From nobody Sun Feb 8 12:31:21 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 90E50C7EE24 for ; Mon, 5 Jun 2023 19:21:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235743AbjFETVK (ORCPT ); Mon, 5 Jun 2023 15:21:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235649AbjFETU4 (ORCPT ); Mon, 5 Jun 2023 15:20:56 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12143E49 for ; Mon, 5 Jun 2023 12:20:42 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 355H9Nkj016762 for ; Mon, 5 Jun 2023 12:20:41 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : content-type : content-transfer-encoding : mime-version; s=s2048-2021-q4; bh=Jst2Lp+guze+PlobngIdDpSIritglNJll7WtUVF7Ztc=; b=ZzYdNmfzlN68a21AEWXResS+uoM0vqu62MVw4h6fyL4kXafwgTICa/sQxawnsXepf5+t jWvu8rwLfL2QXHK6UTOyJ4aq6MBKpWg/vX19NRCjlqQhSWZOR44Lyuy/2k6FIXqnpWyR 9ST7djVUxLn8rSAwtQQ5yAQt1E37/o9kxr5JFU82X1hv/KbegavThu+zwA9v4Trrcj+k bz+nJ9AfxHNZPJ1T5PlzOJx2+EO+Tyoh857OxAM/HB6GlO3yVhXdLeEbJwSK4jG/VP1G xAIsdxUaYofBxFJZcac3oJHLIpXcsLFCa2a18NtL54cTTYC6nldIpyasE8HuIDy+iIn1 /A== Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3r1fxsu0ke-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 05 Jun 2023 12:20:41 -0700 Received: from twshared4466.29.prn2.facebook.com (2620:10d:c0a8:1b::2d) by mail.thefacebook.com (2620:10d:c0a8:83::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Mon, 5 Jun 2023 12:20:40 -0700 Received: by devbig863.prn1.facebook.com (Postfix, from userid 2982) id 55AC573CC1DC; Mon, 5 Jun 2023 12:20:29 -0700 (PDT) From: Tomislav Novak To: Catalin Marinas CC: Alexei Starovoitov , Will Deacon , Mark Rutland , Russell King , , , Tomislav Novak , Samuel Gosselin Subject: [PATCH v2] hw_breakpoint: fix single-stepping when using bpf_overflow_handler Date: Mon, 5 Jun 2023 12:19:23 -0700 Message-ID: <20230605191923.1219974-1-tnovak@meta.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: X-FB-Internal: Safe X-Proofpoint-GUID: vYfw4KwpKXJgeAb4lP4uMlXCBeQ-VZZk X-Proofpoint-ORIG-GUID: vYfw4KwpKXJgeAb4lP4uMlXCBeQ-VZZk Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26 definitions=2023-06-05_31,2023-06-02_02,2023-05-22_02 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Arm platforms use is_default_overflow_handler() to determine if the hw_breakpoint code should single-step over the breakpoint trigger or let the custom handler deal with it. Since bpf_overflow_handler() currently isn't recognized as a default handler, attaching a BPF program to a PERF_TYPE_BREAKPOINT event causes it to keep firing (the instruction triggering the data abort exception is never skipped). For example: # bpftrace -e 'watchpoint:0x10000:4:w { print("hit") }' -c ./test Attaching 1 probe... hit hit [...] ^C (./test performs a single 4-byte store to 0x10000) This patch replaces the check with uses_default_overflow_handler(), which accounts for the bpf_overflow_handler() case by also testing if one of the perf_event_output functions gets invoked indirectly, via orig_default_handler. Signed-off-by: Tomislav Novak Tested-by: Samuel Gosselin # arm64 Reviewed-by: Catalin Marinas Acked-by: Alexei Starovoitov Link: https://lore.kernel.org/linux-arm-kernel/20220923203644.2731604-1-tno= vak@fb.com/ --- arch/arm/kernel/hw_breakpoint.c | 8 ++++---- arch/arm64/kernel/hw_breakpoint.c | 4 ++-- include/linux/perf_event.h | 22 +++++++++++++++++++--- 3 files changed, 25 insertions(+), 9 deletions(-) diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoin= t.c index 054e9199f30d..dc0fb7a81371 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -626,7 +626,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, hw->address &=3D ~alignment_mask; hw->ctrl.len <<=3D offset; =20 - if (is_default_overflow_handler(bp)) { + if (uses_default_overflow_handler(bp)) { /* * Mismatch breakpoints are required for single-stepping * breakpoints. @@ -798,7 +798,7 @@ static void watchpoint_handler(unsigned long addr, unsi= gned int fsr, * Otherwise, insert a temporary mismatch breakpoint so that * we can single-step over the watchpoint trigger. */ - if (!is_default_overflow_handler(wp)) + if (!uses_default_overflow_handler(wp)) continue; step: enable_single_step(wp, instruction_pointer(regs)); @@ -811,7 +811,7 @@ static void watchpoint_handler(unsigned long addr, unsi= gned int fsr, info->trigger =3D addr; pr_debug("watchpoint fired: address =3D 0x%x\n", info->trigger); perf_bp_event(wp, regs); - if (is_default_overflow_handler(wp)) + if (uses_default_overflow_handler(wp)) enable_single_step(wp, instruction_pointer(regs)); } =20 @@ -886,7 +886,7 @@ static void breakpoint_handler(unsigned long unknown, s= truct pt_regs *regs) info->trigger =3D addr; pr_debug("breakpoint fired: address =3D 0x%x\n", addr); perf_bp_event(bp, regs); - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) enable_single_step(bp, addr); goto unlock; } diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_break= point.c index b29a311bb055..9659a9555c63 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -654,7 +654,7 @@ static int breakpoint_handler(unsigned long unused, uns= igned long esr, perf_bp_event(bp, regs); =20 /* Do we need to handle the stepping? */ - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) step =3D 1; unlock: rcu_read_unlock(); @@ -733,7 +733,7 @@ static u64 get_distance_from_watchpoint(unsigned long a= ddr, u64 val, static int watchpoint_report(struct perf_event *wp, unsigned long addr, struct pt_regs *regs) { - int step =3D is_default_overflow_handler(wp); + int step =3D uses_default_overflow_handler(wp); struct arch_hw_breakpoint *info =3D counter_arch_bp(wp); =20 info->trigger =3D addr; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d5628a7b5eaa..079e7e7c6428 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1305,15 +1305,31 @@ extern int perf_event_output(struct perf_event *eve= nt, struct pt_regs *regs); =20 static inline bool -is_default_overflow_handler(struct perf_event *event) +__is_default_overflow_handler(perf_overflow_handler_t overflow_handler) { - if (likely(event->overflow_handler =3D=3D perf_event_output_forward)) + if (likely(overflow_handler =3D=3D perf_event_output_forward)) return true; - if (unlikely(event->overflow_handler =3D=3D perf_event_output_backward)) + if (unlikely(overflow_handler =3D=3D perf_event_output_backward)) return true; return false; } =20 +#define is_default_overflow_handler(event) \ + __is_default_overflow_handler((event)->overflow_handler) + +#ifdef CONFIG_BPF_SYSCALL +static inline bool uses_default_overflow_handler(struct perf_event *event) +{ + if (likely(is_default_overflow_handler(event))) + return true; + + return __is_default_overflow_handler(event->orig_overflow_handler); +} +#else +#define uses_default_overflow_handler(event) \ + is_default_overflow_handler(event) +#endif + extern void perf_event_header__init_id(struct perf_event_header *header, struct perf_sample_data *data, --=20 2.34.1