[Qemu-devel] [[PATCH] 4/7] target-arm: Add AArch64 CPTR registers

[Greg Bellows <greg.bellows@linaro.org>]

Adds CPTR_EL2/3 system registers definitions and access function.

Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
---
 target-arm/cpu.h    | 18 +++++++++++++++++-
 target-arm/helper.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 2178a1f..a811369 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -202,6 +202,7 @@ typedef struct CPUARMState {
             uint64_t sctlr_el[4];
         };
         uint64_t c1_coproc; /* Coprocessor access register.  */
+        uint64_t cptr_el[4];  /* ARMv8 feature trap registers */
         uint32_t c1_xscaleauxcr; /* XScale auxiliary control register.  */
         uint64_t sder; /* Secure debug enable register. */
         uint32_t nsacr; /* Non-secure access control register. */
@@ -575,6 +576,10 @@ void pmccntr_sync(CPUARMState *env);
 #define SCTLR_AFE     (1U << 29)
 #define SCTLR_TE      (1U << 30)
 
+#define CPTR_TCPAC    (1U << 31)
+#define CPTR_TTA      (1U << 20)
+#define CPTR_TFP      (1U << 10)
+
 #define CPSR_M (0x1fU)
 #define CPSR_T (1U << 5)
 #define CPSR_F (1U << 6)
@@ -1813,9 +1818,20 @@ static inline void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
                                         target_ulong *cs_base, int *flags)
 {
     int fpen;
+    int cur_el = arm_current_el(env);
 
     if (arm_feature(env, ARM_FEATURE_V6)) {
-        fpen = extract32(env->cp15.c1_coproc, 20, 2);
+        /* In AArch64, FP can be enabled differently depending on our EL.
+         * If our EL is 2 or 3, we use the EL specific CPTR to determine if FP
+         * is enabled.  Otherwise, we fall back to using CPACR.
+         * CPTR.TFP is clear if FP is enabled whereas CPACR.FPEN is set to some
+         * degree.
+         */
+        if (is_a64(env) && cur_el >= 2) {
+            fpen = !extract32(env->cp15.cptr_el[cur_el], 10, 1);
+        } else {
+            fpen = extract32(env->cp15.c1_coproc, 20, 2);
+        }
     } else {
         /* CPACR doesn't exist before v6, so VFP is always accessible */
         fpen = 3;
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 95383d5..00b457a 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -592,6 +592,39 @@ static void cpacr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     env->cp15.c1_coproc = value;
 }
 
+static CPAccessResult cptr_access(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    int cur_el = arm_current_el(env);
+    bool secure = arm_is_secure(env);
+
+    switch (ri->opc1) {
+    case 0:     /* CPACR and CPACR_EL1 */
+        if (arm_feature(env, ARM_FEATURE_V8) && cur_el == 1) {
+            /* Make sure we have EL2 before routine there */
+            if (arm_feature(env, ARM_FEATURE_EL2) && !secure &&
+                (env->cp15.cptr_el[2] & CPTR_TCPAC)) {
+                env->exception.target_el = 2;
+                return CP_ACCESS_TRAP;
+            /* Make sure we have EL3 before routine there */
+            } else if (arm_feature(env, ARM_FEATURE_EL3) &&
+                       env->cp15.cptr_el[3] & CPTR_TCPAC) {
+                env->exception.target_el = 3;
+                return CP_ACCESS_TRAP;
+            }
+        }
+        break;
+    case 4:     /* CPTR_EL2 */
+        /* It is safe to assume we have EL2 and ARMv8 if we get here */
+        if (cur_el == 2 && (env->cp15.cptr_el[3] & CPTR_TCPAC)) {
+            env->exception.target_el = 3;
+            return CP_ACCESS_TRAP;
+        }
+        break;
+    }
+
+    return CP_ACCESS_OK;
+}
+
 static const ARMCPRegInfo v6_cp_reginfo[] = {
     /* prefetch by MVA in v6, NOP in v7 */
     { .name = "MVA_prefetch",
@@ -614,7 +647,7 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
     { .name = "WFAR", .cp = 15, .crn = 6, .crm = 0, .opc1 = 0, .opc2 = 1,
       .access = PL1_RW, .type = ARM_CP_CONST, .resetvalue = 0, },
     { .name = "CPACR", .state = ARM_CP_STATE_BOTH, .opc0 = 3,
-      .crn = 1, .crm = 0, .opc1 = 0, .opc2 = 2,
+      .crn = 1, .crm = 0, .opc1 = 0, .opc2 = 2, .accessfn = cptr_access,
       .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.c1_coproc),
       .resetvalue = 0, .writefn = cpacr_write },
     REGINFO_SENTINEL
@@ -2537,6 +2570,10 @@ static const ARMCPRegInfo v8_el2_cp_reginfo[] = {
       .opc0 = 3, .opc1 = 6, .crn = 4, .crm = 1, .opc2 = 0,
       .access = PL3_RW, .type = ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, sp_el[2]) },
+    { .name = "CPTR_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 4, .crn = 1, .crm = 1, .opc2 = 2,
+      .access = PL2_RW, .accessfn = cptr_access, .resetvalue = 0,
+      .fieldoffset = offsetof(CPUARMState, cp15.cptr_el[2]) },
     REGINFO_SENTINEL
 };
 
@@ -2598,6 +2635,10 @@ static const ARMCPRegInfo el3_cp_reginfo[] = {
       .access = PL3_RW, .writefn = vbar_write,
       .fieldoffset = offsetof(CPUARMState, cp15.vbar_el[3]),
       .resetvalue = 0 },
+    { .name = "CPTR_EL3", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 6, .crn = 1, .crm = 1, .opc2 = 2,
+      .access = PL3_RW, .accessfn = cptr_access, .resetvalue = 0,
+      .fieldoffset = offsetof(CPUARMState, cp15.cptr_el[3]) },
     REGINFO_SENTINEL
 };
 
-- 
1.8.3.2