target/sh4: trap unaligned accesses

SH4 requires that memory accesses are naturally aligned, except for the
SH4-A movua.l instructions which can do unaligned loads.
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target/sh4/cpu.c

@@ -301,6 +301,7 @@ static void superh_cpu_class_init(ObjectClass *oc, void *data)
 #ifdef CONFIG_USER_ONLY
     cc->handle_mmu_fault = superh_cpu_handle_mmu_fault;
 #else
+    cc->do_unaligned_access = superh_cpu_do_unaligned_access;
     cc->get_phys_page_debug = superh_cpu_get_phys_page_debug;
 #endif
     cc->disas_set_info = superh_cpu_disas_set_info;

target/sh4/cpu.h

@@ -24,6 +24,7 @@
 #include "cpu-qom.h"
 
 #define TARGET_LONG_BITS 32
+#define ALIGNED_ONLY
 
 /* CPU Subtypes */
 #define SH_CPU_SH7750  (1 << 0)
@@ -215,6 +216,9 @@ void superh_cpu_dump_state(CPUState *cpu, FILE *f,
 hwaddr superh_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 int superh_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
 int superh_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
+void superh_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
+                                    MMUAccessType access_type,
+                                    int mmu_idx, uintptr_t retaddr);
 
 void sh4_translate_init(void);
 SuperHCPU *cpu_sh4_init(const char *cpu_model);

target/sh4/op_helper.c

@@ -24,6 +24,22 @@
 
 #ifndef CONFIG_USER_ONLY
 
+void superh_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
+                                    MMUAccessType access_type,
+                                    int mmu_idx, uintptr_t retaddr)
+{
+    switch (access_type) {
+    case MMU_INST_FETCH:
+    case MMU_DATA_LOAD:
+        cs->exception_index = 0x0e0;
+        break;
+    case MMU_DATA_STORE:
+        cs->exception_index = 0x100;
+        break;
+    }
+    cpu_loop_exit_restore(cs, retaddr);
+}
+
 void tlb_fill(CPUState *cs, target_ulong addr, MMUAccessType access_type,
               int mmu_idx, uintptr_t retaddr)
 {

target/sh4/translate.c

@@ -1504,14 +1504,16 @@ static void _decode_opc(DisasContext * ctx)
     case 0x40a9:                /* movua.l @Rm,R0 */
         /* Load non-boundary-aligned data */
         if (ctx->features & SH_FEATURE_SH4A) {
-            tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx, MO_TEUL);
+            tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx,
+                                MO_TEUL | MO_UNALN);
             return;
         }
         break;
     case 0x40e9:                /* movua.l @Rm+,R0 */
         /* Load non-boundary-aligned data */
         if (ctx->features & SH_FEATURE_SH4A) {
-            tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx, MO_TEUL);
+            tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx,
+                                MO_TEUL | MO_UNALN);
             tcg_gen_addi_i32(REG(B11_8), REG(B11_8), 4);
             return;
         }