target/arm: Split M profile MNegPri mmu index into user and priv

For M profile, we currently have an mmu index MNegPri for
"requested execution priority negative". This fails to
distinguish "requested execution priority negative, privileged"
from "requested execution priority negative, usermode", but
the two can return different results for MPU lookups. Fix this
by splitting MNegPri into MNegPriPriv and MNegPriUser, and
similarly for the Secure equivalent MSNegPri.

This takes us from 6 M profile MMU modes to 8, which means
we need to bump NB_MMU_MODES; this is OK since the point
where we are forced to reduce TLB sizes is 9 MMU modes.

(It would in theory be possible to stick with 6 MMU indexes:
{mpu-disabled,user,privileged} x {secure,nonsecure} since
in the MPU-disabled case the result of an MPU lookup is
always the same for both user and privileged code. However
we would then need to rework the TB flags handling to put
user/priv into the TB flags separately from the mmuidx.
Adding an extra couple of mmu indexes is simpler.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1512153879-5291-5-git-send-email-peter.maydell@linaro.org

1 files changed, 33 insertions, 21 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 89d49cdcb2..c42d62d479 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -112,7 +112,7 @@ enum {
 #define ARM_CPU_VIRQ 2
 #define ARM_CPU_VFIQ 3
 
-#define NB_MMU_MODES 7
+#define NB_MMU_MODES 8
 /* ARM-specific extra insn start words:
  * 1: Conditional execution bits
  * 2: Partial exception syndrome for data aborts
@@ -2226,13 +2226,13 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx,
  * They have the following different MMU indexes:
  *  User
  *  Privileged
- *  Execution priority negative (this is like privileged, but the
- *  MPU HFNMIENA bit means that it may have different access permission
- *  check results to normal privileged code, so can't share a TLB).
+ *  User, execution priority negative (ie the MPU HFNMIENA bit may apply)
+ *  Privileged, execution priority negative (ditto)
  * If the CPU supports the v8M Security Extension then there are also:
  *  Secure User
  *  Secure Privileged
- *  Secure, execution priority negative
+ *  Secure User, execution priority negative
+ *  Secure Privileged, execution priority negative
  *
  * The ARMMMUIdx and the mmu index value used by the core QEMU TLB code
  * are not quite the same -- different CPU types (most notably M profile
@@ -2251,11 +2251,18 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx,
  * The constant names here are patterned after the general style of the names
  * of the AT/ATS operations.
  * The values used are carefully arranged to make mmu_idx => EL lookup easy.
+ * For M profile we arrange them to have a bit for priv, a bit for negpri
+ * and a bit for secure.
  */
 #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 */
 
+/* meanings of the bits for M profile mmu idx values */
+#define ARM_MMU_IDX_M_PRIV 0x1
+#define ARM_MMU_IDX_M_NEGPRI 0x2
+#define ARM_MMU_IDX_M_S 0x4
+
 #define ARM_MMU_IDX_TYPE_MASK (~0x7)
 #define ARM_MMU_IDX_COREIDX_MASK 0x7
 
@@ -2269,10 +2276,12 @@ typedef enum ARMMMUIdx {
     ARMMMUIdx_S2NS = 6 | ARM_MMU_IDX_A,
     ARMMMUIdx_MUser = 0 | ARM_MMU_IDX_M,
     ARMMMUIdx_MPriv = 1 | ARM_MMU_IDX_M,
-    ARMMMUIdx_MNegPri = 2 | ARM_MMU_IDX_M,
-    ARMMMUIdx_MSUser = 3 | ARM_MMU_IDX_M,
-    ARMMMUIdx_MSPriv = 4 | ARM_MMU_IDX_M,
-    ARMMMUIdx_MSNegPri = 5 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MUserNegPri = 2 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MPrivNegPri = 3 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MSUser = 4 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MSPriv = 5 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MSUserNegPri = 6 | ARM_MMU_IDX_M,
+    ARMMMUIdx_MSPrivNegPri = 7 | 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.
      */
@@ -2293,10 +2302,12 @@ typedef enum ARMMMUIdxBit {
     ARMMMUIdxBit_S2NS = 1 << 6,
     ARMMMUIdxBit_MUser = 1 << 0,
     ARMMMUIdxBit_MPriv = 1 << 1,
-    ARMMMUIdxBit_MNegPri = 1 << 2,
-    ARMMMUIdxBit_MSUser = 1 << 3,
-    ARMMMUIdxBit_MSPriv = 1 << 4,
-    ARMMMUIdxBit_MSNegPri = 1 << 5,
+    ARMMMUIdxBit_MUserNegPri = 1 << 2,
+    ARMMMUIdxBit_MPrivNegPri = 1 << 3,
+    ARMMMUIdxBit_MSUser = 1 << 4,
+    ARMMMUIdxBit_MSPriv = 1 << 5,
+    ARMMMUIdxBit_MSUserNegPri = 1 << 6,
+    ARMMMUIdxBit_MSPrivNegPri = 1 << 7,
 } ARMMMUIdxBit;
 
 #define MMU_USER_IDX 0
@@ -2322,8 +2333,7 @@ static inline int arm_mmu_idx_to_el(ARMMMUIdx mmu_idx)
     case ARM_MMU_IDX_A:
         return mmu_idx & 3;
     case ARM_MMU_IDX_M:
-        return (mmu_idx == ARMMMUIdx_MUser || mmu_idx == ARMMMUIdx_MSUser)
-            ? 0 : 1;
+        return mmu_idx & ARM_MMU_IDX_M_PRIV;
     default:
         g_assert_not_reached();
     }
@@ -2334,16 +2344,18 @@ static inline ARMMMUIdx arm_v7m_mmu_idx_for_secstate(CPUARMState *env,
                                                      bool secstate)
 {
     int el = arm_current_el(env);
-    ARMMMUIdx mmu_idx;
+    ARMMMUIdx mmu_idx = ARM_MMU_IDX_M;
 
-    if (el == 0) {
-        mmu_idx = secstate ? ARMMMUIdx_MSUser : ARMMMUIdx_MUser;
-    } else {
-        mmu_idx = secstate ? ARMMMUIdx_MSPriv : ARMMMUIdx_MPriv;
+    if (el != 0) {
+        mmu_idx |= ARM_MMU_IDX_M_PRIV;
     }
 
     if (armv7m_nvic_neg_prio_requested(env->nvic, secstate)) {
-        mmu_idx = secstate ? ARMMMUIdx_MSNegPri : ARMMMUIdx_MNegPri;
+        mmu_idx |= ARM_MMU_IDX_M_NEGPRI;
+    }
+
+    if (secstate) {
+        mmu_idx |= ARM_MMU_IDX_M_S;
     }
 
     return mmu_idx;