arm64/traps: Avoid unnecessary kernel/user pointer conversion

Annotating a pointer from kernel to __user and then back again requires
an extra __force annotation to silent sparse warning. In call_undef_hook()
this unnecessary complexity can be avoided by modifying the intermediate
user pointer to unsigned long.

This way there is no inter-changeable use of user and kernel pointers
and the code is consistent.

Note: This patch adds no functional changes to code.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210917055811.22341-1-amit.kachhap@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/traps.c

@@ -400,11 +400,11 @@ static int call_undef_hook(struct pt_regs *regs)
 	unsigned long flags;
 	u32 instr;
 	int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
-	void __user *pc = (void __user *)instruction_pointer(regs);
+	unsigned long pc = instruction_pointer(regs);
 
 	if (!user_mode(regs)) {
 		__le32 instr_le;
-		if (get_kernel_nofault(instr_le, (__force __le32 *)pc))
+		if (get_kernel_nofault(instr_le, (__le32 *)pc))
 			goto exit;
 		instr = le32_to_cpu(instr_le);
 	} else if (compat_thumb_mode(regs)) {