powerpc/align: Convert emulate_spe() to scoped user access

Commit 861574d ("powerpc/uaccess: Implement masked user access")
provides optimised user access by avoiding the cost of access_ok().

Convert emulate_spe() to scoped user access to benefit from masked
user access.

Scoped user access also make the code simpler.

Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/4ff83cb240da4e2d0c34e2bce4b8b6ef19a33777.1773136880.git.chleroy@kernel.org

Author: Christophe Leroy (CS GROUP)

arch/powerpc/kernel/align.c

@@ -165,25 +165,23 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
 		temp.ll = data.ll = 0;
 		p = addr;
 
-		if (!user_read_access_begin(addr, nb))
-			return -EFAULT;
-
-		switch (nb) {
-		case 8:
-			unsafe_get_user(temp.v[0], p++, Efault_read);
-			unsafe_get_user(temp.v[1], p++, Efault_read);
-			unsafe_get_user(temp.v[2], p++, Efault_read);
-			unsafe_get_user(temp.v[3], p++, Efault_read);
-			fallthrough;
-		case 4:
-			unsafe_get_user(temp.v[4], p++, Efault_read);
-			unsafe_get_user(temp.v[5], p++, Efault_read);
-			fallthrough;
-		case 2:
-			unsafe_get_user(temp.v[6], p++, Efault_read);
-			unsafe_get_user(temp.v[7], p++, Efault_read);
+		scoped_user_read_access_size(addr, nb, efault) {
+			switch (nb) {
+			case 8:
+				unsafe_get_user(temp.v[0], p++, efault);
+				unsafe_get_user(temp.v[1], p++, efault);
+				unsafe_get_user(temp.v[2], p++, efault);
+				unsafe_get_user(temp.v[3], p++, efault);
+				fallthrough;
+			case 4:
+				unsafe_get_user(temp.v[4], p++, efault);
+				unsafe_get_user(temp.v[5], p++, efault);
+				fallthrough;
+			case 2:
+				unsafe_get_user(temp.v[6], p++, efault);
+				unsafe_get_user(temp.v[7], p++, efault);
+			}
 		}
-		user_read_access_end();
 
 		switch (instr) {
 		case EVLDD:
@@ -252,38 +250,31 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
 	if (flags & ST) {
 		p = addr;
 
-		if (!user_write_access_begin(addr, nb))
-			return -EFAULT;
-
-		switch (nb) {
-		case 8:
-			unsafe_put_user(data.v[0], p++, Efault_write);
-			unsafe_put_user(data.v[1], p++, Efault_write);
-			unsafe_put_user(data.v[2], p++, Efault_write);
-			unsafe_put_user(data.v[3], p++, Efault_write);
-			fallthrough;
-		case 4:
-			unsafe_put_user(data.v[4], p++, Efault_write);
-			unsafe_put_user(data.v[5], p++, Efault_write);
-			fallthrough;
-		case 2:
-			unsafe_put_user(data.v[6], p++, Efault_write);
-			unsafe_put_user(data.v[7], p++, Efault_write);
+		scoped_user_write_access_size(addr, nb, efault) {
+			switch (nb) {
+			case 8:
+				unsafe_put_user(data.v[0], p++, efault);
+				unsafe_put_user(data.v[1], p++, efault);
+				unsafe_put_user(data.v[2], p++, efault);
+				unsafe_put_user(data.v[3], p++, efault);
+				fallthrough;
+			case 4:
+				unsafe_put_user(data.v[4], p++, efault);
+				unsafe_put_user(data.v[5], p++, efault);
+				fallthrough;
+			case 2:
+				unsafe_put_user(data.v[6], p++, efault);
+				unsafe_put_user(data.v[7], p++, efault);
+			}
 		}
-		user_write_access_end();
 	} else {
 		*evr = data.w[0];
 		regs->gpr[reg] = data.w[1];
 	}
 
 	return 1;
 
-Efault_read:
-	user_read_access_end();
-	return -EFAULT;
-
-Efault_write:
-	user_write_access_end();
+efault:
 	return -EFAULT;
 }
 #endif /* CONFIG_SPE */