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>

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index abcaec5..c6fe80e 100644 (file)
--- 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);