the CFA, RA, and FP tracking information using two FRE data words, a control word and an offset, or a single padding data word of zero (e.g. to represent FP without RA tracking information). The control word contains the following information: - reg_p: Whether to use the register contents (reg_p=3D1) specified by regnum or the CFA (reg_p=3D0) as base. - deref_p: Whether to dereference. - regnum: A DWARF register number. The offset is added to the base (i.e. CFA or register contents). Then the resulting address may optionally be dereferenced. This enables the following flexible CFA and FP/RA recovery rules: - CFA =3D register + offset // reg_p=3D1, deref_p=3D0 - CFA =3D *(register + offset) // reg_p=3D1, deref_p=3D1 - FP/RA =3D *(CFA + offset) // reg_p=3D0, deref_p=3D0 - FP/RA =3D register + offset // reg_p=3D1, deref_p=3D0 - FP/RA =3D *(register + offset) // reg_p=3D1, deref_p=3D1 Note that for the CFA a rule with reg_p=3D0 is invalid, as the value of the CFA cannot be described using itself as base. For FP/RA a rule with reg_p=3D0 and deref_p=3D0 and regnum=3D0 is invalid, as it that is equal to the padding data word of zero. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - __read_flex_fde_fre_datawords(): Add comment on FRE dataword RA/FP location info decoding logic. (Sashiko AI) - Fix outermost frame (FRE without datawords) handling to not cause sframe_init_cfa_rule_data() and ultimately sframe_find() to fail with -EINVAL. (Sashiko AI) - sframe_init_[cfa_]rule_data(): Reject FRE control word with reserved_p=3D1. (Sashiko AI) - __find_fre(): Return RC of sframe_init_[cfa_]rule_data() if bad RC. - Normalize error code usage (.sframe is removed for all but ENOENT): ENOENT: No sframe or no FDE for IP found (FDE found but no FRE is EINVAL) EFAULT: Bad address EINVAL: Invalid input or sframe =20 Changes in v14: - Rename __read_regular_fre_datawords() to __read_default_fre_datawords() to align to SFrame V3 specification (default FRE). - Rename SFRAME_FDE_TYPE_FLEXIBLE to SFRAME_FDE_TYPE_FLEX to match SFrame V3 specification and adjust to rename of SFRAME_FDE_TYPE_*. - Rename SFRAME_V3_FLEX_FDE_CTLWORD_*() to SFRAME_V3_FLEX_FDE_CTRLWORD_*() to match SFrame V3 reference implementation. - Add arch/*/include/asm/unwind_user_sframe.h to MAINTAINERS. MAINTAINERS | 1 + kernel/unwind/sframe.c | 282 +++++++++++++++++++++++++++++++++-------- kernel/unwind/sframe.h | 6 + 3 files changed, 237 insertions(+), 52 deletions(-) diff --git a/MAINTAINERS b/MAINTAINERS index a9b42b67a88d..25f0b933511c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27875,6 +27875,7 @@ M: Josh Poimboeuf M: Steven Rostedt S: Maintained F: arch/*/include/asm/unwind_user.h +F: arch/*/include/asm/unwind_user_sframe.h F: include/asm-generic/unwind_user.h F: include/linux/sframe.h F: include/linux/unwind*.h diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 6187379750db..48709f0bafc7 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -12,6 +12,7 @@ #include #include #include +#include #include =20 #include "sframe.h" @@ -31,8 +32,11 @@ struct sframe_fde_internal { struct sframe_fre_internal { unsigned int size; u32 ip_off; + u32 cfa_ctl; s32 cfa_off; + u32 ra_ctl; s32 ra_off; + u32 fp_ctl; s32 fp_off; u8 info; }; @@ -200,16 +204,158 @@ static __always_inline int __find_fde(struct sframe_= section *sec, s32 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \ s64 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label)) =20 +static __always_inline int +__read_default_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long cur, + unsigned char dataword_count, + unsigned char dataword_size, + struct sframe_fre_internal *fre) +{ + s32 cfa_off, ra_off, fp_off; + unsigned int cfa_regnum; + + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); + dataword_count--; + + ra_off =3D sec->ra_off; + if (!ra_off && dataword_count) { + dataword_count--; + UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault); + } + + fp_off =3D sec->fp_off; + if (!fp_off && dataword_count) { + dataword_count--; + UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault); + } + + if (dataword_count) + return -EINVAL; + + cfa_regnum =3D + (SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME_BASE_REG_FP) ? + SFRAME_REG_FP : SFRAME_REG_SP; + + fre->cfa_ctl =3D (cfa_regnum << 3) | 1; /* regnum, deref_p=3D0, reg_p=3D1= */ + fre->cfa_off =3D cfa_off; + fre->ra_ctl =3D ra_off ? 