[patch V5 03/38] nmi, tracing: Provide nmi_enter/exit_notrace()

Thomas Gleixner
2020-05-12T22:23:59Z

To fully isolate #DB and #BP from instrumentable code it's necessary to
avoid invoking the hardware latency tracer on nmi_enter/exit().

Provide nmi_enter/exit() variants which are not invoking the hardware
latency tracer. That allows to put calls explicitely into the call sites
outside of the kprobe handling.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V5: New patch
---
include/linux/hardirq.h | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -77,28 +77,38 @@ extern void irq_exit(void);
/*
* nmi_enter() can nest up to 15 times; see NMI_BITS.
*/
-#define nmi_enter() \
+#define nmi_enter_notrace() \
do { \
arch_nmi_enter(); \
printk_nmi_enter(); \
lockdep_off(); \
- ftrace_nmi_enter(); \
BUG_ON(in_nmi() == NMI_MASK); \
__preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \
rcu_nmi_enter(); \
lockdep_hardirq_enter(); \
} while (0)

-#define nmi_exit() \
+#define nmi_enter() \
+ do { \
+ nmi_enter_notrace(); \
+ ftrace_nmi_enter(); \
+ } while (0)
+
+#define nmi_exit_notrace() \
do { \
lockdep_hardirq_exit(); \
rcu_nmi_exit(); \
BUG_ON(!in_nmi()); \
__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \
- ftrace_nmi_exit(); \
lockdep_on(); \
printk_nmi_exit(); \
arch_nmi_exit(); \
} while (0)

+#define nmi_exit() \
+ do { \
+ ftrace_nmi_exit(); \
+ nmi_exit_notrace(); \
+ } while (0)
+
#endif /* LINUX_HARDIRQ_H */