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* stacktrace/x86: add function for detecting reliable stack tracesJosh Poimboeuf2017-03-081-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 array Such 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 <jpoimboe@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Ingo Molnar <mingo@kernel.org> # for the x86 changes Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* stacktrace, lockdep: Fix address, newline uglinessOmar Sandoval2017-02-081-8/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since KERN_CONT became meaningful again, lockdep stack traces have had annoying extra newlines, like this: [ 5.561122] -> #1 (B){+.+...}: [ 5.561528] [ 5.561532] [<ffffffff810d8873>] lock_acquire+0xc3/0x210 [ 5.562178] [ 5.562181] [<ffffffff816f6414>] mutex_lock_nested+0x74/0x6d0 [ 5.562861] [ 5.562880] [<ffffffffa01aa3c3>] init_btrfs_fs+0x21/0x196 [btrfs] [ 5.563717] [ 5.563721] [<ffffffff81000472>] do_one_initcall+0x52/0x1b0 [ 5.564554] [ 5.564559] [<ffffffff811a3af6>] do_init_module+0x5f/0x209 [ 5.565357] [ 5.565361] [<ffffffff81122f4d>] load_module+0x218d/0x2b80 [ 5.566020] [ 5.566021] [<ffffffff81123beb>] SyS_finit_module+0xeb/0x120 [ 5.566694] [ 5.566696] [<ffffffff816fd241>] entry_SYSCALL_64_fastpath+0x1f/0xc2 That'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/0xc2 Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Omar Sandoval <osandov@fb.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> 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 <mingo@kernel.org>
* stacktrace: introduce snprint_stack_trace for buffer outputJoonsoo Kim2014-12-131-0/+32
| | | | | | | | | | | | | | | | | | | 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 <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Dave Hansen <dave@sr71.net> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Jungsoo Son <jungsoo.son@lge.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: Map most files to use export.h instead of module.hPaul Gortmaker2011-10-311-1/+1
| | | | | | | | | | | | | | | | 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 <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* stack_trace: Add weak save_stack_trace_regs()Masami Hiramatsu2011-06-141-3/+9
| | | | | | | | | | | | | | 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 <masami.hiramatsu.pt@hitachi.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: yrl.pp-manager.tt@hitachi.com Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Namhyung Kim <namhyung@gmail.com> Link: http://lkml.kernel.org/r/20110608070927.17777.37895.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* stacktrace: provide save_stack_trace_tsk() weak aliasIngo Molnar2008-12-251-0/+11
| | | | | | | | | | | | | 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 <mingo@elte.hu>
* stacktrace: fix modular build, export print_stack_trace and save_stack_traceIngo Molnar2008-06-301-0/+2
| | | | | | | | | | | | | | | | | | fix: ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined! ERROR: "save_stack_trace" [kernel/backtracetest.ko] undefined! Signed-off-by: Ingo Molnar <mingo@elte.hu> and fix: Building modules, stage 2. MODPOST 376 modules ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined! make[1]: *** [__modpost] Error 1 Signed-off-by: Ingo Molnar <mingo@elte.hu>
* stacktrace: print_stack_trace() cleanupVegard Nossum2008-06-131-6/+3
| | | | | | | | | | - 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 <arjan@infradead.org> Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* stacktrace: don't crash on invalid stack trace structsJohannes Berg2008-05-241-0/+3
| | | | | | | | | | | | | | 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 <johannes@sipsolutions.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* [PATCH] lockdep: stacktrace subsystem, coreIngo Molnar2006-07-031-0/+24
Framework to generate and save stacktraces quickly, without printing anything to the console. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>