target/ppc: Move SPR_DSISR setting to powerpc_excp

By doing this while sending the exception, we will have already
done the unwinding, which makes the ppc_cpu_do_unaligned_access
code a bit cleaner.

Update the comment about the expected instruction format.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index b7d176792098d2d03284a5af7a8aa60d2cb2dd86..88a8de4b801aca6afc742b7f4344cd370a087e9e 100644 (file)
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -454,13 +454,15 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
         break;
     }
     case POWERPC_EXCP_ALIGN:     /* Alignment exception                      */
-        /* Get rS/rD and rA from faulting opcode */
         /*
-         * Note: the opcode fields will not be set properly for a
-         * direct store load/store, but nobody cares as nobody
-         * actually uses direct store segments.
+         * Get rS/rD and rA from faulting opcode.
+         * Note: We will only invoke ALIGN for atomic operations,
+         * so all instructions are X-form.
          */
-        env->spr[SPR_DSISR] |= (env->error_code & 0x03FF0000) >> 16;
+        {
+            uint32_t insn = cpu_ldl_code(env, env->nip);
+            env->spr[SPR_DSISR] |= (insn & 0x03FF0000) >> 16;
+        }
         break;
     case POWERPC_EXCP_PROGRAM:   /* Program exception                        */
         switch (env->error_code & ~0xF) {
@@ -1462,14 +1464,9 @@ void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
                                  int mmu_idx, uintptr_t retaddr)
 {
     CPUPPCState *env = cs->env_ptr;
-    uint32_t insn;
-
-    /* Restore state and reload the insn we executed, for filling in DSISR.  */
-    cpu_restore_state(cs, retaddr, true);
-    insn = cpu_ldl_code(env, env->nip);
 
     cs->exception_index = POWERPC_EXCP_ALIGN;
-    env->error_code = insn & 0x03FF0000;
-    cpu_loop_exit(cs);
+    env->error_code = 0;
+    cpu_loop_exit_restore(cs, retaddr);
 }
 #endif