[PATCH -tip v2 5/8] perf probe: Support basic type casting

[Masami Hiramatsu <mhiramat@redhat.com>]

Add basic type casting for arguments to perf probe. This allows
users to specify the actual type of arguments. Of course, if
user sets invalid types, kprobe-tracer rejects that.

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

 tools/perf/Documentation/perf-probe.txt |    3 ++-
 tools/perf/util/probe-event.c           |   23 ++++++++++++++++++++++-
 tools/perf/util/probe-event.h           |    1 +
 tools/perf/util/probe-finder.c          |   10 ++++++++--
 4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 441324f..63c25d3 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -85,9 +85,10 @@ PROBE ARGUMENT
 --------------
 Each probe argument follows below syntax.
 
- [NAME=]LOCALVAR|$retval|%REG|@SYMBOL
+ [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
 
 'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
+'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo.
 
 LINE SYNTAX
 -----------
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 05ca4a9..bef2805 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -435,7 +435,7 @@ 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)
+static void parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
 {
 	char *tmp;
 	struct perf_probe_arg_field **fieldp;
@@ -445,9 +445,17 @@ static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg)
 	tmp = strchr(str, '=');
 	if (tmp) {
 		arg->name = xstrndup(str, tmp - str);
+		pr_debug("name:%s ", arg->name);
 		str = tmp + 1;
 	}
 
+	tmp = strchr(str, ':');
+	if (tmp) {	/* Type setting */
+		*tmp = '\0';
+		arg->type = xstrdup(tmp + 1);
+		pr_debug("type:%s ", arg->type);
+	}
+
 	tmp = strpbrk(str, "-.");
 	if (!is_c_varname(str) || !tmp) {
 		/* A variable, register, symbol or special value */
@@ -603,6 +611,15 @@ int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)
 		len -= ret;
 		field = field->next;
 	}
+
+	if (pa->type) {
+		ret = e_snprintf(tmp, len, ":%s", pa->type);
+		if (ret <= 0)
+			goto error;
+		tmp += ret;
+		len -= ret;
+	}
+
 	return tmp - buf;
 error:
 	die("Failed to synthesize perf probe argument: %s", strerror(-ret));
@@ -825,6 +842,8 @@ void clear_perf_probe_event(struct perf_probe_event *pev)
 			free(pev->args[i].name);
 		if (pev->args[i].var)
 			free(pev->args[i].var);
+		if (pev->args[i].type)
+			free(pev->args[i].type);
 		field = pev->args[i].field;
 		while (field) {
 			next = field->next;
@@ -1145,6 +1164,8 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
 			if (pev->args[i].name)
 				tev->args[i].name = xstrdup(pev->args[i].name);
 			tev->args[i].value = xstrdup(pev->args[i].var);
+			if (pev->args[i].type)
+				tev->args[i].type = xstrdup(pev->args[i].type);
 		}
 	}
 
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 0759db6..5a9837c 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -57,6 +57,7 @@ struct perf_probe_arg_field {
 struct perf_probe_arg {
 	char				*name;	/* Argument name */
 	char				*var;	/* Variable name */
+	char				*type;	/* Type 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 ebeb413..ab47673 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -547,7 +547,10 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
 					&die_mem);
 		vr_die = &die_mem;
 	}
-	convert_variable_type(vr_die, pf->tvar);
+	if (pf->pvar->type)
+		pf->tvar->type = xstrdup(pf->pvar->type);
+	else
+		convert_variable_type(vr_die, pf->tvar);
 	/* *expr will be cached in libdw. Don't free it. */
 	return ;
 error:
@@ -560,13 +563,16 @@ error:
 static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
 	Dwarf_Die vr_die;
-	char buf[32];
+	char buf[32], *ptr;
 
 	/* TODO: Support arrays */
 	if (pf->pvar->name)
 		pf->tvar->name = xstrdup(pf->pvar->name);
 	else {
 		synthesize_perf_probe_arg(pf->pvar, buf, 32);
+		ptr = strchr(buf, ':');	/* Change type separator to _ */
+		if (ptr)
+			*ptr = '_';
 		pf->tvar->name = xstrdup(buf);
 	}
 


-- 
Masami Hiramatsu
e-mail: mhiramat@redhat.com