From ce3ea6b66ded81e8c61897fae81e2173368487a1 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Wed, 19 May 2021 10:45:14 +0300 Subject: [PATCH] perf intel-pt: Fix sample instruction bytes commit c954eb72b31a9dc56c99b450253ec5b121add320 upstream. The decoder reports the current instruction if it was decoded. In some cases the current instruction is not decoded, in which case the instruction bytes length must be set to zero. Ensure that is always done. Note perf script can anyway get the instruction bytes for any samples where they are not present. Also note, that there is a redundant "ptq->insn_len = 0" statement which is not removed until a subsequent patch in order to make this patch apply cleanly to stable branches. Example: A machne that supports TSX is required. It will have flag "rtm". Kernel parameter tsx=on may be required. # for w in `cat /proc/cpuinfo | grep -m1 flags `;do echo $w | grep rtm ; done rtm Test program: #include #include int main() { int x = 0; if (_xbegin() == _XBEGIN_STARTED) { x = 1; _xabort(1); } else { printf("x = %d\n", x); } return 0; } Compile with -mrtm i.e. gcc -Wall -Wextra -mrtm xabort.c -o xabort Record: perf record -e intel_pt/cyc/u --filter 'filter main @ ./xabort' ./xabort Before: # perf script --itrace=xe -F+flags,+insn,-period --xed --ns xabort 1478 [007] 92161.431348581: transactions: x 400b81 main+0x14 (/root/xabort) mov $0xffffffff, %eax xabort 1478 [007] 92161.431348624: transactions: tx abrt 400b93 main+0x26 (/root/xabort) mov $0xffffffff, %eax After: # perf script --itrace=xe -F+flags,+insn,-period --xed --ns xabort 1478 [007] 92161.431348581: transactions: x 400b81 main+0x14 (/root/xabort) xbegin 0x6 xabort 1478 [007] 92161.431348624: transactions: tx abrt 400b93 main+0x26 (/root/xabort) xabort $0x1 Fixes: faaa87680b25d ("perf intel-pt/bts: Report instruction bytes and length in sample") Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Jiri Olsa Cc: stable@vger.kernel.org Link: http://lore.kernel.org/lkml/20210519074515.9262-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman --- tools/perf/util/intel-pt.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c index dc023b8c6003..e5aaf1337be9 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c @@ -647,8 +647,10 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn, *ip += intel_pt_insn->length; - if (to_ip && *ip == to_ip) + if (to_ip && *ip == to_ip) { + intel_pt_insn->length = 0; goto out_no_cache; + } if (*ip >= al.map->end) break; @@ -1131,6 +1133,7 @@ static void intel_pt_set_pid_tid_cpu(struct intel_pt *pt, static void intel_pt_sample_flags(struct intel_pt_queue *ptq) { + ptq->insn_len = 0; if (ptq->state->flags & INTEL_PT_ABORT_TX) { ptq->flags = PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_TX_ABORT; } else if (ptq->state->flags & INTEL_PT_ASYNC) {