target-arm: Decode SETEND correctly in Thumb

Decode the SETEND instruction correctly in Thumb mode,
rather than accidentally treating it like CPS. We don't
support BE8 mode, but this change brings the Thumb mode
in to line with behaviour in ARM mode: 'SETEND BE' is
not supported and will provoke an UNDEF exception, but
'SETEND LE' is correctly handled as a no-op.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reported-by: NDaniel Forsgren <daniel.forsgren@enea.com>
Reviewed-by: NLaurent Desnogues <laurent.desnogues@gmail.com>

target-arm/translate.c

@@ -9704,32 +9704,49 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
             store_reg(s, rd, tmp);
             break;
 
-        case 6: /* cps */
-            ARCH(6);
-            if (IS_USER(s))
+        case 6:
+            switch ((insn >> 5) & 7) {
+            case 2:
+                /* setend */
+                ARCH(6);
+                if (insn & (1 << 3)) {
+                    /* BE8 mode not implemented.  */
+                    goto illegal_op;
+                }
                 break;
-            if (IS_M(env)) {
-                tmp = tcg_const_i32((insn & (1 << 4)) != 0);
-                /* FAULTMASK */
-                if (insn & 1) {
-                    addr = tcg_const_i32(19);
-                    gen_helper_v7m_msr(cpu_env, addr, tmp);
-                    tcg_temp_free_i32(addr);
+            case 3:
+                /* cps */
+                ARCH(6);
+                if (IS_USER(s)) {
+                    break;
                 }
-                /* PRIMASK */
-                if (insn & 2) {
-                    addr = tcg_const_i32(16);
-                    gen_helper_v7m_msr(cpu_env, addr, tmp);
-                    tcg_temp_free_i32(addr);
+                if (IS_M(env)) {
+                    tmp = tcg_const_i32((insn & (1 << 4)) != 0);
+                    /* FAULTMASK */
+                    if (insn & 1) {
+                        addr = tcg_const_i32(19);
+                        gen_helper_v7m_msr(cpu_env, addr, tmp);
+                        tcg_temp_free_i32(addr);
+                    }
+                    /* PRIMASK */
+                    if (insn & 2) {
+                        addr = tcg_const_i32(16);
+                        gen_helper_v7m_msr(cpu_env, addr, tmp);
+                        tcg_temp_free_i32(addr);
+                    }
+                    tcg_temp_free_i32(tmp);
+                    gen_lookup_tb(s);
+                } else {
+                    if (insn & (1 << 4)) {
+                        shift = CPSR_A | CPSR_I | CPSR_F;
+                    } else {
+                        shift = 0;
+                    }
+                    gen_set_psr_im(s, ((insn & 7) << 6), 0, shift);
                 }
-                tcg_temp_free_i32(tmp);
-                gen_lookup_tb(s);
-            } else {
-                if (insn & (1 << 4))
-                    shift = CPSR_A | CPSR_I | CPSR_F;
-                else
-                    shift = 0;
-                gen_set_psr_im(s, ((insn & 7) << 6), 0, shift);
+                break;
+            default:
+                goto undef;
             }
             break;