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[Dle-develop] [PATCH -tip 10/10] perf probe: Accessing members in data structures
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From: Masami H. <mhi...@re...> - 2010-03-16 21:58:21
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Support accessing members in the data structures. With this,
perf-probe accepts data-structure members(IOW, it now accepts
dot '.' and arrow '->' operators) as probe arguemnts.
e.g.
./perf probe --add 'schedule:44 rq->curr'
./perf probe --add 'vfs_read file->f_op->read file->f_path.dentry'
Note that '>' can be interpreted as redirection in command-line.
Signed-off-by: Masami Hiramatsu <mhi...@re...>
Cc: Ingo Molnar <mi...@el...>
Cc: Frederic Weisbecker <fwe...@gm...>
Cc: Arnaldo Carvalho de Melo <ac...@re...>
Cc: Paul Mackerras <pa...@sa...>
Cc: Mike Galbraith <ef...@gm...>
Cc: Peter Zijlstra <a.p...@ch...>
---
tools/perf/util/probe-event.c | 90 +++++++++++++++++++++++++++++++++-
tools/perf/util/probe-event.h | 12 ++++-
tools/perf/util/probe-finder.c | 105 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 201 insertions(+), 6 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 4e3c1ae..64dea6c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -262,6 +262,49 @@ static void parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
pp->lazy_line);
}
+/* Parse perf-probe event argument */
+static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg)
+{
+ const char *tmp;
+ struct perf_probe_arg_field **fieldp;
+
+ pr_debug("parsing arg: %s into ", str);
+
+ 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);
+ return;
+ }
+
+ /* Structure fields */
+ arg->name = xstrndup(str, tmp - str);
+ pr_debug("%s, ", arg->name);
+ fieldp = &arg->field;
+
+ do {
+ *fieldp = xzalloc(sizeof(struct perf_probe_arg_field));
+ 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", str);
+
+ tmp = strpbrk(str, "-.");
+ if (tmp) {
+ (*fieldp)->name = xstrndup(str, tmp - str);
+ pr_debug("%s(%d), ", (*fieldp)->name, (*fieldp)->ref);
+ fieldp = &(*fieldp)->next;
+ }
+ } while (tmp);
+ (*fieldp)->name = xstrdup(str);
+ pr_debug("%s(%d)\n", (*fieldp)->name, (*fieldp)->ref);
+}
+
/* Parse perf-probe event command */
void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)
{
@@ -281,7 +324,7 @@ void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev)
pev->nargs = argc - 1;
pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs);
for (i = 0; i < pev->nargs; i++) {
- pev->args[i].name = xstrdup(argv[i + 1]);
+ parse_perf_probe_arg(argv[i + 1], &pev->args[i]);
if (is_c_varname(pev->args[i].name) && pev->point.retprobe)
semantic_error("You can't specify local variable for"
" kretprobe");
@@ -353,6 +396,33 @@ void parse_kprobe_trace_command(const char *cmd, struct kprobe_trace_event *tev)
argv_free(argv);
}
+/* Compose only probe arg */
+int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len)
+{
+ struct perf_probe_arg_field *field = pa->field;
+ int ret;
+ char *tmp = buf;
+
+ ret = e_snprintf(tmp, len, "%s", pa->name);
+ if (ret <= 0)
+ goto error;
+ tmp += ret;
+ len -= ret;
+
+ while (field) {
+ ret = e_snprintf(tmp, len, "%s%s", field->ref ? "->" : ".",
+ field->name);
+ if (ret <= 0)
+ goto error;
+ tmp += ret;
+ len -= ret;
+ field = field->next;
+ }
+ return tmp - buf;
+error:
+ die("Failed to synthesize perf probe argument: %s", strerror(-ret));
+}
+
/* Compose only probe point (not argument) */
static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
{
@@ -563,6 +633,7 @@ void convert_to_perf_probe_event(struct kprobe_trace_event *tev,
void clear_perf_probe_event(struct perf_probe_event *pev)
{
struct perf_probe_point *pp = &pev->point;
+ struct perf_probe_arg_field *field, *next;
int i;
if (pev->event)
@@ -575,9 +646,18 @@ void clear_perf_probe_event(struct perf_probe_event *pev)
free(pp->function);
if (pp->lazy_line)
free(pp->lazy_line);
- for (i = 0; i < pev->nargs; i++)
+ for (i = 0; i < pev->nargs; i++) {
if (pev->args[i].name)
free(pev->args[i].name);
+ field = pev->args[i].field;
+ while (field) {
+ next = field->next;
+ if (field->name)
+ free(field->name);
+ free(field);
+ field = next;
+ }
+ }
if (pev->args)
free(pev->args);
memset(pev, 0, sizeof(*pev));
@@ -682,8 +762,10 @@ static void show_perf_probe_event(struct perf_probe_event *pev)
if (pev->nargs > 0) {
printf(" with");
- for (i = 0; i < pev->nargs; i++)
- printf(" %s", pev->args[i].name);
+ for (i = 0; i < pev->nargs; i++) {
+ synthesize_perf_probe_arg(&pev->args[i], buf, 128);
+ printf(" %s", buf);
+ }
}
printf(")\n");
free(place);
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 2a2f0a2..cd308b0 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -45,9 +45,17 @@ struct perf_probe_point {
bool retprobe; /* Return probe flag */
};
+/* Perf probe probing argument field chain */
+struct perf_probe_arg_field {
+ struct perf_probe_arg_field *next; /* Next field */
