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

Namhyung Kim
2024-06-25T17:59:55Z

Hello,

On Tue, Jun 25, 2024 at 5:02 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> 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
>

Thanks, I will add

Fixes: 56cbeacf1435 ("perf probe: Add test for regression introduced
by switch to die_get_decl_file()")

Namhyung