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>

1 files changed, 47 insertions, 5 deletions

diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index ab475903175f..7659da224fcd 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/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;