| Message ID | 1489601259-9432-1-git-send-email-abelvesa@linux.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 15, 2017 at 06:07:39PM +0000, Abel Vesa wrote: > 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@linux.com> Acked-by: Rabin Vincent <rabin@rab.in>
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 3f17594..414e60e 100644 --- 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;
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@linux.com> --- arch/arm/kernel/ftrace.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)