Messages in this thread Patch in this message | | | From | Chang Hyun Park <> | Subject | [PATCH 1/1] perf: Fixed perf trace, 32bit return values to 64bit | Date | Fri, 26 Sep 2014 21:54:01 +0900 |
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perf trace for syscalls resulted in mmap return values being stripped of the top 32 bits, and actually printing only the lower 32 bits. This was because the ret value was of an 'int' type and not a 'long' type.
The Problem: 991258501.244 ( 0.004 ms): mmap(len: 40001536, prot: READ|WRITE, flags: PRIVATE|ANONYMOUS, fd: -1) = 0x56691000 991258501.257 ( 0.000 ms): minfault [_int_malloc+0x1038] => //anon@0x7fa056691008 //(d.)
The first line shows an mmap, which succeeds and returns 0x56691000. However the next line shows a memory access to that virtual memory area, specifically to 0x7fa056691008. The upper 32 bit is lost due to the problem mentioned above, and thus mmap's return value didn't have the upper 0x7fa0.
Tested on 3.17-rc5 from the linus's tree, and the HEAD of tip/master
Signed-off-by: Chang Hyun Park <heartinpiece@gmail.com> --- tools/perf/builtin-trace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index a6c3752..31a7b69 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1669,7 +1669,7 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel, union perf_event *event __maybe_unused, struct perf_sample *sample) { - int ret; + long ret; u64 duration = 0; struct thread *thread; int id = perf_evsel__sc_tp_uint(evsel, id, sample); @@ -1722,7 +1722,7 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel, if (sc->fmt == NULL) { signed_print: - fprintf(trace->output, ") = %d", ret); + fprintf(trace->output, ") = %ld", ret); } else if (ret < 0 && sc->fmt->errmsg) { char bf[256]; const char *emsg = strerror_r(-ret, bf, sizeof(bf)), @@ -1732,7 +1732,7 @@ signed_print: } else if (ret == 0 && sc->fmt->timeout) fprintf(trace->output, ") = 0 Timeout"); else if (sc->fmt->hexret) - fprintf(trace->output, ") = %#x", ret); + fprintf(trace->output, ") = %#lx", ret); else goto signed_print; -- 1.9.1
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