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 X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76067C433E1 for ; Mon, 22 Mar 2021 06:44:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 540F861973 for ; Mon, 22 Mar 2021 06:44:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230321AbhCVGny (ORCPT ); Mon, 22 Mar 2021 02:43:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:56766 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230114AbhCVGnV (ORCPT ); Mon, 22 Mar 2021 02:43:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 05BF46196B; Mon, 22 Mar 2021 06:43:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616395401; bh=uS1REgY1mW0kHpi28LD+bK8aSrj7nNHm5BFG/jnr5K0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=S+Bh3JvlKuyMlfUvmsXAUEYHxmx/3fGeFUqBtDuNKu6GBwktJLen7+ZLLPNnjpx78 GzGwxKsxDHvIEU1Wxzcq6SeDKR7NU5hEpWVoX3DrnblC17cdYnhGHU2ZnzeOGFvu4S FZXvlwfBQZUllpYY/9yD2ux6GK/oFl5QvIQ18ig3QzgUR0uFPYR41hbS6d452dyPjt J/UVlGkpyOZnVAeEiMIaJen6dYnoTKOA+eSVzTlqqZkaVtfPTs3OoQbgVc5POtg+py uBjHTvZiehnQxvEmW8jmuUJrj1s/aJeUFs6fIZ3eDDue1ANr6QUv4p04haU3maeryI s37Y0UKOR/W3w== Date: Mon, 22 Mar 2021 15:43:16 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Cc: Steven Rostedt , Ingo Molnar , X86 ML , Daniel Xu , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kuba@kernel.org, mingo@redhat.com, ast@kernel.org, tglx@linutronix.de, kernel-team@fb.com, yhs@fb.com, Josh Poimboeuf , linux-ia64@vger.kernel.org Subject: Re: [PATCH -tip v3 00/12] kprobes: Fix stacktrace with kretprobes on x86 Message-Id: <20210322154316.df024040e26c7027fae3c8d9@kernel.org> In-Reply-To: <161639500599.894584.799900058200543646.stgit@devnote2> References: <161639500599.894584.799900058200543646.stgit@devnote2> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oops, please ignore this. I missed updating the version. Thanks, On Mon, 22 Mar 2021 15:36:46 +0900 Masami Hiramatsu wrote: > Hello, > > Here is the 4th version of the series to fix the stacktrace with kretprobe > on x86. After merging this, I'll fix other architectures. > > The previous version is; > > https://lore.kernel.org/bpf/161615650355.306069.17260992641363840330.stgit@devnote2/ > > This version fixes some build warnings/errors and a bug on arm. (I think > arm's kretprobe implementation is a bit odd. anyway, that is off topic.) > [5/12] fixes objtool warning when CONFIG_FRAME_POINTER=y. [7/12] fixes a > build error on ia64. And add [8/12] for avoiding stack corruption by > instruction_pointer_set() in kretprobe_trampoline_handler on arm. > > With this series, unwinder can unwind stack correctly from ftrace as below; > > # cd /sys/kernel/debug/tracing > # echo > trace > # echo r vfs_read >> kprobe_events > # echo r full_proxy_read >> kprobe_events > # echo traceoff:1 > events/kprobes/r_vfs_read_0/trigger > # echo stacktrace:1 > events/kprobes/r_full_proxy_read_0/trigger > # echo 1 > events/kprobes/enable > # echo 1 > options/sym-offset > # cat /sys/kernel/debug/kprobes/list > ffffffff8133b740 r full_proxy_read+0x0 [FTRACE] > ffffffff812560b0 r vfs_read+0x0 [FTRACE] > # echo 0 > events/kprobes/enable > # cat trace > # tracer: nop > # > # entries-in-buffer/entries-written: 3/3 #P:8 > # > # _-----=> irqs-off > # / _----=> need-resched > # | / _---=> hardirq/softirq > # || / _--=> preempt-depth > # ||| / delay > # TASK-PID CPU# |||| TIMESTAMP FUNCTION > # | | | |||| | | > <...>-135 [005] ...1 9.422114: r_full_proxy_read_0: (vfs_read+0xab/0x1a0 <- full_proxy_read) > <...>-135 [005] ...1 9.422158: > => kretprobe_trace_func+0x209/0x2f0 > => kretprobe_dispatcher+0x4a/0x70 > => __kretprobe_trampoline_handler+0xca/0x150 > => trampoline_handler+0x44/0x70 > => kretprobe_trampoline+0x2a/0x50 > => vfs_read+0xab/0x1a0 > => ksys_read+0x5f/0xe0 > => do_syscall_64+0x33/0x40 > => entry_SYSCALL_64_after_hwframe+0x44/0xae > => 0 > > This shows the double return probes (vfs_read and full_proxy_read) on the stack > correctly unwinded. (vfs_read was called from ksys_read+0x5f and full_proxy_read > was called from vfs_read+0xab) > > This actually changes the kretprobe behavisor a bit, now the instraction pointer in > the pt_regs passed to kretprobe user handler is correctly set the real return > address. So user handlers can get it via instruction_pointer() API. > > You can also get this series from > git://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git kprobes/kretprobe-stackfix-v4 > > > Thank you, > > --- > > Josh Poimboeuf (1): > x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline code > > Masami Hiramatsu (11): > ia64: kprobes: Fix to pass correct trampoline address to the handler > kprobes: treewide: Replace arch_deref_entry_point() with dereference_function_descriptor() > kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() > kprobes: Add kretprobe_find_ret_addr() for searching return address > ARC: Add instruction_pointer_set() API > ia64: Add instruction_pointer_set() API > arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline > kprobes: Setup instruction pointer in __kretprobe_trampoline_handler > x86/kprobes: Push a fake return address at kretprobe_trampoline > x86/unwind: Recover kretprobe trampoline entry > tracing: Show kretprobe unknown indicator only for kretprobe_trampoline > > > arch/arc/include/asm/ptrace.h | 5 ++ > arch/arc/kernel/kprobes.c | 2 - > arch/arm/probes/kprobes/core.c | 5 +- > arch/arm64/kernel/probes/kprobes.c | 3 - > arch/csky/kernel/probes/kprobes.c | 2 - > arch/ia64/include/asm/ptrace.h | 5 ++ > arch/ia64/kernel/kprobes.c | 15 ++--- > arch/mips/kernel/kprobes.c | 3 - > arch/parisc/kernel/kprobes.c | 4 + > arch/powerpc/kernel/kprobes.c | 13 ----- > arch/riscv/kernel/probes/kprobes.c | 2 - > arch/s390/kernel/kprobes.c | 2 - > arch/sh/kernel/kprobes.c | 2 - > arch/sparc/kernel/kprobes.c | 2 - > arch/x86/include/asm/kprobes.h | 1 > arch/x86/include/asm/unwind.h | 17 ++++++ > arch/x86/include/asm/unwind_hints.h | 5 ++ > arch/x86/kernel/kprobes/core.c | 44 ++++++++++++---- > arch/x86/kernel/unwind_frame.c | 4 + > arch/x86/kernel/unwind_guess.c | 3 - > arch/x86/kernel/unwind_orc.c | 6 +- > include/linux/kprobes.h | 41 ++++++++++++-- > kernel/kprobes.c | 99 ++++++++++++++++++++++++----------- > kernel/trace/trace_output.c | 17 +----- > lib/error-inject.c | 3 + > 25 files changed, 200 insertions(+), 105 deletions(-) > > -- > Masami Hiramatsu (Linaro) -- Masami Hiramatsu