trace: conserve gd register

An UEFI application may change the value of the register that gd lives in. But some of our functions like get_ticks() access this register. So we have to set the gd register to the U-Boot value when entering a trace point and set it back to the application value when exiting the trace point. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Reviewed-by: Simon Glass <sjg@chromium.org>

trace: conserve gd register
An UEFI application may change the value of the register that gd lives in. But some of our functions like get_ticks() access this register. So we have to set the gd register to the U-Boot value when entering a trace point and set it back to the application value when exiting the trace point. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Reviewed-by: Simon Glass <sjg@chromium.org>
Heinrich Schuchardt · Simon Glass
1 parent 7ef8e9b09a
Showing 1 changed file with 49 additions and 0 deletions Side-by-side Diff
lib/trace.c
@@ -56,6 +56,49 @@
 	return offset / FUNC_SITE_SIZE;
 }
  
+#ifdef CONFIG_EFI_LOADER
+
+/**
+ * trace_gd - the value of the gd register
+ */
+static volatile void *trace_gd;
+
+/**
+ * trace_save_gd() - save the value of the gd register
+ */
+static void __attribute__((no_instrument_function)) trace_save_gd(void)
+{
+	trace_gd = gd;
+}
+
+/**
+ * trace_swap_gd() - swap between U-Boot and application gd register value
+ *
+ * An UEFI application may change the value of the register that gd lives in.
+ * But some of our functions like get_ticks() access this register. So we
+ * have to set the gd register to the U-Boot value when entering a trace
+ * point and set it back to the application value when exiting the trace point.
+ */
+static void __attribute__((no_instrument_function)) trace_swap_gd(void)
+{
+	volatile void *temp_gd = trace_gd;
+
+	trace_gd = gd;
+	gd = temp_gd;
+}
+
+#else
+
+static void __attribute__((no_instrument_function)) trace_save_gd(void)
+{
+}
+
+static void __attribute__((no_instrument_function)) trace_swap_gd(void)
+{
+}
+
+#endif
+
 static void __attribute__((no_instrument_function)) add_ftrace(void *func_ptr,
 				void *caller, ulong flags)
 {
@@ -100,6 +143,7 @@
 	if (trace_enabled) {
 		int func;
  
+		trace_swap_gd();
 		add_ftrace(func_ptr, caller, FUNCF_ENTRY);
 		func = func_ptr_to_num(func_ptr);
 		if (func < hdr->func_count) {
@@ -111,6 +155,7 @@
 		hdr->depth++;
 		if (hdr->depth > hdr->depth_limit)
 			hdr->max_depth = hdr->depth;
+		trace_swap_gd();
 	}
 }
  
  
@@ -126,8 +171,10 @@
 		void *func_ptr, void *caller)
 {
 	if (trace_enabled) {
+		trace_swap_gd();
 		add_ftrace(func_ptr, caller, FUNCF_EXIT);
 		hdr->depth--;
+		trace_swap_gd();
 	}
 }
  
@@ -283,6 +330,8 @@
 	ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
 	size_t needed;
 	int was_disabled = !trace_enabled;
+
+	trace_save_gd();
  
 	if (!was_disabled) {
 #ifdef CONFIG_TRACE_EARLY
...	...	@@ -56,6 +56,49 @@
56	56	return offset / FUNC_SITE_SIZE;
57	57	}
58	58
	59	+#ifdef CONFIG_EFI_LOADER
	60	+
	61	+/**
	62	+ * trace_gd - the value of the gd register
	63	+ */
	64	+static volatile void *trace_gd;
	65	+
	66	+/**
	67	+ * trace_save_gd() - save the value of the gd register
	68	+ */
	69	+static void __attribute__((no_instrument_function)) trace_save_gd(void)
	70	+{
	71	+ trace_gd = gd;
	72	+}
	73	+
	74	+/**
	75	+ * trace_swap_gd() - swap between U-Boot and application gd register value
	76	+ *
	77	+ * An UEFI application may change the value of the register that gd lives in.
	78	+ * But some of our functions like get_ticks() access this register. So we
	79	+ * have to set the gd register to the U-Boot value when entering a trace
	80	+ * point and set it back to the application value when exiting the trace point.
	81	+ */
	82	+static void __attribute__((no_instrument_function)) trace_swap_gd(void)
	83	+{
	84	+ volatile void *temp_gd = trace_gd;
	85	+
	86	+ trace_gd = gd;
	87	+ gd = temp_gd;
	88	+}
	89	+
	90	+#else
	91	+
	92	+static void __attribute__((no_instrument_function)) trace_save_gd(void)
	93	+{
	94	+}
	95	+
	96	+static void __attribute__((no_instrument_function)) trace_swap_gd(void)
	97	+{
	98	+}
	99	+
	100	+#endif
	101	+
59	102	static void __attribute__((no_instrument_function)) add_ftrace(void *func_ptr,
60	103	void *caller, ulong flags)
61	104	{
...	...	@@ -100,6 +143,7 @@
100	143	if (trace_enabled) {
101	144	int func;
102	145
	146	+ trace_swap_gd();
103	147	add_ftrace(func_ptr, caller, FUNCF_ENTRY);
104	148	func = func_ptr_to_num(func_ptr);
105	149	if (func < hdr->func_count) {
...	...	@@ -111,6 +155,7 @@
111	155	hdr->depth++;
112	156	if (hdr->depth > hdr->depth_limit)
113	157	hdr->max_depth = hdr->depth;
	158	+ trace_swap_gd();
114	159	}
115	160	}
116	161
117	162
...	...	@@ -126,8 +171,10 @@
126	171	void func_ptr, void caller)
127	172	{
128	173	if (trace_enabled) {
	174	+ trace_swap_gd();
129	175	add_ftrace(func_ptr, caller, FUNCF_EXIT);
130	176	hdr->depth--;
	177	+ trace_swap_gd();
131	178	}
132	179	}
133	180
...	...	@@ -283,6 +330,8 @@
283	330	ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
284	331	size_t needed;
285	332	int was_disabled = !trace_enabled;
	333	+
	334	+ trace_save_gd();
286	335
287	336	if (!was_disabled) {
288	337	#ifdef CONFIG_TRACE_EARLY