Re: [PATCH V4 1/3] tools/perf: Fix the string match for "/tmp/perf-$PID.map" files in dso__load

Adrian Hunter
2024-06-25T12:02:28Z

On 25/06/24 14:57, Adrian Hunter wrote:
> On 23/06/24 09:48, Athira Rajeev wrote:
>> 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. In "struct dso",
>> dso->long_name holds the long name of the dso file. Since the
>> /tmp/perf-$PID.map check uses the complete name, use dso___long_name for
>> the string name.
>>
>> 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>
>
> Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
>

Although it could use a Fixes tag