On Tue, Apr 08, 2014 at 01:19:01PM -0700, Kees Cook wrote:
> > To prevent any stale entries being used indefinitely, perhaps the all
> > CPU TLB flush can be inserted into
> > ftrace_arch_code_modify_post_process(), which is called after the
> > stop_machine() and which is where x86 for example makes the entries
> > read-only again.
>
> Do you mean something like this?
Yes, something like that should probably be sufficient.
>
> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
> index ea446ae09c89..b8c75e45a950 100644
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -90,6 +90,8 @@ int ftrace_arch_code_modify_prepare(void)
> int ftrace_arch_code_modify_post_process(void)
> {
> set_all_modules_text_ro();
> + /* Make sure any TLB misses during machine stop are cleared. */
> + flush_tlb_all();
> return 0;
> }
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