target-mips: fix page fault address for LWL/LWR/LDL/LDR

When a LWL, LWR, LDL or LDR instruction triggers a page fault, QEMU
currently reports the aligned address in CP0 BadVAddr, while the Windows
NT kernel expects the unaligned address.

This patch adds a byte access with the unaligned address at the
beginning of the LWL/LWR/LDL/LDR instructions to possibly trigger a page
fault and fill the QEMU TLB.

Cc: Leon Alrae <leon.alrae@imgtec.com>
Reported-by: Hervé Poussineau <hpoussin@reactos.org>
Tested-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>

target-mips/translate.c

@@ -2142,6 +2142,9 @@ static void gen_ld(DisasContext *ctx, uint32_t opc,
         break;
     case OPC_LDL:
         t1 = tcg_temp_new();
+        /* Do a byte access to possibly trigger a page
+           fault with the unaligned address.  */
+        tcg_gen_qemu_ld_tl(t1, t0, ctx->mem_idx, MO_UB);
         tcg_gen_andi_tl(t1, t0, 7);
 #ifndef TARGET_WORDS_BIGENDIAN
         tcg_gen_xori_tl(t1, t1, 7);
@@ -2163,6 +2166,9 @@ static void gen_ld(DisasContext *ctx, uint32_t opc,
         break;
     case OPC_LDR:
         t1 = tcg_temp_new();
+        /* Do a byte access to possibly trigger a page
+           fault with the unaligned address.  */
+        tcg_gen_qemu_ld_tl(t1, t0, ctx->mem_idx, MO_UB);
         tcg_gen_andi_tl(t1, t0, 7);
 #ifdef TARGET_WORDS_BIGENDIAN
         tcg_gen_xori_tl(t1, t1, 7);
@@ -2229,6 +2235,9 @@ static void gen_ld(DisasContext *ctx, uint32_t opc,
         break;
     case OPC_LWL:
         t1 = tcg_temp_new();
+        /* Do a byte access to possibly trigger a page
+           fault with the unaligned address.  */
+        tcg_gen_qemu_ld_tl(t1, t0, ctx->mem_idx, MO_UB);
         tcg_gen_andi_tl(t1, t0, 3);
 #ifndef TARGET_WORDS_BIGENDIAN
         tcg_gen_xori_tl(t1, t1, 3);
@@ -2251,6 +2260,9 @@ static void gen_ld(DisasContext *ctx, uint32_t opc,
         break;
     case OPC_LWR:
         t1 = tcg_temp_new();
+        /* Do a byte access to possibly trigger a page
+           fault with the unaligned address.  */
+        tcg_gen_qemu_ld_tl(t1, t0, ctx->mem_idx, MO_UB);
         tcg_gen_andi_tl(t1, t0, 3);
 #ifdef TARGET_WORDS_BIGENDIAN
         tcg_gen_xori_tl(t1, t1, 3);