perf probe: Support tracing an entry of array
Add array-entry tracing support to perf probe. This enables to trace an entry
of array which is indexed by constant value, e.g. array[0].
For example:
$ perf probe -a 'bio_split bi->bi_io_vec[0]'
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195742.2885.5344.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 914c670..351baa9 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -557,7 +557,7 @@
/* Parse perf-probe event argument */
static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
{
- char *tmp;
+ char *tmp, *goodname;
struct perf_probe_arg_field **fieldp;
pr_debug("parsing arg: %s into ", str);
@@ -580,7 +580,7 @@
pr_debug("type:%s ", arg->type);
}
- tmp = strpbrk(str, "-.");
+ tmp = strpbrk(str, "-.[");
if (!is_c_varname(str) || !tmp) {
/* A variable, register, symbol or special value */
arg->var = strdup(str);
@@ -590,10 +590,11 @@
return 0;
}
- /* Structure fields */
+ /* Structure fields or array element */
arg->var = strndup(str, tmp - str);
if (arg->var == NULL)
return -ENOMEM;
+ goodname = arg->var;
pr_debug("%s, ", arg->var);
fieldp = &arg->field;
@@ -601,22 +602,38 @@
*fieldp = zalloc(sizeof(struct perf_probe_arg_field));
if (*fieldp == NULL)
return -ENOMEM;
- if (*tmp == '.') {
- str = tmp + 1;
- (*fieldp)->ref = false;
- } else if (tmp[1] == '>') {
- str = tmp + 2;
+ if (*tmp == '[') { /* Array */
+ str = tmp;
+ (*fieldp)->index = strtol(str + 1, &tmp, 0);
(*fieldp)->ref = true;
- } else {
- semantic_error("Argument parse error: %s\n", str);
- return -EINVAL;
+ if (*tmp != ']' || tmp == str + 1) {
+ semantic_error("Array index must be a"
+ " number.\n");
+ return -EINVAL;
+ }
+ tmp++;
+ if (*tmp == '\0')
+ tmp = NULL;
+ } else { /* Structure */
+ if (*tmp == '.') {
+ str = tmp + 1;
+ (*fieldp)->ref = false;
+ } else if (tmp[1] == '>') {
+ str = tmp + 2;
+ (*fieldp)->ref = true;
+ } else {
+ semantic_error("Argument parse error: %s\n",
+ str);
+ return -EINVAL;
+ }
+ tmp = strpbrk(str, "-.[");
}
-
- tmp = strpbrk(str, "-.");
if (tmp) {
(*fieldp)->name = strndup(str, tmp - str);
if ((*fieldp)->name == NULL)
return -ENOMEM;
+ if (*str != '[')
+ goodname = (*fieldp)->name;
pr_debug("%s(%d), ", (*fieldp)->name, (*fieldp)->ref);
fieldp = &(*fieldp)->next;
}
@@ -624,11 +641,13 @@
(*fieldp)->name = strdup(str);
if ((*fieldp)->name == NULL)
return -ENOMEM;
+ if (*str != '[')
+ goodname = (*fieldp)->name;
pr_debug("%s(%d)\n", (*fieldp)->name, (*fieldp)->ref);
- /* If no name is specified, set the last field name */
+ /* If no name is specified, set the last field name (not array index)*/
if (!arg->name) {
- arg->name = strdup((*fieldp)->name);
+ arg->name = strdup(goodname);
if (arg->name == NULL)
return -ENOMEM;
}
@@ -776,8 +795,11 @@
len -= ret;
while (field) {
- ret = e_snprintf(tmp, len, "%s%s", field->ref ? "->" : ".",
- field->name);
+ if (field->name[0] == '[')
+ ret = e_snprintf(tmp, len, "%s", field->name);
+ else
+ ret = e_snprintf(tmp, len, "%s%s",
+ field->ref ? "->" : ".", field->name);
if (ret <= 0)
goto error;
tmp += ret;