[PATCH v2 1/3] ARM: cpu: suppress arm_early_mmu_cache_invalidate if dcache enabled

[Lucas Stach]

Am Dienstag, dem 25.08.2026 um 10:13 +0200 schrieb Ahmad Fatoum:
> barebox built as EFI payload on ARM invalidates the data caches inside
> barebox_arm_entry(), which may lead to memory corruption.
> 
> Generally, calling arm_early_mmu_cache_invalidate() while the caches are
> enabled is a bad idea, so add a function that protects against that and
> use it in common code.
> 
> Fixes: 742e78976dd4 ("ARM64: add optional EFI stub")
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>

Entire series looks good to me.

Reviewed-by: Lucas Stach <l.stach at pengutronix.de>

> ---
> v1 -> v2:
>   - rename dcache_invalidate_stale(to cache_invalidate_stale (Lucas)
> ---
>  arch/arm/cpu/common.c        | 16 ++++++++++++++++
>  arch/arm/cpu/entry_ll_32.S   |  2 +-
>  arch/arm/cpu/entry_ll_64.S   |  2 +-
>  arch/arm/include/asm/cache.h |  3 +++
>  4 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/cpu/common.c b/arch/arm/cpu/common.c
> index adb5d6a02bc8..e079f55b8bb7 100644
> --- a/arch/arm/cpu/common.c
> +++ b/arch/arm/cpu/common.c
> @@ -37,6 +37,22 @@ void sync_caches_for_execution(void)
>  	arm_early_mmu_cache_flush();
>  }
>  
> +/**
> + * cache_invalidate_stale - invalidate caches prior to enabling them
> + *
> + * Some SoCs can come up with invalid entries, but with the valid bit set.
> + * This function discards them, as that would lead to memory corruption
> + * otherwise.
> + */
> +void cache_invalidate_stale(void)
> +{
> +	/* if caches are already enabled, don't cause data loss */
> +	if (get_cr() & CR_C)
> +		return;
> +
> +	arm_early_mmu_cache_invalidate();
> +}
> +
>  void pbl_barebox_break(void)
>  {
>  	__asm__ __volatile__ (
> diff --git a/arch/arm/cpu/entry_ll_32.S b/arch/arm/cpu/entry_ll_32.S
> index 0d4c47c1c870..0763581fded4 100644
> --- a/arch/arm/cpu/entry_ll_32.S
> +++ b/arch/arm/cpu/entry_ll_32.S
> @@ -15,7 +15,7 @@ ENTRY(__barebox_arm_entry)
>  	mov	r4, r0
>  	mov	r5, r1
>  	mov	r6, r2
> -	bl	arm_early_mmu_cache_invalidate
> +	bl	cache_invalidate_stale
>  	mov	r0, r4
>  	mov	r1, r5
>  	mov	r2, r6
> diff --git a/arch/arm/cpu/entry_ll_64.S b/arch/arm/cpu/entry_ll_64.S
> index 5eb6efed5baf..c80a23c6506d 100644
> --- a/arch/arm/cpu/entry_ll_64.S
> +++ b/arch/arm/cpu/entry_ll_64.S
> @@ -15,7 +15,7 @@ ENTRY(__barebox_arm_entry)
>  	mov	x19, x0
>  	mov	x20, x1
>  	mov	x21, x2
> -	bl	arm_early_mmu_cache_invalidate
> +	bl	cache_invalidate_stale
>  	mov	x0, x19
>  	mov	x1, x20
>  	mov	x2, x21
> diff --git a/arch/arm/include/asm/cache.h b/arch/arm/include/asm/cache.h
> index ea78ae123aec..9dbf433356b9 100644
> --- a/arch/arm/include/asm/cache.h
> +++ b/arch/arm/include/asm/cache.h
> @@ -26,6 +26,9 @@ static inline void icache_invalidate(void)
>  #endif
>  }
>  
> +
> +void cache_invalidate_stale(void);
> +
>  void arm_early_mmu_cache_flush(void);
>  void arm_early_mmu_cache_invalidate(void);
>