From 2c96b2fe9c57b4267c3f0a680d82d7cc52e1c447 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 9 Jan 2017 12:00:24 -0600 Subject: x86/unwind: Include __schedule() in stack traces In the following commit: 0100301bfdf5 ("sched/x86: Rewrite the switch_to() code") ... the layout of the 'inactive_task_frame' struct was designed to have a frame pointer header embedded in it, so that the unwinder could use the 'bp' and 'ret_addr' fields to report __schedule() on the stack (or ret_from_fork() for newly forked tasks which haven't actually run yet). Finish the job by changing get_frame_pointer() to return a pointer to inactive_task_frame's 'bp' field rather than 'bp' itself. This allows the unwinder to start one frame higher on the stack, so that it properly reports __schedule(). Reported-by: Miroslav Benes Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Jones Cc: Denys Vlasenko Cc: Dmitry Vyukov Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/598e9f7505ed0aba86e8b9590aa528c6c7ae8dcd.1483978430.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/stacktrace.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'arch/x86/include/asm/stacktrace.h') diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h index 20ce3db20f24..2e41c50ddf47 100644 --- a/arch/x86/include/asm/stacktrace.h +++ b/arch/x86/include/asm/stacktrace.h @@ -52,16 +52,13 @@ static inline bool on_stack(struct stack_info *info, void *addr, size_t len) static inline unsigned long * get_frame_pointer(struct task_struct *task, struct pt_regs *regs) { - struct inactive_task_frame *frame; - if (regs) return (unsigned long *)regs->bp; if (task == current) return __builtin_frame_address(0); - frame = (struct inactive_task_frame *)task->thread.sp; - return (unsigned long *)READ_ONCE_NOCHECK(frame->bp); + return &((struct inactive_task_frame *)task->thread.sp)->bp; } #else static inline unsigned long * -- cgit v1.2.3