[Qemu-devel] [RFC 3/3] arm: Use different ARMMMUIdx values for M profile

[Peter Maydell <peter.maydell@linaro.org>]

Make M profile use completely separate ARMMMUIdx values from
those that A profile CPUs use. This is a prelude to adding
support for the MPU and for v8M, which together will require
6 MMU indexes which don't map cleanly onto the A profile
uses:
 non secure User
 non secure Privileged
 non secure Privileged, execution priority < 0
 secure User
 secure Privileged
 secure Privileged, execution priority < 0

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/cpu.h       | 21 ++++++++++++++++++---
 target/arm/helper.c    |  5 +++++
 target/arm/translate.c |  3 +++
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index c162d43..226ddd9 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -2055,8 +2055,9 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx,
  * of the AT/ATS operations.
  * The values used are carefully arranged to make mmu_idx => EL lookup easy.
  */
-#define ARM_MMU_IDX_A 0x10 /* A profile (and M profile, for the moment) */
+#define ARM_MMU_IDX_A 0x10 /* A profile */
 #define ARM_MMU_IDX_NOTLB 0x20 /* does not have a TLB */
+#define ARM_MMU_IDX_M 0x40 /* M profile */
 
 typedef enum ARMMMUIdx {
     ARMMMUIdx_S12NSE0 = 0 | ARM_MMU_IDX_A,
@@ -2066,6 +2067,8 @@ typedef enum ARMMMUIdx {
     ARMMMUIdx_S1SE0 = 4 | ARM_MMU_IDX_A,
     ARMMMUIdx_S1SE1 = 5 | ARM_MMU_IDX_A,
     ARMMMUIdx_S2NS = 6 | ARM_MMU_IDX_A,
+    ARMMMUIdx_MUser = 0 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MPriv = 1 | ARM_MMU_IDX_M,
     /* Indexes below here don't have TLBs and are used only for AT system
      * instructions or for the first stage of an S12 page table walk.
      */
@@ -2084,6 +2087,8 @@ typedef enum ARMMMUIdxBit {
     ARMMMUIdxBit_S1SE0 = 1 << 4,
     ARMMMUIdxBit_S1SE1 = 1 << 5,
     ARMMMUIdxBit_S2NS = 1 << 6,
+    ARMMMUIdxBit_MUser = 1 << 0,
+    ARMMMUIdxBit_MPriv = 1 << 1,
 } ARMMMUIdxBit;
 
 #define MMU_USER_IDX 0
@@ -2095,13 +2100,17 @@ static inline int arm_to_core_mmu_idx(ARMMMUIdx mmu_idx)
 
 static inline ARMMMUIdx core_to_arm_mmu_idx(CPUARMState *env, int mmu_idx)
 {
-    return mmu_idx | ARM_MMU_IDX_A;
+    if (arm_feature(env, ARM_FEATURE_M)) {
+        return mmu_idx | ARM_MMU_IDX_M;
+    } else {
+        return mmu_idx | ARM_MMU_IDX_A;
+    }
 }
 
 /* Return the exception level we're running at if this is our mmu_idx */
 static inline int arm_mmu_idx_to_el(ARMMMUIdx mmu_idx)
 {
-    assert(mmu_idx < ARMMMUIdx_S2NS);
+    assert((mmu_idx & ~7) != ARM_MMU_IDX_NOTLB);
     return mmu_idx & 3;
 }
 
@@ -2110,6 +2119,12 @@ static inline int cpu_mmu_index(CPUARMState *env, bool ifetch)
 {
     int el = arm_current_el(env);
 
+    if (arm_feature(env, ARM_FEATURE_M)) {
+        ARMMMUIdx mmu_idx = el == 0 ? ARMMMUIdx_MUser : ARMMMUIdx_MPriv;
+
+        return arm_to_core_mmu_idx(mmu_idx);
+    }
+
     if (el < 2 && arm_is_secure_below_el3(env)) {
         return arm_to_core_mmu_idx(ARMMMUIdx_S1SE0 + el);
     }
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 520adcc..791332c 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6992,6 +6992,8 @@ static inline uint32_t regime_el(CPUARMState *env, ARMMMUIdx mmu_idx)
     case ARMMMUIdx_S1SE1:
     case ARMMMUIdx_S1NSE0:
     case ARMMMUIdx_S1NSE1:
+    case ARMMMUIdx_MPriv:
+    case ARMMMUIdx_MUser:
         return 1;
     default:
         g_assert_not_reached();
@@ -7008,6 +7010,8 @@ static inline bool regime_is_secure(CPUARMState *env, ARMMMUIdx mmu_idx)
     case ARMMMUIdx_S1NSE1:
     case ARMMMUIdx_S1E2:
     case ARMMMUIdx_S2NS:
+    case ARMMMUIdx_MPriv:
+    case ARMMMUIdx_MUser:
         return false;
     case ARMMMUIdx_S1E3:
     case ARMMMUIdx_S1SE0:
@@ -7146,6 +7150,7 @@ static inline bool regime_is_user(CPUARMState *env, ARMMMUIdx mmu_idx)
     switch (mmu_idx) {
     case ARMMMUIdx_S1SE0:
     case ARMMMUIdx_S1NSE0:
+    case ARMMMUIdx_MUser:
         return true;
     default:
         return false;
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 8d509a2..ac905dd 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -161,6 +161,9 @@ static inline int get_a32_user_mem_index(DisasContext *s)
     case ARMMMUIdx_S1SE0:
     case ARMMMUIdx_S1SE1:
         return arm_to_core_mmu_idx(ARMMMUIdx_S1SE0);
+    case ARMMMUIdx_MUser:
+    case ARMMMUIdx_MPriv:
+        return arm_to_core_mmu_idx(ARMMMUIdx_MUser);
     case ARMMMUIdx_S2NS:
     default:
         g_assert_not_reached();
-- 
2.7.4