arm/ptw: Honour WXN/UWXN and SIF in short-format descriptors

Currently the handling of page protection in the short-format
descriptor is open-coded. This means that we forgot to update
it to handle some newer architectural features, including:
 * handling of SCTLR.{UWXN,WXN}
 * handling of SCR.SIF

Make the short-format descriptor code call the same get_S1prot()
that we already use for the LPAE descriptor format. This makes
the code simpler and means it now correctly honours the WXN/UWXN
and SIF bits.

Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Message-id: 20241118152537.45277-1-paskripkin@gmail.com
[PMM: fixed a couple of checkpatch nits, tweaked commit message]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/ptw.c

@@ -85,6 +85,10 @@ static bool get_phys_addr_gpc(CPUARMState *env, S1Translate *ptw,
                               GetPhysAddrResult *result,
                               ARMMMUFaultInfo *fi);
 
+static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64,
+                      int user_rw, int prot_rw, int xn, int pxn,
+                      ARMSecuritySpace in_pa, ARMSecuritySpace out_pa);
+
 /* This mapping is common between ID_AA64MMFR0.PARANGE and TCR_ELx.{I}PS. */
 static const uint8_t pamax_map[] = {
     [0] = 32,
@@ -1148,7 +1152,7 @@ static bool get_phys_addr_v6(CPUARMState *env, S1Translate *ptw,
     hwaddr phys_addr;
     uint32_t dacr;
     bool ns;
-    int user_prot;
+    ARMSecuritySpace out_space;
 
     /* Pagetable walk.  */
     /* Lookup l1 descriptor.  */
@@ -1240,16 +1244,19 @@ static bool get_phys_addr_v6(CPUARMState *env, S1Translate *ptw,
             g_assert_not_reached();
         }
     }
+    out_space = ptw->in_space;
+    if (ns) {
+        /*
+         * The NS bit will (as required by the architecture) have no effect if
+         * the CPU doesn't support TZ or this is a non-secure translation
+         * regime, because the output space will already be non-secure.
+         */
+        out_space = ARMSS_NonSecure;
+    }
     if (domain_prot == 3) {
         result->f.prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
     } else {
-        if (pxn && !regime_is_user(env, mmu_idx)) {
-            xn = 1;
-        }
-        if (xn && access_type == MMU_INST_FETCH) {
-            fi->type = ARMFault_Permission;
-            goto do_fault;
-        }
+        int user_rw, prot_rw;
 
         if (arm_feature(env, ARM_FEATURE_V6K) &&
                 (regime_sctlr(env, mmu_idx) & SCTLR_AFE)) {
@@ -1259,37 +1266,23 @@ static bool get_phys_addr_v6(CPUARMState *env, S1Translate *ptw,
                 fi->type = ARMFault_AccessFlag;
                 goto do_fault;
             }
-            result->f.prot = simple_ap_to_rw_prot(env, mmu_idx, ap >> 1);
-            user_prot = simple_ap_to_rw_prot_is_user(ap >> 1, 1);
+            prot_rw = simple_ap_to_rw_prot(env, mmu_idx, ap >> 1);
+            user_rw = simple_ap_to_rw_prot_is_user(ap >> 1, 1);
         } else {
-            result->f.prot = ap_to_rw_prot(env, mmu_idx, ap, domain_prot);
-            user_prot = ap_to_rw_prot_is_user(env, mmu_idx, ap, domain_prot, 1);
-        }
-        if (result->f.prot && !xn) {
-            result->f.prot |= PAGE_EXEC;
+            prot_rw = ap_to_rw_prot(env, mmu_idx, ap, domain_prot);
+            user_rw = ap_to_rw_prot_is_user(env, mmu_idx, ap, domain_prot, 1);
         }
+
+        result->f.prot = get_S1prot(env, mmu_idx, false, user_rw, prot_rw,
+                                    xn, pxn, result->f.attrs.space, out_space);
         if (!(result->f.prot & (1 << access_type))) {
             /* Access permission fault.  */
             fi->type = ARMFault_Permission;
             goto do_fault;
         }
-        if (regime_is_pan(env, mmu_idx) &&
-            !regime_is_user(env, mmu_idx) &&
-            user_prot &&
-            access_type != MMU_INST_FETCH) {
-            /* Privileged Access Never fault */
-            fi->type = ARMFault_Permission;
-            goto do_fault;
-        }
-    }
-    if (ns) {
-        /* The NS bit will (as required by the architecture) have no effect if
-         * the CPU doesn't support TZ or this is a non-secure translation
-         * regime, because the attribute will already be non-secure.
-         */
-        result->f.attrs.secure = false;
-        result->f.attrs.space = ARMSS_NonSecure;
     }
+    result->f.attrs.space = out_space;
+    result->f.attrs.secure = arm_space_is_secure(out_space);
     result->f.phys_addr = phys_addr;
     return false;
 do_fault: