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;
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index e9db1a2..bc06d3e 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -50,6 +50,7 @@
struct perf_probe_arg_field {
struct perf_probe_arg_field *next; /* Next field */
char *name; /* Name of the field */
+ long index; /* Array index number */
bool ref; /* Referencing flag */
};
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index aaea16b..308664d 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -485,6 +485,9 @@
return -ENOENT;
}
+ pr_debug("%s type is %s.\n",
+ dwarf_diename(vr_die), dwarf_diename(&type));
+
if (cast && strcmp(cast, "string") == 0) { /* String type */
ret = dwarf_tag(&type);
if (ret != DW_TAG_pointer_type &&
@@ -553,16 +556,44 @@
struct kprobe_trace_arg_ref *ref = *ref_ptr;
Dwarf_Die type;
Dwarf_Word offs;
- int ret;
+ int ret, tag;
pr_debug("converting %s in %s\n", field->name, varname);
if (die_get_real_type(vr_die, &type) == NULL) {
pr_warning("Failed to get the type of %s.\n", varname);
return -ENOENT;
}
+ pr_debug2("Var real type: (%x)\n", (unsigned)dwarf_dieoffset(&type));
+ tag = dwarf_tag(&type);
- /* Check the pointer and dereference */
- if (dwarf_tag(&type) == DW_TAG_pointer_type) {
+ if (field->name[0] == '[' &&
+ (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
+ if (field->next)
+ /* Save original type for next field */
+ memcpy(die_mem, &type, sizeof(*die_mem));
+ /* Get the type of this array */
+ if (die_get_real_type(&type, &type) == NULL) {
+ pr_warning("Failed to get the type of %s.\n", varname);
+ return -ENOENT;
+ }
+ pr_debug2("Array real type: (%x)\n",
+ (unsigned)dwarf_dieoffset(&type));
+ if (tag == DW_TAG_pointer_type) {
+ ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
+ if (ref == NULL)
+ return -ENOMEM;
+ if (*ref_ptr)
+ (*ref_ptr)->next = ref;
+ else
+ *ref_ptr = ref;
+ }
+ ref->offset += die_get_byte_size(&type) * field->index;
+ if (!field->next)
+ /* Save vr_die for converting types */
+ memcpy(die_mem, vr_die, sizeof(*die_mem));
+ goto next;
+ } else if (tag == DW_TAG_pointer_type) {
+ /* Check the pointer and dereference */
if (!field->ref) {
pr_err("Semantic error: %s must be referred by '->'\n",
field->name);
@@ -588,10 +619,15 @@
*ref_ptr = ref;
} else {
/* Verify it is a data structure */
- if (dwarf_tag(&type) != DW_TAG_structure_type) {
+ if (tag != DW_TAG_structure_type) {
pr_warning("%s is not a data structure.\n", varname);
return -EINVAL;
}
+ if (field->name[0] == '[') {
+ pr_err("Semantic error: %s is not a pointor nor array.",
+ varname);
+ return -EINVAL;
+ }
if (field->ref) {
pr_err("Semantic error: %s must be referred by '.'\n",
field->name);
@@ -618,6 +654,7 @@
}
ref->offset += (long)offs;
+next:
/* Converting next field */
if (field->next)
return convert_variable_fields(die_mem, field->name,
@@ -667,7 +704,6 @@
char buf[32], *ptr;
int ret;
- /* TODO: Support arrays */
if (pf->pvar->name)
pf->tvar->name = strdup(pf->pvar->name);
else {