3 Commits

Author SHA1 Message Date
Tiezhu Yang
370a3b8f58 LoongArch: Check unwind_error() in arch_stack_walk()
We can see the following messages with CONFIG_PROVE_LOCKING=y on
LoongArch:

  BUG: MAX_STACK_TRACE_ENTRIES too low!
  turning off the locking correctness validator.

This is because stack_trace_save() returns a big value after call
arch_stack_walk(), here is the call trace:

  save_trace()
    stack_trace_save()
      arch_stack_walk()
        stack_trace_consume_entry()

arch_stack_walk() should return immediately if unwind_next_frame()
failed, no need to do the useless loops to increase the value of c->len
in stack_trace_consume_entry(), then we can fix the above problem.

Cc: stable@vger.kernel.org
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/all/8a44ad71-68d2-4926-892f-72bfc7a67e2a@roeck-us.net/
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-04-19 12:07:27 +08:00
Qing Zhang
4d7bf939df LoongArch: Add USER_STACKTRACE support
To get the best stacktrace output, you can compile your userspace
programs with frame pointers (at least glibc + the app you are tracing).

1, export "CC = gcc -fno-omit-frame-pointer";
2, compile your programs with "CC";
3, use uprobe to get stacktrace output.

...
     echo 'p:malloc /usr/lib64/libc.so.6:0x0a4704 size=%r4:u64' > uprobe_events
     echo 'p:free /usr/lib64/libc.so.6:0x0a4d50 ptr=%r4:x64' >> uprobe_events
     echo 'comm == "demo"' > ./events/uprobes/malloc/filter
     echo 'comm == "demo"' > ./events/uprobes/free/filter
     echo 1 > ./options/userstacktrace
     echo 1 > ./options/sym-userobj
...

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-08-12 13:10:11 +08:00
Qing Zhang
93a4fa622e LoongArch: Add STACKTRACE support
1. Use common arch_stack_walk() infrastructure to avoid duplicated code
   and avoid taking care of the stack storage and filtering.
2. Add sched_ra (means sched return address) and sched_cfa (means sched
   call frame address) to thread_info, and store them in switch_to().
3. Add __get_wchan() implementation.

Now we can print the process stack and wait channel by cat /proc/*/stack
and /proc/*/wchan.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-08-12 13:10:11 +08:00