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authorPeter Zijlstra <peterz@infradead.org>2020-10-30 13:43:16 +0100
committerPeter Zijlstra <peterz@infradead.org>2020-11-09 18:12:34 +0100
commit09da9c81253dd8e43e0d2d7cea02de6f9f19499d (patch)
treeed3c3929c7ceefb88bab0e7c35fcd238f5467ac4 /kernel/events
parentce0f17fc93f63ee91428af10b7b2ddef38cd19e5 (diff)
perf: Optimize get_recursion_context()
"Look ma, no branches!" Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Link: https://lkml.kernel.org/r/20201030151955.187580298@infradead.org
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/internal.h16
1 files changed, 6 insertions, 10 deletions
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 402054e755f2..228801e20788 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -205,16 +205,12 @@ DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)
static inline int get_recursion_context(int *recursion)
{
- int rctx;
-
- if (unlikely(in_nmi()))
- rctx = 3;
- else if (in_irq())
- rctx = 2;
- else if (in_serving_softirq())
- rctx = 1;
- else
- rctx = 0;
+ unsigned int pc = preempt_count();
+ unsigned char rctx = 0;
+
+ rctx += !!(pc & (NMI_MASK));
+ rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK));
+ rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET));
if (recursion[rctx])
return -1;