[PATCH 11/24] target-arm: Implement AArch64 DAIF system register

[Peter Maydell <peter.maydell@xxxxxxxxxx>]

Implement the DAIF system register which is a view of the
DAIF bits in PSTATE.

TODO: include support for the MSR_i encodings?

Signed-off-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
---
 target-arm/helper.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index 51b71a4..f23b500 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -1590,6 +1590,27 @@ static int aa64_fpsr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     return 0;
 }
 
+static int aa64_daif_read(CPUARMState *env, const ARMCPRegInfo *ri,
+                          uint64_t *value)
+{
+    if (arm_current_pl(env) == 0 && !(env->cp15.c1_sys & SCTLR_UMA)) {
+        return EXCP_UDEF;
+    }
+    *value = pstate_read(env) & PSTATE_DAIF;
+    return 0;
+}
+
+static int aa64_daif_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                           uint64_t value)
+{
+    if (arm_current_pl(env) == 0 && !(env->cp15.c1_sys & SCTLR_UMA)) {
+        return EXCP_UDEF;
+    }
+    env->pstate &= ~PSTATE_DAIF;
+    env->pstate |= (value & PSTATE_DAIF);
+    return 0;
+}
+
 static const ARMCPRegInfo v8_cp_reginfo[] = {
     /* Minimal set of EL0-visible registers. This will need to be expanded
      * significantly for system emulation of AArch64 CPUs.
@@ -1597,6 +1618,10 @@ static const ARMCPRegInfo v8_cp_reginfo[] = {
     { .name = "NZCV", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .opc2 = 0, .crn = 4, .crm = 2,
       .access = PL0_RW, .type = ARM_CP_NZCV },
+    { .name = "DAIF", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 3, .opc2 = 1, .crn = 4, .crm = 2,
+      .access = PL0_RW, .type = ARM_CP_NO_MIGRATE,
+      .readfn = aa64_daif_read, .writefn = aa64_daif_write },
     { .name = "FPCR", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .opc2 = 0, .crn = 4, .crm = 4,
       .access = PL0_RW, .readfn = aa64_fpcr_read, .writefn = aa64_fpcr_write },
-- 
1.8.5

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