linux-toradex.git/arch/x86/kernel/dumpstack_32.c, branch v2.6.29.3

ftrace: print real return in dumpstack for function graph

2008-12-03T07:56:25+00:00

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 
Signed-off-by: Ingo Molnar

x86: unify appropriate bits from dumpstack_32 and dumpstack_64

2008-10-27T18:21:19+00:00

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 
Acked-by: Alexander van Heukelum 
Signed-off-by: Ingo Molnar 

 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(-)

i386, dumpstack: unify die()

2008-10-22T12:00:26+00:00

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 
Acked-by: Neil Horman 
Signed-off-by: Ingo Molnar

i386, dumpstack: use oops_begin/oops_end in die_nmi

2008-10-22T12:00:26+00:00

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 
Acked-by: Neil Horman 
Signed-off-by: Ingo Molnar

i386, dumpstack: use x86_64's method to account die_nest_count

2008-10-22T12:00:25+00:00

oops_begin/oops_end should always be used in pairs. On x86_64
oops_begin increments die_nest_count, and oops_end decrements
die_nest_count. Doing this makes oops_begin and oops_end equal
to the x86_64 versions.

Signed-off-by: Alexander van Heukelum 
Acked-by: Neil Horman 
Signed-off-by: Ingo Molnar

x86, dumpstack: always call oops_exit from oops_end

2008-10-22T12:00:24+00:00

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 
Acked-by: Neil Horman 
Signed-off-by: Ingo Molnar

x86, dumpstack: let signr=0 signal no do_exit

2008-10-22T12:00:23+00:00

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 
Acked-by: Neil Horman 
Signed-off-by: Ingo Molnar

i386, dumpstack: move crash_kexec before bust_spinlocks(0) in oops_end

2008-10-22T12:00:22+00:00

crash_kexec should not be called with console_sem held. Move
the call before bust_spinlocks(0) in oops_end to avoid the
problem.

Signed-off-by: Alexander van Heukelum 
Acked-by: "Neil Horman" 
Signed-off-by: Ingo Molnar

x86, kexec: fix hang on i386 when panic occurs while console_sem is held

2008-10-22T11:59:44+00:00

There's a corner case in 32 bit x86 kdump at the moment.  When the box
panics via nmi, we call bust_spinlocks(1) to disable sensitivity to the
console_sem (allowing us to print to the console in all cases), but we don't
call crash_kexec, until after we call bust_spinlocks(0), which re-enables
console_sem sensitivity.

The result is that, if we get an nmi while the console_sem is held and
kdump is configured, and we try to print something to the console during
kdump shutdown (which we often do) we deadlock the box.  The fix is to
simply do what 64 bit die_nmi does which is to not call bust_spinlocks(0)
until after we call crash_kexec.

Patch below tested successfully by me.

Signed-off-by: Neil Horman 
Signed-off-by: Ingo Molnar

sysfs: crash debugging

2008-10-16T16:24:41+00:00

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 
Cc: Mathieu Desnoyers 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman