| Date | Thu, 24 Feb 2022 15:02:03 -0800 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2 13/39] x86/livepatch: Validate __fentry__ location |
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On Thu, Feb 24, 2022 at 03:51:51PM +0100, Peter Zijlstra wrote: > Currently livepatch assumes __fentry__ lives at func+0, which is most > likely untrue with IBT on. Instead make it use ftrace_location() by > default which both validates and finds the actual ip if there is any > in the same symbol. > > 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/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);
Now that ftrace is doing the dirty work, I think this means we can get rid of klp_get_ftrace_location() altogether:
diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h index 4fe018cc207b..7b9dcd51af32 100644 --- a/arch/powerpc/include/asm/livepatch.h +++ b/arch/powerpc/include/asm/livepatch.h @@ -19,16 +19,6 @@ static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip) regs_set_return_ip(regs, ip); } -#define klp_get_ftrace_location klp_get_ftrace_location -static inline unsigned long klp_get_ftrace_location(unsigned long faddr) -{ - /* - * Live patch works only with -mprofile-kernel on PPC. In this case, - * the ftrace location is always within the first 16 bytes. - */ - return ftrace_location_range(faddr, faddr + 16); -} - static inline void klp_init_thread_info(struct task_struct *p) { /* + 1 to account for STACK_END_MAGIC */ diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c index fd295bbbcbc7..ed3464e68bda 100644 --- a/kernel/livepatch/patch.c +++ b/kernel/livepatch/patch.c @@ -124,19 +124,6 @@ static void notrace klp_ftrace_handler(unsigned long ip, ftrace_test_recursion_unlock(bit); } -/* - * Convert a function address into the appropriate ftrace location. - * - * Usually this is just the address of the function, but on some architectures - * it's more complicated so allow them to provide a custom behaviour. - */ -#ifndef klp_get_ftrace_location -static unsigned long klp_get_ftrace_location(unsigned long faddr) -{ - return ftrace_location(faddr); -} -#endif - static void klp_unpatch_func(struct klp_func *func) { struct klp_ops *ops; @@ -153,8 +140,7 @@ static void klp_unpatch_func(struct klp_func *func) if (list_is_singular(&ops->func_stack)) { unsigned long ftrace_loc; - ftrace_loc = - klp_get_ftrace_location((unsigned long)func->old_func); + ftrace_loc = ftrace_location((unsigned long)func->old_func); if (WARN_ON(!ftrace_loc)) return;
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