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Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull perf fixes from Ingo Molnar:
 "Four fixes.  The mmap ones are unfortunately larger than desired -
  fuzzing uncovered bugs that needed perf context life time management
  changes to fix properly"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Fix broken PEBS-LL support on SNB-EP/IVB-EP
  perf: Fix mmap() accounting hole
  perf: Fix perf mmap bugs
  kprobes: Fix to free gone and unused optprobes
This commit is contained in:
Linus Torvalds 2013-06-20 08:17:36 -10:00
commit 86c76676cf
5 changed files with 188 additions and 86 deletions
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2
arch/x86/kernel/cpu/perf_event_intel.c
View File

@ -165,13 +165,13 @@ static struct extra_reg intel_snb_extra_regs[] __read_mostly = {
INTEL_EVENT_EXTRA_REG(0xb7, MSR_OFFCORE_RSP_0, 0x3f807f8fffull, RSP_0),
INTEL_EVENT_EXTRA_REG(0xbb, MSR_OFFCORE_RSP_1, 0x3f807f8fffull, RSP_1),
INTEL_UEVENT_PEBS_LDLAT_EXTRA_REG(0x01cd),
INTEL_UEVENT_PEBS_LDLAT_EXTRA_REG(0x01cd),
EVENT_EXTRA_END
};
static struct extra_reg intel_snbep_extra_regs[] __read_mostly = {
INTEL_EVENT_EXTRA_REG(0xb7, MSR_OFFCORE_RSP_0, 0x3fffff8fffull, RSP_0),
INTEL_EVENT_EXTRA_REG(0xbb, MSR_OFFCORE_RSP_1, 0x3fffff8fffull, RSP_1),
INTEL_UEVENT_PEBS_LDLAT_EXTRA_REG(0x01cd),
EVENT_EXTRA_END
};

3
include/linux/perf_event.h
View File

@ -389,8 +389,7 @@ struct perf_event {
/* mmap bits */
struct mutex mmap_mutex;
atomic_t mmap_count;
int mmap_locked;
struct user_struct *mmap_user;
struct ring_buffer *rb;
struct list_head rb_entry;

