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Message-ID: <tip-6b099d9b040b0f3d0aec05b560d7caf879af5077@git.kernel.org>
Date: Fri, 19 Jun 2015 10:58:19 -0700
From: tip-bot for Alexander Shishkin <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: dvlasenk@...hat.com, luto@...capital.net, peterz@...radead.org,
mingo@...nel.org, akpm@...ux-foundation.org, oleg@...hat.com,
linux-kernel@...r.kernel.org, brgerst@...il.com, hpa@...or.com,
alexander.shishkin@...ux.intel.com, tglx@...utronix.de,
bp@...en8.de, torvalds@...ux-foundation.org
Subject: [tip:perf/urgent] perf/x86/intel/bts:
Fix DS area sharing with x86_pmu events
Commit-ID: 6b099d9b040b0f3d0aec05b560d7caf879af5077
Gitweb: http://git.kernel.org/tip/6b099d9b040b0f3d0aec05b560d7caf879af5077
Author: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
AuthorDate: Thu, 11 Jun 2015 15:13:56 +0300
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 19 Jun 2015 09:38:47 +0200
perf/x86/intel/bts: Fix DS area sharing with x86_pmu events
Currently, the intel_bts driver relies on the DS area allocated by the x86_pmu
code in its event_init() path, which is a bug: creating a BTS event while
no x86_pmu events are present results in a NULL pointer dereference.
The same DS area is also used by PEBS sampling, which makes it quite a bit
trickier to have a separate one for intel_bts' purposes.
This patch makes intel_bts driver use the same DS allocation and reference
counting code as x86_pmu to make sure it is always present when either
intel_bts or x86_pmu need it.
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: acme@...radead.org
Cc: adrian.hunter@...el.com
Link: http://lkml.kernel.org/r/1434024837-9916-2-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/kernel/cpu/perf_event.c | 52 +++++++++++++++++++-----------
arch/x86/kernel/cpu/perf_event.h | 4 +++
arch/x86/kernel/cpu/perf_event_intel_bts.c | 9 ++++++
3 files changed, 46 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 4f7001f..aa4e3a7 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -270,11 +270,7 @@ msr_fail:
static void hw_perf_event_destroy(struct perf_event *event)
{
- if (atomic_dec_and_mutex_lock(&active_events, &pmc_reserve_mutex)) {
- release_pmc_hardware();
- release_ds_buffers();
- mutex_unlock(&pmc_reserve_mutex);
- }
+ x86_release_hardware();
}
void hw_perf_lbr_event_destroy(struct perf_event *event)
@@ -324,6 +320,35 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
return x86_pmu_extra_regs(val, event);
}
+int x86_reserve_hardware(void)
+{
+ int err = 0;
+
+ if (!atomic_inc_not_zero(&active_events)) {
+ mutex_lock(&pmc_reserve_mutex);
+ if (atomic_read(&active_events) == 0) {
+ if (!reserve_pmc_hardware())
+ err = -EBUSY;
+ else
+ reserve_ds_buffers();
+ }
+ if (!err)
+ atomic_inc(&active_events);
+ mutex_unlock(&pmc_reserve_mutex);
+ }
+
+ return err;
+}
+
+void x86_release_hardware(void)
+{
+ if (atomic_dec_and_mutex_lock(&active_events, &pmc_reserve_mutex)) {
+ release_pmc_hardware();
+ release_ds_buffers();
+ mutex_unlock(&pmc_reserve_mutex);
+ }
+}
+
/*
* Check if we can create event of a certain type (that no conflicting events
* are present).
@@ -336,9 +361,10 @@ int x86_add_exclusive(unsigned int what)
return 0;
mutex_lock(&pmc_reserve_mutex);
- for (i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++)
+ for (i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++) {
if (i != what && atomic_read(&x86_pmu.lbr_exclusive[i]))
goto out;
+ }
atomic_inc(&x86_pmu.lbr_exclusive[what]);
ret = 0;
@@ -527,19 +553,7 @@ static int __x86_pmu_event_init(struct perf_event *event)
if (!x86_pmu_initialized())
return -ENODEV;
- err = 0;
- if (!atomic_inc_not_zero(&active_events)) {
- mutex_lock(&pmc_reserve_mutex);
- if (atomic_read(&active_events) == 0) {
- if (!reserve_pmc_hardware())
- err = -EBUSY;
- else
- reserve_ds_buffers();
- }
- if (!err)
- atomic_inc(&active_events);
- mutex_unlock(&pmc_reserve_mutex);
- }
+ err = x86_reserve_hardware();
if (err)
return err;
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index ef78516..f068695 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -703,6 +703,10 @@ int x86_add_exclusive(unsigned int what);
void x86_del_exclusive(unsigned int what);
+int x86_reserve_hardware(void);
+
+void x86_release_hardware(void);
+
void hw_perf_lbr_event_destroy(struct perf_event *event);
int x86_setup_perfctr(struct perf_event *event);
diff --git a/arch/x86/kernel/cpu/perf_event_intel_bts.c b/arch/x86/kernel/cpu/perf_event_intel_bts.c
index ac1f0c5..7795f3f 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_bts.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_bts.c
@@ -483,17 +483,26 @@ static int bts_event_add(struct perf_event *event, int mode)
static void bts_event_destroy(struct perf_event *event)
{
+ x86_release_hardware();
x86_del_exclusive(x86_lbr_exclusive_bts);
}
static int bts_event_init(struct perf_event *event)
{
+ int ret;
+
if (event->attr.type != bts_pmu.type)
return -ENOENT;
if (x86_add_exclusive(x86_lbr_exclusive_bts))
return -EBUSY;
+ ret = x86_reserve_hardware();
+ if (ret) {
+ x86_del_exclusive(x86_lbr_exclusive_bts);
+ return ret;
+ }
+
event->destroy = bts_event_destroy;
return 0;
--
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