From bb53c820c5b0f1a52804e32683aa7874db27392d Mon Sep 17 00:00:00 2001 From: Prakash Gupta Date: Wed, 13 Sep 2017 16:28:32 -0700 Subject: [PATCH] arm64: stacktrace: avoid listing stacktrace functions in stacktrace The stacktraces always begin as follows: [] save_stack_trace_tsk+0x0/0x98 [] save_stack_trace+0x24/0x28 ... This is because the stack trace code includes the stack frames for itself. This is incorrect behaviour, and also leads to "skip" doing the wrong thing (which is the number of stack frames to avoid recording.) Perversely, it does the right thing when passed a non-current thread. Fix this by ensuring that we have a known constant number of frames above the main stack trace function, and always skip these. This was fixed for arch arm by commit 3683f44c42e9 ("ARM: stacktrace: avoid listing stacktrace functions in stacktrace") Link: http://lkml.kernel.org/r/1504078343-28754-1-git-send-email-guptap@codeaurora.org Signed-off-by: Prakash Gupta Cc: Russell King Cc: Michal Hocko Cc: Vlastimil Babka Cc: Will Deacon Cc: Catalin Marinas Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm64/kernel/stacktrace.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 3144584..76809cc 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -140,7 +140,8 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) trace->entries[trace->nr_entries++] = ULONG_MAX; } -void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +static noinline void __save_stack_trace(struct task_struct *tsk, + struct stack_trace *trace, unsigned int nosched) { struct stack_trace_data data; struct stackframe frame; @@ -150,15 +151,16 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) data.trace = trace; data.skip = trace->skip; + data.no_sched_functions = nosched; if (tsk != current) { - data.no_sched_functions = 1; frame.fp = thread_saved_fp(tsk); frame.pc = thread_saved_pc(tsk); } else { - data.no_sched_functions = 0; + /* We don't want this function nor the caller */ + data.skip += 2; frame.fp = (unsigned long)__builtin_frame_address(0); - frame.pc = (unsigned long)save_stack_trace_tsk; + frame.pc = (unsigned long)__save_stack_trace; } #ifdef CONFIG_FUNCTION_GRAPH_TRACER frame.graph = tsk->curr_ret_stack; @@ -172,9 +174,15 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +{ + __save_stack_trace(tsk, trace, 1); +} + void save_stack_trace(struct stack_trace *trace) { - save_stack_trace_tsk(current, trace); + __save_stack_trace(current, trace, 0); } + EXPORT_SYMBOL_GPL(save_stack_trace); #endif -- 2.7.4