235
kernel/events/core.c
View File

@ -196,9 +196,6 @@ static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
static void update_context_time(struct perf_event_context *ctx);
static u64 perf_event_time(struct perf_event *event);
static void ring_buffer_attach(struct perf_event *event,
struct ring_buffer *rb);
void __weak perf_event_print_debug(void) { }
extern __weak const char *perf_pmu_name(void)
@ -2918,6 +2915,7 @@ static void free_event_rcu(struct rcu_head *head)
}
static void ring_buffer_put(struct ring_buffer *rb);
static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb);
static void free_event(struct perf_event *event)
{
@ -2942,15 +2940,30 @@ static void free_event(struct perf_event *event)
if (has_branch_stack(event)) {
static_key_slow_dec_deferred(&perf_sched_events);
/* is system-wide event */
if (!(event->attach_state & PERF_ATTACH_TASK))
if (!(event->attach_state & PERF_ATTACH_TASK)) {
atomic_dec(&per_cpu(perf_branch_stack_events,
event->cpu));
}
}
}
if (event->rb) {
ring_buffer_put(event->rb);
event->rb = NULL;
struct ring_buffer *rb;
/*
* Can happen when we close an event with re-directed output.
*
* Since we have a 0 refcount, perf_mmap_close() will skip
* over us; possibly making our ring_buffer_put() the last.
*/
mutex_lock(&event->mmap_mutex);
rb = event->rb;
if (rb) {
rcu_assign_pointer(event->rb, NULL);
ring_buffer_detach(event, rb);
ring_buffer_put(rb); /* could be last */
}
mutex_unlock(&event->mmap_mutex);
}
if (is_cgroup_event(event))
@ -3188,30 +3201,13 @@ static unsigned int perf_poll(struct file *file, poll_table *wait)
unsigned int events = POLL_HUP;
/*
* Race between perf_event_set_output() and perf_poll(): perf_poll()
* grabs the rb reference but perf_event_set_output() overrides it.
* Here is the timeline for two threads T1, T2:
* t0: T1, rb = rcu_dereference(event->rb)
* t1: T2, old_rb = event->rb
* t2: T2, event->rb = new rb
* t3: T2, ring_buffer_detach(old_rb)
* t4: T1, ring_buffer_attach(rb1)
* t5: T1, poll_wait(event->waitq)
*
* To avoid this problem, we grab mmap_mutex in perf_poll()
* thereby ensuring that the assignment of the new ring buffer
* and the detachment of the old buffer appear atomic to perf_poll()
* Pin the event->rb by taking event->mmap_mutex; otherwise
* perf_event_set_output() can swizzle our rb and make us miss wakeups.
*/
mutex_lock(&event->mmap_mutex);
rcu_read_lock();
rb = rcu_dereference(event->rb);
if (rb) {
ring_buffer_attach(event, rb);
rb = event->rb;
if (rb)
events = atomic_xchg(&rb->poll, 0);
}
rcu_read_unlock();
mutex_unlock(&event->mmap_mutex);
poll_wait(file, &event->waitq, wait);
@ -3521,16 +3517,12 @@ static void ring_buffer_attach(struct perf_event *event,
return;
spin_lock_irqsave(&rb->event_lock, flags);
if (!list_empty(&event->rb_entry))
goto unlock;
list_add(&event->rb_entry, &rb->event_list);
unlock:
if (list_empty(&event->rb_entry))
list_add(&event->rb_entry, &rb->event_list);
spin_unlock_irqrestore(&rb->event_lock, flags);
}
static void ring_buffer_detach(struct perf_event *event,
struct ring_buffer *rb)
static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb)
{
unsigned long flags;
@ -3549,13 +3541,10 @@ static void ring_buffer_wakeup(struct perf_event *event)
rcu_read_lock();
rb = rcu_dereference(event->rb);
if (!rb)
goto unlock;
list_for_each_entry_rcu(event, &rb->event_list, rb_entry)
wake_up_all(&event->waitq);
unlock:
if (rb) {
list_for_each_entry_rcu(event, &rb->event_list, rb_entry)
wake_up_all(&event->waitq);
}
rcu_read_unlock();
}
@ -3584,18 +3573,10 @@ static struct ring_buffer *ring_buffer_get(struct perf_event *event)
static void ring_buffer_put(struct ring_buffer *rb)
{
struct perf_event *event, *n;
unsigned long flags;
if (!atomic_dec_and_test(&rb->refcount))
return;
spin_lock_irqsave(&rb->event_lock, flags);
list_for_each_entry_safe(event, n, &rb->event_list, rb_entry) {
list_del_init(&event->rb_entry);
wake_up_all(&event->waitq);
}
spin_unlock_irqrestore(&rb->event_lock, flags);
WARN_ON_ONCE(!list_empty(&rb->event_list));
call_rcu(&rb->rcu_head, rb_free_rcu);
}
@ -3605,26 +3586,100 @@ static void perf_mmap_open(struct vm_area_struct *vma)
struct perf_event *event = vma->vm_file->private_data;
atomic_inc(&event->mmap_count);
atomic_inc(&event->rb->mmap_count);
}
/*
* A buffer can be mmap()ed multiple times; either directly through the same
* event, or through other events by use of perf_event_set_output().
*
* In order to undo the VM accounting done by perf_mmap() we need to destroy
* the buffer here, where we still have a VM context. This means we need
* to detach all events redirecting to us.
*/
static void perf_mmap_close(struct vm_area_struct *vma)
{
struct perf_event *event = vma->vm_file->private_data;
if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
