Re: [PATCH v3 1/7 UPDATE] perf tools: Find vdso with the consider of cross-platform

From: Hekuang
Date: Tue May 17 2016 - 05:07:12 EST




å 2016/5/17 15:33, Adrian Hunter åé:
On 13/05/16 11:51, He Kuang wrote:
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 exsiting 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.

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
tools/perf/util/vdso.c | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
index 44d440d..99f4a3d 100644
--- a/tools/perf/util/vdso.c
+++ b/tools/perf/util/vdso.c
@@ -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);
So if we have not yet added the 32-bit vdso but have added the 64-bit vdso,
we will return the wrong one.

Can we check it? e.g.

if (!dso)
dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
true);
if (dso_type != dso__type(dso, machine))
dso = NULL;

+ break;
+ case DSO__TYPE_X32BIT:
+ dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
+ if (!dso)
+ dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
+ true);
The x32 vdso is never called DSO__NAME_VDSO so this is not correct, but for
the same reason we don't need this __dsos__find() anyway.

Thanks, update
+ 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;