Messages in this thread | | | From | Arnaldo Carvalho de Melo <> | Date | Mon, 30 Sep 2019 07:50:23 -0300 | Subject | Re: [PATCH 1/3] perf script brstackinsn: Fix recovery from LBR/binary mismatch |
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Em Fri, Sep 27, 2019 at 04:35:44PM -0700, Andi Kleen escreveu: > From: Andi Kleen <ak@linux.intel.com> > > When the LBR data and the instructions in a binary do not match the > loop printing instructions could get confused and print a long > stream of bogus <bad> instructions. > > The problem was that if the instruction decoder cannot decode an > instruction it ilen wasn't initialized, so the loop going through > the basic block would continue with the previous value. > > Harden the code to avoid such problems: > - Make sure ilen is always freshly initialized and is 0 for bad > instructions. > - Do not overrun the code buffer while printing instructions > - Print a warning message if the final jump is not on an > instruction boundary.
Thanks, applied.
- Arnaldo
> Signed-off-by: Andi Kleen <ak@linux.intel.com> > --- > tools/perf/builtin-script.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c > index e079b34201f2..32b17d51c982 100644 > --- a/tools/perf/builtin-script.c > +++ b/tools/perf/builtin-script.c > @@ -1061,7 +1061,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample, > continue; > > insn = 0; > - for (off = 0;; off += ilen) { > + for (off = 0; off < (unsigned)len; off += ilen) { > uint64_t ip = start + off; > > printed += ip__fprintf_sym(ip, thread, x.cpumode, x.cpu, &lastsym, attr, fp); > @@ -1072,6 +1072,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample, > printed += print_srccode(thread, x.cpumode, ip); > break; > } else { > + ilen = 0; > printed += fprintf(fp, "\t%016" PRIx64 "\t%s\n", ip, > dump_insn(&x, ip, buffer + off, len - off, &ilen)); > if (ilen == 0) > @@ -1081,6 +1082,8 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample, > insn++; > } > } > + if (off != (unsigned)len) > + printed += fprintf(fp, "\tmismatch of LBR data and executable\n"); > } > > /* > @@ -1121,6 +1124,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample, > goto out; > } > for (off = 0; off <= end - start; off += ilen) { > + ilen = 0; > printed += fprintf(fp, "\t%016" PRIx64 "\t%s\n", start + off, > dump_insn(&x, start + off, buffer + off, len - off, &ilen)); > if (ilen == 0) > -- > 2.21.0
--
- Arnaldo
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