Messages in this thread Patch in this message | | | Date | Thu, 20 Apr 2017 08:42:52 -0500 | From | Josh Poimboeuf <> | Subject | Re: WARNING: kernel stack regs at ffffc9000024fea8 in udevadm:92 has bad 'bp' value 00007fffc4614d30 |
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On Thu, Apr 20, 2017 at 08:30:21AM -0500, Josh Poimboeuf wrote: > On Thu, Apr 20, 2017 at 01:06:10PM +0200, Borislav Petkov wrote: > > Hi, > > > > the splat below started appearing on one of the boxes here with > > rc7+tip/master from yesterday. > > > > Ideas? > > Thanks for reporting it. This is another false positive. It unwinded > from an interrupt which came in right after calling into C code, but > before it could set up the frame pointer. This needs another unwinder > check.
If it's recreatable, can you test with the following patch?
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index bda82df..abe36ff 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -91,16 +91,26 @@ static bool in_entry_code(unsigned long ip) return false; } +static inline unsigned long *last_frame(struct unwind_state *state) +{ + return (unsigned long *)task_pt_regs(state->task) - 2; +} + #ifdef CONFIG_X86_32 #define GCC_REALIGN_WORDS 3 #else #define GCC_REALIGN_WORDS 1 #endif +static inline unsigned long *last_aligned_frame(struct unwind_state *state) +{ + return last_frame(state) - GCC_REALIGN_WORDS; +} + static bool is_last_task_frame(struct unwind_state *state) { - unsigned long *last_bp = (unsigned long *)task_pt_regs(state->task) - 2; - unsigned long *aligned_bp = last_bp - GCC_REALIGN_WORDS; + unsigned long *last_bp = last_frame(state); + unsigned long *aligned_bp = last_aligned_frame(state); /* * We have to check for the last task frame at two different locations @@ -277,10 +287,12 @@ bool unwind_next_frame(struct unwind_state *state) /* * Don't warn if the unwinder got lost due to an interrupt in entry - * code before the stack was set up: + * code before the first frame pointer got set up: */ if (state->got_irq && in_entry_code(state->ip)) goto the_end; + if (state->regs && (unsigned long *)state->regs->sp >= last_aligned_frame(state)) + goto the_end; if (state->regs) { printk_deferred_once(KERN_WARNING
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