From mboxrd@z Thu Jan 1 00:00:00 1970 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 AE093EEB568 for ; Fri, 8 Sep 2023 18:04:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343559AbjIHSEm (ORCPT ); Fri, 8 Sep 2023 14:04:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343557AbjIHSEl (ORCPT ); Fri, 8 Sep 2023 14:04:41 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E03D61FE4; Fri, 8 Sep 2023 11:04:13 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 364E7C116A3; Fri, 8 Sep 2023 18:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1694196252; bh=e9weMesk8QdrOasbyYzFhtGZrpedZ3ADoEH6cSti4MI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DP0O2PzdJTRV6g+zWHCpUUNyEwbIvvwl4560WRbjU1Nt8D72pd+hVA9tqcNubTKAy fTBPTaH8ePiESHXBPpZ6X3cmK3Xn23mIlXNfRkXHvYWWW/AayFOzKArgAVsap16qF6 zp5fztcHb0icEmuN4cWbkyqT4WHwL/dsGbAKh5DW6jf1BpIsFnA/XYMcIEuqTTznRQ ZzK2kg5wSUlmKYQomL2Ot3qwQhi73Z+SnrfG1Qgy4laCEQw0Z7ZILlVJazO5y7vV4t LUmZgK4OkPoisFKd2dRyoC0pybNOUX6m0n2BOQ0z+UBj7SvgCRtrdXDqO6JMxWWXQu 4tvlYXcAbnMGA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Tomislav Novak , Samuel Gosselin , Catalin Marinas , Alexei Starovoitov , Will Deacon , Sasha Levin , mark.rutland@arm.com, linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 5/5] hw_breakpoint: fix single-stepping when using bpf_overflow_handler Date: Fri, 8 Sep 2023 14:03:51 -0400 Message-Id: <20230908180352.3458731-5-sashal@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230908180352.3458731-1-sashal@kernel.org> References: <20230908180352.3458731-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.256 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org From: Tomislav Novak [ Upstream commit d11a69873d9a7435fe6a48531e165ab80a8b1221 ] 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-tnovak@fb.com/ Link: https://lore.kernel.org/r/20230605191923.1219974-1-tnovak@meta.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- 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_breakpoint.c index b06d9ea07c846..a69dd64a84017 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -623,7 +623,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, hw->address &= ~alignment_mask; hw->ctrl.len <<= offset; - if (is_default_overflow_handler(bp)) { + if (uses_default_overflow_handler(bp)) { /* * Mismatch breakpoints are required for single-stepping * breakpoints. @@ -795,7 +795,7 @@ static void watchpoint_handler(unsigned long addr, unsigned 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)); @@ -808,7 +808,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, info->trigger = addr; pr_debug("watchpoint fired: address = 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)); } @@ -883,7 +883,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) info->trigger = addr; pr_debug("breakpoint fired: address = 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_breakpoint.c index b4a1607958246..534578eba556e 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, unsigned int esr, perf_bp_event(bp, regs); /* Do we need to handle the stepping? */ - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) step = 1; unlock: rcu_read_unlock(); @@ -733,7 +733,7 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val, static int watchpoint_report(struct perf_event *wp, unsigned long addr, struct pt_regs *regs) { - int step = is_default_overflow_handler(wp); + int step = uses_default_overflow_handler(wp); struct arch_hw_breakpoint *info = counter_arch_bp(wp); info->trigger = addr; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index b7ac395513c0f..c99e2f851d312 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1018,15 +1018,31 @@ extern int perf_event_output(struct perf_event *event, struct pt_regs *regs); 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 == perf_event_output_forward)) + if (likely(overflow_handler == perf_event_output_forward)) return true; - if (unlikely(event->overflow_handler == perf_event_output_backward)) + if (unlikely(overflow_handler == perf_event_output_backward)) return true; return false; } +#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, -- 2.40.1