2 : 0; /* regnum=3D0, deref_p=3D(ra_off !=3D 0),= reg_p=3D0 */ + fre->ra_off =3D ra_off; + fre->fp_ctl =3D fp_off ? 2 : 0; /* regnum=3D0, deref_p=3D(fp_off !=3D 0),= reg_p=3D0 */ + fre->fp_off =3D fp_off; + + return 0; + +Efault: + return -EFAULT; +} + +static __always_inline int +__read_flex_fde_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long cur, + unsigned char dataword_count, + unsigned char dataword_size, + struct sframe_fre_internal *fre) +{ + u32 cfa_ctl, ra_ctl, fp_ctl; + s32 cfa_off, ra_off, fp_off; + + if (dataword_count < 2) + return -EINVAL; + UNSAFE_GET_USER_INC(cfa_ctl, cur, dataword_size, Efault); + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); + dataword_count -=3D 2; + + /* + * Each RA/FP location info consumes either two datawords + * (control word + offset) or one padding word substituting + * for that pair. Padding is only valid as substitution if + * followed by further non-padding location info. Therefore + * decoding only proceeds with at least two datawords. Any + * leftover trailing datawords are invalid and rejected by + * the final check. + */ + + ra_off =3D sec->ra_off; + ra_ctl =3D ra_off ? 2 : 0; /* regnum=3D0, deref_p=3D(ra_off !=3D 0), reg_= p=3D0 */ + if (dataword_count >=3D 2) { + UNSAFE_GET_USER_INC(ra_ctl, cur, dataword_size, Efault); + dataword_count--; + if (ra_ctl) { + UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault); + dataword_count--; + } else { + /* Padding RA location info */ + ra_ctl =3D ra_off ? 2 : 0; /* re-deduce (see above) */ + } + } + + fp_off =3D sec->fp_off; + fp_ctl =3D fp_off ? 2 : 0; /* regnum=3D0, deref_p=3D(fp_off !=3D 0), reg_= p=3D0 */ + if (dataword_count >=3D 2) { + UNSAFE_GET_USER_INC(fp_ctl, cur, dataword_size, Efault); + dataword_count--; + if (fp_ctl) { + UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault); + dataword_count--; + } else { + /* Padding FP location info */ + fp_ctl =3D fp_off ? 2 : 0; /* re-deduce (see above) */ + } + } + + /* Reject trailing padding or unknown extra datawords */ + if (dataword_count) + return -EINVAL; + + fre->cfa_ctl =3D cfa_ctl; + fre->cfa_off =3D cfa_off; + fre->ra_ctl =3D ra_ctl; + fre->ra_off =3D ra_off; + fre->fp_ctl =3D fp_ctl; + fre->fp_off =3D fp_off; + + return 0; + +Efault: + return -EFAULT; +} + +static __always_inline int +__read_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long cur, + unsigned char dataword_count, + unsigned char dataword_size, + struct sframe_fre_internal *fre) +{ + unsigned char fde_type =3D SFRAME_V3_FDE_TYPE(fde->info2); + + switch (fde_type) { + case SFRAME_FDE_TYPE_DEFAULT: + return __read_default_fre_datawords(sec, fde, cur, + dataword_count, + dataword_size, + fre); + case SFRAME_FDE_TYPE_FLEX: + return __read_flex_fde_fre_datawords(sec, fde, cur, + dataword_count, + dataword_size, + fre); + default: + return -EINVAL; + } +} + static __always_inline int __read_fre(struct sframe_section *sec, struct sframe_fde_internal *fde, unsigned long fre_addr, struct sframe_fre_internal *fre) { - unsigned char fde_type =3D SFRAME_V3_FDE_TYPE(fde->info2); unsigned char fde_pctype =3D SFRAME_V3_FDE_PCTYPE(fde->info); unsigned char fre_type =3D SFRAME_V3_FDE_FRE_TYPE(fde->info); unsigned char dataword_count, dataword_size; - s32 cfa_off, ra_off, fp_off; unsigned long cur =3D fre_addr; unsigned char addr_size; u32 ip_off; @@ -236,75 +382,101 @@ static __always_inline int __read_fre(struct sframe_= section *sec, if (cur + (dataword_count * dataword_size) > sec->fres_end) return -EFAULT; =20 - /* TODO: Support for flexible FDEs not implemented yet. */ - if (fde_type !