arm: ftrace: fix dynamic ftrace with DEBUG_RODATA and !FRAME_POINTER

The support for dynamic ftrace with CONFIG_DEBUG_RODATA involves overriding the weak arch_ftrace_update_code() with a variant which makes the kernel text writable around the patching.

This override was however added under the CONFIG_OLD_MCOUNT ifdef, and CONFIG_OLD_MCOUNT is only enabled if frame pointers are enabled.

This leads to non-functional dynamic ftrace (ftrace triggers a WARN_ON()) when CONFIG_DEBUG_RODATA is enabled and CONFIG_FRAME_POINTER is not.

Move the override out of that ifdef and into the CONFIG_DYNAMIC_FTRACE ifdef where it belongs.

Fixes 80d6b0c2eed2a ("ARM: mm: allow text and rodata sections to be read-only")

Suggested-by Nicolai Stange <[email protected]>

Suggested-by Rabin Vincent <[email protected]>

Signed-off-by Abel Vesa <[email protected]>

Acked-by Rabin Vincent <[email protected]>

---
 arch/arm/kernel/ftrace.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

arch/arm/kernel/ftrace.c +6 -6

index 3f17594..414e60e 100644
@@ -29,11 +29,6 @@
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-#ifdef CONFIG_OLD_MCOUNT
-#define OLD_MCOUNT_ADDR        ((unsigned long) mcount)
-#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
-
-#define        OLD_NOP         0xe1a00000      /* mov r0, r0 */
 
 static int __ftrace_modify_code(void *data)
 {

@@ -51,6 +46,12 @@ void arch_ftrace_update_code(int command)
        stop_machine(__ftrace_modify_code, &command, NULL);
 }
 
+#ifdef CONFIG_OLD_MCOUNT
+#define OLD_MCOUNT_ADDR        ((unsigned long) mcount)
+#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
+
+#define        OLD_NOP         0xe1a00000      /* mov r0, r0 */
+
 static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
 {
        return rec->arch.old_mcount ? OLD_NOP : NOP;
--

2.7.4