linux.git/arch/x86/kernel/dumpstack_64.c, branch v3.17

x86: Fix dumpstack_64 irq stack handling

2014-04-02T18:46:50+00:00

Commit 2223f6f6eeaa "x86: Clean up dumpstack_64.c code" changed
the irq_stack processing a little from what it was before.
The irq_stack_end variable needed to be cleared after its first
use. By setting irq_stack to the per cpu irq_stack and passing
that to analyze_stack(), and then clearing it after it is processed,
we can get back the original behavior.

Signed-off-by: Steven Rostedt 
Signed-off-by: Linus Torvalds

x86: Fix dumpstack_64 to keep state of "used" variable in loop

2014-04-02T18:46:50+00:00

Commit 2223f6f6eeaa "x86: Clean up dumpstack_64.c code" moved the used
variable to a local within the loop, but the in_exception_stack()
depended on being non-volatile with the ability to change it.

By always re-initializing the "used" variable to zero, it would cause
the in_exception_stack() to return the same thing each time, and
cause the dump_stack loop to go into an infinite loop.

Reported-by: Linus Torvalds 
Signed-off-by: Steven Rostedt 
Signed-off-by: Linus Torvalds

x86: Clean up dumpstack_64.c code

2014-03-07T00:56:55+00:00

The dump_trace() function in dumpstack_64.c is hard to follow.
The test for exception stack is processed differently than the
test for irq stack, and the normal stack is outside completely.

By restructuring this code to have all the stacks determined by
a single function that returns an enum of the following:

 STACK_IS_NORMAL
 STACK_IS_EXCEPTION
 STACK_IS_IRQ
 STACK_IS_UNKNOWN

and has the logic of each within a switch statement.
This should make the code much easier to read and understand.

Link: http://lkml.kernel.org/r/20110806012354.684598995@goodmis.org

Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Brian Gerst 
Signed-off-by: Steven Rostedt 
Link: http://lkml.kernel.org/r/20140206144322.086050042@goodmis.org
Signed-off-by: H. Peter Anvin

dump_stack: unify debug information printed by show_regs()

2013-05-01T00:04:02+00:00

show_regs() is inherently arch-dependent but it does make sense to print
generic debug information and some archs already do albeit in slightly
different forms.  This patch introduces a generic function to print debug
information from show_regs() so that different archs print out the same
information and it's much easier to modify what's printed.

show_regs_print_info() prints out the same debug info as dump_stack()
does plus task and thread_info pointers.

* Archs which didn't print debug info now do.

  alpha, arc, blackfin, c6x, cris, frv, h8300, hexagon, ia64, m32r,
  metag, microblaze, mn10300, openrisc, parisc, score, sh64, sparc,
  um, xtensa

* Already prints debug info.  Replaced with show_regs_print_info().
  The printed information is superset of what used to be there.

  arm, arm64, avr32, mips, powerpc, sh32, tile, unicore32, x86

* s390 is special in that it used to print arch-specific information
  along with generic debug info.  Heiko and Martin think that the
  arch-specific extra isn't worth keeping s390 specfic implementation.
  Converted to use the generic version.

Note that now all archs print the debug info before actual register
dumps.

An example BUG() dump follows.

 kernel BUG at /work/os/work/kernel/workqueue.c:4841!
 invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #7
 Hardware name: empty empty/S3992, BIOS 080011  10/26/2007
 task: ffff88007c85e040 ti: ffff88007c860000 task.ti: ffff88007c860000
 RIP: 0010:[]  [] init_workqueues+0x4/0x6
 RSP: 0000:ffff88007c861ec8  EFLAGS: 00010246
 RAX: ffff88007c861fd8 RBX: ffffffff824466a8 RCX: 0000000000000001
 RDX: 0000000000000046 RSI: 0000000000000001 RDI: ffffffff8234a07a
 RBP: ffff88007c861ec8 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8234a07a
 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: ffff88015f7ff000 CR3: 00000000021f1000 CR4: 00000000000007f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Stack:
  ffff88007c861ef8 ffffffff81000312 ffffffff824466a8 ffff88007c85e650
  0000000000000003 0000000000000000 ffff88007c861f38 ffffffff82335e5d
  ffff88007c862080 ffffffff8223d8c0 ffff88007c862080 ffffffff81c47760
 Call Trace:
  [] do_one_initcall+0x122/0x170
  [] kernel_init_freeable+0x9b/0x1c8
  [] ? rest_init+0x140/0x140
  [] kernel_init+0xe/0xf0
  [] ret_from_fork+0x7c/0xb0
  [] ? rest_init+0x140/0x140
  ...

v2: Typo fix in x86-32.

v3: CPU number dropped from show_regs_print_info() as
    dump_stack_print_info() has been updated to print it.  s390
    specific implementation dropped as requested by s390 maintainers.