=3D SFRAME_FDE_TYPE_DEFAULT) - return -EINVAL; + fre->size =3D addr_size + 1 + (dataword_count * dataword_size); + fre->ip_off =3D ip_off; + fre->info =3D info; =20 if (!dataword_count) { /* - * A FRE without data words indicates RA undefined / - * outermost frame. + * A FRE without datawords indicates an outermost + * frame. Zero-initialize CFA, RA, and FP location + * info, except for the CFA control word, so that + * neither sframe_init_cfa_rule_data() nor + * sframe_init_rule_data() fail. */ - cfa_off =3D 0; - ra_off =3D 0; - fp_off =3D 0; - goto done; - } - - UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); - dataword_count--; - - ra_off =3D sec->ra_off; - if (!ra_off && dataword_count) { - dataword_count--; - UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault); - } + fre->cfa_ctl =3D (SFRAME_REG_SP << 3) | 1; /* regnum=3DSP, deref_p=3D0, = reg_p=3D1 */ + fre->cfa_off =3D 0; + fre->ra_ctl =3D 0; + fre->ra_off =3D 0; + fre->fp_ctl =3D 0; + fre->fp_off =3D 0; =20 - fp_off =3D sec->fp_off; - if (!fp_off && dataword_count) { - dataword_count--; - UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault); + return 0; } =20 - if (dataword_count) - return -EINVAL; - -done: - fre->size =3D addr_size + 1 + (dataword_count * dataword_size); - fre->ip_off =3D ip_off; - fre->cfa_off =3D cfa_off; - fre->ra_off =3D ra_off; - fre->fp_off =3D fp_off; - fre->info =3D info; - - return 0; + return __read_fre_datawords(sec, fde, cur, dataword_count, dataword_size,= fre); =20 Efault: return -EFAULT; } =20 -static __always_inline void +static __always_inline int sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data, - unsigned char fre_info, - s32 offset) + u32 ctlword, s32 offset) { - if (SFRAME_V3_FRE_CFA_BASE_REG_ID(fre_info) =3D=3D SFRAME_BASE_REG_FP) - cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_FP_OFFSET; - else + bool deref_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_DEREF_P(ctlword); + bool reg_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_REG_P(ctlword); + bool reserved_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_RESERVED_P(ctlword); + unsigned int regnum =3D SFRAME_V3_FLEX_FDE_CTRLWORD_REGNUM(ctlword); + + if (reserved_p) + return -EINVAL; + + /* CFA recovery rule must be register-based */ + if (!reg_p) + return -EINVAL; + + switch (regnum) { + case SFRAME_REG_SP: cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_SP_OFFSET; + break; + case SFRAME_REG_FP: + cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_FP_OFFSET; + break; + default: + cfa_rule_data->rule =3D UNWIND_USER_CFA_RULE_REG_OFFSET; + cfa_rule_data->regnum =3D regnum; + } + + if (deref_p) + cfa_rule_data->rule |=3D UNWIND_USER_RULE_DEREF; + cfa_rule_data->offset =3D offset; + + return 0; } =20 -static __always_inline void +static __always_inline int sframe_init_rule_data(struct unwind_user_rule_data *rule_data, - s32 offset) + u32 ctlword, s32 offset) { - if (offset) { - rule_data->rule =3D UNWIND_USER_RULE_CFA_OFFSET_DEREF; - rule_data->offset =3D offset; - } else { + bool deref_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_DEREF_P(ctlword); + bool reg_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_REG_P(ctlword); + bool reserved_p =3D SFRAME_V3_FLEX_FDE_CTRLWORD_RESERVED_P(ctlword); + + if (!ctlword && !offset) { rule_data->rule =3D UNWIND_USER_RULE_RETAIN; + return 0; } + + if (reserved_p) + return -EINVAL; + + if (reg_p) { + unsigned int regnum =3D SFRAME_V3_FLEX_FDE_CTRLWORD_REGNUM(ctlword); + + rule_data->rule =3D UNWIND_USER_RULE_REG_OFFSET; + rule_data->regnum =3D regnum; + } else { + rule_data->rule =3D UNWIND_USER_RULE_CFA_OFFSET; + } + + if (deref_p) + rule_data->rule |=3D UNWIND_USER_RULE_DEREF; + + rule_data->offset =3D offset; + + return 0; } =20 static __always_inline int __find_fre(struct sframe_section *sec, @@ -356,9 +528,15 @@ static __always_inline int __find_fre(struct sframe_se= ction *sec, return -EINVAL; fre =3D prev_fre; =20 - sframe_init_cfa_rule_data(&frame->cfa, fre->info, fre->cfa_off); - sframe_init_rule_data(&frame->ra, fre->ra_off); - sframe_init_rule_data(&frame->fp, fre->fp_off); + ret =3D sframe_init_cfa_rule_data(&frame->cfa, fre->cfa_ctl, fre->cfa_off= ); + if (ret) + return ret; + ret =3D sframe_init_rule_data(&frame->ra, fre->ra_ctl, fre->ra_off); + if (ret) + return ret; + ret =3D sframe_init_rule_data(&frame->fp, fre->fp_ctl, fre->fp_off); + if (ret) + return ret; frame->outermost =3D SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); =20 return 0; diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h index ed111fd0d702..1a2528e4b149 