• Sasha Levin's avatar
    decode_stacktrace: make stack dump output useful again · dbd1abb2
    Sasha Levin authored
    Right now when people try to report issues in the kernel they send stack
    dumps to eachother, which looks something like this:
    
      [    6.906437]  [<ffffffff811f0e90>] ? backtrace_test_irq_callback+0x20/0x20
      [    6.907121]  [<ffffffff84388ce8>] dump_stack+0x52/0x7f
      [    6.907640]  [<ffffffff811f0ec8>] backtrace_regression_test+0x38/0x110
      [    6.908281]  [<ffffffff813596a0>] ? proc_create_data+0xa0/0xd0
      [    6.908870]  [<ffffffff870a8040>] ? proc_modules_init+0x22/0x22
      [    6.909480]  [<ffffffff810020c2>] do_one_initcall+0xc2/0x1e0
      [...]
    
    However, most of the text you get is pure garbage.
    
    The only useful thing above is the function name.  Due to the amount of
    different kernel code versions and various configurations being used,
    the kernel address and the offset into the function are not really
    helpful in determining where the problem actually occured.
    
    Too often the result of someone looking at a stack dump is asking the
    person who sent it for a translation for one or more 'addr2line'
    translations.  Which slows down the entire process of debugging the
    issue (and really annoying).
    
    The decode_stacktrace script is an attempt to make the output more
    useful and easy to work with by translating all kernel addresses in the
    stack dump into line numbers.  Which means that the stack dump would
    look like this:
    
      [  635.148361]  dump_stack (lib/dump_stack.c:52)
      [  635.149127]  warn_slowpath_common (kernel/panic.c:418)
      [  635.150214]  warn_slowpath_null (kernel/panic.c:453)
      [  635.151031]  _oalloc_pages_slowpath+0x6a/0x7d0
      [  635.152171]  ? zone_watermark_ok (mm/page_alloc.c:1728)
      [  635.152988]  ? get_page_from_freelist (mm/page_alloc.c:1939)
      [  635.154766]  __alloc_pages_nodemask (mm/page_alloc.c:2766)
    
    It's pretty obvious why this is better than the previous stack dump
    before.
    
    Usage is pretty simple:
    
            ./decode_stacktrace.sh [vmlinux] [base path]
    
    Where vmlinux is the vmlinux to extract line numbers from and base path
    is the path that points to the root of the build tree, for example:
    
            ./decode_stacktrace.sh vmlinux /home/sasha/linux/ < input.log > output.log
    
    The stack trace should be piped through it (I, for example, just pipe
    the output of the serial console of my KVM test box through it).
    Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    dbd1abb2
decode_stacktrace.sh 3.01 KB