Signed-off-by: Tejun Heo 
Acked-by: David S. Miller 
Acked-by: Jesper Nilsson 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: Bjorn Helgaas 
Cc: Fengguang Wu 
Cc: Mike Frysinger 
Cc: Vineet Gupta 
Cc: Sam Ravnborg 
Acked-by: Chris Metcalf 		[tile bits]
Acked-by: Richard Kuo 		[hexagon bits]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86: Move call to print_modules() out of show_regs()

2012-06-20T12:33:48+00:00

Printing the list of loaded modules is really unrelated to what
this function is about, and is particularly unnecessary in the
context of the SysRQ key handling (gets printed so far over and
over).

It should really be the caller of the function to decide whether
this piece of information is useful (and to avoid redundantly
printing it).

Signed-off-by: Jan Beulich 
Link: http://lkml.kernel.org/r/4FDF21A4020000780008A67F@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar

x86/debug: Add KERN_ to bare printks, convert printks to pr_

2012-06-06T07:17:22+00:00

Use a more current logging style:

 - Bare printks should have a KERN_ for consistency's sake
 - Add pr_fmt where appropriate
 - Neaten some macro definitions
 - Convert some Ok output to OK
 - Use "%s: ", __func__ in pr_fmt for summit
 - Convert some printks to pr_

Message output is not identical in all cases.

Signed-off-by: Joe Perches 
Cc: levinsasha928@gmail.com
Link: http://lkml.kernel.org/r/1337655007.24226.10.camel@joe2Laptop
[ merged two similar patches, tidied up the changelog ]
Signed-off-by: Ingo Molnar

x86: Avoid double stack traces with show_regs()

2012-05-09T09:44:42+00:00

What was called show_registers() so far already showed a stack
trace for kernel faults, and kernel_stack_pointer() isn't even
valid to be used for faults from user mode, hence it was
pointless for show_regs() to call show_trace() after
show_registers().

Simply rename show_registers() to show_regs() and eliminate
the old definition.

Signed-off-by: Jan Beulich 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Arjan van de Ven 
Cc: Frederic Weisbecker 
Link: http://lkml.kernel.org/r/4FAA3D3902000078000826E1@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar

Merge branches 'core-urgent-for-linus', 'perf-urgent-for-linus', 'sched-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-02-02T19:11:13+00:00

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  bugs, x86: Fix printk levels for panic, softlockups and stack dumps

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf top: Fix number of samples displayed
  perf tools: Fix strlen() bug in perf_event__synthesize_event_type()
  perf tools: Fix broken build by defining _GNU_SOURCE in Makefile
  x86/dumpstack: Remove unneeded check in dump_trace()
  perf: Fix broken interrupt rate throttling

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSW
  sched: Fix ancient race in do_exit()
  sched/nohz: Fix nohz cpu idle load balancing state with cpu hotplug
  sched/s390: Fix compile error in sched/core.c
  sched: Fix rq->nr_uninterruptible update race

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/reboot: Remove VersaLogic Menlow reboot quirk
  x86/reboot: Skip DMI checks if reboot set by user
  x86: Properly parenthesize cmpxchg() macro arguments

x86/dumpstack: Remove unneeded check in dump_trace()

2012-01-28T12:09:06+00:00

Smatch complains that we have some inconsistent NULL checking.

If "task" were NULL then it would lead to a NULL dereference
later. We can remove this test because earlier on in the
function we have:

 if (!task)
	task = current;

Signed-off-by: Dan Carpenter 
Acked-by: Frederic Weisbecker 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Clemens Ladisch 
Link: http://lkml.kernel.org/r/20120128105246.GA25092@elgon.mountain
Signed-off-by: Ingo Molnar

bugs, x86: Fix printk levels for panic, softlockups and stack dumps

2012-01-26T20:28:45+00:00

rsyslog will display KERN_EMERG messages on a connected
terminal.  However, these messages are useless/undecipherable
for a general user.

For example, after a softlockup we get:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Stack:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Call Trace:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89
 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9  ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89

This happens because the printk levels for these messages are
incorrect. Only an informational message should be displayed on
a terminal.

I modified the printk levels for various messages in the kernel
and tested the output by using the drivers/misc/lkdtm.c kernel
modules (ie, softlockups, panics, hard lockups, etc.) and
confirmed that the console output was still the same and that
the output to the terminals was correct.

For example, in the case of a softlockup we now see the much
more informative:

 Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ...
 BUG: soft lockup - CPU4 stuck for 60s!

instead of the above confusing messages.

AFAICT, the messages no longer have to be KERN_EMERG.  In the
most important case of a panic we set console_verbose().  As for
the other less severe cases the correct data is output to the
console and /var/log/messages.

Successfully tested by me using the drivers/misc/lkdtm.c module.

Signed-off-by: Prarit Bhargava 
Cc: dzickus@redhat.com
Cc: Linus Torvalds 
Cc: Andrew Morton 
Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com
Signed-off-by: Ingo Molnar