linux-kernel - [PATCH 22/22] perf script: Fix invalid LBR/binary mismatch error

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Message-Id: <20191128134027.23726-23-acme@kernel.org>
Date:   Thu, 28 Nov 2019 10:40:27 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 22/22] perf script: Fix invalid LBR/binary mismatch error

From: Adrian Hunter <adrian.hunter@...el.com>

The 'len' returned by grab_bb() includes an extra MAXINSN bytes to allow
for the last instruction, so the the final 'offs' will not be 'len'.
Fix the error condition logic accordingly.

Before:

  $ perf record -e '{intel_pt//,cpu/mem_inst_retired.all_loads,aux-sample-size=8192/pp}:u' grep -rqs jhgjhg /boot
  [ perf record: Woken up 19 times to write data ]
  [ perf record: Captured and wrote 2.274 MB perf.data ]
  $ perf script -F +brstackinsn --xed --itrace=i1usl100 | head
            grep 13759 [002]  8091.310257:       1862                                        instructions:uH:      5641d58069eb bmexec+0x86b (/bin/grep)
        bmexec+2485:
        00005641d5806b35                        jnz 0x5641d5806bd0              # MISPRED
        00005641d5806bd0                        movzxb  (%r13,%rdx,1), %eax
        00005641d5806bd6                        add %rdi, %rax
        00005641d5806bd9                        movzxb  -0x1(%rax), %edx
        00005641d5806bdd                        cmp %rax, %r14
        00005641d5806be0                        jnb 0x5641d58069c0              # MISPRED
        mismatch of LBR data and executable
        00005641d58069c0                        movzxb  (%r13,%rdx,1), %edi

After:

  $ perf script -F +brstackinsn --xed --itrace=i1usl100 | head
            grep 13759 [002]  8091.310257:       1862                                        instructions:uH:      5641d58069eb bmexec+0x86b (/bin/grep)
        bmexec+2485:
        00005641d5806b35                        jnz 0x5641d5806bd0              # MISPRED
        00005641d5806bd0                        movzxb  (%r13,%rdx,1), %eax
        00005641d5806bd6                        add %rdi, %rax
        00005641d5806bd9                        movzxb  -0x1(%rax), %edx
        00005641d5806bdd                        cmp %rax, %r14
        00005641d5806be0                        jnb 0x5641d58069c0              # MISPRED
        00005641d58069c0                        movzxb  (%r13,%rdx,1), %edi
        00005641d58069c6                        add %rax, %rdi

Fixes: e98df280bc2a ("perf script brstackinsn: Fix recovery from LBR/binary mismatch")
Reported-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Link: http://lore.kernel.org/lkml/20191127095631.15663-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-script.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index e8db26b9b29e..e2406b291c1c 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1126,7 +1126,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,
 				insn++;
 			}
 		}
-		if (off != (unsigned)len)
+		if (off != end - start)
 			printed += fprintf(fp, "\tmismatch of LBR data and executable\n");
 	}
 
-- 
2.21.0