Impact: better dumpstack output
I noticed in my crash dumps and even in the stack tracer that a
lot of functions listed in the stack trace are simply
return_to_handler which is ftrace graphs way to insert its own
call into the return of a function.
But we lose out where the actually function was called from.
This patch adds in hooks to the dumpstack mechanism that detects
this and finds the real function to print. Both are printed to
let the user know that a hook is still in place.
This does give a funny side effect in the stack tracer output:
Depth Size Location (80 entries)
----- ---- --------
0) 4144 48 save_stack_trace+0x2f/0x4d
1) 4096 128 ftrace_call+0x5/0x2b
2) 3968 16 mempool_alloc_slab+0x16/0x18
3) 3952 384 return_to_handler+0x0/0x73
4) 3568 -240 stack_trace_call+0x11d/0x209
5) 3808 144 return_to_handler+0x0/0x73
6) 3664 -128 mempool_alloc+0x4d/0xfe
7) 3792 128 return_to_handler+0x0/0x73
8) 3664 -32 scsi_sg_alloc+0x48/0x4a [scsi_mod]
As you can see, the real functions are now negative. This is due
to them not being found inside the stack.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup As promised, now that dumpstack_32 and dumpstack_64 have so many bits in common, we should merge the in-sync bits into a common file, to prevent them from diverging again. This patch removes bits which are common between dumpstack_32.c and dumpstack_64.c and places them in a common dumpstack.c which is built for both 32 and 64 bit arches. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu> Makefile | 2 arch/x86/kernel/Makefile | 2 arch/x86/kernel/Makefile | 2 arch/x86/kernel/Makefile | 2 arch/x86/kernel/Makefile | 2 arch/x86/kernel/Makefile | 2 arch/x86/kernel/dumpstack.c | 319 +++++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/dumpstack.h | 39 +++++ arch/x86/kernel/dumpstack_32.c | 294 ------------------------------------- arch/x86/kernel/dumpstack_64.c | 285 ------------------------------------ 5 files changed, 363 insertions(+), 576 deletions(-)
Make i386's die() equal to x86_64's version. Whitespace-only changes on x86_64, to make it equal to i386's version. (user_mode and user_mode_vm are equal on x86_64.) Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use oops_begin and oops_end in die_nmi. Whitespace-only changes on x86_64, to make it equal to i386's version. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Always call oops_exit from oops_end, even if signr==0. Also, move add_taint(TAINT_DIE) from __die to oops_end on x86_64 and interchange two lines to make oops_end more similar to the i386-version. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
oops_end is preceded by either a call to __die, or a conditional call to crash_kexec. Move the conditional call to crash_kexec from the end of __die to the start of oops_end and remove the superfluous call to crash_kexec in die_nmi. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change oops_end such that signr=0 signals that do_exit is not to be called. Currently, each use of __die is soon followed by a call to oops_end and 'regs' is set to NULL if oops_end is expected not to call do_exit. Change all such pairs to set signr=0 instead. On x86_64 oops_end is used 'bare' in die_nmi; use signr=0 instead of regs=NULL there, too. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Print the name of the last-accessed sysfs file when we oops, to help track down oopses which occur in sysfs store/read handlers. Because these oopses tend to not leave any trace of the offending code in the stack traces. Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
After "dumpstack: x86: various small unification steps", the
assembler gives the following compile error. The error is in
dumpstack_64.c.
{standard input}: Assembler messages:
{standard input}:720: Error: Incorrect register `%rbx' used with `l' suffix
{standard input}:1340: Error: Incorrect register `%r12' used with `l' suffix
Indeed the suffix in get_bp() was wrong.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
- define STACKSLOTS_PER_LINE and use it - define get_bp macro to hide the %%ebp/%%rbp difference - i386: check task==NULL in dump_trace, like x86_64 - i386: show_trace(NULL, ...) uses current automatically - x86_64: use [#%d] for die_counter, like i386 - whitespace and comments Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>