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

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Pull x86 perf updates from Ingo Molnar:
 "This series tightens up RDPMC permissions: currently even highly
  sandboxed x86 execution environments (such as seccomp) have permission
  to execute RDPMC, which may leak various perf events / PMU state such
  as timing information and other CPU execution details.

  This 'all is allowed' RDPMC mode is still preserved as the
  (non-default) /sys/devices/cpu/rdpmc=2 setting.  The new default is
  that RDPMC access is only allowed if a perf event is mmap-ed (which is
  needed to correctly interpret RDPMC counter values in any case).

  As a side effect of these changes CR4 handling is cleaned up in the
  x86 code and a shadow copy of the CR4 value is added.

  The extra CR4 manipulation adds ~ <50ns to the context switch cost
  between rdpmc-capable and rdpmc-non-capable mms"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks
  perf/x86: Only allow rdpmc if a perf_event is mapped
  perf: Pass the event to arch_perf_update_userpage()
  perf: Add pmu callbacks to track event mapping and unmapping
  x86: Add a comment clarifying LDT context switching
  x86: Store a per-cpu shadow copy of CR4
  x86: Clean up cr4 manipulation
This commit is contained in:
Linus Torvalds
2015-02-16 14:58:12 -08:00
parent a68fb48380 a66734297f
commit 37507717de
35 changed files with 253 additions and 120 deletions
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14
kernel/events/core.c
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@@ -4101,7 +4101,8 @@ unlock:
rcu_read_unlock();
}
void __weak arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
void __weak arch_perf_update_userpage(
struct perf_event *event, struct perf_event_mmap_page *userpg, u64 now)
{
}
@@ -4151,7 +4152,7 @@ void perf_event_update_userpage(struct perf_event *event)
userpg->time_running = running +
atomic64_read(&event->child_total_time_running);
arch_perf_update_userpage(userpg, now);
arch_perf_update_userpage(event, userpg, now);
barrier();
++userpg->lock;
@@ -4293,6 +4294,9 @@ static void perf_mmap_open(struct vm_area_struct *vma)
atomic_inc(&event->mmap_count);
atomic_inc(&event->rb->mmap_count);
if (event->pmu->event_mapped)
event->pmu->event_mapped(event);
}
/*
@@ -4312,6 +4316,9 @@ static void perf_mmap_close(struct vm_area_struct *vma)
int mmap_locked = rb->mmap_locked;
unsigned long size = perf_data_size(rb);
if (event->pmu->event_unmapped)
event->pmu->event_unmapped(event);
atomic_dec(&rb->mmap_count);
if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
@@ -4513,6 +4520,9 @@ unlock:
vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = &perf_mmap_vmops;
if (event->pmu->event_mapped)
event->pmu->event_mapped(event);
return ret;
}