Messages in this thread Patch in this message | | | From | Andy Lutomirski <> | Subject | [PATCH 04/11] x86/dumpstack: Try harder to get a call trace on stack overflow | Date | Thu, 14 Jul 2016 13:22:52 -0700 |
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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.
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Andy Lutomirski <luto@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 ef8017ca5ba9..cc88e25d73e9 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; -- 2.7.4
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