On Sun, Mar 26, 2017 at 8:55 AM, Abel Vesa <[email protected]> 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 <[email protected]> > Suggested-by: Rabin Vincent <[email protected]> > Signed-off-by: Abel Vesa <[email protected]> > Acked-by: Rabin Vincent <[email protected]>
This looks fine to me. I'd send it to the ARM patch tracker since you've gotten an Ack: http://www.arm.linux.org.uk/developer/patches/info.php -Kees > --- > arch/arm/kernel/ftrace.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > 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; > -- > 2.7.4 > -- Kees Cook Pixel Security
