[PATCH V2 1/3] tools/perf: Fix the string match for "/tmp/perf-$PID.map" files in dso__load

[PATCH V2 1/3] tools/perf: Fix the string match for "/tmp/perf-$PID.map" files in dso__load

[Athira Rajeev]

Perf test for perf probe of function from different CU fails
as below:

	./perf test -vv "test perf probe of function from different CU"
	116: test perf probe of function from different CU:
	--- start ---
	test child forked, pid 2679
	Failed to find symbol foo in /tmp/perf-uprobe-different-cu-sh.Msa7iy89bx/testfile
	  Error: Failed to add events.
	--- Cleaning up ---
	"foo" does not hit any event.
	  Error: Failed to delete events.
	---- end(-1) ----
	116: test perf probe of function from different CU                   : FAILED!

The test does below to probe function "foo" :

	# gcc -g -Og -flto -c /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.c
	-o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.o
	# gcc -g -Og -c /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.c
	-o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.o
	# gcc -g -Og -o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile
	/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.o
	/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.o

	# ./perf probe -x /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile foo
	Failed to find symbol foo in /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile
	   Error: Failed to add events.

Perf probe fails to find symbol foo in the executable placed in
/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7

Simple reproduce:

 # mktemp -d /tmp/perf-checkXXXXXXXXXX
   /tmp/perf-checkcWpuLRQI8j

 # gcc -g -o test test.c
 # cp test /tmp/perf-checkcWpuLRQI8j/
 # nm /tmp/perf-checkcWpuLRQI8j/test | grep foo
   00000000100006bc T foo

 # ./perf probe -x /tmp/perf-checkcWpuLRQI8j/test foo
   Failed to find symbol foo in /tmp/perf-checkcWpuLRQI8j/test
      Error: Failed to add events.

But it works with any files like /tmp/perf/test. Only for
patterns with "/tmp/perf-", this fails.

Further debugging, commit 80d496be89ed ("perf report: Add support
for profiling JIT generated code") added support for profiling JIT
generated code. This patch handles dso's of form
"/tmp/perf-$PID.map" .

The check used "if (strncmp(self->name, "/tmp/perf-", 10) == 0)"
to match "/tmp/perf-$PID.map". With this commit, any dso in
/tmp/perf- folder will be considered separately for processing
(not only JIT created map files ). Fix this by changing the
string pattern to check for "/tmp/perf-%d.map". Add a helper
function is_perf_pid_map_name to do this check.

With the fix,
	# ./perf test "test perf probe of function from different CU"
	117: test perf probe of function from different CU                   : Ok

Signed-off-by: Athira Rajeev<atrajeev@linux.vnet.ibm.com>
---
Changelog:
v2 -> v2:
 Addressed review comments from Adrian.
 Added helper function is_perf_pid_map_name to check
 dso name of form "/tmp/perf-%d.map". Used sscanf
 instead of regex comparison.

 tools/perf/util/dso.c    | 7 +++++++
 tools/perf/util/dso.h    | 3 +++
 tools/perf/util/symbol.c | 3 ++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index dde706b71da7..4dabb82d8018 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1652,3 +1652,10 @@ int dso__strerror_load(struct dso *dso, char *buf, size_t buflen)
 	scnprintf(buf, buflen, "%s", dso_load__error_str[idx]);
 	return 0;
 }
+
+bool is_perf_pid_map_name(const char *dso_name)
+{
+	int tid;
+
+	return sscanf(dso_name, "/tmp/perf-%d.map", &tid) == 1;
+}
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index df2c98402af3..44a3a5c97daf 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -809,4 +809,7 @@ void reset_fd_limit(void);
 u64 dso__find_global_type(struct dso *dso, u64 addr);
 u64 dso__findnew_global_type(struct dso *dso, u64 addr, u64 offset);
 
