perf probe: Support global variables

Allow users to set external defined global variables as event arguments (e.g.
jiffies).

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20101021101316.3542.1999.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>

1 files changed, 17 insertions, 8 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index abcaec555204..c6fe80ebb262 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -406,6 +406,9 @@ static int convert_variable_location(Dwarf_Die *vr_die, struct probe_finder *pf)
         struct probe_trace_arg *tvar = pf->tvar;
         int ret;
 
+        if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
+                goto static_var;
+
         /* TODO: handle more than 1 exprs */
         if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL ||
             dwarf_getlocation_addr(&attr, pf->addr, &op, &nops, 1) <= 0 ||
@@ -417,6 +420,7 @@ static int convert_variable_location(Dwarf_Die *vr_die, struct probe_finder *pf)
         }
 
         if (op->atom == DW_OP_addr) {
+static_var:
                 /* Static variables on memory (not stack), make @varname */
                 ret = strlen(dwarf_diename(vr_die));
                 tvar->value = zalloc(ret + 2);
@@ -746,17 +750,22 @@ static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
         else {
                 /* Search upper class */
                 nscopes = dwarf_getscopes_die(sp_die, &scopes);
-                if (nscopes > 0) {
-                        ret = dwarf_getscopevar(scopes, nscopes, pf->pvar->var,
-                                                0, NULL, 0, 0, &vr_die);
-                        if (ret >= 0)
+                while (nscopes-- > 1) {
+                        pr_debug("Searching variables in %s\n",
+                                 dwarf_diename(&scopes[nscopes]));
+                        /* We should check this scope, so give dummy address */
+                        if (die_find_variable_at(&scopes[nscopes],
+                                                 pf->pvar->var, 0,
+                                                 &vr_die)) {
                                 ret = convert_variable(&vr_die, pf);
-                        else
-                                ret = -ENOENT;
+                                goto found;
+                        }
+                }
+                if (scopes)
                         free(scopes);
-                } else
-                        ret = -ENOENT;
+                ret = -ENOENT;
         }
+found:
         if (ret < 0)
                 pr_warning("Failed to find '%s' in this function.\n",
                            pf->pvar->var);