linux-stable.git/arch/x86/kernel/dumpstack_32.c, branch linux-3.4.y

x86/32: Print control and debug registers for kerenel context

2012-03-08T09:57:35+00:00

While for a user mode register dump it may be reasonable to skip
those (albeit x86-64 doesn't do so), for kernel mode dumps these
should be printed to make sure all information possibly
necessary for analysis is available.

Signed-off-by: Jan Beulich 
Link: http://lkml.kernel.org/r/4F58889202000078000770E7@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar

x86, dumpstack: Fix code bytes breakage due to missing KERN_CONT

2011-12-19T21:09:56+00:00

When printing the code bytes in show_registers(), the markers around the
byte at the fault address could make the printk() format string look
like a valid log level and facility code.  This would prevent this byte
from being printed and result in a spurious newline:

[ 7555.765589] Code: 8b 32 e9 94 00 00 00 81 7d 00 ff 00 00 00 0f 87 96 00 00 00 48 8b 83 c0 00 00 00 44 89 e2 44 89 e6 48 89 df 48 8b 80 d8 02 00 00
[ 7555.765683]  8b 48 28 48 89 d0 81 e2 ff 0f 00 00 48 c1 e8 0c 48 c1 e0 04

Add KERN_CONT where needed, and elsewhere in show_registers() for
consistency.

Signed-off-by: Clemens Ladisch 
Link: http://lkml.kernel.org/r/4EEFA7AE.9020407@ladisch.de
Signed-off-by: H. Peter Anvin

x86, dumpstack: Correct stack dump info when frame pointer is available

2011-03-18T09:51:42+00:00

Current stack dump code scans entire stack and check each entry
contains a pointer to kernel code. If CONFIG_FRAME_POINTER=y it
could mark whether the pointer is valid or not based on value of
the frame pointer. Invalid entries could be preceded by '?' sign.

However this was not going to happen because scan start point
was always higher than the frame pointer so that they could not
meet.

Commit 9c0729dc8062 ("x86: Eliminate bp argument from the stack
tracing routines") delayed bp acquisition point, so the bp was
read in lower frame, thus all of the entries were marked
invalid.

This patch fixes this by reverting above commit while retaining
stack_frame() helper as suggested by Frederic Weisbecker.

End result looks like below:

before:

 [    3.508329] Call Trace:
 [    3.508551]  [] ? panic+0x91/0x199
 [    3.508662]  [] ? printk+0x68/0x6a
 [    3.508770]  [] ? mount_block_root+0x257/0x26e
 [    3.508876]  [] ? mount_root+0x56/0x5a
 [    3.508975]  [] ? prepare_namespace+0x170/0x1a9
 [    3.509216]  [] ? kernel_init+0x1d2/0x1e2
 [    3.509335]  [] ? kernel_thread_helper+0x4/0x10
 [    3.509442]  [] ? restore_args+0x0/0x30
 [    3.509542]  [] ? kernel_init+0x0/0x1e2
 [    3.509641]  [] ? kernel_thread_helper+0x0/0x10

after:

 [    3.522991] Call Trace:
 [    3.523351]  [] panic+0x91/0x199
 [    3.523468]  [] ? printk+0x68/0x6a
 [    3.523576]  [] mount_block_root+0x257/0x26e
 [    3.523681]  [] mount_root+0x56/0x5a
 [    3.523780]  [] prepare_namespace+0x170/0x1a9
 [    3.523885]  [] kernel_init+0x1d2/0x1e2
 [    3.523987]  [] kernel_thread_helper+0x4/0x10
 [    3.524228]  [] ? restore_args+0x0/0x30
 [    3.524345]  [] ? kernel_init+0x0/0x1e2
 [    3.524445]  [] ? kernel_thread_helper+0x0/0x10

 -v5:
   * fix build breakage with oprofile

 -v4:
   * use 0 instead of regs->bp
   * separate out printk changes

 -v3:
   * apply comment from Frederic
   * add a couple of printk fixes

Signed-off-by: Namhyung Kim 
Acked-by: Peter Zijlstra 
Acked-by: Frederic Weisbecker 
Cc: Soren Sandmann 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Cc: Robert Richter 
LKML-Reference: <1300416006-3163-1-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar

x86: Eliminate bp argument from the stack tracing routines

2010-11-18T13:37:34+00:00

The various stack tracing routines take a 'bp' argument in which the
caller is supposed to provide the base pointer to use, or 0 if doesn't
have one. Since bp is garbage whenever CONFIG_FRAME_POINTER is not
defined, this means all callers in principle should either always pass
0, or be conditional on CONFIG_FRAME_POINTER.

However, there are only really three use cases for stack tracing:

(a) Trace the current task, including IRQ stack if any
(b) Trace the current task, but skip IRQ stack
(c) Trace some other task

In all cases, if CONFIG_FRAME_POINTER is not defined, bp should just
be 0.  If it _is_ defined, then

- in case (a) bp should be gotten directly from the CPU's register, so
  the caller should pass NULL for regs,

- in case (b) the caller should should pass the IRQ registers to
  dump_trace(),

- in case (c) bp should be gotten from the top of the task's stack, so
  the caller should pass NULL for regs.

