save_stack_trace_reliable now returns "non reliable" when there are kernel pt_regs on stack. This means an interrupt or exception happened somewhere down the route. It is a problem for frame pointer unwinder, because the frame might not have been set up yet when the irq happened, so the unwinder might fail to unwind from the interrupted function.
With ORC, this is not a problem, as ORC has out-of-band data. We can find ORC data even for the IP in the interrupted function and always unwind one level up reliably. So lift the check to apply only when CONFIG_FRAME_POINTER is enabled. [v2] - rewrite the code in favor of Josh's suggestions Signed-off-by: Jiri Slaby <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: [email protected] Cc: Josh Poimboeuf <[email protected]> --- arch/x86/kernel/stacktrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 9da8af2922b6..45915bd01692 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -113,7 +113,8 @@ __save_stack_trace_reliable(struct stack_trace *trace, * or a page fault), which can make frame pointers * unreliable. */ - return -EINVAL; + if (IS_ENABLED(CONFIG_FRAME_POINTER)) + return -EINVAL; } addr = unwind_get_return_address(&state); -- 2.15.1
