Re: [PATCH V2 8/8] perf test: Check output of the probe ... --funcs command

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Tue, Apr 09, 2024 at 08:09:02AM +0900, Masami Hiramatsu wrote:
> On Mon,  8 Apr 2024 11:52:30 +0530
> Chaitanya S Prakash <ChaitanyaS.Prakash@arm.com> wrote:
> 
> > From: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
> > 
> > Test "perf probe of function from different CU" only checks if the perf
> > command has failed and doesn't test the --funcs output. In the issue
> > reported in the previous commit, the garbage output of the --funcs
> > command was being ignored by the test when it could have been caught.
> > 
> > An additional check to grep for "foo" has been added to test the --funcs
> > output.
> 
> Looks good to me.
> 
> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

> > +++ b/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
> > @@ -77,7 +77,7 @@ gcc -g -Og -flto -c ${temp_dir}/testfile-foo.c -o ${temp_dir}/testfile-foo.o
> >  gcc -g -Og -c ${temp_dir}/testfile-main.c -o ${temp_dir}/testfile-main.o
> >  gcc -g -Og -o ${temp_dir}/testfile ${temp_dir}/testfile-foo.o ${temp_dir}/testfile-main.o
> >  
> > -perf probe -x ${temp_dir}/testfile --funcs foo
> > +perf probe -x ${temp_dir}/testfile --funcs foo | grep "foo"
> >  perf probe -x ${temp_dir}/testfile foo

Have you tested this?

Because:

root@x1:~# perf probe -x /lib64/libc.so.6 malloc | grep malloc || echo failure
Added new event:
  probe_libc:malloc    (on malloc in /usr/lib64/libc.so.6)

You can now use it in all perf tools, such as:

	perf record -e probe_libc:malloc -aR sleep 1

failure
root@x1:~# perf probe -d *:*
Removed event: probe_libc:malloc
root@x1:~# perf probe -x /lib64/libc.so.6 malloc |& grep malloc || echo failure
  probe_libc:malloc    (on malloc in /usr/lib64/libc.so.6)
	perf record -e probe_libc:malloc -aR sleep 1
root@x1:~#


that plain '| grep "foo"' isn't enough, will always fail, as the output
isn't sent to stdout, but to stderr, so, with your patch:

root@x1:~# perf test different
121: test perf probe of function from different CU                   : FAILED!
root@x1:~# set -o vi
root@x1:~# perf test -v different
121: test perf probe of function from different CU:
--- start ---
test child forked, pid 938178
--- Cleaning up ---
"foo" does not hit any event.
  Error: Failed to delete events.
---- end(-1) ----
121: test perf probe of function from different CU                   : FAILED!
root@x1:~# 


We need to use '|&' to grep in both stdout and stderr, see how 'perf
probe' uses stderr:

root@x1:~# perf probe -d *:*
Removed event: probe_libc:malloc
root@x1:~# perf probe -x /lib64/libc.so.6 malloc > /dev/null
Added new event:
  probe_libc:malloc    (on malloc in /usr/lib64/libc.so.6)

You can now use it in all perf tools, such as:

	perf record -e probe_libc:malloc -aR sleep 1

root@x1:~


Using '|&' to grep:

diff --git a/tools/perf/tests/shell/test_uprobe_from_different_cu.sh b/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
index 82bc774a078a15d5..af8b1fa639f3daa4 100755
--- a/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
+++ b/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
@@ -77,7 +77,7 @@ gcc -g -Og -flto -c ${temp_dir}/testfile-foo.c -o ${temp_dir}/testfile-foo.o
 gcc -g -Og -c ${temp_dir}/testfile-main.c -o ${temp_dir}/testfile-main.o
 gcc -g -Og -o ${temp_dir}/testfile ${temp_dir}/testfile-foo.o ${temp_dir}/testfile-main.o
 
-perf probe -x ${temp_dir}/testfile --funcs foo | grep "foo"
+perf probe -x ${temp_dir}/testfile --funcs foo |& grep "foo"
 perf probe -x ${temp_dir}/testfile foo
 
 cleanup
⬢[acme@toolbox perf-tools-next]$

root@x1:~# perf test different
121: test perf probe of function from different CU                   : Ok
root@x1:~# set -o vi
root@x1:~# perf test -v different
121: test perf probe of function from different CU                   : Ok
root@x1:~# perf test -vv different
121: test perf probe of function from different CU:
--- start ---
test child forked, pid 1048947
Added new event:
  probe_testfile:foo   (on foo in /tmp/perf-uprobe-different-cu-sh.5qg9UX2dUJ/testfile)

You can now use it in all perf tools, such as:

	perf record -e probe_testfile:foo -aR sleep 1

--- Cleaning up ---
Removed event: probe_testfile:foo
---- end(0) ----
121: test perf probe of function from different CU                   : Ok
root@x1:~#

I'm amending the patch with this fix.


Thanks,

- Arnaldo