perf: Fix hypervisor branch sampling permission check

Commit 2b923c8 perf/x86: Check branch sampling priv level in generic code
was missing the check for the hypervisor (HV) priv level, so add it back.

With this patch, we get the following correct behavior:

  # echo 2 >/proc/sys/kernel/perf_event_paranoid

  $ perf record -j any,k noploop 1
  Error:
  You may not have permission to collect stats.
  Consider tweaking /proc/sys/kernel/perf_event_paranoid:
   -1 - Not paranoid at all
    0 - Disallow raw tracepoint access for unpriv
    1 - Disallow cpu events for unpriv
    2 - Disallow kernel profiling for unpriv

   $ perf record -j any,hv noploop 1
   Error:
   You may not have permission to collect stats.
   Consider tweaking /proc/sys/kernel/perf_event_paranoid:
    -1 - Not paranoid at all
     0 - Disallow raw tracepoint access for unpriv
     1 - Disallow cpu events for unpriv
     2 - Disallow kernel profiling for unpriv

Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Petr Matousek <pmatouse@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130606090204.GA3725@quad
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d0e0d0d2025fb0786a5957b0edee4cc3055c5156..aca95bce34c89f6dde0f922bd8b53d5848133de3 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6573,8 +6573,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
                         */
                        attr->branch_sample_type = mask;
                }
-               /* kernel level capture: check permissions */
-               if ((mask & PERF_SAMPLE_BRANCH_KERNEL)
+               /* privileged levels capture (kernel, hv): check permissions */
+               if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
                    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
                        return -EACCES;
        }