100644 --- a/kernel/unwind/sframe.h +++ b/kernel/unwind/sframe.h @@ -66,6 +66,7 @@ struct sframe_fda_v3 { #define SFRAME_V3_AARCH64_FDE_PAUTH_KEY(info) (((info) >> 5) & 0x1) =20 #define SFRAME_FDE_TYPE_DEFAULT 0 +#define SFRAME_FDE_TYPE_FLEX 1 =20 #define SFRAME_V3_FDE_TYPE_MASK 0x1f #define SFRAME_V3_FDE_TYPE(info2) ((info2) & SFRAME_V3_FDE_TYPE_MASK) @@ -79,4 +80,9 @@ struct sframe_fda_v3 { #define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info) (((info) >> 7) & 0x1) #define SFRAME_V3_FRE_RA_UNDEFINED_P(info) (SFRAME_V3_FRE_DATAWORD_COUNT(= info) =3D=3D 0) =20 +#define SFRAME_V3_FLEX_FDE_CTRLWORD_REGNUM(data) (((data) >> 3) & 0x1f) +#define SFRAME_V3_FLEX_FDE_CTRLWORD_RESERVED_P(data) (((data) >> 2) & 0x1) +#define SFRAME_V3_FLEX_FDE_CTRLWORD_DEREF_P(data) (((data) >> 1) & 0x1) +#define SFRAME_V3_FLEX_FDE_CTRLWORD_REG_P(data) ((data) & 0x1) + #endif /* _SFRAME_H */ --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCD863FA5D5; 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 17/20] unwind_user/sframe: Separate reading of FRE from reading of FRE data words Date: Wed, 20 May 2026 17:40:01 +0200 Message-ID: <20260520154004.3845823-18-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX0Trjn55NgIGF nFmj/AwOweeBjV4fx2+U7L9IXxopDOpSf3IMh+f+iQuKqg2g/UFGCEWRJLxq1evIeIipnxL1wD4 WO5Ugye7TwkFmDmUsmSDTv2Px4OEmXuRE9rpQf+8iJuKl0mup4uxrAbeSA5+sTPkIcBUp1EZ5a9 31OyFIv+q+f+IBHE+E7hjXnt41amhLbONtF/nZVwNviCKmT0cNZOR2be22oYgcNXMknU37TSenK oDpmuIEMqKxIBQQDqnAMtSa2HZVcioTqs1mit4BSIlUv7NuGvpEfEean+BqxtdPiNQY3iSMqc9K J8YjX1wmXYo0gFU3qYhnukPCGT+v+MRBuCWAro9c9G2MV5OPUiSdoU2EMUfT49QbFr0/yFw+pQR QE6SvzIzOtrNFpIiyh8o6vmJprL+biT1rHv9eMBwye72Lbeigoh+s/xsiBNoA9SbnGD5eWf4YCZ fux8iZg6Sw96LsdfbUA== X-Proofpoint-GUID: daHlmjUCKwnUU2QR6CcS6CYQF7OeHemo X-Proofpoint-ORIG-GUID: EJZsbENNxJMgg-1nssR3pfk7dgGh3IgB X-Authority-Analysis: v=2.4 cv=aYBRWxot c=1 sm=1 tr=0 ts=6a0dd5e6 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=RXKZOtKmAAAA:8 a=p_lxmaMNnb8s4VerTYQA:9 a=UFF3uGjEBZWolfm0k6KQ:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" __find_fre() performs linear search for a matching SFrame FRE for a given IP. For that purpose it uses __read_fre(), which reads the whole FRE. That is the variable-size FRE structure as well as the trailing variable-length array of variable-size data words. For the search logic to skip over the FRE it would be sufficient to read the variable-size FRE structure only, which includes the count and size of data words. Add fields to struct sframe_fre_internal to store the FRE data word's address, count, and size. Change __read_fre() to read the variable- size FRE structure only and populate those new fields. Change __read_fre_datawords() to use those new fields. Change __find_fre() to use __read_fre_datawords() to read the FRE data words only after a matching FRE has been found. Introduce safe_read_fre_datawords() and use it in sframe_validate_section() to validate that the FRE data words. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - sframe_validate_section(): Fix format specifier for number of FREs in debug message. (Sashiko AI) =20 Changes in v14: - Adjust to rename of SFRAME_FDE_TYPE_* and __read_default_fre_datawords(). - Update function name in debug message. kernel/unwind/sframe.c | 100 ++++++++++++++++++++++++++--------------- 1 file changed, 64 insertions(+), 36 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 48709f0bafc7..ec8318977a2e 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -39,6 +39,9 @@ struct sframe_fre_internal { u32 fp_ctl; s32 fp_off; u8 info; + unsigned long dw_addr; + unsigned char dw_count; + unsigned char dw_size; }; =20 DEFINE_STATIC_SRCU(sframe_srcu); @@ -207,11 +210,11 @@ static __always_inline int __find_fde(struct sframe_s= ection *sec, static __always_inline int __read_default_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { + unsigned char dataword_count =3D fre->dw_count; + unsigned char dataword_size =3D fre->dw_size; + unsigned long cur =3D fre->dw_addr; s32 cfa_off, ra_off, fp_off; unsigned int cfa_regnum; =20 @@ -253,11 +256,11 @@ __read_default_fre_datawords(struct sframe_section *s= ec, static __always_inline int __read_flex_fde_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { + unsigned char dataword_count =3D fre->dw_count; + unsigned char dataword_size =3D fre->dw_size; + unsigned long cur =3D fre->dw_addr; u32 cfa_ctl, ra_ctl, fp_ctl; s32 cfa_off, ra_off, fp_off; =20 @@ -325,24 +328,34 @@ __read_flex_fde_fre_datawords(struct sframe_section *= sec, static __always_inline int __read_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { unsigned char fde_type =3D SFRAME_V3_FDE_TYPE(fde->info2); + unsigned char dataword_count =3D fre->dw_count; + + if (!dataword_count) { + /* + * A FRE without datawords indicates an outermost + * frame. Zero-initialize CFA, RA, and FP location + * info, except for the CFA control word, so that + * neither sframe_init_cfa_rule_data() nor + * sframe_init_rule_data() fail. + */ + fre->cfa_ctl =3D (SFRAME_REG_SP << 3) | 1; /* regnum=3DSP, deref_p=3D0, = reg_p=3D1 */ + fre->cfa_off =3D 0; + fre->ra_ctl =3D 0; + fre->ra_off =3D 0; + fre->fp_ctl =3D 0; + fre->fp_off =3D 0; + + return 0; + } =20 switch (fde_type) { case SFRAME_FDE_TYPE_DEFAULT: - return __read_default_fre_datawords(sec, fde, cur, - dataword_count, - dataword_size, - fre); + return __read_default_fre_datawords(sec, fde, fre); case SFRAME_FDE_TYPE_FLEX: - return __read_flex_fde_fre_datawords(sec, fde, cur, - dataword_count, - dataword_size, - fre); + return __read_flex_fde_fre_datawords(sec, fde, fre); default: return -EINVAL; } @@ -385,26 +398,11 @@ static __always_inline int __read_fre(struct sframe_s= ection *sec, fre->size =3D addr_size + 1 + (dataword_count * dataword_size); fre->ip_off =3D ip_off; fre->info =3D info; + fre->dw_addr =3D cur; + fre->dw_count =3D dataword_count; + fre->dw_size =3D dataword_size; =20 - if (!dataword_count) { - /* - * A FRE without datawords indicates an outermost - * frame. Zero-initialize CFA, RA, and FP location - * info, except for the CFA control word, so that - * neither sframe_init_cfa_rule_data() nor - * sframe_init_rule_data() fail. - */ - fre->cfa_ctl =3D (SFRAME_REG_SP << 3) | 1; /* regnum=3DSP, deref_p=3D0, = reg_p=3D1 */ - fre->cfa_off =3D 0; - fre->ra_ctl =3D 0; - fre->ra_off =3D 0; - fre->fp_ctl =3D 0; - fre->fp_off =3D 0; - - return 0; - } - - return __read_fre_datawords(sec, fde, cur, dataword_count, dataword_size,= fre); + return 0; =20 Efault: return -EFAULT; @@ -491,6 +489,7 @@ static __always_inline int __find_fre(struct sframe_sec= tion *sec, bool which =3D false; unsigned int i; u32 ip_off; + int ret; =20 ip_off =3D ip - fde->func_addr; =20 @@ -528,6 +527,10 @@ static __always_inline int __find_fre(struct sframe_se= ction *sec, return -EINVAL; fre =3D prev_fre; =20 + ret =3D __read_fre_datawords(sec, fde, fre); + if (ret) + return ret; + ret =3D sframe_init_cfa_rule_data(&frame->cfa, fre->cfa_ctl, fre->cfa_off= ); if (ret) return ret; @@ -611,6 +614,20 @@ static int safe_read_fre(struct sframe_section *sec, return ret; } =20 +static int safe_read_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + struct sframe_fre_internal *fre) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret =3D __read_fre_datawords(sec, fde, fre); + user_read_access_end(); + return ret; +} + static int sframe_validate_section(struct sframe_section *sec) { unsigned long prev_ip =3D 0; @@ -656,6 +673,17 @@ static int sframe_validate_section(struct sframe_secti= on *sec) fde.rep_size); return ret; } + ret =3D safe_read_fre_datawords(sec, &fde, fre); + if (ret) { + dbg_sec("FDE %u: safe_read_fre_datawords(%u) failed\n", i, j); + dbg_sec("FDE: func_addr:%#lx func_size:%#x fda_off:%#x fres_off:%#x fr= es_num:%u info:%u info2:%u rep_size:%u\n", + fde.func_addr, fde.func_size, + fde.fda_off, + fde.fres_off, fde.fres_num, + fde.info, fde.info2, + fde.rep_size); 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 18/20] unwind_user/sframe: Duplicate registered .sframe section data on clone/fork Date: Wed, 20 May 2026 17:40:02 +0200 Message-ID: <20260520154004.3845823-19-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfXzDf0BBVwHN8H OeYMoeWwylZgdLIw/zdKsHPEr0h8qkx6aYfbKMNVY9M4EMtgIL7FrGt/O8Naku/9q0paeWVFdT4 gTsgm4xKJrGYSMlt0O2RDqFlmAUBKrEsCB1AxRjVb2EvoJ2E9H0YcTI+wp9lFMafcrpr0kZmm+5 2ydSK8BuLe5n5lKwwDWKM2PPlEx8YzqBbcsyc8jVx/Qhw6RKIVi7RcqOxVA1aK9voiJwsqlaTPj