From: madvenka@linux.microsoft.com To: mark.rutland@arm.com, broonie@kernel.org, jpoimboe@redhat.com, ardb@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [PATCH v11 1/5] arm64: Call stack_backtrace() only from within walk_stackframe() Date: Tue, 23 Nov 2021 13:37:19 -0600 [thread overview] Message-ID: <20211123193723.12112-2-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20211123193723.12112-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> Currently, arch_stack_walk() calls start_backtrace() and walk_stackframe() separately. There is no need to do that. Instead, call start_backtrace() from within walk_stackframe(). In other words, walk_stackframe() is the only unwind function a consumer needs to call. Currently, the only consumer is arch_stack_walk(). In the future, arch_stack_walk_reliable() will be another consumer. Currently, there is a check for a NULL task in unwind_frame(). It is not needed since all current consumers pass a non-NULL task. Use struct stackframe only within the unwind functions. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- arch/arm64/kernel/stacktrace.c | 41 ++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 0fb58fed54cb..7217c4f63ef7 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -69,9 +69,6 @@ static int notrace unwind_frame(struct task_struct *tsk, unsigned long fp = frame->fp; struct stack_info info; - if (!tsk) - tsk = current; - /* Final frame; nothing to unwind */ if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) return -ENOENT; @@ -143,15 +140,19 @@ static int notrace unwind_frame(struct task_struct *tsk, NOKPROBE_SYMBOL(unwind_frame); static void notrace walk_stackframe(struct task_struct *tsk, - struct stackframe *frame, + unsigned long fp, unsigned long pc, bool (*fn)(void *, unsigned long), void *data) { + struct stackframe frame; + + start_backtrace(&frame, fp, pc); + while (1) { int ret; - if (!fn(data, frame->pc)) + if (!fn(data, frame.pc)) break; - ret = unwind_frame(tsk, frame); + ret = unwind_frame(tsk, &frame); if (ret < 0) break; } @@ -195,17 +196,19 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, struct task_struct *task, struct pt_regs *regs) { - struct stackframe frame; - - if (regs) - start_backtrace(&frame, regs->regs[29], regs->pc); - else if (task == current) - start_backtrace(&frame, - (unsigned long)__builtin_frame_address(1), - (unsigned long)__builtin_return_address(0)); - else - start_backtrace(&frame, thread_saved_fp(task), - thread_saved_pc(task)); - - walk_stackframe(task, &frame, consume_entry, cookie); + unsigned long fp, pc; + + if (regs) { + fp = regs->regs[29]; + pc = regs->pc; + } else if (task == current) { + /* Skip arch_stack_walk() in the stack trace. */ + fp = (unsigned long)__builtin_frame_address(1); + pc = (unsigned long)__builtin_return_address(0); + } else { + /* Caller guarantees that the task is not running. */ + fp = thread_saved_fp(task); + pc = thread_saved_pc(task); + } + walk_stackframe(task, fp, pc, consume_entry, cookie); } -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: madvenka@linux.microsoft.com To: mark.rutland@arm.com, broonie@kernel.org, jpoimboe@redhat.com, ardb@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [PATCH v11 1/5] arm64: Call stack_backtrace() only from within walk_stackframe() Date: Tue, 23 Nov 2021 13:37:19 -0600 [thread overview] Message-ID: <20211123193723.12112-2-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20211123193723.12112-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> Currently, arch_stack_walk() calls start_backtrace() and walk_stackframe() separately. There is no need to do that. Instead, call start_backtrace() from within walk_stackframe(). In other words, walk_stackframe() is the only unwind function a consumer needs to call. Currently, the only consumer is arch_stack_walk(). In the future, arch_stack_walk_reliable() will be another consumer. Currently, there is a check for a NULL task in unwind_frame(). It is not needed since all current consumers pass a non-NULL task. Use struct stackframe only within the unwind functions. