@@ -12,7 +12,16 @@
*
* Please use one of the three interfaces below.
*/
-extern unsigned long long notrace sched_clock(void);
+extern u64 sched_clock(void);
+
+#if defined(CONFIG_ARCH_WANTS_NO_INSTR) || defined(CONFIG_GENERIC_SCHED_CLOCK)
+extern u64 sched_clock_noinstr(void);
+#else
+__always_inline u64 sched_clock_noinstr(void)
+{
+ return sched_clock();
+}
+#endif
/*
* See the comment in kernel/sched/clock.c
@@ -45,6 +54,11 @@ static inline u64 cpu_clock(int cpu)
return sched_clock();
}
+static __always_inline u64 local_clock_noinstr(void)
+{
+ return sched_clock_noinstr();
+}
+
static __always_inline u64 local_clock(void)
{
return sched_clock();
@@ -79,6 +93,7 @@ static inline u64 cpu_clock(int cpu)
return sched_clock_cpu(cpu);
}
+extern u64 local_clock_noinstr(void);
extern u64 local_clock(void);
#endif
@@ -266,7 +266,7 @@ static __always_inline u64 sched_clock_l
s64 delta;
again:
- now = sched_clock();
+ now = sched_clock_noinstr();
delta = now - scd->tick_raw;
if (unlikely(delta < 0))
delta = 0;
@@ -293,22 +293,29 @@ static __always_inline u64 sched_clock_l
return clock;
}
-noinstr u64 local_clock(void)
+noinstr u64 local_clock_noinstr(void)
{
u64 clock;
if (static_branch_likely(&__sched_clock_stable))
- return sched_clock() + __sched_clock_offset;
+ return sched_clock_noinstr() + __sched_clock_offset;
if (!static_branch_likely(&sched_clock_running))
- return sched_clock();
+ return sched_clock_noinstr();
- preempt_disable_notrace();
clock = sched_clock_local(this_scd());
- preempt_enable_notrace();
return clock;
}
+
+u64 local_clock(void)
+{
+ u64 now;
+ preempt_disable_notrace();
+ now = local_clock_noinstr();
+ preempt_enable_notrace();
+ return now;
+}
EXPORT_SYMBOL_GPL(local_clock);
static notrace u64 sched_clock_remote(struct sched_clock_data *scd)
Now that all ARCH_WANTS_NO_INSTR architectures (arm64, loongarch, s390, x86) provide sched_clock_noinstr(), use this to provide local_clock_noinstr(). This local_clock_noinstr() will be safe to use from noinstr code with the assumption that any such noinstr code is non-preemptible (it had better be, entry code will have IRQs disabled while __cpuidle must have preemption disabled). Specifically, preempt_enable_notrace(), a common part of many a sched_clock() implementation calls out to schedule() -- even though, per the above, it will never trigger -- which frustrates noinstr validation. vmlinux.o: warning: objtool: local_clock+0xb5: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- include/linux/sched/clock.h | 17 ++++++++++++++++- kernel/sched/clock.c | 19 +++++++++++++------ 2 files changed, 29 insertions(+), 7 deletions(-)