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Commit 2c82c3ad authored by Chang Hyun Park's avatar Chang Hyun Park Committed by Arnaldo Carvalho de Melo
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perf trace: Fix mmap return address truncation to 32-bit 



Using 'perf trace' for mmap is truncating return values by stripping the
top 32 bits, 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: default avatarChang Hyun Park <heartinpiece@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1411736041-8017-1-git-send-email-heartinpiece@gmail.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 46441bdc

tools/perf/builtin-trace.c

+3 −3
Original line number Diff line number Diff line
@@ -1695,7 +1695,7 @@ 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);
@@ -1748,7 +1748,7 @@ 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[STRERR_BUFSIZE];

		const char *emsg = strerror_r(-ret, bf, sizeof(bf)),
@@ -1758,7 +1758,7 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel, 
	} 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;