[RFC PATCH -next V2 5/7] arm64: add get_user to machine check safe

[Tong Tiangen]

Add scenarios get_user to machine check safe. The processing of
EX_TYPE_UACCESS_ERR_ZERO and EX_TYPE_UACCESS_ERR_ZERO_UCE_RECOVERY is same
and both return -EFAULT.

Signed-off-by: Tong Tiangen <tongtiangen at huawei.com>
---
 arch/arm64/include/asm/asm-extable.h | 14 +++++++++++++-
 arch/arm64/include/asm/uaccess.h     |  2 +-
 arch/arm64/mm/extable.c              |  1 +
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h
index 74d1db74fd86..bfc2d224cbae 100644
--- a/arch/arm64/include/asm/asm-extable.h
+++ b/arch/arm64/include/asm/asm-extable.h
@@ -10,8 +10,11 @@
 
 /* _MC indicates that can fixup from machine check errors */
 #define EX_TYPE_FIXUP_MC		5
+#define EX_TYPE_UACCESS_ERR_ZERO_MC	6
 
-#define IS_EX_TYPE_MC(type) (type == EX_TYPE_FIXUP_MC)
+#define IS_EX_TYPE_MC(type)			\
+	(type == EX_TYPE_FIXUP_MC ||		\
+	 type == EX_TYPE_UACCESS_ERR_ZERO_MC)
 
 #ifdef __ASSEMBLY__
 
@@ -77,6 +80,15 @@
 #define EX_DATA_REG(reg, gpr)						\
 	"((.L__gpr_num_" #gpr ") << " __stringify(EX_DATA_REG_##reg##_SHIFT) ")"
 
+#define _ASM_EXTABLE_UACCESS_ERR_ZERO_MC(insn, fixup, err, zero)		\
+	__DEFINE_ASM_GPR_NUMS							\
+	__ASM_EXTABLE_RAW(#insn, #fixup,					\
+			  __stringify(EX_TYPE_UACCESS_ERR_ZERO_MC),		\
+			  "("							\
+			    EX_DATA_REG(ERR, err) " | "				\
+			    EX_DATA_REG(ZERO, zero)				\
+			  ")")
+
 #define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero)		\
 	__DEFINE_ASM_GPR_NUMS						\
 	__ASM_EXTABLE_RAW(#insn, #fixup, 				\
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index e8dce0cc5eaa..24b662407fbd 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -236,7 +236,7 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
 	asm volatile(							\
 	"1:	" load "	" reg "1, [%2]\n"			\
 	"2:\n"								\
-	_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %w0, %w1)			\
+	_ASM_EXTABLE_UACCESS_ERR_ZERO_MC(1b, 2b, %w0, %w1)		\
 	: "+r" (err), "=&r" (x)						\
 	: "r" (addr))
 
diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
index f1134c88e849..7c05f8d2bce0 100644
--- a/arch/arm64/mm/extable.c
+++ b/arch/arm64/mm/extable.c
@@ -95,6 +95,7 @@ bool fixup_exception(struct pt_regs *regs, unsigned int esr)
 	case EX_TYPE_BPF:
 		return ex_handler_bpf(ex, regs);
 	case EX_TYPE_UACCESS_ERR_ZERO:
+	case EX_TYPE_UACCESS_ERR_ZERO_MC:
 		return ex_handler_uaccess_err_zero(ex, regs);
 	case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
 		return ex_handler_load_unaligned_zeropad(ex, regs);
-- 
2.18.0.huawei.25