target-mips: fix updating XContext on mmu exception

Correct updating XContext.Region field on mmu exceptions.
If Config3.CTXTC = 0 then the R field of XContext has to be updated
with the value of bits 63..62 of the virtual address upon a TLB
exception.
Also fixed the below line which overs 80 characters.
Signed-off-by: NYongbok Kim <yongbok.kim@imgtec.com>
Reviewed-by: NJames Hogan <james.hogan@imgtec.com>
Reviewed-by: NLeon Alrae <leon.alrae@imgtec.com>
Signed-off-by: NLeon Alrae <leon.alrae@imgtec.com>

target-mips/helper.c

@@ -293,9 +293,10 @@ static void raise_mmu_exception(CPUMIPSState *env, target_ulong address,
         (env->CP0_EntryHi & 0xFF) | (address & (TARGET_PAGE_MASK << 1));
 #if defined(TARGET_MIPS64)
     env->CP0_EntryHi &= env->SEGMask;
-    env->CP0_XContext = (env->CP0_XContext & ((~0ULL) << (env->SEGBITS - 7))) |
-                        ((address & 0xC00000000000ULL) >> (55 - env->SEGBITS)) |
-                        ((address & ((1ULL << env->SEGBITS) - 1) & 0xFFFFFFFFFFFFE000ULL) >> 9);
+    env->CP0_XContext =
+        /* PTEBase */   (env->CP0_XContext & ((~0ULL) << (env->SEGBITS - 7))) |
+        /* R */         (extract64(address, 62, 2) << (env->SEGBITS - 9)) |
+        /* BadVPN2 */   (extract64(address, 13, env->SEGBITS - 13) << 4);
 #endif
     cs->exception_index = exception;
     env->error_code = error_code;