From nobody Thu Apr 2 19:49:06 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E186C6FA82 for ; Wed, 21 Sep 2022 19:38:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230101AbiIUTiT (ORCPT ); Wed, 21 Sep 2022 15:38:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229935AbiIUTiE (ORCPT ); Wed, 21 Sep 2022 15:38:04 -0400 Received: from barracuda.ebox.ca (barracuda.ebox.ca [96.127.255.19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48CBD9E693 for ; Wed, 21 Sep 2022 12:38:02 -0700 (PDT) X-ASG-Debug-ID: 1663788303-0c856e13fd3500a0001-xx1T2L Received: from smtp.ebox.ca (smtp.ebox.ca [96.127.255.82]) by barracuda.ebox.ca with ESMTP id vKxaDsCJ59XdehvH (version=TLSv1 cipher=AES128-SHA bits=128 verify=NO); Wed, 21 Sep 2022 15:25:03 -0400 (EDT) X-Barracuda-Envelope-From: mathieu.desnoyers@efficios.com X-Barracuda-RBL-Trusted-Forwarder: 96.127.255.82 Received: from localhost.localdomain (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by smtp.ebox.ca (Postfix) with ESMTP id 4B86D441D64; Wed, 21 Sep 2022 15:25:03 -0400 (EDT) From: Mathieu Desnoyers X-Barracuda-RBL-IP: 192.222.180.24 X-Barracuda-Effective-Source-IP: 192-222-180-24.qc.cable.ebox.net[192.222.180.24] X-Barracuda-Apparent-Source-IP: 192.222.180.24 To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "Paul E . 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Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, Christian Brauner , Florian Weimer , David.Laight@ACULAB.COM, carlos@redhat.com, Peter Oskolkov , Alexander Mikhalitsyn , Mathieu Desnoyers Subject: [RFC PATCH v4 01/25] rseq: Introduce feature size and alignment ELF auxiliary vector entries Date: Wed, 21 Sep 2022 15:24:30 -0400 X-ASG-Orig-Subj: [RFC PATCH v4 01/25] rseq: Introduce feature size and alignment ELF auxiliary vector entries Message-Id: <20220921192454.231662-2-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220921192454.231662-1-mathieu.desnoyers@efficios.com> References: <20220921192454.231662-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Barracuda-Connect: smtp.ebox.ca[96.127.255.82] X-Barracuda-Start-Time: 1663788303 X-Barracuda-Encrypted: AES128-SHA X-Barracuda-URL: https://96.127.255.19:443/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at ebox.ca X-Barracuda-Scan-Msg-Size: 2197 X-Barracuda-BRTS-Status: 1 X-Barracuda-Spam-Score: 0.50 X-Barracuda-Spam-Status: No, SCORE=0.50 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=5.0 tests=BSF_RULE7568M X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.100943 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 0.50 BSF_RULE7568M Custom Rule 7568M Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Export the rseq feature size supported by the kernel as well as the required allocation alignment for the rseq per-thread area to user-space through ELF auxiliary vector entries. This is part of the extensible rseq ABI. Signed-off-by: Mathieu Desnoyers --- fs/binfmt_elf.c | 5 +++++ include/uapi/linux/auxvec.h | 2 ++ include/uapi/linux/rseq.h | 5 +++++ 3 files changed, 12 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 63c7ebb0da89..04fca1e4cbd2 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include =20 @@ -288,6 +289,10 @@ create_elf_tables(struct linux_binprm *bprm, const str= uct elfhdr *exec, if (bprm->have_execfd) { NEW_AUX_ENT(AT_EXECFD, bprm->execfd); } +#ifdef CONFIG_RSEQ + NEW_AUX_ENT(AT_RSEQ_FEATURE_SIZE, offsetof(struct rseq, end)); + NEW_AUX_ENT(AT_RSEQ_ALIGN, __alignof__(struct rseq)); +#endif #undef NEW_AUX_ENT /* AT_NULL is zero; clear the rest too */ memset(elf_info, 0, (char *)mm->saved_auxv + diff --git a/include/uapi/linux/auxvec.h b/include/uapi/linux/auxvec.h index c7e502bf5a6f..6991c4b8ab18 100644 --- a/include/uapi/linux/auxvec.h +++ b/include/uapi/linux/auxvec.h @@ -30,6 +30,8 @@ * differ from AT_PLATFORM. */ #define AT_RANDOM 25 /* address of 16 random bytes */ #define AT_HWCAP2 26 /* extension of AT_HWCAP */ +#define AT_RSEQ_FEATURE_SIZE 27 /* rseq supported feature size */ +#define AT_RSEQ_ALIGN 28 /* rseq allocation alignment */ =20 #define AT_EXECFN 31 /* filename of program */ =20 diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index 77ee207623a9..05d3c4cdeb40 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -130,6 +130,11 @@ struct rseq { * this thread. */ __u32 flags; + + /* + * Flexible array member at end of structure, after last feature field. + */ + char end[]; } __attribute__((aligned(4 * sizeof(__u64)))); =20 #endif /* _UAPI_LINUX_RSEQ_H */ --=20 2.25.1