Hence, the bp argument is not necessary because the combination of
task and regs is sufficient to determine an appropriate value for bp.

This patch introduces a new inline function stack_frame(task, regs)
that computes the desired bp. This function is then called from the
two versions of dump_stack().

Signed-off-by: Soren Sandmann 
Acked-by: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Cc: Peter Zijlstra 
Cc: Arjan van de Ven ,
Cc: Frederic Weisbecker ,
Cc: Arnaldo Carvalho de Melo ,
LKML-Reference: >
Signed-off-by: Frederic Weisbecker

x86, printk: Get rid of <0> from stack output

2010-10-23T18:03:03+00:00

The stack output currently looks like this:

 7fffffffffffffff 0000000a00000000 ffffffff81093341 0000000000000046
<0> ffff88003a545fd8 0000000000000000 0000000000000000 00007fffa39769c0
<0> ffff88003e403f58 ffffffff8102fc4c ffff88003e403f58 ffff88003e403f78

The superfluous <0> are caused by recent printk KERN_CONT
change. <*> is now ignored in printk unless some text follows
the level and even then it still has to be the first in the
format message.

Note that the log_lvl parameter is now completely ignored in
show_stack_log_lvl and the stack is dumped with the default
level (like for quite some time already). It behaves the same as
the rest of the dump, function traces are dumped in the very
same manner. Only Code and maybe some lines are printed with
EMERG level.

Unfortunately I see no way how to fix this conceptually to have
the whole oops/BUG/panic output with the same level, so this
removed only the superfluous characters for the time being.

Just for illustration:

<4>Process kworker/0:0 (pid: 0, threadinfo ffff88003c8a6000, task ffff88003c85c100)
<0>Stack:
<4> ffffffff818022c0 0000000a00000001 0000000000000001 0000000000000046
<4> ffff88003c8a7fd8 0000000000000001 ffff88003c8a7e58 0000000000000000
<4> ffff88003e503f48 ffffffff8102fc4c ffff88003e503f48 ffff88003e503f68
<0>Call Trace:
<0> 
<4> [] ? call_softirq+0x1c/0x30 ...
<0>Code: 00 01 00 00 65 8b 04 25 80 c5 00 00 c7 45 ...

Signed-off-by: Jiri Slaby 
Cc: jirislaby@gmail.com
Cc: Linus Torvalds 
Cc: Andrew Morton 
LKML-Reference: <1287586131-16222-1-git-send-email-jslaby@suse.cz>
Signed-off-by: Ingo Molnar

x86: Unify dumpstack.h and stacktrace.h

2010-06-08T21:29:52+00:00

arch/x86/include/asm/stacktrace.h and arch/x86/kernel/dumpstack.h
declare headers of objects that deal with the same topic.
Actually most of the files that include stacktrace.h also include
dumpstack.h

Although dumpstack.h seems more reserved for internals of stack
traces, those are quite often needed to define specialized stack
trace operations. And perf event arch headers are going to need
access to such low level operations anyway. So don't continue to
bother with dumpstack.h as it's not anymore about isolated deep
internals.

v2: fix struct stack_frame definition conflict in sysprof

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Cc: Thomas Gleixner 
Cc: Soeren Sandmann

perf: Drop useless check for ignored frame

2010-01-13T09:09:08+00:00

The check that ignores the debug and nmi stack frames is useless
now that we have a frame pointer that makes us start at the
right place. We don't anymore have to deal with these.

Signed-off-by: Frederic Weisbecker 
Cc: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Paul Mackerras 
LKML-Reference: <1262235183-5320-2-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar

perf events, x86/stacktrace: Make stack walking optional

2009-12-17T08:56:19+00:00

The current print_context_stack helper that does the stack
walking job is good for usual stacktraces as it walks through
all the stack and reports even addresses that look unreliable,
which is nice when we don't have frame pointers for example.

But we have users like perf that only require reliable
stacktraces, and those may want a more adapted stack walker, so
lets make this function a callback in stacktrace_ops that users
can tune for their needs.

Signed-off-by: Frederic Weisbecker 
Cc: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Paul Mackerras 
LKML-Reference: <1261024834-5336-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar

x86: dumpstack: Clean up the x86_stack_ids[][] initalization and other details

2009-11-26T07:24:33+00:00

Make the initialization more readable, plus tidy up a few small
visual details as well.

No change in functionality.

LKML-Reference: 
Signed-off-by: Ingo Molnar

headers: utsname.h redux

2009-09-24T01:13:10+00:00

* remove asm/atomic.h inclusion from linux/utsname.h --
   not needed after kref conversion
 * remove linux/utsname.h inclusion from files which do not need it

NOTE: it looks like fs/binfmt_elf.c do not need utsname.h, however
due to some personality stuff it _is_ needed -- cowardly leave ELF-related
headers and files alone.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Linus Torvalds