perf probe: Support argument name

Set given names to event arguments. The syntax is same as kprobe-tracer,
you can add 'NAME=' right before each argument.

e.g.
  ./perf probe vfs_read foo=file

 then, 'foo' is set to the argument name as below.

  ./perf probe -l
  probe:vfs_read       (on vfs_read@linux-2.6-tip/fs/read_write.c with foo)

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100412171653.3790.74624.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 24 insertions, 10 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 3fc0be741b8e..ab6f53deabad 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -437,22 +437,28 @@ static void parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 /* Parse perf-probe event argument */
 static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg)
 {
-        const char *tmp;
+        char *tmp;
         struct perf_probe_arg_field **fieldp;
 
         pr_debug("parsing arg: %s into ", str);
 
+        tmp = strchr(str, '=');
+        if (tmp) {
+                arg->name = xstrndup(str, tmp - str);
+                str = tmp + 1;
+        }
+
         tmp = strpbrk(str, "-.");
         if (!is_c_varname(str) || !tmp) {
                 /* A variable, register, symbol or special value */
-                arg->name = xstrdup(str);
-                pr_debug("%s\n", arg->name);
+                arg->var = xstrdup(str);
+                pr_debug("%s\n", arg->var);
                 return;
         }
 
         /* Structure fields */
-        arg->name = xstrndup(str, tmp - str);
-        pr_debug("%s, ", arg->name);
+        arg->var = xstrndup(str, tmp - str);
+        pr_debug("%s, ", arg->var);
         fieldp = &arg->field;
 
         do {
@@ -497,7 +503,7 @@ void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)
         pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs);
         for (i = 0; i < pev->nargs; i++) {
                 parse_perf_probe_arg(argv[i + 1], &pev->args[i]);
-                if (is_c_varname(pev->args[i].name) && pev->point.retprobe)
+                if (is_c_varname(pev->args[i].var) && pev->point.retprobe)
                         semantic_error("You can't specify local variable for"
                                        " kretprobe");
         }
@@ -514,7 +520,7 @@ bool perf_probe_event_need_dwarf(struct perf_probe_event *pev)
                 return true;
 
         for (i = 0; i < pev->nargs; i++)
-                if (is_c_varname(pev->args[i].name))
+                if (is_c_varname(pev->args[i].var))
                         return true;
 
         return false;
@@ -575,7 +581,10 @@ int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)
         int ret;
         char *tmp = buf;
 
-        ret = e_snprintf(tmp, len, "%s", pa->name);
+        if (pa->name && pa->var)
+                ret = e_snprintf(tmp, len, "%s=%s", pa->name, pa->var);
+        else
+                ret = e_snprintf(tmp, len, "%s", pa->name ? pa->name : pa->var);
         if (ret <= 0)
                 goto error;
         tmp += ret;
@@ -803,6 +812,8 @@ void clear_perf_probe_event(struct perf_probe_event *pev)
         for (i = 0; i < pev->nargs; i++) {
                 if (pev->args[i].name)
                         free(pev->args[i].name);
+                if (pev->args[i].var)
+                        free(pev->args[i].var);
                 field = pev->args[i].field;
                 while (field) {
                         next = field->next;
@@ -1117,8 +1128,11 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
         if (tev->nargs) {
                 tev->args = xzalloc(sizeof(struct kprobe_trace_arg)
                                     * tev->nargs);
-                for (i = 0; i < tev->nargs; i++)
-                        tev->args[i].value = xstrdup(pev->args[i].name);
+                for (i = 0; i < tev->nargs; i++) {
+                        if (pev->args[i].name)
+                                tev->args[i].name = xstrdup(pev->args[i].name);
+                        tev->args[i].value = xstrdup(pev->args[i].var);
+                }
         }
 
         /* Currently just checking function name from symbol map */