On Sun, 13 Jul 2025 10:17:29 +0300
Mike Rapoport <r...@kernel.org> wrote:
> From: "Mike Rapoport (Microsoft)" <r...@kernel.org>
>
> x86::alloc_insn_page() always allocates ROX memory.
>
> Instead of overriding this method, add EXECMEM_KPROBES entry in
> execmem_info with pgprot set to PAGE_KERNEL_ROX and use ROX cache when
> configuration and CPU features allow it.
>
Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Thanks!
> Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> Signed-off-by: Mike Rapoport (Microsoft) <r...@kernel.org>
> ---
> arch/x86/kernel/kprobes/core.c | 18 ------------------
> arch/x86/mm/init.c | 9 ++++++++-
> 2 files changed, 8 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 47cb8eb138ba..6079d15dab8c 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -481,24 +481,6 @@ static int prepare_singlestep(kprobe_opcode_t *buf,
> struct kprobe *p,
> return len;
> }
>
> -/* Make page to RO mode when allocate it */
> -void *alloc_insn_page(void)
> -{
> - void *page;
> -
> - page = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
> - if (!page)
> - return NULL;
> -
> - /*
> - * TODO: Once additional kernel code protection mechanisms are set,
> ensure
> - * that the page was not maliciously altered and it is still zeroed.
> - */
> - set_memory_rox((unsigned long)page, 1);
> -
> - return page;
> -}
> -
> /* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */
>
> static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs
> *regs)
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index dbc63f0d538f..442fafd8ff52 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -1098,7 +1098,14 @@ struct execmem_info __init *execmem_arch_setup(void)
> .pgprot = pgprot,
> .alignment = MODULE_ALIGN,
> },
> - [EXECMEM_KPROBES ... EXECMEM_BPF] = {
> + [EXECMEM_KPROBES] = {
> + .flags = flags,
> + .start = start,
> + .end = MODULES_END,
> + .pgprot = PAGE_KERNEL_ROX,
> + .alignment = MODULE_ALIGN,
> + },
> + [EXECMEM_FTRACE ... EXECMEM_BPF] = {
> .flags = EXECMEM_KASAN_SHADOW,
> .start = start,
> .end = MODULES_END,
> --
> 2.47.2
>
--
Masami Hiramatsu (Google) <mhira...@kernel.org>
