1 files changed, 118 insertions, 15 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index c09e0a9fdf4..c04405296e5 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -273,12 +273,15 @@ static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
 /*
  * Convert a location into trace_arg.
  * If tvar == NULL, this just checks variable can be converted.
+ * If fentry == true and vr_die is a parameter, do huristic search
+ * for the location fuzzed by function entry mcount.
  */
 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
-				     Dwarf_Op *fb_ops,
+				     Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
 				     struct probe_trace_arg *tvar)
 {
 	Dwarf_Attribute attr;
+	Dwarf_Addr tmp = 0;
 	Dwarf_Op *op;
 	size_t nops;
 	unsigned int regn;
@@ -291,12 +294,29 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
 		goto static_var;
 
 	/* TODO: handle more than 1 exprs */
-	if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL ||
-	    dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0 ||
-	    nops == 0) {
-		/* TODO: Support const_value */
+	if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
+		return -EINVAL;	/* Broken DIE ? */
+	if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
+		ret = dwarf_entrypc(sp_die, &tmp);
+		if (ret || addr != tmp ||
+		    dwarf_tag(vr_die) != DW_TAG_formal_parameter ||
+		    dwarf_highpc(sp_die, &tmp))
+			return -ENOENT;
+		/*
+		 * This is fuzzed by fentry mcount. We try to find the
+		 * parameter location at the earliest address.
+		 */
+		for (addr += 1; addr <= tmp; addr++) {
+			if (dwarf_getlocation_addr(&attr, addr, &op,
+						   &nops, 1) > 0)
+				goto found;
+		}
 		return -ENOENT;
 	}
+found:
+	if (nops == 0)
+		/* TODO: Support const_value */
+		return -ENOENT;
 
 	if (op->atom == DW_OP_addr) {
 static_var:
@@ -600,7 +620,7 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
 		 dwarf_diename(vr_die));
 
 	ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
-					pf->tvar);
+					&pf->sp_die, pf->tvar);
 	if (ret == -ENOENT)
 		pr_err("Failed to find the location of %s at this address.\n"
 		       " Perhaps, it has been optimized out.\n", pf->pvar->var);
@@ -1136,12 +1156,80 @@ found:
 	return ret;
 }
 
+struct local_vars_finder {
+	struct probe_finder *pf;
+	struct perf_probe_arg *args;
+	int max_args;
+	int nargs;
+	int ret;
+};
+
+/* Collect available variables in this scope */
+static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
+{
+	struct local_vars_finder *vf = data;
+	struct probe_finder *pf = vf->pf;
+	int tag;
+
+	tag = dwarf_tag(die_mem);
+	if (tag == DW_TAG_formal_parameter ||
+	    tag == DW_TAG_variable) {
+		if (convert_variable_location(die_mem, vf->pf->addr,
+					      vf->pf->fb_ops, &pf->sp_die,
+					      NULL) == 0) {
+			vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
+			if (vf->args[vf->nargs].var == NULL) {
+				vf->ret = -ENOMEM;
+				return DIE_FIND_CB_END;
+			}
+			pr_debug(" %s", vf->args[vf->nargs].var);
+			vf->nargs++;
+		}
+	}
+
+	if (dwarf_haspc(die_mem, vf->pf->addr))
+		return DIE_FIND_CB_CONTINUE;
+	else
+		return DIE_FIND_CB_SIBLING;
+}
+
+static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
+			     struct perf_probe_arg *args)
+{
+	Dwarf_Die die_mem;
+	int i;
+	int n = 0;
+	struct local_vars_finder vf = {.pf = pf, .args = args,
+				.max_args = MAX_PROBE_ARGS, .ret = 0};
+
+	for (i = 0; i < pf->pev->nargs; i++) {
+		/* var never be NULL */
+		if (strcmp(pf->pev->args[i].var, "$vars") == 0) {
+			pr_debug("Expanding $vars into:");
+			vf.nargs = n;
+			/* Special local variables */
+			die_find_child(sc_die, copy_variables_cb, (void *)&vf,
+				       &die_mem);
+			pr_debug(" (%d)\n", vf.nargs - n);
+			if (vf.ret < 0)
+				return vf.ret;
+			n = vf.nargs;
+		} else {
+			/* Copy normal argument */
+			args[n] = pf->pev->args[i];
+			n++;
+		}
+	}
+	return n;
+}
+
 /* Add a found probe point into trace event list */
 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
 	struct trace_event_finder *tf =
 			container_of(pf, struct trace_event_finder, pf);
 	struct probe_trace_event *tev;
+	struct perf_probe_arg *args;
 	int ret, i;
 
 	/* Check number of tevs */
@@ -1161,21 +1249,35 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
 	pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
 		 tev->point.offset);
 
-	/* Find each argument */
-	tev->nargs = pf->pev->nargs;
-	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
-	if (tev->args == NULL)
+	/* Expand special probe argument if exist */
+	args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
+	if (args == NULL)
 		return -ENOMEM;
-	for (i = 0; i < pf->pev->nargs; i++) {
-		pf->pvar = &pf->pev->args[i];
+
+	ret = expand_probe_args(sc_die, pf, args);
+	if (ret < 0)
+		goto end;
+
+	tev->nargs = ret;
+	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
+	if (tev->args == NULL) {
+		ret = -ENOMEM;
+		goto end;
+	}
+
+	/* Find each argument */
+	for (i = 0; i < tev->nargs; i++) {
+		pf->pvar = &args[i];
 		pf->tvar = &tev->args[i];
 		/* Variable should be found from scope DIE */
 		ret = find_variable(sc_die, pf);
 		if (ret != 0)
-			return ret;
+			break;
 	}
 
-	return 0;
+end:
+	free(args);
+	return ret;
 }
 
 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
@@ -1222,7 +1324,8 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
 	if (tag == DW_TAG_formal_parameter ||
 	    tag == DW_TAG_variable) {
 		ret = convert_variable_location(die_mem, af->pf.addr,
-						af->pf.fb_ops, NULL);
+						af->pf.fb_ops, &af->pf.sp_die,
+						NULL);
 		if (ret == 0) {
 			ret = die_get_varname(die_mem, buf, MAX_VAR_LEN);
 			pr_debug2("Add new var: %s\n", buf);