[PATCH -tip 6/7] perf probe: Support basic type casting

Masami Hiramatsu
2010-03-29T20:32:04Z

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 d781fc5..21820c3 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 f3c2706..11d6592 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -541,7 +541,10 @@ 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:
@@ -554,13 +557,16 @@ 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);
}