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authorTristan Hume <tristan@thume.ca>2022-01-27 17:08:06 -0500
committerPeter Zijlstra <peterz@infradead.org>2022-02-02 13:11:40 +0100
commit1d9093457b243061a9bba23543c38726e864a643 (patch)
tree614f8cd4fe5fe58686035bedad67d331b5f492dc /arch
parentddecd22878601a606d160680fa85802b75d92eb6 (diff)
perf/x86/intel/pt: Fix crash with stop filters in single-range mode
Add a check for !buf->single before calling pt_buffer_region_size in a place where a missing check can cause a kernel crash. Fixes a bug introduced by commit 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode"), which added a support for PT single-range output mode. Since that commit if a PT stop filter range is hit while tracing, the kernel will crash because of a null pointer dereference in pt_handle_status due to calling pt_buffer_region_size without a ToPA configured. The commit which introduced single-range mode guarded almost all uses of the ToPA buffer variables with checks of the buf->single variable, but missed the case where tracing was stopped by the PT hardware, which happens when execution hits a configured stop filter. Tested that hitting a stop filter while PT recording successfully records a trace with this patch but crashes without this patch. Fixes: 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode") Signed-off-by: Tristan Hume <tristan@thume.ca> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@kernel.org Link: https://lkml.kernel.org/r/20220127220806.73664-1-tristan@thume.ca
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/events/intel/pt.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 7f406c14715f..2d33bba9a144 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -897,8 +897,9 @@ static void pt_handle_status(struct pt *pt)
* means we are already losing data; need to let the decoder
* know.
*/
- if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) ||
- buf->output_off == pt_buffer_region_size(buf)) {
+ if (!buf->single &&
+ (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) ||
+ buf->output_off == pt_buffer_region_size(buf))) {
perf_aux_output_flag(&pt->handle,
PERF_AUX_FLAG_TRUNCATED);
advance++;