[PATCH] arm64: kprobes: Drop ID map text from kprobes blacklist

[Nathan Chancellor]

On Sat, Feb 04, 2023 at 11:18:07AM +0100, Ard Biesheuvel wrote:
> The ID mapped text region is never accessed via the normal kernel
> mapping of text, and so it was moved into .rodata instead. This means it
> is no longer considered as a suitable place for kprobes by default, and
> the explicit blacklist is unnecessary, and actually results in an error
> message at boot:
> 
>   kprobes: Failed to populate blacklist (error -22), kprobes not restricted, be careful using them!
> 
> So stop blacklisting the ID map text explicitly.
> 
> Fixes: af7249b317e4d0b3d ("arm64: kernel: move identity map out of .text mapping")
> Reported-by: Nathan Chancellor <nathan at kernel.org>
> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>

Thank you for the quick fix!

Tested-by: Nathan Chancellor <nathan at kernel.org>

> ---
>  arch/arm64/kernel/probes/kprobes.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index f35d059a9a366fa6..70b91a8c6bb3f358 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -387,10 +387,6 @@ int __init arch_populate_kprobe_blacklist(void)
>  					(unsigned long)__irqentry_text_end);
>  	if (ret)
>  		return ret;
> -	ret = kprobe_add_area_blacklist((unsigned long)__idmap_text_start,
> -					(unsigned long)__idmap_text_end);
> -	if (ret)
> -		return ret;
>  	ret = kprobe_add_area_blacklist((unsigned long)__hyp_text_start,
>  					(unsigned long)__hyp_text_end);
>  	if (ret || is_kernel_in_hyp_mode())
> -- 
> 2.39.1
>