arm64: ptrace: fix compat registes get/set to be endian clean

On a BE system the wrong half of the X registers is retrieved/written
when attempting to get/set the value of aarch32 registers through
ptrace.

Ensure that types are the correct width so that the relevant
casting occurs.

Signed-off-by: Matthew Leach <[email protected]>
Reviewed-by: Will Deacon <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>

arch/arm64/kernel/ptrace.c

@@ -636,28 +636,27 @@ static int compat_gpr_get(struct task_struct *target,
 
 	for (i = 0; i < num_regs; ++i) {
 		unsigned int idx = start + i;
-		void *reg;
+		compat_ulong_t reg;
 
 		switch (idx) {
 		case 15:
-			reg = (void *)&task_pt_regs(target)->pc;
+			reg = task_pt_regs(target)->pc;
 			break;
 		case 16:
-			reg = (void *)&task_pt_regs(target)->pstate;
+			reg = task_pt_regs(target)->pstate;
 			break;
 		case 17:
-			reg = (void *)&task_pt_regs(target)->orig_x0;
+			reg = task_pt_regs(target)->orig_x0;
 			break;
 		default:
-			reg = (void *)&task_pt_regs(target)->regs[idx];
+			reg = task_pt_regs(target)->regs[idx];
 		}
 
-		ret = copy_to_user(ubuf, reg, sizeof(compat_ulong_t));
-
+		ret = copy_to_user(ubuf, &reg, sizeof(reg));
 		if (ret)
 			break;
-		else
-			ubuf += sizeof(compat_ulong_t);
+
+		ubuf += sizeof(reg);
 	}
 
 	return ret;
@@ -685,36 +684,35 @@ static int compat_gpr_set(struct task_struct *target,
 
 	for (i = 0; i < num_regs; ++i) {
 		unsigned int idx = start + i;
-		void *reg;
+		compat_ulong_t reg;
+
+		ret = copy_from_user(&reg, ubuf, sizeof(reg));
+		if (ret)
+			return ret;
+
+		ubuf += sizeof(reg);
 
 		switch (idx) {
 		case 15:
-			reg = (void *)&newregs.pc;
+			newregs.pc = reg;
 			break;
 		case 16:
-			reg = (void *)&newregs.pstate;
+			newregs.pstate = reg;
 			break;
 		case 17:
-			reg = (void *)&newregs.orig_x0;
+			newregs.orig_x0 = reg;
 			break;
 		default:
-			reg = (void *)&newregs.regs[idx];
+			newregs.regs[idx] = reg;
 		}
 
-		ret = copy_from_user(reg, ubuf, sizeof(compat_ulong_t));
-
-		if (ret)
-			goto out;
-		else
-			ubuf += sizeof(compat_ulong_t);
 	}
 
 	if (valid_user_regs(&newregs.user_regs))
 		*task_pt_regs(target) = newregs;
 	else
 		ret = -EINVAL;
 
-out:
 	return ret;
 }