+/* Check if dso name is of format "/tmp/perf-%d.map" */
+bool is_perf_pid_map_name(const char *dso_name);
+
 #endif /* __PERF_DSO */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 9e5940b5bc59..aee0a4cfb383 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1799,7 +1799,8 @@ int dso__load(struct dso *dso, struct map *map)
 	const char *map_path = dso__long_name(dso);
 
 	mutex_lock(dso__lock(dso));
-	perfmap = strncmp(dso__name(dso), "/tmp/perf-", 10) == 0;
+	perfmap = is_perf_pid_map_name(map_path);
+
 	if (perfmap) {
 		if (dso__nsinfo(dso) &&
 		    (dso__find_perf_map(newmapname, sizeof(newmapname),
-- 
2.35.3

[PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

[Athira Rajeev]

commit 80d496be89ed ("perf report: Add support for profiling JIT
generated code") added support for profiling JIT generated code.
This patch handles dso's of form "/tmp/perf-$PID.map".

Some of the references doesn't check exactly for same pattern.
some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
this by using helper function is_perf_pid_map_name which looks
for proper pattern of form: "/tmp/perf-$PID.map" for these checks.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
 tools/perf/util/dsos.c    | 2 +-
 tools/perf/util/srcline.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
index ab3d0c01dd63..23cd02aa701d 100644
--- a/tools/perf/util/dsos.c
+++ b/tools/perf/util/dsos.c
@@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
 	char *base, *lname;
 	int tid;
 
-	if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
+	if (is_perf_pid_map_name(dso__long_name(dso))) {
 		if (asprintf(&base, "[JIT] tid %d", tid) < 0)
 			return;
 	} else {
diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index 9d670d8c1c08..51eb78993fe2 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
 	if (dso_name[0] == '[')
 		return NULL;
 
-	if (!strncmp(dso_name, "/tmp/perf-", 10))
+	if (is_perf_pid_map_name(dso_name))
 		return NULL;
 
 	return dso_name;
-- 
2.35.3

[PATCH V2 3/3] tools/perf: Fix parallel-perf python script to replace new python syntax ":=" usage

[Athira Rajeev]

perf test "perf script tests" fails as below in systems
with python 3.6

	File "/home/athira/linux/tools/perf/tests/shell/../../scripts/python/parallel-perf.py", line 442
	if line := p.stdout.readline():
             ^
	SyntaxError: invalid syntax
	--- Cleaning up ---
	---- end(-1) ----
	92: perf script tests: FAILED!

This happens because ":=" is a new syntax that assigns values
to variables as part of a larger expression. This is introduced
from python 3.8 and hence fails in setup with python 3.6
Address this by splitting the large expression and check the
value in two steps:
Previous line: if line := p.stdout.readline():
Current change:
	line = p.stdout.readline()
	if line:

With patch

	./perf test "perf script tests"
	 93: perf script tests:  Ok

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
---
Changelog:
 v1 -> v2
 Added "Acked-by" from Adrian

 tools/perf/scripts/python/parallel-perf.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/scripts/python/parallel-perf.py b/tools/perf/scripts/python/parallel-perf.py
index 21f32ec5ed46..be85fd7f6632 100755
--- a/tools/perf/scripts/python/parallel-perf.py
+++ b/tools/perf/scripts/python/parallel-perf.py
@@ -439,7 +439,8 @@ def ProcessCommandOutputLines(cmd, per_cpu, fn, *x):
 	pat = re.compile(r"\s*\[[0-9]+\]")
 	p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
 	while True:
-		if line := p.stdout.readline():
+		line = p.stdout.readline()
+		if line:
 			line = line.decode("utf-8")
 			if pat.match(line):
 				line = line.split()
-- 
2.35.3

Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

[James Clark]