jk5RhH3M9d6K/Yf9SrOe5RMg2N8S3TLy7o6W/7o62UTeiW2fgCgm2TmTU3Qndx3jJ7cDxoBUTeI +zogwZ3kW8aNY9XginzO89ilwIE7sHIiAc/mYrLI3FcSmuijRjUw2MHdlGPqRe56gV6LwYFCP3a UrC+ER0nKFYbe6vXYBtEQpvek90hqt4hoMEZXida0H8Erda/xzhjqn7rAjEn4dvzVZcsg+j/76v 9Jvx3aYknaAT05uHjeA== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0dd5e6 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=H1ImvsCuyUzGZUZlsssA:9 X-Proofpoint-ORIG-GUID: 0v1vB95jkJXiZWaV3My4cqKvh1HEwtRJ X-Proofpoint-GUID: eDqNSvCepqPb2rATY0Fc-wAC4b6k_woA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" When duplicating a process' virtual memory mappings also duplicate all of its registered .sframe sections stored in the per-mm maple tree to enable stacktracing using sframe of the child process. Signed-off-by: Jens Remus --- include/linux/sframe.h | 5 ++++ kernel/unwind/sframe.c | 48 ++++++++++++++++++++++++++++++++++++ kernel/unwind/sframe_debug.h | 7 ++++++ mm/mmap.c | 9 +++++++ 4 files changed, 69 insertions(+) diff --git a/include/linux/sframe.h b/include/linux/sframe.h index b79c5ec09229..91889b4fe3dd 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -28,6 +28,7 @@ struct sframe_section { }; =20 #define INIT_MM_SFRAME .sframe_mt =3D MTREE_INIT(sframe_mt, 0), +extern int sframe_dup_mm(struct mm_struct *mm, struct mm_struct *oldmm); extern void sframe_free_mm(struct mm_struct *mm); =20 extern int sframe_add_section(unsigned long sframe_start, unsigned long sf= rame_end, @@ -45,6 +46,10 @@ static inline bool current_has_sframe(void) #else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */ =20 #define INIT_MM_SFRAME +static inline int sframe_dup_mm(struct mm_struct *mm, struct mm_struct *ol= dmm) +{ + return 0; +} static inline void sframe_free_mm(struct mm_struct *mm) {} static inline int sframe_add_section(unsigned long sframe_start, unsigned = long sframe_end, unsigned long text_start, unsigned long text_end) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index ec8318977a2e..0661090dd5bc 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -886,6 +886,54 @@ int sframe_remove_section(unsigned long sframe_start) return 0; } =20 +static void __sframe_dup_section(struct sframe_section *sec, struct sframe= _section *oldsec) +{ + sec->sframe_start =3D oldsec->sframe_start; + sec->sframe_end =3D oldsec->sframe_end; + sec->text_start =3D oldsec->text_start; + sec->text_end =3D oldsec->text_end; + + sec->fdes_start =3D oldsec->fdes_start; + sec->fres_start =3D oldsec->fres_start; + sec->fres_end =3D oldsec->fres_end; + sec->num_fdes =3D oldsec->num_fdes; + + sec->ra_off =3D oldsec->ra_off; + sec->fp_off =3D oldsec->fp_off; + + dbg_dup(sec, oldsec); +} + +int sframe_dup_mm(struct mm_struct *mm, struct mm_struct *oldmm) +{ + struct sframe_section *sec, *oldsec; + unsigned long index =3D 0; + int ret; + + guard(srcu)(&sframe_srcu); + + mt_for_each(&oldmm->sframe_mt, oldsec, index, ULONG_MAX) { + sec =3D kzalloc(sizeof(*sec), GFP_KERNEL_ACCOUNT); + if (!sec) + return -ENOMEM; + + __sframe_dup_section(sec, oldsec); + + ret =3D mtree_insert_range(&mm->sframe_mt, + sec->text_start, + sec->text_end - 1, + sec, GFP_KERNEL_ACCOUNT); + if (ret) + goto err_free; + } + + return 0; + +err_free: + free_section(sec); + return ret; +} + void sframe_free_mm(struct mm_struct *mm) { struct sframe_section *sec; diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h index a63e75cccc70..2503972155e8 100644 --- a/kernel/unwind/sframe_debug.h +++ b/kernel/unwind/sframe_debug.h @@ -48,6 +48,12 @@ static inline void dbg_init(struct sframe_section *sec) sec->filename =3D kstrdup("(anonymous)", GFP_KERNEL_ACCOUNT); } =20 +static inline void dbg_dup(struct sframe_section *sec, struct sframe_secti= on *oldsec) +{ + if (oldsec->filename) + sec->filename =3D kstrdup(oldsec->filename, GFP_KERNEL_ACCOUNT); +} + static inline void dbg_free(struct sframe_section *sec) { kfree(sec->filename); @@ -61,6 +67,7 @@ static inline void dbg_free(struct sframe_section *sec) static inline void dbg_print_header(struct sframe_section *sec) {} =20 static inline void dbg_init(struct sframe_section *sec) {} +static inline void dbg_dup(struct sframe_section *sec, struct sframe_secti= on *oldsec) {} static