Commit 76c588f1 authored May 17, 2016 by He Kuang Committed by Arnaldo Carvalho de Melo Jun 23, 2016

perf tools: Find right DSO taking into account if binary is 32 or 64-bit



There's a problem in machine__findnew_vdso(), vdso buildid generated by a
32-bit machine stores it with the name 'vdso', but when processing buildid on a
64-bit machine with the same 'perf.data', perf will search for vdso named as
'vdso32' and get failed.

This patch tries to find the existing dsos in machine->dsos by thread dso_type.
64-bit thread tries to find vdso with name 'vdso', because all 64-bit vdso is
named as that. 32-bit thread first tries to find vdso with name 'vdso32' if
this thread was run on 64-bit machine, if failed, then it tries 'vdso' which
indicates that the thread was run on 32-bit machine when recording.

Committer note:

Additional explanation by Adrian Hunter:

We match maps to builds ids using the file name - consider
machine__findnew_[v]dso() called in map__new().  So in the context of a perf
data file, we consider the file name to be unique.

A vdso map does not have a file name - all we know is that it is vdso.  We look
at the thread to tell if it is 32-bit, 64-bit or x32.  Then we need to get the
build id which has been recorded using short name "[vdso]" or "[vdso32]" or
"[vdsox32]".

The problem is that on a 32-bit machine, we use the name "[vdso]".  If you take
a 32-bit perf data file to a 64-bit machine, it gets hard to figure out if
"[vdso]" is 32-bit or 64-bit.

This patch solves that problem.

 ----

This also merges a followup patch fixing a problem introduced by the
original submission of this patch, that would crash 'perf record' when
recording samples for a 32-bit app on a 64-bit system.

Signed-off-by: He Kuang <hekuang@huawei.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1463475894-163531-1-git-send-email-hekuang@huawei.com
Link: http://lkml.kernel.org/r/1466578626-92406-6-git-send-email-hekuang@huawei.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 41840d21

tools/perf/util/vdso.c

+37 −3

Original line number	Diff line number	Diff line
		@@ -134,8 +134,6 @@ static struct dso __machine__addnew_vdso(struct machine machine, const char *s
		return dso;
		}

		#if BITS_PER_LONG == 64

		static enum dso_type machine__thread_dso_type(struct machine *machine,
		struct thread *thread)
		{
		@@ -156,6 +154,8 @@ static enum dso_type machine__thread_dso_type(struct machine *machine,
		return dso_type;
		}

		#if BITS_PER_LONG == 64

		static int vdso__do_copy_compat(FILE *f, int fd)
		{
		char buf[4096];
		@@ -283,8 +283,38 @@ static int __machine__findnew_vdso_compat(struct machine *machine,

		#endif

		static struct dso machine__find_vdso(struct machine machine,
		struct thread *thread)
		{
		struct dso *dso = NULL;
		enum dso_type dso_type;

		dso_type = machine__thread_dso_type(machine, thread);
		switch (dso_type) {
		case DSO__TYPE_32BIT:
		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
		if (!dso) {
		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
		true);
		if (dso && dso_type != dso__type(dso, machine))
		dso = NULL;
		}
		break;
		case DSO__TYPE_X32BIT:
		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
		break;
		case DSO__TYPE_64BIT:
		case DSO__TYPE_UNKNOWN:
		default:
		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
		break;
		}

		return dso;
		}

		struct dso machine__findnew_vdso(struct machine machine,
		struct thread *thread __maybe_unused)
		struct thread *thread)
		{
		struct vdso_info *vdso_info;
		struct dso *dso = NULL;
		@@ -297,6 +327,10 @@ struct dso machine__findnew_vdso(struct machine machine,
		if (!vdso_info)
		goto out_unlock;

		dso = machine__find_vdso(machine, thread);
		if (dso)
		goto out_unlock;

		#if BITS_PER_LONG == 64
		if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
		goto out_unlock;