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arm64: stacktrace: avoid listing stacktrace functions in stacktrace

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The stacktraces always begin as follows:

  [<c00117b4>] save_stack_trace_tsk+0x0/0x98
  [<c0011870>] 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 3683f44c42 ("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 <guptap@codeaurora.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Prakash Gupta 2017-09-13 16:28:32 -07:00 committed by Linus Torvalds
parent 0ee931c4e3
commit bb53c820c5
1 changed files with 13 additions and 5 deletions
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18
arch/arm64/kernel/stacktrace.c
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@ -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