perf intel-pt: Fix unassigned instruction op (discovered by MemorySanitizer)

MemorySanitizer discovered instances where the instruction op value was
not assigned.:

  WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5581c00a76b3 in intel_pt_sample_flags tools/perf/util/intel-pt.c:1527:17
  Uninitialized value was stored to memory at
    #0 0x5581c005ddf8 in intel_pt_walk_insn tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:1256:25

The op value is used to set branch flags for branch instructions
encountered when walking the code, so fix by setting op to
INTEL_PT_OP_OTHER in other cases.

Fixes: 4c761d805bb2d2ea ("perf intel-pt: Fix intel_pt_fup_event() assumptions about setting state type")
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Closes: https://lore.kernel.org/linux-perf-users/20240320162619.1272015-1-irogers@google.com/
Link: https://lore.kernel.org/r/20240326083223.10883-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index b450178e3420baa00fdb32dcc61bd230f858cdbb..e733f6b1f7ac5816a1f3322d4ae308c9cbc21fe4 100644 (file)
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1319,6 +1319,8 @@ static bool intel_pt_fup_event(struct intel_pt_decoder *decoder, bool no_tip)
        bool ret = false;
 
        decoder->state.type &= ~INTEL_PT_BRANCH;
+       decoder->state.insn_op = INTEL_PT_OP_OTHER;
+       decoder->state.insn_len = 0;
 
        if (decoder->set_fup_cfe_ip || decoder->set_fup_cfe) {
                bool ip = decoder->set_fup_cfe_ip;

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index f38893e0b036921cd3f576a2905b38cfde74003f..4db9a098f592620974a68eb881862001970b5bcc 100644 (file)
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -764,6 +764,7 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
 
        addr_location__init(&al);
        intel_pt_insn->length = 0;
+       intel_pt_insn->op = INTEL_PT_OP_OTHER;
 
        if (to_ip && *ip == to_ip)
                goto out_no_cache;
@@ -898,6 +899,7 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
 
                        if (to_ip && *ip == to_ip) {
                                intel_pt_insn->length = 0;
+                               intel_pt_insn->op = INTEL_PT_OP_OTHER;
                                goto out_no_cache;
                        }