On 17/06/2024 14:03, Athira Rajeev wrote:
> commit 80d496be89ed ("perf report: Add support for profiling JIT
> generated code") added support for profiling JIT generated code.
> This patch handles dso's of form "/tmp/perf-$PID.map".
> 
> Some of the references doesn't check exactly for same pattern.
> some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
> this by using helper function is_perf_pid_map_name which looks
> for proper pattern of form: "/tmp/perf-$PID.map" for these checks.
> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> ---
>  tools/perf/util/dsos.c    | 2 +-
>  tools/perf/util/srcline.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
> index ab3d0c01dd63..23cd02aa701d 100644
> --- a/tools/perf/util/dsos.c
> +++ b/tools/perf/util/dsos.c
> @@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
>  	char *base, *lname;
>  	int tid;
>  
> -	if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
> +	if (is_perf_pid_map_name(dso__long_name(dso))) {
>  		if (asprintf(&base, "[JIT] tid %d", tid) < 0)
>  			return;
>  	} else {
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index 9d670d8c1c08..51eb78993fe2 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
>  	if (dso_name[0] == '[')
>  		return NULL;
>  
> -	if (!strncmp(dso_name, "/tmp/perf-", 10))
> +	if (is_perf_pid_map_name(dso_name))
>  		return NULL;
>  
>  	return dso_name;

Duplicate of [1] but the latest version of the other one looks like it
might have a mistake in it.

For this one I get this compilation error:

util/dsos.c: In function ‘dso__set_basename’:
util/dsos.c:279:21: error: ‘tid’ may be used uninitialized
[-Werror=maybe-uninitialized]
  279 |                 if (asprintf(&base, "[JIT] tid %d", tid) < 0)



[1]:
https://lore.kernel.org/linux-perf-users/20240601125946.1741414-10-ChaitanyaS.Prakash@arm.com/

Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

[Athira Rajeev]

> On 17 Jun 2024, at 7:29 PM, James Clark <james.clark@arm.com> wrote:
> 
> 
> 
> On 17/06/2024 14:03, Athira Rajeev wrote:
>> commit 80d496be89ed ("perf report: Add support for profiling JIT
>> generated code") added support for profiling JIT generated code.
>> This patch handles dso's of form "/tmp/perf-$PID.map".
>> 
>> Some of the references doesn't check exactly for same pattern.
>> some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
>> this by using helper function is_perf_pid_map_name which looks
>> for proper pattern of form: "/tmp/perf-$PID.map" for these checks.
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
>> ---
>> tools/perf/util/dsos.c    | 2 +-
>> tools/perf/util/srcline.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
>> index ab3d0c01dd63..23cd02aa701d 100644
>> --- a/tools/perf/util/dsos.c
>> +++ b/tools/perf/util/dsos.c
>> @@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
>> char *base, *lname;
>> int tid;
>> 
>> - if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
>> + if (is_perf_pid_map_name(dso__long_name(dso))) {
>> if (asprintf(&base, "[JIT] tid %d", tid) < 0)
>> return;
>> } else {
>> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
>> index 9d670d8c1c08..51eb78993fe2 100644
>> --- a/tools/perf/util/srcline.c
>> +++ b/tools/perf/util/srcline.c
>> @@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
>> if (dso_name[0] == '[')
>> return NULL;
>> 
>> - if (!strncmp(dso_name, "/tmp/perf-", 10))
>> + if (is_perf_pid_map_name(dso_name))
>> return NULL;
>> 
>> return dso_name;
> 
> Duplicate of [1] but the latest version of the other one looks like it
> might have a mistake in it.
> 
> For this one I get this compilation error:
> 
> util/dsos.c: In function ‘dso__set_basename’:
> util/dsos.c:279:21: error: ‘tid’ may be used uninitialized
> [-Werror=maybe-uninitialized]
>  279 |                 if (asprintf(&base, "[JIT] tid %d", tid) < 0)
> 

Hi James,

Thanks for pointing this. I had my first version here: https://lore.kernel.org/linux-perf-users/5d9a9842-9b8a-428c-898f-e1ff866a6e66@intel.com/T/#m5fbfa712a411c0e09b8177d31fc1c2d12f437fa5 which used regex for matching the dso name in util/symbol.c

Got suggestion from Adrian to use “sscanf” and have a helper function since this /tmp/perf-%d.map check is done in other places as well ( in util/dsos.c, util/srcline.c ). This V2 address those changes. I didn’t hit the compile error, but that is a valid one which you reported since “tid” needs to be taken care of. I will check this compile error

Thanks
Athira 
> 
> 
> [1]:
> https://lore.kernel.org/linux-perf-users/20240601125946.1741414-10-ChaitanyaS.Prakash@arm.com/

Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

[Adrian Hunter]

On 17/06/24 16:03, Athira Rajeev wrote:
> commit 80d496be89ed ("perf report: Add support for profiling JIT
> generated code") added support for profiling JIT generated code.
> This patch handles dso's of form "/tmp/perf-$PID.map".
> 
> Some of the references doesn't check exactly for same pattern.
> some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
> this by using helper function is_perf_pid_map_name which looks
> for proper pattern of form: "/tmp/perf-$PID.map" for these checks.
> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> ---
>  tools/perf/util/dsos.c    | 2 +-
>  tools/perf/util/srcline.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
> index ab3d0c01dd63..23cd02aa701d 100644
> --- a/tools/perf/util/dsos.c
> +++ b/tools/perf/util/dsos.c
> @@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
>  	char *base, *lname;
>  	int tid;
>  
> -	if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
> +	if (is_perf_pid_map_name(dso__long_name(dso))) {

Perhaps add another helper for this case:

bool perf_pid_map_tid(const char *dso_name, int *tid)
{
	return sscanf(dso_name, "/tmp/perf-%d.map", &tid) == 1;
}

bool is_perf_pid_map_name(const char *dso_name)
{
	int tid;

	return perf_pid_map_tid(dso_name, &tid);
}

And then:

	if (perf_pid_map_tid(dso__long_name(dso), &tid)) {



>  		if (asprintf(&base, "[JIT] tid %d", tid) < 0)
>  			return;
>  	} else {
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index 9d670d8c1c08..51eb78993fe2 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
>  	if (dso_name[0] == '[')
>  		return NULL;
>  
> -	if (!strncmp(dso_name, "/tmp/perf-", 10))
> +	if (is_perf_pid_map_name(dso_name))
>  		return NULL;
>  
>  	return dso_name;

Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

[Athira Rajeev]

> On 18 Jun 2024, at 12:41 PM, Adrian Hunter <adrian.hunter@intel.com> wrote:
> 
> On 17/06/24 16:03, Athira Rajeev wrote:
>> commit 80d496be89ed ("perf report: Add support for profiling JIT
>> generated code") added support for profiling JIT generated code.
>> This patch handles dso's of form "/tmp/perf-$PID.map".
>> 
>> Some of the references doesn't check exactly for same pattern.
>> some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
>> this by using helper function is_perf_pid_map_name which looks
>> for proper pattern of form: "/tmp/perf-$PID.map" for these checks.
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
>> ---
>> tools/perf/util/dsos.c    | 2 +-
>> tools/perf/util/srcline.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
>> index ab3d0c01dd63..23cd02aa701d 100644
>> --- a/tools/perf/util/dsos.c
>> +++ b/tools/perf/util/dsos.c
>> @@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
>> char *base, *lname;
>> int tid;
>> 
>> - if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
>> + if (is_perf_pid_map_name(dso__long_name(dso))) {
> 
> Perhaps add another helper for this case:
> 
> bool perf_pid_map_tid(const char *dso_name, int *tid)
> {
> return sscanf(dso_name, "/tmp/perf-%d.map", &tid) == 1;
> }
> 
> bool is_perf_pid_map_name(const char *dso_name)
> {
> int tid;
> 
> return perf_pid_map_tid(dso_name, &tid);
> }
> 
> And then:
> 
> if (perf_pid_map_tid(dso__long_name(dso), &tid)) {
> 
> 

Hi Adrian

Thanks for suggestions. I will be posting V3 soon.

Athira
> 
>> if (asprintf(&base, "[JIT] tid %d", tid) < 0)
>> return;
>> } else {
>> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
>> index 9d670d8c1c08..51eb78993fe2 100644
>> --- a/tools/perf/util/srcline.c
>> +++ b/tools/perf/util/srcline.c
>> @@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
>> if (dso_name[0] == '[')
>> return NULL;
>> 
>> - if (!strncmp(dso_name, "/tmp/perf-", 10))
>> + if (is_perf_pid_map_name(dso_name))
>> return NULL;
>> 
>> return dso_name;
>