[GIT PULL] perf fix

From: Ingo Molnar
Date: Fri Oct 27 2017 - 15:14:21 EST


Linus,

Please pull the latest perf-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus

# HEAD: 2eece390bf68ec8f733d7e4a3ba8a5ea350082ae perf/x86/intel/bts: Fix exclusive event reference leak

A fix for a misplaced permission check that can leave perf PT or LBR disabled (on
Intel CPUs) permanently until the next reboot.

Thanks,

Ingo

------------------>
Alexander Shishkin (1):
perf/x86/intel/bts: Fix exclusive event reference leak


arch/x86/events/intel/bts.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 16076eb34699..141e07b06216 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -546,9 +546,6 @@ static int bts_event_init(struct perf_event *event)
if (event->attr.type != bts_pmu.type)
return -ENOENT;

- if (x86_add_exclusive(x86_lbr_exclusive_bts))
- return -EBUSY;
-
/*
* BTS leaks kernel addresses even when CPL0 tracing is
* disabled, so disallow intel_bts driver for unprivileged
@@ -562,6 +559,9 @@ static int bts_event_init(struct perf_event *event)
!capable(CAP_SYS_ADMIN))
return -EACCES;

+ if (x86_add_exclusive(x86_lbr_exclusive_bts))
+ return -EBUSY;
+
ret = x86_reserve_hardware();
if (ret) {
x86_del_exclusive(x86_lbr_exclusive_bts);