Messages in this thread Patch in this message | | | Date | Sun, 08 Mar 2020 23:24:01 +0100 | From | Thomas Gleixner <> | Subject | [patch part-II V2 02/13] x86/entry: Mark enter_from_user_mode() notrace and NOKPROBE |
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Both the callers in the low level ASM code and __context_tracking_exit() which is invoked from enter_from_user_mode() via user_exit_irqoff() are marked NOKPROBE. Allowing enter_from_user_mode() to be probed is inconsistent at best.
Aside of that while function tracing per se is safe the function trace entry/exit points can be used via BPF as well which is not safe to use before context tracking has reached CONTEXT_KERNEL and adjusted RCU.
Mark it notrace and NOKROBE.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/entry/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -40,11 +40,12 @@ #ifdef CONFIG_CONTEXT_TRACKING /* Called on entry from user mode with IRQs off. */ -__visible inline void enter_from_user_mode(void) +__visible inline notrace void enter_from_user_mode(void) { CT_WARN_ON(ct_state() != CONTEXT_USER); user_exit_irqoff(); } +NOKPROBE_SYMBOL(enter_from_user_mode); #else static inline void enter_from_user_mode(void) {} #endif
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