[PATCH v9 7/7] powerpc: add machine check safe copy_to_user

[Balbir Singh]

On 12/8/19 7:22 pm, Santosh Sivaraj wrote:
> Use  memcpy_mcsafe() implementation to define copy_to_user_mcsafe()
> 
> Signed-off-by: Santosh Sivaraj <santosh at fossix.org>
> ---
>  arch/powerpc/Kconfig               |  1 +
>  arch/powerpc/include/asm/uaccess.h | 14 ++++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 77f6ebf97113..4316e36095a2 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -137,6 +137,7 @@ config PPC
>  	select ARCH_HAS_STRICT_KERNEL_RWX	if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION)
>  	select ARCH_HAS_TICK_BROADCAST		if GENERIC_CLOCKEVENTS_BROADCAST
>  	select ARCH_HAS_UACCESS_FLUSHCACHE	if PPC64
> +	select ARCH_HAS_UACCESS_MCSAFE		if PPC64
>  	select ARCH_HAS_UBSAN_SANITIZE_ALL
>  	select ARCH_HAVE_NMI_SAFE_CMPXCHG
>  	select ARCH_KEEP_MEMBLOCK
> diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
> index 8b03eb44e876..15002b51ff18 100644
> --- a/arch/powerpc/include/asm/uaccess.h
> +++ b/arch/powerpc/include/asm/uaccess.h
> @@ -387,6 +387,20 @@ static inline unsigned long raw_copy_to_user(void __user *to,
>  	return ret;
>  }
>  
> +static __always_inline unsigned long __must_check
> +copy_to_user_mcsafe(void __user *to, const void *from, unsigned long n)
> +{
> +	if (likely(check_copy_size(from, n, true))) {
> +		if (access_ok(to, n)) {
> +			allow_write_to_user(to, n);
> +			n = memcpy_mcsafe((void *)to, from, n);
> +			prevent_write_to_user(to, n);
> +		}
> +	}
> +
> +	return n;

Do we always return n independent of the check_copy_size return value and access_ok return values?

Balbir Singh.

> +}
> +
>  extern unsigned long __clear_user(void __user *addr, unsigned long size);
>  
>  static inline unsigned long clear_user(void __user *addr, unsigned long size)
>