perf probe: Show accessible global variables

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.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20101021101335.3542.31003.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

6 files changed, 41 insertions, 14 deletions

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 72f5d9e21432..148c178a35aa 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 c777bec28466..bdf60cfdf70f 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 83192a59f02a..82b0976e2053 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 were 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 83130f634f01..c74b1fd2c1fa 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 986027fa495f..a274fd0c143e 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 baffd25f39c9..516912a04011 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 {