[added to the 3.18 stable tree] MIPS: unaligned: Fix regular load/store instruction emulation for EVA

[Sasha Levin <sasha.levin@xxxxxxxxxx>]

From: Markos Chandras <markos.chandras@xxxxxxxxxx>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 6eae35485b26f9e51ab896eb8a936bed9908fdf6 ]

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@xxxxxxxxxx>
Fixes: c1771216ab48 ("MIPS: kernel: unaligned: Handle unaligned accesses for EVA")
Cc: <stable@xxxxxxxxxxxxxxx> # v3.15+
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/9503/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
 arch/mips/kernel/unaligned.c | 52 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 5 deletions(-)

diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index e11906d..91d5006 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/arch/mips/kernel/unaligned.c
@@ -564,7 +564,15 @@ 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);
@@ -575,7 +583,15 @@ 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);
@@ -586,7 +602,15 @@ 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);
@@ -645,7 +669,16 @@ 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;
@@ -656,7 +689,16 @@ 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;
-- 
2.1.0