unsigned long size = perf_data_size(event->rb);
struct user_struct *user = event->mmap_user;
struct ring_buffer *rb = event->rb;
struct ring_buffer *rb = event->rb;
struct user_struct *mmap_user = rb->mmap_user;
int mmap_locked = rb->mmap_locked;
unsigned long size = perf_data_size(rb);
atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
vma->vm_mm->pinned_vm -= event->mmap_locked;
rcu_assign_pointer(event->rb, NULL);
ring_buffer_detach(event, rb);
mutex_unlock(&event->mmap_mutex);
atomic_dec(&rb->mmap_count);
ring_buffer_put(rb);
free_uid(user);
if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
return;
/* Detach current event from the buffer. */
rcu_assign_pointer(event->rb, NULL);
ring_buffer_detach(event, rb);
mutex_unlock(&event->mmap_mutex);
/* If there's still other mmap()s of this buffer, we're done. */
if (atomic_read(&rb->mmap_count)) {
ring_buffer_put(rb); /* can't be last */
return;
}
/*
* No other mmap()s, detach from all other events that might redirect
* into the now unreachable buffer. Somewhat complicated by the
* fact that rb::event_lock otherwise nests inside mmap_mutex.
*/
again:
rcu_read_lock();
list_for_each_entry_rcu(event, &rb->event_list, rb_entry) {
if (!atomic_long_inc_not_zero(&event->refcount)) {
/*
* This event is en-route to free_event() which will
* detach it and remove it from the list.
*/
continue;
}
rcu_read_unlock();
mutex_lock(&event->mmap_mutex);
/*
* Check we didn't race with perf_event_set_output() which can
* swizzle the rb from under us while we were waiting to
* acquire mmap_mutex.
*
* If we find a different rb; ignore this event, a next
* iteration will no longer find it on the list. We have to
* still restart the iteration to make sure we're not now
* iterating the wrong list.
*/
if (event->rb == rb) {
rcu_assign_pointer(event->rb, NULL);
ring_buffer_detach(event, rb);
ring_buffer_put(rb); /* can't be last, we still have one */
}
mutex_unlock(&event->mmap_mutex);
put_event(event);
/*
* Restart the iteration; either we're on the wrong list or
* destroyed its integrity by doing a deletion.
*/
goto again;
}
rcu_read_unlock();
/*
* It could be there's still a few 0-ref events on the list; they'll
* get cleaned up by free_event() -- they'll also still have their
* ref on the rb and will free it whenever they are done with it.
*
* Aside from that, this buffer is 'fully' detached and unmapped,
* undo the VM accounting.
*/
atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm);
vma->vm_mm->pinned_vm -= mmap_locked;
free_uid(mmap_user);
ring_buffer_put(rb); /* could be last */
}
static const struct vm_operations_struct perf_mmap_vmops = {
@ -3674,12 +3729,24 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
return -EINVAL;
WARN_ON_ONCE(event->ctx->parent_ctx);
again:
mutex_lock(&event->mmap_mutex);
if (event->rb) {
if (event->rb->nr_pages == nr_pages)
atomic_inc(&event->rb->refcount);
else
if (event->rb->nr_pages != nr_pages) {
ret = -EINVAL;
goto unlock;
}
if (!atomic_inc_not_zero(&event->rb->mmap_count)) {
/*
* Raced against perf_mmap_close() through
* perf_event_set_output(). Try again, hope for better
* luck.
*/
mutex_unlock(&event->mmap_mutex);
goto again;
}
goto unlock;
}
@ -3720,12 +3787,16 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
ret = -ENOMEM;
goto unlock;
}
rcu_assign_pointer(event->rb, rb);
atomic_set(&rb->mmap_count, 1);
rb->mmap_locked = extra;
rb->mmap_user = get_current_user();
atomic_long_add(user_extra, &user->locked_vm);
event->mmap_locked = extra;
event->mmap_user = get_current_user();
vma->vm_mm->pinned_vm += event->mmap_locked;
vma->vm_mm->pinned_vm += extra;
ring_buffer_attach(event, rb);
rcu_assign_pointer(event->rb, rb);
perf_event_update_userpage(event);
@ -3734,7 +3805,11 @@ unlock:
atomic_inc(&event->mmap_count);
mutex_unlock(&event->mmap_mutex);
vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
/*
* Since pinned accounting is per vm we cannot allow fork() to copy our
* vma.
*/
vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = &perf_mmap_vmops;
return ret;
@ -6412,6 +6487,8 @@ set:
if (atomic_read(&event->mmap_count))
goto unlock;
old_rb = event->rb;
if (output_event) {
/* get the rb we want to redirect to */
rb = ring_buffer_get(output_event);
@ -6419,16 +6496,28 @@ set:
goto unlock;
}
old_rb = event->rb;
rcu_assign_pointer(event->rb, rb);
if (old_rb)
ring_buffer_detach(event, old_rb);
if (rb)
ring_buffer_attach(event, rb);
rcu_assign_pointer(event->rb, rb);
if (old_rb) {
ring_buffer_put(old_rb);
/*
* Since we detached before setting the new rb, so that we
* could attach the new rb, we could have missed a wakeup.
* Provide it now.
*/
wake_up_all(&event->waitq);
}
ret = 0;
unlock:
mutex_unlock(&event->mmap_mutex);
if (old_rb)
ring_buffer_put(old_rb);
out:
return ret;
}

