[PATCH 06/11] target/arm: Update MSR access for PAN

[Richard Henderson <richard.henderson@linaro.org>]

For aarch64, there's a dedicated msr (imm, reg) insn.
For aarch32, this is done via msr to cpsr; and writes
from el0 are ignored.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.h           |  2 ++
 target/arm/helper.c        | 22 ++++++++++++++++++++++
 target/arm/translate-a64.c | 14 ++++++++++++++
 target/arm/translate.c     |  4 ++++
 4 files changed, 42 insertions(+)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 170dd5b124..f0e61bf34f 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1159,6 +1159,7 @@ void pmu_init(ARMCPU *cpu);
  * We will need to move AArch32 SS somewhere else at that point.
  */
 #define CPSR_RESERVED (1U << 21)
+#define CPSR_PAN (1U << 22)
 #define CPSR_J (1U << 24)
 #define CPSR_IT_0_1 (3U << 25)
 #define CPSR_Q (1U << 27)
@@ -1225,6 +1226,7 @@ void pmu_init(ARMCPU *cpu);
 #define PSTATE_BTYPE (3U << 10)
 #define PSTATE_IL (1U << 20)
 #define PSTATE_SS (1U << 21)
+#define PSTATE_PAN (1U << 22)
 #define PSTATE_V (1U << 28)
 #define PSTATE_C (1U << 29)
 #define PSTATE_Z (1U << 30)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 4e3fe00316..512be5c644 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -4112,6 +4112,17 @@ static void aa64_daif_write(CPUARMState *env, const ARMCPRegInfo *ri,
     env->daif = value & PSTATE_DAIF;
 }
 
+static uint64_t aa64_pan_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    return env->pstate & PSTATE_PAN;
+}
+
+static void aa64_pan_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                           uint64_t value)
+{
+    env->pstate = (env->pstate & ~PSTATE_PAN) | (value & PSTATE_PAN);
+}
+
 static CPAccessResult aa64_cacheop_access(CPUARMState *env,
                                           const ARMCPRegInfo *ri,
                                           bool isread)
@@ -7405,6 +7416,17 @@ void register_cp_regs_for_features(ARMCPU *cpu)
         define_arm_cp_regs(cpu, lor_reginfo);
     }
 
+    if (cpu_isar_feature(aa64_pan, cpu)) {
+        static const ARMCPRegInfo pan_reginfo[] = {
+            { .name = "PAN", .state = ARM_CP_STATE_AA64,
+              .opc0 = 3, .opc1 = 0, .crn = 4, .crm = 2, .opc2 = 3,
+              .type = ARM_CP_NO_RAW, .access = PL1_RW,
+              .readfn = aa64_pan_read, .writefn = aa64_pan_write, },
+            REGINFO_SENTINEL
+        };
+        define_arm_cp_regs(cpu, pan_reginfo);
+    }
+
     if (arm_feature(env, ARM_FEATURE_EL2) && cpu_isar_feature(aa64_vh, cpu)) {
         static const ARMCPRegInfo vhe_reginfo[] = {
             { .name = "CONTEXTIDR_EL2", .state = ARM_CP_STATE_AA64,
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index b5c7bc2d76..7f5a68106b 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -1601,6 +1601,20 @@ static void handle_msr_i(DisasContext *s, uint32_t insn,
         s->base.is_jmp = DISAS_NEXT;
         break;
 
+    case 0x04: /* PAN */
+        if (!dc_isar_feature(aa64_pan, s) || s->current_el == 0) {
+            goto do_unallocated;
+        }
+        if (crm & 1) {
+            set_pstate_bits(PSTATE_PAN);
+        } else {
+            clear_pstate_bits(PSTATE_PAN);
+        }
+        t1 = tcg_const_i32(s->current_el);
+        gen_helper_rebuild_hflags_a64(cpu_env, t1);
+        tcg_temp_free_i32(t1);
+        break;
+
     case 0x05: /* SPSel */
         if (s->current_el == 0) {
             goto do_unallocated;
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 47a374b53d..98e6072dd4 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -2785,6 +2785,10 @@ static int gen_set_psr(DisasContext *s, uint32_t mask, int spsr, TCGv_i32 t0)
         tcg_gen_or_i32(tmp, tmp, t0);
         store_cpu_field(tmp, spsr);
     } else {
+        /* Data writes to CPSR.PAN using an MSR insn at EL0 are ignored.  */
+        if (IS_USER(s)) {
+            mask &= ~CPSR_PAN;
+        }
         gen_set_cpsr(t0, mask);
     }
     tcg_temp_free_i32(t0);
-- 
2.17.1