Commit-ID: 9a2e9da3e003112399f2863b7b6b911043c01895 Gitweb: http://git.kernel.org/tip/9a2e9da3e003112399f2863b7b6b911043c01895 Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Thu, 14 Jul 2016 13:22:52 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 15 Jul 2016 10:26:26 +0200
x86/dumpstack: Try harder to get a call trace on stack overflow If we overflow the stack, print_context_stack() will abort. Detect this case and rewind back into the valid part of the stack so that we can trace it. Signed-off-by: Andy Lutomirski <l...@kernel.org> Reviewed-by: Josh Poimboeuf <jpoim...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/ee1690eb2715ccc5dc187fde94effa4ca0ccbbcd.1468527351.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/kernel/dumpstack.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index ef8017c..cc88e25 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -87,7 +87,7 @@ static inline int valid_stack_ptr(struct task_struct *task, else return 0; } - return p > t && p < t + THREAD_SIZE - size; + return p >= t && p < t + THREAD_SIZE - size; } unsigned long @@ -98,6 +98,14 @@ print_context_stack(struct task_struct *task, { struct stack_frame *frame = (struct stack_frame *)bp; + /* + * If we overflowed the stack into a guard page, jump back to the + * bottom of the usable stack. + */ + if ((unsigned long)task_stack_page(task) - (unsigned long)stack < + PAGE_SIZE) + stack = (unsigned long *)task_stack_page(task); + while (valid_stack_ptr(task, stack, sizeof(*stack), end)) { unsigned long addr;
