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>

3 files changed, 41 insertions, 21 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 */
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 9d99fc24c4fc..10411f596321 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -55,6 +55,7 @@ struct perf_probe_arg_field {
 /* Perf probe probing argument */
 struct perf_probe_arg {
         char                            *name;  /* Argument name */
+        char                            *var;   /* Variable name */
         struct perf_probe_arg_field     *field; /* Structure fields */
 };
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index a8513772df08..105e95c95eeb 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -484,35 +484,40 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
         convert_location(expr, pf);
 
         if (pf->pvar->field)
-                convert_variable_fields(vr_die, pf->pvar->name,
+                convert_variable_fields(vr_die, pf->pvar->var,
                                         pf->pvar->field, &pf->tvar->ref);
         /* *expr will be cached in libdw. Don't free it. */
         return ;
 error:
         /* TODO: Support const_value */
         die("Failed to find the location of %s at this address.\n"
-            " Perhaps, it has been optimized out.", pf->pvar->name);
+            " Perhaps, it has been optimized out.", pf->pvar->var);
 }
 
 /* Find a variable in a subprogram die */
 static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
         Dwarf_Die vr_die;
-        char buf[128];
+        char buf[32];
 
-        /* TODO: Support struct members and arrays */
-        if (!is_c_varname(pf->pvar->name)) {
+        /* TODO: Support arrays */
+        if (pf->pvar->name)
+                pf->tvar->name = xstrdup(pf->pvar->name);
+        else {
+                synthesize_perf_probe_arg(pf->pvar, buf, 32);
+                pf->tvar->name = xstrdup(buf);
+        }
+
+        if (!is_c_varname(pf->pvar->var)) {
                 /* Copy raw parameters */
-                pf->tvar->value = xstrdup(pf->pvar->name);
+                pf->tvar->value = xstrdup(pf->pvar->var);
         } else {
-                synthesize_perf_probe_arg(pf->pvar, buf, 128);
-                pf->tvar->name = xstrdup(buf);
                 pr_debug("Searching '%s' variable in context.\n",
-                         pf->pvar->name);
+                         pf->pvar->var);
                 /* Search child die for local variables and parameters. */
-                if (!die_find_variable(sp_die, pf->pvar->name, &vr_die))
+                if (!die_find_variable(sp_die, pf->pvar->var, &vr_die))
                         die("Failed to find '%s' in this function.",
-                            pf->pvar->name);
+                            pf->pvar->var);
                 convert_variable(&vr_die, pf);
         }
 }