[Crash-utility] given a makedumpfile processed coredump, generate a symbolic backtrace containing the same info as a standard gdb backtrace

[Cody P Schafer]

On 09/10/2013 08:38 AM, Hammond, John wrote:
>
> I had partial success at a crash extension that used DWARF debuginfo to display a symbolic backtrace. You can find it at https://github.com/jhammond/xbt.
>

I noticed that when searching for a solution, but hadn't tried it until 
seeing this email.
After trying it, the xbt appears incorrect: it traces through some 
functions not shown by bt and only has 6 frames vs bt's 22.

I've pasted the output below:
----

crash> bt
PID: 12982  TASK: ffff8803c50b6100  CPU: 0   COMMAND: "flush-9:100"
  #0 [ffff8803df6714c0] machine_kexec at ffffffff81027a50
  #1 [ffff8803df671520] crash_kexec at ffffffff81088ffd
  #2 [ffff8803df6715f0] oops_end at ffffffff810074d0
  #3 [ffff8803df671620] no_context at ffffffff8102e983
  #4 [ffff8803df671670] __bad_area_nosemaphore at ffffffff8102ec05
  #5 [ffff8803df6716c0] bad_area_nosemaphore at ffffffff8102ecce
  #6 [ffff8803df6716d0] do_page_fault at ffffffff8102f1c8
  #7 [ffff8803df6717e0] page_fault at ffffffff813be61f
     [exception RIP: __bio_add_page+264]
     RIP: ffffffff8114b818  RSP: ffff8803df671890  RFLAGS: 00010246
     RAX: 0000000000040000  RBX: 0000000000000000  RCX: 0000000000000002
     RDX: 0000000000000000  RSI: ffff880467e1df20  RDI: ffff88046c07fa00
     RBP: ffff880300000001   R8: 0000000000000001   R9: 0000000000000000
     R10: 0000000000000008  R11: 0000000000000001  R12: ffff880400000000
     R13: 0000000000001000  R14: ffffea000d425170  R15: 0000000000000000
     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  #8 [ffff8803df6718f8] bio_add_page at ffffffff8114b971
  #9 [ffff8803df671908] __mpage_writepage at ffffffff81150840
#10 [ffff8803df671a58] write_cache_pages at ffffffff810d6c09
#11 [ffff8803df671b88] mpage_writepages at ffffffff81150dd9
#12 [ffff8803df671bc8] _nzt_writepages at ffffffffa0183280 [nztmpfs]
#13 [ffff8803df671bd8] do_writepages at ffffffff810d6f4c
#14 [ffff8803df671be8] writeback_single_inode at ffffffff8113f5e9
#15 [ffff8803df671c28] writeback_sb_inodes at ffffffff8113ff18
#16 [ffff8803df671c88] writeback_inodes_wb at ffffffff8114062a
#17 [ffff8803df671cd8] wb_writeback at ffffffff811409db
#18 [ffff8803df671dd8] wb_do_writeback at ffffffff81140c03
#19 [ffff8803df671e68] bdi_writeback_task at ffffffff81140ddb
#20 [ffff8803df671eb8] bdi_start_fn at ffffffff810e5571
#21 [ffff8803df671ee8] kthread at ffffffff8106a24e
#22 [ffff8803df671f48] kernel_thread at ffffffff81003d1a
crash> xbt
#0
	mod NONE, name schedule, RIP 0xffffffff813bb56c
	frame start 0xffff8803df671d80, end 0xffff8803df671d88, *base 
0000000000000000
	&prev = ffff8803df671c80
	prev = ffff8803df671cd0 ...
	&next = ffff8803df671c78
[... trimmed ...]
	&next = ffff8803df671c78
	next = ffff8803df671d20 ...
	&prev = ffff8803df671c80
	prev = ffff8803df671cd0 ...

#1
	mod NONE, name thread_return, RIP 0xffffffff813bb5aa
	frame start 0xffff8803df671d88, end 0xffff8803df671dd8, *base 
0xffff8803df671e60
	&prev = ffff8803df671cd0
	prev = ffff8803df671dd0 ...
[... trimmed ...]
	&prev = ffff8803df671cd0
	prev = ffff8803df671dd0 ...

#2
	mod NONE, name wb_do_writeback, RIP 0xffffffff81140c03
	frame start 0xffff8803df671dd8, end 0xffff8803df671e68, *base 
0xffff8803df671eb0
	&force_wait = ffff8803df671dec
	force_wait = ffff8803 ...
	&work = ffff8803df671df8
	work = ffff88045f6f97d8 ...

#3
	mod NONE, name bdi_writeback_task, RIP 0xffffffff81140ddb
	frame start 0xffff8803df671e68, end 0xffff8803df671eb8, *base 
0xffff8803df671ee0
	XBT_R12 = ffff88045f6f9760
	XBT_R13 = ffff8803c50b6100
	XBT_R14 = 10001ee46
	XBT_R15 = 124f8
	wb = ffff88045f6f9760
	last_active = 10001ee46

#4
	mod NONE, name bdi_start_fn, RIP 0xffffffff810e5571
	frame start 0xffff8803df671eb8, end 0xffff8803df671ee8, *base 
0xffff8803df671f40
	XBT_R12 = ffff88045f6f9760
	XBT_R13 = ffffffff810e54f0
	XBT_R14 = ffff88045f6f97c0
	XBT_R15 = ffff88046e4a9840
	ptr = ffff88045f6f9760
	wb = ffff88045f6f9760

#5
	mod NONE, name kthread, RIP 0xffffffff8106a24e
	frame start 0xffff8803df671ee8, end 0xffff8803df671f48, *base 
0xffff88046e4b5f40
	XBT_R12 = ffffffff810e5571
	&self = ffff8803df671ee8
	self = ffffffff8106a24e ...
	x = ffff8803df671ef0

#6
	mod NONE, name kernel_thread, RIP 0xffffffff81003d1a
	frame start 0xffff8803df671f48, end 0xffff8803df671f48, *base 
0xffff88046e4b5f40