+ char *name; /* Name of the field */
+ bool ref; /* Referencing flag */
+};
+
/* Perf probe probing argument */
struct perf_probe_arg {
- char *name; /* Argument name */
+ char *name; /* Argument name */
+ struct perf_probe_arg_field *field; /* Structure fields */
};
/* Perf probe probing event (point + arg) */
@@ -86,6 +94,8 @@ extern void parse_kprobe_trace_command(const char *cmd,
/* Events to command string */
extern char *synthesize_perf_probe_command(struct perf_probe_event *pev);
extern char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev);
+extern int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf,
+ size_t len);
/* Check the perf_probe_event needs debuginfo */
extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index e02b607..db52ec2 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -206,6 +206,28 @@ static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die)
return epc;
}
+/* Get type die, but skip qualifiers and typedef */
+static Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
+{
+ Dwarf_Attribute attr;
+ int tag;
+
+ do {
+ if (dwarf_attr(vr_die, DW_AT_type, &attr) == NULL ||
+ dwarf_formref_die(&attr, die_mem) == NULL)
+ return NULL;
+
+ tag = dwarf_tag(die_mem);
+ vr_die = die_mem;
+ } while (tag == DW_TAG_const_type ||
+ tag == DW_TAG_restrict_type ||
+ tag == DW_TAG_volatile_type ||
+ tag == DW_TAG_shared_type ||
+ tag == DW_TAG_typedef);
+
+ return die_mem;
+}
+
/* Return values for die_find callbacks */
enum {
DIE_FIND_CB_FOUND = 0, /* End of Search */
@@ -314,6 +336,25 @@ static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name,
die_mem);
}
+static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
+{
+ const char *name = data;
+
+ if ((dwarf_tag(die_mem) == DW_TAG_member) &&
+ (die_compare_name(die_mem, name) == 0))
+ return DIE_FIND_CB_FOUND;
+
+ return DIE_FIND_CB_SIBLING;
+}
+
+/* Find a member called 'name' */
+static Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
+ Dwarf_Die *die_mem)
+{
+ return die_find_child(st_die, __die_find_member_cb, (void *)name,
+ die_mem);
+}
+
/*
* Probe finder related functions
*/
@@ -363,6 +404,62 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf)
}
}
+static void convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
+ struct perf_probe_arg_field *field,
+ struct kprobe_trace_arg_ref **ref_ptr)
+{
+ struct kprobe_trace_arg_ref *ref = *ref_ptr;
+ Dwarf_Attribute attr;
+ Dwarf_Die member;
+ Dwarf_Die type;
+ Dwarf_Word offs;
+
+ pr_debug("converting %s in %s\n", field->name, varname);
+ if (die_get_real_type(vr_die, &type) == NULL)
+ die("Failed to get a type information of %s.", varname);
+
+ /* Check the pointer and dereference */
+ if (dwarf_tag(&type) == DW_TAG_pointer_type) {
+ if (!field->ref)
+ die("Semantic error: %s must be referred by '->'",
+ field->name);
+ /* Get the type pointed by this pointer */
+ if (die_get_real_type(&type, &type) == NULL)
+ die("Failed to get a type information of %s.", varname);
+
+ ref = xzalloc(sizeof(struct kprobe_trace_arg_ref));
+ if (*ref_ptr)
+ (*ref_ptr)->next = ref;
+ else
+ *ref_ptr = ref;
+ } else {
+ if (field->ref)
+ die("Semantic error: %s must be referred by '.'",
+ field->name);
+ if (!ref)
+ die("Structure on a register is not supported yet.");
+ }
+
+ /* Verify it is a data structure */
+ if (dwarf_tag(&type) != DW_TAG_structure_type)
+ die("%s is not a data structure.", varname);
+
+ if (die_find_member(&type, field->name, &member) == NULL)
+ die("%s(tyep:%s) has no member %s.", varname,
+ dwarf_diename(&type), field->name);
+
+ /* Get the offset of the field */
+ if (dwarf_attr(&member, DW_AT_data_member_location, &attr) == NULL ||
+ dwarf_formudata(&attr, &offs) != 0)
+ die("Failed to get the offset of %s.", field->name);
+ ref->offset += (long)offs;
+
+ /* Converting next field */
+ if (field->next)
+ convert_variable_fields(&member, field->name, field->next,
+ &ref);
+}
+
/* Show a variables in kprobe event format */
static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
{
@@ -379,6 +476,10 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
goto error;
convert_location(expr, pf);
+
+ if (pf->pvar->field)
+ convert_variable_fields(vr_die, pf->pvar->name,
+ pf->pvar->field, &pf->tvar->ref);
/* *expr will be cached in libdw. Don't free it. */
return ;
error:
@@ -391,13 +492,15 @@ error:
static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
{
Dwarf_Die vr_die;
+ char buf[128];
/* TODO: Support struct members and arrays */
if (!is_c_varname(pf->pvar->name)) {
/* Copy raw parameters */
pf->tvar->value = xstrdup(pf->pvar->name);
} else {
- pf->tvar->name = xstrdup(pf->pvar->name);
+ synthesize_perf_probe_arg(pf->pvar, buf, 128);
+ pf->tvar->name = xstrdup(buf);
pr_debug("Searching '%s' variable in context.\n",
pf->pvar->name);
/* Search child die for local variables and parameters. */
--
Masami Hiramatsu
e-mail: mhi...@re...
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