Re: [PATCH] powerpc/603: Fix boot failure with DEBUG_PAGEALLOC and KFENCE

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Michael, ping.

Le 07/12/2021 à 07:10, Christophe Leroy a écrit :
> Allthough kernel text is always mapped with BATs, we still have
> inittext mapped with pages, so TLB miss handling is required
> when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.
> 
> The final solution should be to set a BAT that also maps inittext
> but that BAT then needs to be cleared at end of init, and it will
> require more changes to be able to do it properly.
> 
> As DEBUG_PAGEALLOC or KFENCE are debugging, performance is not a big
> deal so let's fix it simply for now to enable easy stable application.
> 
> Reported-by: Maxime Bizon <mbizon@freebox.fr>
> Fixes: 035b19a15a98 ("powerpc/32s: Always map kernel text and rodata with BATs")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>   arch/powerpc/kernel/head_book3s_32.S | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
> index 68e5c0a7e99d..2e2a8211b17b 100644
> --- a/arch/powerpc/kernel/head_book3s_32.S
> +++ b/arch/powerpc/kernel/head_book3s_32.S
> @@ -421,14 +421,14 @@ InstructionTLBMiss:
>    */
>   	/* Get PTE (linux-style) and check access */
>   	mfspr	r3,SPRN_IMISS
> -#ifdef CONFIG_MODULES
> +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
>   	lis	r1, TASK_SIZE@h		/* check if kernel address */
>   	cmplw	0,r1,r3
>   #endif
>   	mfspr	r2, SPRN_SDR1
>   	li	r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC | _PAGE_USER
>   	rlwinm	r2, r2, 28, 0xfffff000
> -#ifdef CONFIG_MODULES
> +#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
>   	bgt-	112f
>   	lis	r2, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
>   	li	r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC