[PATCH 1/2] perf/x86/intel: Fix redundant branch type check in intel_pmu_lbr_filter()

[Dapeng Mi]

In intel_pmu_lbr_filter(), the 'type' variable is bitwise ORed with
'to_plm' (which contains X86_BR_USER and/or X86_BR_KERNEL bits). Because
of this, 'type' can never equal X86_BR_NONE (0) after the assignment.

As a result, the subsequent check 'if (type == X86_BR_NONE)' is dead code
and the entries with X86_BR_NONE type would not be skipped eventually.

Correct this by masking out the X86_BR_KERNEL and X86_BR_USER bits
before performing the X86_BR_NONE comparison.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 47125db27e47 ("perf/x86/intel/lbr: Support Architectural LBR")
Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
 arch/x86/events/intel/lbr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 72f2adcda7c6..16977e4c6f8a 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1245,7 +1245,7 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
 		}
 
 		/* if type does not correspond, then discard */
-		if (type == X86_BR_NONE || (br_sel & type) != type) {
+		if ((type & ~X86_BR_PLM) == X86_BR_NONE || (br_sel & type) != type) {
 			cpuc->lbr_entries[i].from = 0;
 			compress = true;
 		}
-- 
2.34.1