Re: [v4 5/6] powerpc: add machine check safe copy_to_user

Use  memcpy_mcsafe() implementation to define copy_to_user_mcsafe()

Signed-off-by: Santosh Sivaraj <redacted>
---
  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 8c1c636308c8..a173b392c272 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -134,6 +134,7 @@ 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_HAS_ZONE_DEVICE		if PPC_BOOK3S_64
  	select ARCH_HAVE_NMI_SAFE_CMPXCHG

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 76f34346b642..8899864a5552 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h

@@ -386,6 +386,20 @@ 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;

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