Hi Balbir,
Balbir Singh <bsinghar...@gmail.com> writes:
> 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 <sant...@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?
Yes we always return the remaining bytes not copied even if check_copy_size
or access_ok fails.
Santosh
>
> 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)
>>
