[PATCH 1/2] 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 regex of form "/tmp/perf-*.map"

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<atraj...@linux.vnet.ibm.com>
---
 tools/perf/util/symbol.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 9e5940b5bc59..bfb88a4b0987 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -41,6 +41,7 @@
 #include <limits.h>
 #include <symbol/kallsyms.h>
 #include <sys/utsname.h>
+#include <regex.h>
 
 static int dso__load_kernel_sym(struct dso *dso, struct map *map);
 static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
@@ -1797,9 +1798,18 @@ int dso__load(struct dso *dso, struct map *map)
        struct nscookie nsc;
        char newmapname[PATH_MAX];
        const char *map_path = dso__long_name(dso);
+       regex_t    regex;
+       const char *pattern =  "(^/tmp/perf-).*(map)";
 
        mutex_lock(dso__lock(dso));
-       perfmap = strncmp(dso__name(dso), "/tmp/perf-", 10) == 0;
+       if (regcomp(&regex, pattern, REG_EXTENDED)) {
+               pr_debug("regcomp() failed in dso__load\n");
+               ret = -1;
+               goto out;
+       }
+
+       perfmap = !regexec(&regex, dso__name(dso), 0, NULL, 0);
+
        if (perfmap) {
                if (dso__nsinfo(dso) &&
                    (dso__find_perf_map(newmapname, sizeof(newmapname),
-- 
2.35.3