4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Abel Vesa abelvesa@linux.com
[ Upstream commit 6f05d0761af612e04572ba4d65b4c0274a88444f ]
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 nicstange@gmail.com Suggested-by: Rabin Vincent rabin@rab.in Signed-off-by: Abel Vesa abelvesa@gmail.com Acked-by: Rabin Vincent rabin@rab.in Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/kernel/ftrace.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -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;