perf sdt: Add scanning of sdt probes arguments

During a "perf buildid-cache --add" command, the section ".note.stapsdt"
of the "added" binary is scanned in order to list the available SDT
markers available in a binary. The parts containing the probes arguments
were left unscanned.

The whole section is now parsed; the probe arguments are extracted for
later use.

Signed-off-by: Alexis Berlemont <alexis.berlemont@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20161214000732.1710-2-alexis.berlemont@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 4e59ddeb4eda7cd8e75ec2c0c42e1fec4de0432a..0e660dba58adfdc108e240826cba59603bbd73f1 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1828,7 +1828,7 @@ void kcore_extract__delete(struct kcore_extract *kce)
 static int populate_sdt_note(Elf **elf, const char *data, size_t len,
                             struct list_head *sdt_notes)
 {
-       const char *provider, *name;
+       const char *provider, *name, *args;
        struct sdt_note *tmp = NULL;
        GElf_Ehdr ehdr;
        GElf_Addr base_off = 0;
@@ -1887,6 +1887,25 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
                goto out_free_prov;
        }
 
+       args = memchr(name, '\0', data + len - name);
+
+       /*
+        * There is no argument if:
+        * - We reached the end of the note;
+        * - There is not enough room to hold a potential string;
+        * - The argument string is empty or just contains ':'.
+        */
+       if (args == NULL || data + len - args < 2 ||
+               args[1] == ':' || args[1] == '\0')
+               tmp->args = NULL;
+       else {
+               tmp->args = strdup(++args);
+               if (!tmp->args) {
+                       ret = -ENOMEM;
+                       goto out_free_name;
+               }
+       }
+
        if (gelf_getclass(*elf) == ELFCLASS32) {
                memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
                tmp->bit32 = true;
@@ -1898,7 +1917,7 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
        if (!gelf_getehdr(*elf, &ehdr)) {
                pr_debug("%s : cannot get elf header.\n", __func__);
                ret = -EBADF;
-               goto out_free_name;
+               goto out_free_args;
        }
 
        /* Adjust the prelink effect :
@@ -1923,6 +1942,8 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
        list_add_tail(&tmp->note_list, sdt_notes);
        return 0;
 
+out_free_args:
+       free(tmp->args);
 out_free_name:
        free(tmp->name);
 out_free_prov:

diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 6c358b7ed336c72fe9984c8f5b33fb3d200c638c..9222c7e702f39d30ac4aac965843f9f00c1fbf87 100644 (file)
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -351,6 +351,7 @@ int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb);
 struct sdt_note {
        char *name;                     /* name of the note*/
        char *provider;                 /* provider name */
+       char *args;
        bool bit32;                     /* whether the location is 32 bits? */
        union {                         /* location, base and semaphore addrs */
                Elf64_Addr a64[3];