target/arm: Cache the GP bit for a page in MemTxAttrs

Caching the bit means that we will not have to re-walk the
page tables to look up the bit during translation.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20190128223118.5255-6-richard.henderson@linaro.org
[PMM: no need to OR in guarded bit status]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 45ba678a7dfa0cbd25bf5a755bd2f5c76d49ecbd..be0ec7de2a41bc70a20a47b54bd78b665773a75f 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10577,6 +10577,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
     bool ttbr1_valid;
     uint64_t descaddrmask;
     bool aarch64 = arm_el_is_aa64(env, el);
+    bool guarded = false;
 
     /* TODO:
      * This code does not handle the different format TCR for VTCR_EL2.
@@ -10756,6 +10757,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
         }
         /* Merge in attributes from table descriptors */
         attrs |= nstable << 3; /* NS */
+        guarded = extract64(descriptor, 50, 1);  /* GP */
         if (param.hpd) {
             /* HPD disables all the table attributes except NSTable.  */
             break;
@@ -10801,6 +10803,10 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
          */
         txattrs->secure = false;
     }
+    /* When in aarch64 mode, and BTI is enabled, remember GP in the IOTLB.  */
+    if (aarch64 && guarded && cpu_isar_feature(aa64_bti, cpu)) {
+        txattrs->target_tlb_bit0 = true;
+    }
 
     if (cacheattrs != NULL) {
         if (mmu_idx == ARMMMUIdx_S2NS) {