Commit-ID: bfe334924ccd9f4a53f30240c03cf2f43f5b2df1
Gitweb: http://git.kernel.org/tip/bfe334924ccd9f4a53f30240c03cf2f43f5b2df1
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 2 Aug 2017 19:39:30 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 10 Aug 2017 12:01:08 +0200
perf/x86: Fix RDPMC vs. mm_struct tracking
Vince reported the following rdpmc() testcase failure:
> Failing test case:
>
> fd=perf_event_open();
> addr=mmap(fd);
> exec() // without closing or unmapping the event
> fd=perf_event_open();
> addr=mmap(fd);
> rdpmc() // GPFs due to rdpmc being disabled
The problem is of course that exec() plays tricks with what is
current->mm, only destroying the old mappings after having
installed the new mm.
Fix this confusion by passing along vma->vm_mm instead of relying on
current->mm.
Reported-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Tested-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 1e0fb9ec679c ("perf: Add pmu callbacks to track event mapping and unmapping")
Link: http://lkml.kernel.org/r/20170802173930.cstykcqefmqt7jau@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[ Minor cleanups. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/events/core.c | 16 +++++++---------
include/linux/perf_event.h | 4 ++--
kernel/events/core.c | 6 +++---
3 files changed, 12 insertions(+), 14 deletions(-)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 8e3db8f..af12e29 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2114,7 +2114,7 @@ static void refresh_pce(void *ignored)
load_mm_cr4(this_cpu_read(cpu_tlbstate.loaded_mm));
}
-static void x86_pmu_event_mapped(struct perf_event *event)
+static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
{
if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
return;
@@ -2129,22 +2129,20 @@ static void x86_pmu_event_mapped(struct perf_event *event)
* For now, this can't happen because all callers hold mmap_sem
* for write. If this changes, we'll need a different solution.
*/
- lockdep_assert_held_exclusive(¤t->mm->mmap_sem);
+ lockdep_assert_held_exclusive(&mm->mmap_sem);
- if (atomic_inc_return(¤t->mm->context.perf_rdpmc_allowed) == 1)
- on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+ if (atomic_inc_return(&mm->context.perf_rdpmc_allowed) == 1)
+ on_each_cpu_mask(mm_cpumask(mm), refresh_pce, NULL, 1);
}
-static void x86_pmu_event_unmapped(struct perf_event *event)
+static void x86_pmu_event_unmapped(struct perf_event *event, struct mm_struct *mm)
{
- if (!current->mm)
- return;
if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
return;
- if (atomic_dec_and_test(¤t->mm->context.perf_rdpmc_allowed))
- on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+ if (atomic_dec_and_test(&mm->context.perf_rdpmc_allowed))
+ on_each_cpu_mask(mm_cpumask(mm), refresh_pce, NULL, 1);
}
static int x86_pmu_event_idx(struct perf_event *event)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index a3b873f..b14095b 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -310,8 +310,8 @@ struct pmu {
* Notification that the event was mapped or unmapped. Called
* in the context of the mapping task.
*/
- void (*event_mapped) (struct perf_event *event); /*optional*/
- void (*event_unmapped) (struct perf_event *event); /*optional*/
+ void (*event_mapped) (struct perf_event *event, struct mm_struct *mm); /* optional */
+ void (*event_unmapped) (struct perf_event *event, struct mm_struct *mm); /* optional */
/*
* Flags for ->add()/->del()/ ->start()/->stop(). There are
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 426c2ff..a654b8a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5090,7 +5090,7 @@ static void perf_mmap_open(struct vm_area_struct *vma)
atomic_inc(&event->rb->aux_mmap_count);
if (event->pmu->event_mapped)
- event->pmu->event_mapped(event);
+ event->pmu->event_mapped(event, vma->vm_mm);
}
static void perf_pmu_output_stop(struct perf_event *event);
@@ -5113,7 +5113,7 @@ static void perf_mmap_close(struct vm_area_struct *vma)
unsigned long size = perf_data_size(rb);
if (event->pmu->event_unmapped)
- event->pmu->event_unmapped(event);
+ event->pmu->event_unmapped(event, vma->vm_mm);
/*
* rb->aux_mmap_count will always drop before rb->mmap_count and
@@ -5411,7 +5411,7 @@ aux_unlock:
vma->vm_ops = &perf_mmap_vmops;
if (event->pmu->event_mapped)
- event->pmu->event_mapped(event);
+ event->pmu->event_mapped(event, vma->vm_mm);
return ret;
}
--
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