[PATCH 3/4] perf_events: Support a lock_parent event flag

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

Add a new lock_parent flag to the event attribute. When it is set
account spinlocks to the parent.  This is similar to how oprofile
behaves on x86. This just reuses the oprofile code for this.

The main advantage is that it allows to make more sense of locking
problems without requiring full callgraphs.

Right now only implemented on x86.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/perf_event.c |    3 +++
 include/linux/perf_event.h       |    3 ++-
 2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 373a614..f2caa6e 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1933,6 +1933,9 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs,
 	else
 		ip = instruction_pointer(regs);
 
+	if (event->attr.lock_parent)
+		ip = __profile_pc(ip, regs);
+
 	return ip;
 }
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f8b93ec..51da085 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -219,8 +219,9 @@ struct perf_event_attr {
 				precise_ip     :  2, /* skid constraint       */
 				mmap_data      :  1, /* non-exec mmap data    */
 				sample_id_all  :  1, /* sample_type all events */
+				lock_parent    :  1, /* count locks in parent */
 
-				__reserved_1   : 45;
+				__reserved_1   : 44;
 
 	union {
 		__u32		wakeup_events;	  /* wakeup every n events */
-- 
1.7.4.4

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