[Qemu-devel] [PATCH RFC 3/8] target-arm: Add support for S2 page-table protection bits

[Edgar E. Iglesias]

From: "Edgar E. Iglesias" <address@hidden>

Signed-off-by: Edgar E. Iglesias <address@hidden>
---
 target-arm/helper.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index 33be8c2..6f0ed51 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -6008,6 +6008,38 @@ simple_ap_to_rw_prot(CPUARMState *env, ARMMMUIdx 
mmu_idx, int ap)
     return simple_ap_to_rw_prot_is_user(ap, regime_is_user(env, mmu_idx));
 }
 
+/* Translate S2 section/page access permissions to protection flags
+ *
+ * @env:     CPUARMState
+ * @ap:      The 2-bit simple AP (AP[2:1])
+ * @xn:      XN (execute-never) bit
+ */
+static int get_S2prot(CPUARMState *env, int ap, int xn)
+{
+    int prot_rw;
+
+    switch (ap) {
+    default:
+    case 0:
+        prot_rw = 0;
+        break;
+    case 1:
+        prot_rw = PAGE_READ | PAGE_EXEC;
+        break;
+    case 2:
+        prot_rw = PAGE_WRITE;
+        break;
+    case 3:
+        prot_rw = PAGE_READ | PAGE_EXEC | PAGE_WRITE;
+        break;
+    }
+
+    if (xn) {
+        prot_rw &= ~PAGE_EXEC;
+    }
+    return prot_rw;
+}
+
 /* Translate section/page access permissions to protection flags
  *
  * @env:     CPUARMState
@@ -6617,6 +6649,11 @@ static bool get_phys_addr_lpae(CPUARMState *env, 
target_ulong address,
         /* Extract attributes from the descriptor and merge with table attrs */
         attrs = extract64(descriptor, 2, 10)
             | (extract64(descriptor, 52, 12) << 10);
+
+        if (mmu_idx == ARMMMUIdx_S2NS) {
+            /* The following extractions do not apply to S2.  */
+            break;
+        }
         attrs |= extract32(tableattrs, 0, 2) << 11; /* XN, PXN */
         attrs |= extract32(tableattrs, 3, 1) << 5; /* APTable[1] => AP[2] */
         /* The sense of AP[1] vs APTable[0] is reversed, as APTable[0] == 1
@@ -6638,11 +6675,16 @@ static bool get_phys_addr_lpae(CPUARMState *env, 
target_ulong address,
     }
 
     ap = extract32(attrs, 4, 2);
-    ns = extract32(attrs, 3, 1);
     xn = extract32(attrs, 12, 1);
-    pxn = extract32(attrs, 11, 1);
 
-    *prot = get_S1prot(env, mmu_idx, va_size == 64, ap, ns, xn, pxn);
+    if (mmu_idx == ARMMMUIdx_S2NS) {
+        ns = true;
+        *prot = get_S2prot(env, ap, xn);
+    } else {
+        ns = extract32(attrs, 3, 1);
+        pxn = extract32(attrs, 11, 1);
+        *prot = get_S1prot(env, mmu_idx, va_size == 64, ap, ns, xn, pxn);
+    }
 
     fault_type = permission_fault;
     if (!(*prot & (1 << access_type))) {
-- 
1.9.1