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author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2015-06-11 15:13:56 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-06-19 09:38:47 +0200 |
commit | 6b099d9b040b0f3d0aec05b560d7caf879af5077 (patch) | |
tree | 4a5397edb18cbf62dfb7472b4eb28406f868d635 | |
parent | 4b36f1a4139c9284df74c0f5d7655603d67807df (diff) | |
download | op-kernel-dev-6b099d9b040b0f3d0aec05b560d7caf879af5077.zip op-kernel-dev-6b099d9b040b0f3d0aec05b560d7caf879af5077.tar.gz |
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>
-rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 52 | ||||
-rw-r--r-- | arch/x86/kernel/cpu/perf_event.h | 4 | ||||
-rw-r--r-- | 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; |