Messages in this thread Patch in this message | | | Date | Fri, 18 Feb 2022 17:49:06 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 04/29] x86/livepatch: Validate __fentry__ location |
| |
Currently livepatch assumes __fentry__ lives at func+0, which is most likely untrue with IBT on. Override the weak klp_get_ftrace_location() function with an arch specific version that's IBT aware.
Also make the weak fallback verify the location is an actual ftrace location as a sanity check.
Suggested-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/include/asm/livepatch.h | 9 +++++++++ kernel/livepatch/patch.c | 2 +- 2 files changed, 10 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/livepatch.h +++ b/arch/x86/include/asm/livepatch.h @@ -17,4 +17,13 @@ static inline void klp_arch_set_pc(struc ftrace_instruction_pointer_set(fregs, ip); } +#define klp_get_ftrace_location klp_get_ftrace_location +static inline unsigned long klp_get_ftrace_location(unsigned long faddr) +{ + unsigned long addr = ftrace_location(faddr); + if (!addr && IS_ENABLED(CONFIG_X86_IBT)) + addr = ftrace_location(faddr + 4); + return addr; +} + #endif /* _ASM_X86_LIVEPATCH_H */ --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -133,7 +133,7 @@ static void notrace klp_ftrace_handler(u #ifndef klp_get_ftrace_location static unsigned long klp_get_ftrace_location(unsigned long faddr) { - return faddr; + return ftrace_location(faddr); } #endif
| |