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 3fc0be741b8..ab6f53deaba 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 9d99fc24c4f..10411f59632 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 a8513772df0..105e95c95ee 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);
 	}
 }