08 Mar, 2017
1 commit
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For live patching and possibly other use cases, a stack trace is only
useful if it can be assured that it's completely reliable. Add a new
save_stack_trace_tsk_reliable() function to achieve that.Note that if the target task isn't the current task, and the target task
is allowed to run, then it could be writing the stack while the unwinder
is reading it, resulting in possible corruption. So the caller of
save_stack_trace_tsk_reliable() must ensure that the task is either
'current' or inactive.save_stack_trace_tsk_reliable() relies on the x86 unwinder's detection
of pt_regs on the stack. If the pt_regs are not user-mode registers
from a syscall, then they indicate an in-kernel interrupt or exception
(e.g. preemption or a page fault), in which case the stack is considered
unreliable due to the nature of frame pointers.It also relies on the x86 unwinder's detection of other issues, such as:
- corrupted stack data
- stack grows the wrong way
- stack walk doesn't reach the bottom
- user didn't provide a large enough entries arraySuch issues are reported by checking unwind_error() and !unwind_done().
Also add CONFIG_HAVE_RELIABLE_STACKTRACE so arch-independent code can
determine at build time whether the function is implemented.Signed-off-by: Josh Poimboeuf
Reviewed-by: Miroslav Benes
Acked-by: Ingo Molnar # for the x86 changes
Signed-off-by: Jiri Kosina
08 Feb, 2017
1 commit
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Since KERN_CONT became meaningful again, lockdep stack traces have had
annoying extra newlines, like this:[ 5.561122] -> #1 (B){+.+...}:
[ 5.561528]
[ 5.561532] [] lock_acquire+0xc3/0x210
[ 5.562178]
[ 5.562181] [] mutex_lock_nested+0x74/0x6d0
[ 5.562861]
[ 5.562880] [] init_btrfs_fs+0x21/0x196 [btrfs]
[ 5.563717]
[ 5.563721] [] do_one_initcall+0x52/0x1b0
[ 5.564554]
[ 5.564559] [] do_init_module+0x5f/0x209
[ 5.565357]
[ 5.565361] [] load_module+0x218d/0x2b80
[ 5.566020]
[ 5.566021] [] SyS_finit_module+0xeb/0x120
[ 5.566694]
[ 5.566696] [] entry_SYSCALL_64_fastpath+0x1f/0xc2That's happening because each printk() call now gets printed on its own
line, and we do a separate call to print the spaces before the symbol.
Fix it by doing the printk() directly instead of using the
print_ip_sym() helper.Additionally, the symbol address isn't very helpful, so let's get rid of
that, too. The final result looks like this:[ 5.194518] -> #1 (B){+.+...}:
[ 5.195002] lock_acquire+0xc3/0x210
[ 5.195439] mutex_lock_nested+0x74/0x6d0
[ 5.196491] do_one_initcall+0x52/0x1b0
[ 5.196939] do_init_module+0x5f/0x209
[ 5.197355] load_module+0x218d/0x2b80
[ 5.197792] SyS_finit_module+0xeb/0x120
[ 5.198251] entry_SYSCALL_64_fastpath+0x1f/0xc2Suggested-by: Linus Torvalds
Signed-off-by: Omar Sandoval
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: kernel-team@fb.com
Fixes: 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines")
Link: http://lkml.kernel.org/r/43b4e114724b2bdb0308fa86cb33aa07d3d67fad.1486510315.git.osandov@fb.com
Signed-off-by: Ingo Molnar
14 Dec, 2014
1 commit
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Current stacktrace only have the function for console output. page_owner
that will be introduced in following patch needs to print the output of
stacktrace into the buffer for our own output format so so new function,
snprint_stack_trace(), is needed.Signed-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Minchan Kim
Cc: Dave Hansen
Cc: Michal Nazarewicz
Cc: Jungsoo Son
Cc: Ingo Molnar
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Oct, 2011
1 commit
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The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else. Revector them
onto the isolated export header for faster compile times.Nothing to see here but a whole lot of instances of:
-#include
+#includeThis commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.Signed-off-by: Paul Gortmaker
15 Jun, 2011
1 commit
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Add weak symbol of save_stack_trace_regs() as same as
save_stack_trace_tsk() since that is not implemented
except x86 yet.Signed-off-by: Masami Hiramatsu
Cc: Frederic Weisbecker
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Peter Zijlstra
Cc: Namhyung Kim
Link: http://lkml.kernel.org/r/20110608070927.17777.37895.stgit@fedora15
Signed-off-by: Steven Rostedt
25 Dec, 2008
1 commit
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Impact: build fix
Some architectures have not implemented save_stack_trace_tsk() yet:
fs/built-in.o: In function `proc_pid_stack':
base.c:(.text+0x3f140): undefined reference to `save_stack_trace_tsk'So warn about that if the facility is used.
Signed-off-by: Ingo Molnar
30 Jun, 2008
1 commit
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fix:
ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined!
ERROR: "save_stack_trace" [kernel/backtracetest.ko] undefined!Signed-off-by: Ingo Molnar
and fix:
Building modules, stage 2.
MODPOST 376 modules
ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined!
make[1]: *** [__modpost] Error 1Signed-off-by: Ingo Molnar
13 Jun, 2008
1 commit
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- shorter code and better atomicity with regards to printk().
(It's been tested with the backtrace self-test code on i386 and x86_64.)
Cc: Arjan van de Ven
Signed-off-by: Vegard Nossum
Signed-off-by: Ingo Molnar
24 May, 2008
1 commit
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This patch makes the stacktrace printout code \warn when the entries
pointer is unset rather than crashing when trying to access it in an
attempt to make it a bit more robust.I was saving a stacktrace into an skb and forgot to copy it across skb
copies... I have since fixed the code, but it would have been easier
had the kernel not crashed in an interrupt.Signed-off-by: Johannes Berg
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
04 Jul, 2006
1 commit
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Framework to generate and save stacktraces quickly, without printing anything
to the console.Signed-off-by: Ingo Molnar
Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds