microblaze: Trap on unaligned data accesses.

Untested...
Signed-off-by: NEdgar E. Iglesias <edgar.iglesias@gmail.com>

target-microblaze/helper.h

@@ -16,4 +16,6 @@ DEF_HELPER_1(mmu_read, i32, i32)
 DEF_HELPER_2(mmu_write, void, i32, i32)
 #endif
 
+DEF_HELPER_4(memalign, void, i32, i32, i32, i32)
+
 #include "def-helper.h"

target-microblaze/op_helper.c

@@ -206,6 +206,33 @@ uint32_t helper_pcmpbf(uint32_t a, uint32_t b)
     return 0;
 }
 
+void helper_memalign(uint32_t addr, uint32_t dr, uint32_t wr, uint32_t size)
+{
+    uint32_t mask;
+
+    switch (size) {
+        case 4: mask = 3; break;
+        case 2: mask = 1; break;
+        default:
+        case 1: mask = 0; break;
+    }
+
+    if (addr & mask) {
+            qemu_log("unaligned access addr=%x size=%d, wr=%d\n",
+                     addr, size, wr);
+            if (!(env->sregs[SR_MSR] & MSR_EE)) {
+                return;
+            }
+
+            env->sregs[SR_ESR] = ESR_EC_UNALIGNED_DATA | (wr << 10) \
+                                 | (dr & 31) << 5;
+            if (size == 4) {
+                env->sregs[SR_ESR] |= 1 << 11;
+            }
+            helper_raise_exception(EXCP_HW_EXCP);
+    }
+}
+
 #if !defined(CONFIG_USER_ONLY)
 /* Writes/reads to the MMU's special regs end up here.  */
 uint32_t helper_mmu_read(uint32_t rn)

target-microblaze/translate.c

@@ -810,9 +810,16 @@ static void dec_load(DisasContext *dc)
 
     /* If we get a fault on a dslot, the jmpstate better be in sync.  */
     sync_jmpstate(dc);
-    if (dc->rd)
+
+    /* Verify alignment if needed.  */
+    if ((dc->env->pvr.regs[2] & PVR2_UNALIGNED_EXC_MASK) && size > 1) {
+        gen_helper_memalign(*addr, tcg_const_tl(dc->rd),
+                            tcg_const_tl(0), tcg_const_tl(size));
+    }
+
+    if (dc->rd) {
         gen_load(dc, cpu_R[dc->rd], *addr, size);
-    else {
+    } else {
         gen_load(dc, env_imm, *addr, size);
     }
 
@@ -847,6 +854,13 @@ static void dec_store(DisasContext *dc)
     /* If we get a fault on a dslot, the jmpstate better be in sync.  */
     sync_jmpstate(dc);
     addr = compute_ldst_addr(dc, &t);
+
+    /* Verify alignment if needed.  */
+    if ((dc->env->pvr.regs[2] & PVR2_UNALIGNED_EXC_MASK) && size > 1) {
+        gen_helper_memalign(*addr, tcg_const_tl(dc->rd),
+                            tcg_const_tl(1), tcg_const_tl(size));
+    }
+
     gen_store(dc, *addr, cpu_R[dc->rd], size);
     if (addr == &t)
         tcg_temp_free(t);