MIPS: unaligned: Fix regular load/store instruction emulation for EVA

When emulating a regular lh/lw/lhu/sh/sw we need to use the appropriate
instruction if we are in EVA mode. This is necessary for userspace
applications which trigger alignment exceptions. In such case, the
userspace load/store instruction needs to be emulated with the correct
eva/non-eva instruction by the kernel emulator.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Fixes: c1771216ab48 ("MIPS: kernel: unaligned: Handle unaligned accesses for EVA")
Cc: <stable@vger.kernel.org> # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9503/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/unaligned.c

@@ -1023,7 +1023,15 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 		if (!access_ok(VERIFY_READ, addr, 2))
 			goto sigbus;
 
-		LoadHW(addr, value, res);
+		if (config_enabled(CONFIG_EVA)) {
+			if (segment_eq(get_fs(), get_ds()))
+				LoadHW(addr, value, res);
+			else
+				LoadHWE(addr, value, res);
+		} else {
+			LoadHW(addr, value, res);
+		}
+
 		if (res)
 			goto fault;
 		compute_return_epc(regs);
@@ -1034,7 +1042,15 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 		if (!access_ok(VERIFY_READ, addr, 4))
 			goto sigbus;
 
-		LoadW(addr, value, res);
+		if (config_enabled(CONFIG_EVA)) {
+			if (segment_eq(get_fs(), get_ds()))
+				LoadW(addr, value, res);
+			else
+				LoadWE(addr, value, res);
+		} else {
+			LoadW(addr, value, res);
+		}
+
 		if (res)
 			goto fault;
 		compute_return_epc(regs);
@@ -1045,7 +1061,15 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 		if (!access_ok(VERIFY_READ, addr, 2))
 			goto sigbus;
 
-		LoadHWU(addr, value, res);
+		if (config_enabled(CONFIG_EVA)) {
+			if (segment_eq(get_fs(), get_ds()))
+				LoadHWU(addr, value, res);
+			else
+				LoadHWUE(addr, value, res);
+		} else {
+			LoadHWU(addr, value, res);
+		}
+
 		if (res)
 			goto fault;
 		compute_return_epc(regs);
@@ -1104,7 +1128,16 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 
 		compute_return_epc(regs);
 		value = regs->regs[insn.i_format.rt];
-		StoreHW(addr, value, res);
+
+		if (config_enabled(CONFIG_EVA)) {
+			if (segment_eq(get_fs(), get_ds()))
+				StoreHW(addr, value, res);
+			else
+				StoreHWE(addr, value, res);
+		} else {
+			StoreHW(addr, value, res);
+		}
+
 		if (res)
 			goto fault;
 		break;
@@ -1115,7 +1148,16 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 
 		compute_return_epc(regs);
 		value = regs->regs[insn.i_format.rt];
-		StoreW(addr, value, res);
+
+		if (config_enabled(CONFIG_EVA)) {
+			if (segment_eq(get_fs(), get_ds()))
+				StoreW(addr, value, res);
+			else
+				StoreWE(addr, value, res);
+		} else {
+			StoreW(addr, value, res);
+		}
+
 		if (res)
 			goto fault;
 		break;