[PATCH 30/32] perf,perf/x86: add hook perf_event_arch_exec

[David Carrillo-Cisneros]

perf_event context switches events to newly exec'ed tasks using
perf_event_exec. Add a hook for such path.

In x86, perf_event_arch_exec is used to synchronize the software
cache of the PQR_ASSOC msr, setting the right RMID for the new task.

Reviewed-by: Stephane Eranian <eran...@google.com>
Signed-off-by: David Carrillo-Cisneros <davi...@google.com>
---
 arch/x86/include/asm/perf_event.h | 2 ++
 include/linux/perf_event.h        | 5 +++++
 kernel/events/core.c              | 1 +
 3 files changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/perf_event.h 
b/arch/x86/include/asm/perf_event.h
index 99fc206..c13f501 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -332,6 +332,8 @@ extern struct cftype perf_event_cgrp_arch_subsys_cftypes[];
        .dfl_cftypes = perf_event_cgrp_arch_subsys_cftypes, \
        .legacy_cftypes = perf_event_cgrp_arch_subsys_cftypes,
 
+#define perf_event_arch_exec pqr_update
+
 #else
 
 #define PERF_CGROUP_ARCH_CGRP_SUBSYS_ATTS
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 9c973bd..99b4393 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1289,4 +1289,9 @@ static struct device_attribute format_attr_##_name = 
__ATTR_RO(_name)
 #define PERF_CGROUP_ARCH_CGRP_SUBSYS_ATTS
 #endif
 
+#ifndef perf_event_arch_exec
+#define perf_event_arch_exec() do { } while (0)
+#endif
+
+
 #endif /* _LINUX_PERF_EVENT_H */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index cfffa50..5c675b4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3248,6 +3248,7 @@ void perf_event_exec(void)
        for_each_task_context_nr(ctxn)
                perf_event_enable_on_exec(ctxn);
        rcu_read_unlock();
+       perf_event_arch_exec();
 }
 
 struct perf_read_data {
-- 
2.8.0.rc3.226.g39d4020