[PATCH RFC] preempt: Put preempt_enable() within an instrumentation*() section.

[Sebastian Andrzej Siewior]

Callers of preempt_enable() can be within an noinstr section leading to:
| vmlinux.o: warning: objtool: native_sched_clock+0x97: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: kvm_clock_read+0x22: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: local_clock+0xb4: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: enter_from_user_mode+0xea: call to preempt_schedule_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x140: call to preempt_schedule_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0xf2: call to preempt_schedule_thunk() leaves .noinstr.text section
| vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0xea: call to preempt_schedule_thunk() leaves .noinstr.text section

This only happens on CONFIG_PREEMPT+ due to the conditional call into the scheduler.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 include/linux/preempt.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 12f59cdaaedda..05338f00a5907 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -238,15 +238,21 @@ do { \
 #define preempt_enable() \
 do { \
 	barrier(); \
-	if (unlikely(preempt_count_dec_and_test())) \
+	if (unlikely(preempt_count_dec_and_test())) { \
+		instrumentation_begin(); \
 		__preempt_schedule(); \
+		instrumentation_end(); \
+	} \
 } while (0)
 
 #define preempt_enable_notrace() \
 do { \
 	barrier(); \
-	if (unlikely(__preempt_count_dec_and_test())) \
+	if (unlikely(__preempt_count_dec_and_test())) { \
+		instrumentation_begin(); \
 		__preempt_schedule_notrace(); \
+		instrumentation_end(); \
+	} \
 } while (0)
 
 #define preempt_check_resched() \
-- 
2.39.2