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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2015-06-11 15:13:56 +0300
committerIngo Molnar <mingo@kernel.org>2015-06-19 10:38:47 +0300
commit6b099d9b040b0f3d0aec05b560d7caf879af5077 (patch)
tree4a5397edb18cbf62dfb7472b4eb28406f868d635 /arch/x86
parent4b36f1a4139c9284df74c0f5d7655603d67807df (diff)
downloadlinux-6b099d9b040b0f3d0aec05b560d7caf879af5077.tar.xz
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@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: acme@infradead.org Cc: adrian.hunter@intel.com Link: http://lkml.kernel.org/r/1434024837-9916-2-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c52
-rw-r--r--arch/x86/kernel/cpu/perf_event.h4
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel_bts.c9
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 4f7001f28936..aa4e3a74e541 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 ef78516850fb..f068695eaca0 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 ac1f0c55f379..7795f3f8b1d5 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;