[PATCHv3 10/17] arm64: uaccess: simplify __copy_user_flushcache()

[Robin Murphy]

On 2020-10-26 13:31, Mark Rutland wrote:
> Currently __copy_user_flushcache() open-codes raw_copy_from_user(), and
> doesn't use uaccess_mask_ptr() on the user address. Let's have it call
> raw_copy_from_user(), which is both a simplification and ensures that
> user pointers are masked under speculation.

I think this originally stems from the fact that "raw_*" were merely 
generic aliases for "__arch_*" at the time. Then whichever chump 
subsequently implemented uaccess_mask_ptr() for arm64 clearly did a 
terrible job... ;)

> There should be no functional change as a result of this patch.

Reviewed-by: Robin Murphy <robin.murphy at arm.com>

> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Christoph Hellwig <hch at lst.de>
> Cc: Robin Murphy <robin.murphy at arm.com>
> Cc: Will Deacon <will at kernel.org>
> ---
>   arch/arm64/lib/uaccess_flushcache.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/lib/uaccess_flushcache.c b/arch/arm64/lib/uaccess_flushcache.c
> index bfa30b75b2b8e..c83bb5a4aad2c 100644
> --- a/arch/arm64/lib/uaccess_flushcache.c
> +++ b/arch/arm64/lib/uaccess_flushcache.c
> @@ -30,9 +30,7 @@ unsigned long __copy_user_flushcache(void *to, const void __user *from,
>   {
>   	unsigned long rc;
>   
> -	uaccess_enable_not_uao();
> -	rc = __arch_copy_from_user(to, from, n);
> -	uaccess_disable_not_uao();
> +	rc = raw_copy_from_user(to, from, n);
>   
>   	/* See above */
>   	__clean_dcache_area_pop(to, n - rc);
>