inline void dbg_free(struct sframe_section *sec) {} =20 #endif /* !CONFIG_DYNAMIC_DEBUG */ diff --git a/mm/mmap.c b/mm/mmap.c index 5754d1c36462..250e8bea73ef 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -48,6 +48,7 @@ #include #include #include +#include =20 #include #include @@ -1846,6 +1847,11 @@ __latent_entropy int dup_mmap(struct mm_struct *mm, = struct mm_struct *oldmm) } /* a new mm has just been created */ retval =3D arch_dup_mmap(oldmm, mm); +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + if (!retval) { + retval =3D sframe_dup_mm(mm, oldmm); + } +#endif loop_out: vma_iter_free(&vmi); if (!retval) { @@ -1893,6 +1899,9 @@ __latent_entropy int dup_mmap(struct mm_struct *mm, s= truct mm_struct *oldmm) vm_unacct_memory(charge); } __mt_destroy(&mm->mm_mt); +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + sframe_free_mm(mm); +#endif /* * The mm_struct is going to exit, but the locks will be dropped * first. 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 19/20] unwind_user/sframe/x86: Enable sframe unwinding on x86 Date: Wed, 20 May 2026 17:40:03 +0200 Message-ID: <20260520154004.3845823-20-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX1ynlGov/rsON ONpIgpdK/avkbTb7ZZZvkfzF6YGwh4OQEO1iP4y0mzix3CRsnkfAe4OxJsWfeTkyal6ZBnSGZds PHvbCTPIjXa1A74yNjXEftL/S6ji6anH1FY2m44uaCHmXJgsDSzr/AzjReP2/vFtbaSDJQ2Ib0I 6Yk2WS6y77HwI59arU7bm2tsbOqHjqNhC1EmtLfelw08L5yun8E4M8MzAjBH2xoP4rmV4mKJzBC G4A9/y0TxBAXxZY9MtVuHcpLV29baPqcp+dUmpl4GGAmHKSIES6xTcip4N5bbWmjWge6oNRMtra NgcyF2WJLE/d8xjWezuKz+PlP+t1Hk2tBmC+0Ewjyae8g7rPnTKH2co8xCPH5bBRlE5xEM7Jd3L UVKc7ERzeHawHQemetQmdAjDxxeY7Ly9oEb3zo6El4/ksr8OO6c8iQSUnnJkilvFHfLCNk+p47W YhSFMsigHLvtK7lPNOQ== X-Proofpoint-GUID: MY3deY7T0eQoBbntI9zjLIpcrmO-vjbB X-Proofpoint-ORIG-GUID: xgx2UBI6tlWlIKVb1qHEiuYVnXS55moD X-Authority-Analysis: v=2.4 cv=aYBRWxot c=1 sm=1 tr=0 ts=6a0dd5e7 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=BJDwMle8H-fvePKCLUUA:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf The x86 SFrame V3 implementation works fairly well, starting with binutils 2.46. Enable it. [ Jens Remus: Reword commit message for SFrame V3, starting with binutils 2.46. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - unwind_user_get_reg(): Fail if !user_64bit_mode(). (Sashiko AI) - unwind_user_get_reg(): Simplify guarding using CONFIG_X86_64. - unwind_user_get_reg(): Add pr_debug_once() if unsupported register number. =20 Changes in v14: - Drop superfluous empty line in unwind_user_get_reg(). =20 Changes in v13: - Naive implementation of unwind_user_get_reg() to support SFrame V3 flexible FDEs (e.g. used to represent DRAP pattern). - Define SFRAME_REG_SP and SFRAME_REG_FP to the respective x86-64 DWARF register numbers. - Reword commit message for SFrame V3 and (upcoming) binutils 2.46. arch/x86/Kconfig | 1 + arch/x86/include/asm/unwind_user.h | 39 +++++++++++++++++++++++ arch/x86/include/asm/unwind_user_sframe.h | 12 +++++++ 3 files changed, 52 insertions(+) create mode 100644 arch/x86/include/asm/unwind_user_sframe.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f3f7cb01d69d..51286dfdb5f4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -302,6 +302,7 @@ config X86 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_UNWIND_USER_FP if X86_64 + select HAVE_UNWIND_USER_SFRAME if X86_64 select HAVE_USER_RETURN_NOTIFIER select HAVE_GENERIC_VDSO select VDSO_GETRANDOM if X86_64 diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwi= nd_user.h index f38f7c5ff1de..942475235431 100644 --- a/arch/x86/include/asm/unwind_user.h +++ b/arch/x86/include/asm/unwind_user.h @@ -15,6 +15,45 @@ static inline int unwind_user_word_size(struct pt_regs *= regs) return user_64bit_mode(regs) ? 8 : 4; } =20 +#ifdef CONFIG_X86_64 + +static inline int unwind_user_get_reg(unsigned long *val, unsigned int reg= num) +{ + struct pt_regs *regs =3D task_pt_regs(current); + + /* SFrame only supports x86-64 */ + if (!user_64bit_mode(regs)) + return -EINVAL; + + switch (regnum) { + /* DWARF register numbers 0..15 */ + case 0: *val =3D regs->ax; break; + case 1: *val =3D regs->dx; break; + case 2: *val =3D regs->cx; break; + case 3: *val =3D regs->bx; break; + case 4: *val =3D regs->si; break; + case 5: *val =3D regs->di; break; + case 6: *val =3D regs->bp; break; + case 7: *val =3D regs->sp; break; + case 8: *val =3D regs->r8; break; + case 9: *val =3D regs->r9; break; + case 10: *val =3D regs->r10; break; + case 11: *val =3D regs->r11; break; + case 12: *val =3D regs->r12; break; + case 13: *val =3D regs->r13; break; + case 14: *val =3D regs->r14; break; + case 15: *val =3D regs->r15; break; + default: + pr_debug_once("%s (%d): unwind_user_get_reg(%u): unsupported register nu= mber\n", + current->comm, current->pid, regnum); + return -EINVAL; + } + return 0; +} +#define unwind_user_get_reg unwind_user_get_reg + +#endif /* CONFIG_X86_64 */ + #endif /* CONFIG_UNWIND_USER */ =20 #ifdef CONFIG_HAVE_UNWIND_USER_FP diff --git a/arch/x86/include/asm/unwind_user_sframe.h b/arch/x86/include/a= sm/unwind_user_sframe.h new file mode 100644 index 000000000000..d828ae1a4aac --- /dev/null +++ b/arch/x86/include/asm/unwind_user_sframe.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_UNWIND_USER_SFRAME_H +#define _ASM_X86_UNWIND_USER_SFRAME_H + +#ifdef CONFIG_X86_64 + +#define SFRAME_REG_SP 7 +#define SFRAME_REG_FP 6 + +#endif + +#endif /* _ASM_X86_UNWIND_USER_SFRAME_H */ --=20 2.51.0 From nobody Sun May 24 22:35:58 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 24B563F1AC4; Wed, 20 May 2026 15:40:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v15 20/20] unwind_user/sframe: Add prctl() interface for registering .sframe sections Date: Wed, 20 May 2026 17:40:04 +0200 Message-ID: <20260520154004.3845823-21-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 8r4Jt1uPtErt-p80F5ARJZjJU30LBmBj X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0dd5e9 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=1RKwvADtGVyjO38rMG4A:9 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-ORIG-GUID: mjXy61-ALNHMmMxx1WsbOKx6Ph1jwlyl X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX7JfboGGTW41p XDOHgShkDe/wpP2e0PXh/NeE07prsJJAQtbcvDgJyFfh9ORKY5ctpBKa2GImqvsb9BYX5Dl2UIR a4z+hPRnfb/25tSVVzV7q0B0Zo5KueRA+o4cj4/8Ri4EjiZb2yn3b0crinZq6oyxEGekYO3EpyD AtuzEFqyxlPLN5JV1hKeQEoMg+NVORfXB3r48SrqSDP98MsS2lpFo5RO0xNrVDM59A+nteFTCdL 61ePrUsjdAvXBdF1KhjqMmkg6xevbS+QCNe7i0l783bK4UdiO33kWAdgJApHPCTUW+3wuldkoLU 1HF45OQ3oVZVlQxt2VgsbQcEtw8NhxAVwVMmWMYRLUDm8KJfZTDN8qtnXGRFWI33/3jRHMf0iCK C2jnFU5OYUV3TSe+j7H5ha6VxxTjJONsKyIqF9V7BcHraBzEFTcAgtZs0GZpITxPmNJFhVRniC3 3pK4cj/XcPfSGNQhRfg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 Content-Type: text/plain; charset="utf-8" From: Josh Poimboeuf The kernel doesn't have direct visibility to the ELF contents of shared libraries. Add some prctl() interfaces which allow glibc to tell the kernel where to find .sframe sections. [ This adds an interface for prctl() for testing loading of sframes for libraries. But this interface should really be a system call. This patch is for testing purposes only and should not be applied to mainline. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - Fix rebase error (missing break). (Sashiko AI) =20 Changes in v14: - Bump PR_ADD_SFRAME and PR_REMOVE_SFRAME. include/uapi/linux/prctl.h | 4 ++++ kernel/sys.c | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index b6ec6f693719..bd0bf828b033 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -416,4 +416,8 @@ struct prctl_mm_map { # define PR_CFI_DISABLE _BITUL(1) # define PR_CFI_LOCK _BITUL(2) =20 +/* SFRAME management */ +#define PR_ADD_SFRAME 82 +#define PR_REMOVE_SFRAME 83 + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index 62e842055cc9..b0a9b1e3ccd7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -65,6 +65,7 @@ #include #include #include +#include =20 #include =20 @@ -2907,6 +2908,14 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, a= rg2, unsigned long, arg3, if (arg3 & PR_CFI_LOCK && !(arg3 & PR_CFI_DISABLE)) error =3D arch_prctl_lock_branch_landing_pad_state(me); break; + case PR_ADD_SFRAME: + error =3D sframe_add_section(arg2, arg3, arg4, arg5); + break; + case PR_REMOVE_SFRAME: + if (arg3 || arg4 || arg5) + return -EINVAL; + error =3D sframe_remove_section(arg2); + break; default: trace_task_prctl_unknown(option, arg2, arg3, arg4, arg5); error =3D -EINVAL; --=20 2.51.0