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- arch/arm64/kernel/stacktrace.c | 41 ++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 0fb58fed54cb..7217c4f63ef7 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -69,9 +69,6 @@ static int notrace unwind_frame(struct task_struct *tsk, unsigned long fp = frame->fp; struct stack_info info; - if (!tsk) - tsk = current; - /* Final frame; nothing to unwind */ if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) return -ENOENT; @@ -143,15 +140,19 @@ static int notrace unwind_frame(struct task_struct *tsk, NOKPROBE_SYMBOL(unwind_frame); static void notrace walk_stackframe(struct task_struct *tsk, - struct stackframe *frame, + unsigned long fp, unsigned long pc, bool (*fn)(void *, unsigned long), void *data) { + struct stackframe frame; + + start_backtrace(&frame, fp, pc); + while (1) { int ret; - if (!fn(data, frame->pc)) + if (!fn(data, frame.pc)) break; - ret = unwind_frame(tsk, frame); + ret = unwind_frame(tsk, &frame); if (ret < 0) break; } @@ -195,17 +196,19 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, struct task_struct *task, struct pt_regs *regs) { - struct stackframe frame; - - if (regs) - start_backtrace(&frame, regs->regs[29], regs->pc); - else if (task == current) - start_backtrace(&frame, - (unsigned long)__builtin_frame_address(1), - (unsigned long)__builtin_return_address(0)); - else - start_backtrace(&frame, thread_saved_fp(task), - thread_saved_pc(task)); - - walk_stackframe(task, &frame, consume_entry, cookie); + unsigned long fp, pc; + + if (regs) { + fp = regs->regs[29]; + pc = regs->pc; + } else if (task == current) { + /* Skip arch_stack_walk() in the stack trace. */ + fp = (unsigned long)__builtin_frame_address(1); + pc = (unsigned long)__builtin_return_address(0); + } else { + /* Caller guarantees that the task is not running. */ + fp = thread_saved_fp(task); + pc = thread_saved_pc(task); + } + walk_stackframe(task, fp, pc, consume_entry, cookie); } -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-11-23 19:37 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <8b861784d85a21a9bf08598938c11aff1b1249b9> 2021-11-23 19:37 ` [PATCH v11 0/5] arm64: Reorganize the unwinder and implement stack trace reliability checks madvenka 2021-11-23 19:37 ` madvenka 2021-11-23 19:37 ` madvenka [this message] 2021-11-23 19:37 ` [PATCH v11 1/5] arm64: Call stack_backtrace() only from within walk_stackframe() madvenka 2021-11-25 13:48 ` Mark Brown 2021-11-25 13:48 ` Mark Brown 2021-11-30 15:05 ` Mark Rutland 2021-11-30 15:05 ` Mark Rutland 2021-11-30 17:13 ` Madhavan T. Venkataraman 2021-11-30 17:13 ` Madhavan T. Venkataraman 2021-11-30 18:29 ` Mark Rutland 2021-11-30 18:29 ` Mark Rutland 2021-11-30 20:29 ` Madhavan T. Venkataraman 2021-11-30 20:29 ` Madhavan T. Venkataraman 2021-12-10 4:13 ` Madhavan T. Venkataraman 2021-12-10 4:13 ` Madhavan T. Venkataraman 2021-11-23 19:37 ` [PATCH v11 2/5] arm64: Rename unwinder functions madvenka 2021-11-23 19:37 ` madvenka 2021-11-24 17:10 ` Mark Brown 2021-11-24 17:10 ` Mark Brown 2021-11-30 15:08 ` Mark Rutland 2021-11-30 15:08 ` Mark Rutland 2021-11-30 17:15 ` Madhavan T. Venkataraman 2021-11-30 17:15 ` Madhavan T. Venkataraman 2021-11-23 19:37 ` [PATCH v11 3/5] arm64: Make the unwind loop in unwind() similar to other architectures madvenka 2021-11-23 19:37 ` madvenka 2021-11-25 14:30 ` Mark Brown 2021-11-25 14:30 ` Mark Brown 2021-11-23 19:37 ` [PATCH v11 4/5] arm64: Introduce stack trace reliability checks in the unwinder madvenka 2021-11-23 19:37 ` madvenka 2021-11-25 14:56 ` Mark Brown 2021-11-25 14:56 ` Mark Brown 2021-11-25 16:59 ` Madhavan T. Venkataraman 2021-11-25 16:59 ` Madhavan T. Venkataraman 2021-11-26 13:29 ` Mark Brown 2021-11-26 13:29 ` Mark Brown 2021-11-26 17:23 ` Madhavan T. Venkataraman 2021-11-26 17:23 ` Madhavan T. Venkataraman 2021-11-23 19:37 ` [PATCH v11 5/5] arm64: Create a list of SYM_CODE functions, check return PC against list madvenka 2021-11-23 19:37 ` madvenka 2021-11-25 15:05 ` Mark Brown 2021-11-25 15:05 ` Mark Brown
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