[PATCH] arm64: Update memcpy_{from, to}io() helpers

[Patrick DELAUNAY]

Hi Patrice,

On 2/26/21 1:44 PM, Patrice Chotard wrote:
> At early U-Boot stage, before relocation, MMU is not yet configured
> and disabled. DDR may not be configured with the correct memory
> attributes (can be configured in MT_DEVICE instead of MT_MEMORY).
>
> In this case, usage of memcpy_{from, to}io() may leads to synchronous
> abort in AARCH64 in case the normal memory address is not 64Bits aligned.
>
> To avoid such situation, forbid usage of normal memory cast to (u64 *) in
> case MMU is not enabled.
>
> Signed-off-by: Patrice Chotard <patrice.chotard at foss.st.com>
> Cc: mark.kettenis at xs4all.nl
> ---
>
>   arch/arm/cpu/armv8/cache_v8.c | 10 ++++++++++
>   arch/arm/include/asm/io.h     | 25 +++++++++++++++----------
>   include/cpu_func.h            |  1 +
>   3 files changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
> index 15cecb5e0b..3de18c7675 100644
> --- a/arch/arm/cpu/armv8/cache_v8.c
> +++ b/arch/arm/cpu/armv8/cache_v8.c
> @@ -719,6 +719,11 @@ int icache_status(void)
>   	return (get_sctlr() & CR_I) != 0;
>   }
>   
> +int mmu_status(void)
> +{
> +	return (get_sctlr() & CR_M) != 0;
> +}
> +
>   void invalidate_icache_all(void)
>   {
>   	__asm_invalidate_icache_all();
> @@ -740,6 +745,11 @@ int icache_status(void)
>   	return 0;
>   }
>   
> +int mmu_status(void)
> +{
> +	return 0;
> +}
> +
>   void invalidate_icache_all(void)
>   {
>   }
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index df264a170b..36b840378a 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -338,6 +338,7 @@ extern void __readwrite_bug(const char *fn);
>   
>   /* Optimized copy functions to read from/write to IO sapce */
>   #ifdef CONFIG_ARM64
> +#include <cpu_func.h>
>   /*
>    * Copy data from IO memory space to "real" memory space.
>    */
> @@ -351,11 +352,13 @@ void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
>   		count--;
>   	}
>   
> -	while (count >= 8) {
> -		*(u64 *)to = __raw_readq(from);
> -		from += 8;
> -		to += 8;
> -		count -= 8;
> +	if (mmu_status()) {
> +		while (count >= 8) {
> +			*(u64 *)to = __raw_readq(from);
> +			from += 8;
> +			to += 8;
> +			count -= 8;
> +		}
>   	}
>   
>   	while (count) {
> @@ -379,11 +382,13 @@ void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
>   		count--;
>   	}
>   
> -	while (count >= 8) {
> -		__raw_writeq(*(u64 *)from, to);
> -		from += 8;
> -		to += 8;
> -		count -= 8;
> +	if (mmu_status()) {
> +		while (count >= 8) {
> +			__raw_writeq(*(u64 *)from, to);
> +			from += 8;
> +			to += 8;
> +			count -= 8;
> +		}
>   	}
>   
>   	while (count) {
> diff --git a/include/cpu_func.h b/include/cpu_func.h
> index 8aa825daa4..a8806dd295 100644
> --- a/include/cpu_func.h
> +++ b/include/cpu_func.h
> @@ -59,6 +59,7 @@ int dcache_status(void);
>   void dcache_enable(void);
>   void dcache_disable(void);
>   void mmu_disable(void);
> +int mmu_status(void);
>   
>   /* arch/$(ARCH)/lib/cache.c */
>   void enable_caches(void);


Reviewed-by: Patrick Delaunay <patrick.delaunay at foss.st.com>

Thanks
Patrick