target-arm: A64: Implement MSR (immediate) instructions

Implement the MSR (immediate) instructions, which can update the
PSTATE SP and DAIF fields.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPeter Crosthwaite <peter.crosthwaite@xilinx.com>

target-arm/helper.h

@@ -63,6 +63,8 @@ DEF_HELPER_2(get_cp_reg, i32, env, ptr)
 DEF_HELPER_3(set_cp_reg64, void, env, ptr, i64)
 DEF_HELPER_2(get_cp_reg64, i64, env, ptr)
 
+DEF_HELPER_3(msr_i_pstate, void, env, i32, i32)
+
 DEF_HELPER_2(get_r13_banked, i32, env, i32)
 DEF_HELPER_3(set_r13_banked, void, env, i32, i32)
 

target-arm/op_helper.c

@@ -319,6 +319,31 @@ uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void *rip)
     return ri->readfn(env, ri);
 }
 
+void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, uint32_t imm)
+{
+    /* MSR_i to update PSTATE. This is OK from EL0 only if UMA is set.
+     * Note that SPSel is never OK from EL0; we rely on handle_msr_i()
+     * to catch that case at translate time.
+     */
+    if (arm_current_pl(env) == 0 && !(env->cp15.c1_sys & SCTLR_UMA)) {
+        raise_exception(env, EXCP_UDEF);
+    }
+
+    switch (op) {
+    case 0x05: /* SPSel */
+        env->pstate = deposit32(env->pstate, 0, 1, imm);
+        break;
+    case 0x1e: /* DAIFSet */
+        env->daif |= (imm << 6) & PSTATE_DAIF;
+        break;
+    case 0x1f: /* DAIFClear */
+        env->daif &= ~((imm << 6) & PSTATE_DAIF);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+}
+
 /* ??? Flag setting arithmetic is awkward because we need to do comparisons.
    The only way to do that in TCG is a conditional branch, which clobbers
    all our temporaries.  For now implement these as helper functions.  */

target-arm/translate-a64.c

@@ -1128,7 +1128,30 @@ static void handle_sync(DisasContext *s, uint32_t insn,
 static void handle_msr_i(DisasContext *s, uint32_t insn,
                          unsigned int op1, unsigned int op2, unsigned int crm)
 {
-    unsupported_encoding(s, insn);
+    int op = op1 << 3 | op2;
+    switch (op) {
+    case 0x05: /* SPSel */
+        if (s->current_pl == 0) {
+            unallocated_encoding(s);
+            return;
+        }
+        /* fall through */
+    case 0x1e: /* DAIFSet */
+    case 0x1f: /* DAIFClear */
+    {
+        TCGv_i32 tcg_imm = tcg_const_i32(crm);
+        TCGv_i32 tcg_op = tcg_const_i32(op);
+        gen_a64_set_pc_im(s->pc - 4);
+        gen_helper_msr_i_pstate(cpu_env, tcg_op, tcg_imm);
+        tcg_temp_free_i32(tcg_imm);
+        tcg_temp_free_i32(tcg_op);
+        s->is_jmp = DISAS_UPDATE;
+        break;
+    }
+    default:
+        unallocated_encoding(s);
+        return;
+    }
 }
 
 static void gen_get_nzcv(TCGv_i64 tcg_rt)