This is a note to let you know that I've just added the patch titled

ARM: 8668/1: ftrace: Fix dynamic ftrace with DEBUG_RODATA and !FRAME_POINTER

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: arm-8668-1-ftrace-fix-dynamic-ftrace-with-debug_rodata-and-frame_pointer.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Mar 22 14:57:32 CET 2018

From: Abel Vesa abelvesa@linux.com Date: Mon, 3 Apr 2017 23:58:54 +0100 Subject: ARM: 8668/1: ftrace: Fix dynamic ftrace with DEBUG_RODATA and !FRAME_POINTER

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;

Patches currently in stable-queue which might be from abelvesa@linux.com are

queue-4.4/arm-8668-1-ftrace-fix-dynamic-ftrace-with-debug_rodata-and-frame_pointer.patch