4
kernel/events/internal.h
View File

@ -31,6 +31,10 @@ struct ring_buffer {
spinlock_t event_lock;
struct list_head event_list;
atomic_t mmap_count;
unsigned long mmap_locked;
struct user_struct *mmap_user;
struct perf_event_mmap_page *user_page;
void *data_pages[0];
};

30
kernel/kprobes.c
View File

@ -467,6 +467,7 @@ static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
/* Optimization staging list, protected by kprobe_mutex */
static LIST_HEAD(optimizing_list);
static LIST_HEAD(unoptimizing_list);
static LIST_HEAD(freeing_list);
static void kprobe_optimizer(struct work_struct *work);
static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
@ -504,7 +505,7 @@ static __kprobes void do_optimize_kprobes(void)
* Unoptimize (replace a jump with a breakpoint and remove the breakpoint
* if need) kprobes listed on unoptimizing_list.
*/
static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
static __kprobes void do_unoptimize_kprobes(void)
{
struct optimized_kprobe *op, *tmp;
@ -515,9 +516,9 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
/* Ditto to do_optimize_kprobes */
get_online_cpus();
mutex_lock(&text_mutex);
arch_unoptimize_kprobes(&unoptimizing_list, free_list);
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop free_list for disarming */
list_for_each_entry_safe(op, tmp, free_list, list) {
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
/* Disarm probes if marked disabled */
if (kprobe_disabled(&op->kp))
arch_disarm_kprobe(&op->kp);
@ -536,11 +537,11 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
}
/* Reclaim all kprobes on the free_list */
static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
static __kprobes void do_free_cleaned_kprobes(void)
{
struct optimized_kprobe *op, *tmp;
list_for_each_entry_safe(op, tmp, free_list, list) {
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
BUG_ON(!kprobe_unused(&op->kp));
list_del_init(&op->list);
free_aggr_kprobe(&op->kp);
@ -556,8 +557,6 @@ static __kprobes void kick_kprobe_optimizer(void)
/* Kprobe jump optimizer */
static __kprobes void kprobe_optimizer(struct work_struct *work)
{
LIST_HEAD(free_list);
mutex_lock(&kprobe_mutex);
/* Lock modules while optimizing kprobes */
mutex_lock(&module_mutex);
@ -566,7 +565,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
* Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
* kprobes before waiting for quiesence period.
*/
do_unoptimize_kprobes(&free_list);
do_unoptimize_kprobes();
/*
* Step 2: Wait for quiesence period to ensure all running interrupts
@ -581,7 +580,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
do_optimize_kprobes();
/* Step 4: Free cleaned kprobes after quiesence period */
do_free_cleaned_kprobes(&free_list);
do_free_cleaned_kprobes();
mutex_unlock(&module_mutex);
mutex_unlock(&kprobe_mutex);
@ -723,8 +722,19 @@ static void __kprobes kill_optimized_kprobe(struct kprobe *p)
if (!list_empty(&op->list))
/* Dequeue from the (un)optimization queue */
list_del_init(&op->list);
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
if (kprobe_unused(p)) {
/* Enqueue if it is unused */
list_add(&op->list, &freeing_list);
/*
* Remove unused probes from the hash list. After waiting
* for synchronization, this probe is reclaimed.
* (reclaiming is done by do_free_cleaned_kprobes().)
*/
hlist_del_rcu(&op->kp.hlist);
}
/* Don't touch the code, because it is already freed. */
arch_remove_optimized_kprobe(op);
}