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Subject[PATCH -tip 6/7] perf probe: Show accessible global variables
Date
Add --externs for allowing --vars to show accessible
global(externally defined) variables from a given probe
point too.
This will give you a hint which globals can be accessible
from the probe point.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
---
tools/perf/Documentation/perf-probe.txt | 6 +++++-
tools/perf/builtin-probe.c | 8 ++++++--
tools/perf/util/probe-event.c | 8 ++++----
tools/perf/util/probe-event.h | 2 +-
tools/perf/util/probe-finder.c | 26 +++++++++++++++++++++-----
tools/perf/util/probe-finder.h | 5 ++++-
6 files changed, 41 insertions(+), 14 deletions(-)
diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 72f5d9e..148c178 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -18,7 +18,7 @@ or
or
'perf probe' --line='FUNC[:RLN[+NUM|:RLN2]]|SRC:ALN[+NUM|:ALN2]'
or
-'perf probe' --vars='PROBEPOINT'
+'perf probe' [--externs] --vars='PROBEPOINT'

DESCRIPTION
-----------
@@ -64,6 +64,10 @@ OPTIONS
Show available local variables at given probe point. The argument
syntax is same as PROBE SYNTAX, but NO ARGs.

+--externs::
+ (Only for --vars) Show external defined variables in addition to local
+ variables.
+
-f::
--force::
Forcibly add events with existing name.
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index c777bec..bdf60cf 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -51,6 +51,7 @@ static struct {
bool force_add;
bool show_lines;
bool show_vars;
+ bool show_ext_vars;
bool mod_events;
int nevents;
struct perf_probe_event events[MAX_PROBES];
@@ -162,7 +163,7 @@ static const char * const probe_usage[] = {
"perf probe --list",
#ifdef DWARF_SUPPORT
"perf probe --line 'LINEDESC'",
- "perf probe --vars 'PROBEPOINT'",
+ "perf probe [--externs] --vars 'PROBEPOINT'",
#endif
NULL
};
@@ -207,6 +208,8 @@ static const struct option options[] = {
OPT_CALLBACK('V', "vars", NULL,
"FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT",
"Show accessible variables on PROBEDEF", opt_show_vars),
+ OPT_BOOLEAN('\0', "externs", &params.show_ext_vars,
+ "Show external variables too (with --vars only)"),
OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
"file", "vmlinux pathname"),
OPT_STRING('s', "source", &symbol_conf.source_prefix,
@@ -287,7 +290,8 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
usage_with_options(probe_usage, options);
}
ret = show_available_vars(params.events, params.nevents,
- params.max_probe_points);
+ params.max_probe_points,
+ params.show_ext_vars);
if (ret < 0)
pr_err(" Error: Failed to show vars. (%d)\n", ret);
return ret;
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index cafddc9..1b462cc 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -379,7 +379,7 @@ end:
}

static int show_available_vars_at(int fd, struct perf_probe_event *pev,
- int max_vls)
+ int max_vls, bool externs)
{
char *buf;
int ret, i;
@@ -391,7 +391,7 @@ static int show_available_vars_at(int fd, struct perf_probe_event *pev,
return -EINVAL;
pr_debug("Searching variables at %s\n", buf);

- ret = find_available_vars_at(fd, pev, &vls, max_vls);
+ ret = find_available_vars_at(fd, pev, &vls, max_vls, externs);
if (ret > 0) {
/* Some variables are found */
fprintf(stdout, "Available variables at %s\n", buf);
@@ -421,7 +421,7 @@ static int show_available_vars_at(int fd, struct perf_probe_event *pev,

/* Show available variables on given probe point */
int show_available_vars(struct perf_probe_event *pevs, int npevs,
- int max_vls)
+ int max_vls, bool externs)
{
int i, fd, ret = 0;

@@ -438,7 +438,7 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
setup_pager();

for (i = 0; i < npevs && ret >= 0; i++)
- ret = show_available_vars_at(fd, &pevs[i], max_vls);
+ ret = show_available_vars_at(fd, &pevs[i], max_vls, externs);

close(fd);
return ret;
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 83130f6..c74b1fd 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -122,7 +122,7 @@ extern int del_perf_probe_events(struct strlist *dellist);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
extern int show_available_vars(struct perf_probe_event *pevs, int npevs,
- int max_probe_points);
+ int max_probe_points, bool externs);


/* Maximum index number of event-name postfix */
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 986027f..a274fd0 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1312,12 +1312,13 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
af->pf.fb_ops, NULL);
if (ret == 0) {
ret = die_get_varname(die_mem, buf, MAX_VAR_LEN);
+ pr_debug2("Add new var: %s\n", buf);
if (ret > 0)
strlist__add(vl->vars, buf);
}
}

- if (dwarf_haspc(die_mem, af->pf.addr))
+ if (af->child && dwarf_haspc(die_mem, af->pf.addr))
return DIE_FIND_CB_CONTINUE;
else
return DIE_FIND_CB_SIBLING;
@@ -1329,8 +1330,8 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf)
struct available_var_finder *af =
container_of(pf, struct available_var_finder, pf);
struct variable_list *vl;
- Dwarf_Die die_mem;
- int ret;
+ Dwarf_Die die_mem, *scopes = NULL;
+ int ret, nscopes;

/* Check number of tevs */
if (af->nvls == af->max_vls) {
@@ -1351,8 +1352,22 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf)
vl->vars = strlist__new(true, NULL);
if (vl->vars == NULL)
return -ENOMEM;
+ af->child = true;
die_find_child(sp_die, collect_variables_cb, (void *)af, &die_mem);

+ /* Find external variables */
+ if (!af->externs)
+ goto out;
+ /* Don't need to search child DIE for externs. */
+ af->child = false;
+ nscopes = dwarf_getscopes_die(sp_die, &scopes);
+ while (nscopes-- > 1)
+ die_find_child(&scopes[nscopes], collect_variables_cb,
+ (void *)af, &die_mem);
+ if (scopes)
+ free(scopes);
+
+out:
if (strlist__empty(vl->vars)) {
strlist__delete(vl->vars);
vl->vars = NULL;
@@ -1363,11 +1378,12 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf)

/* Find available variables at given probe point */
int find_available_vars_at(int fd, struct perf_probe_event *pev,
- struct variable_list **vls, int max_vls)
+ struct variable_list **vls, int max_vls,
+ bool externs)
{
struct available_var_finder af = {
.pf = {.pev = pev, .callback = add_available_vars},
- .max_vls = max_vls};
+ .max_vls = max_vls, .externs = externs};
int ret;

/* Allocate result vls array */
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index baffd25..516912a 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -30,7 +30,8 @@ extern int find_line_range(int fd, struct line_range *lr);

/* Find available variables */
extern int find_available_vars_at(int fd, struct perf_probe_event *pev,
- struct variable_list **vls, int max_points);
+ struct variable_list **vls, int max_points,
+ bool externs);

#include <dwarf.h>
#include <libdw.h>
@@ -70,6 +71,8 @@ struct available_var_finder {
struct variable_list *vls; /* Found variable lists */
int nvls; /* Number of variable lists */
int max_vls; /* Max no. of variable lists */
+ bool externs; /* Find external vars too */
+ bool child; /* Search child scopes */
};

struct line_finder {


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