[PATCH 14/22] target/arm: Handle no-execute for Realm and Root regimes

[Richard Henderson <richard.henderson@linaro.org>]

While Root and Realm may read and write data from other spaces,
neither may execute from other pa spaces.

This happens for Stage1 EL3, EL2, EL2&0, but stage2 EL1&0.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/ptw.c | 66 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 58 insertions(+), 8 deletions(-)

diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index 849f5e89ca..6b6f8195eb 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -909,7 +909,7 @@ do_fault:
  * @xn:      XN (execute-never) bits
  * @s1_is_el0: true if this is S2 of an S1+2 walk for EL0
  */
-static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
+static int get_S2prot_noexecute(int s2ap)
 {
     int prot = 0;
 
@@ -919,6 +919,12 @@ static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
     if (s2ap & 2) {
         prot |= PAGE_WRITE;
     }
+    return prot;
+}
+
+static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
+{
+    int prot = get_S2prot_noexecute(s2ap);
 
     if (cpu_isar_feature(any_tts2uxn, env_archcpu(env))) {
         switch (xn) {
@@ -956,12 +962,14 @@ static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0)
  * @mmu_idx: MMU index indicating required translation regime
  * @is_aa64: TRUE if AArch64
  * @ap:      The 2-bit simple AP (AP[2:1])
- * @ns:      NS (non-secure) bit
  * @xn:      XN (execute-never) bit
  * @pxn:     PXN (privileged execute-never) bit
+ * @in_pa:   The original input pa space
+ * @out_pa:  The output pa space, modified by NSTable, NS, and NSE
  */
 static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64,
-                      int ap, int ns, int xn, int pxn)
+                      int ap, int xn, int pxn,
+                      ARMSecuritySpace in_pa, ARMSecuritySpace out_pa)
 {
     bool is_user = regime_is_user(env, mmu_idx);
     int prot_rw, user_rw;
@@ -982,8 +990,39 @@ static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64,
         }
     }
 
-    if (ns && arm_is_secure(env) && (env->cp15.scr_el3 & SCR_SIF)) {
-        return prot_rw;
+    if (in_pa != out_pa) {
+        switch (in_pa) {
+        case ARMSS_Root:
+            /*
+             * R_ZWRVD: permission fault for insn fetched from non-Root,
+             * I_WWBFB: SIF has no effect in EL3.
+             */
+            return prot_rw;
+        case ARMSS_Realm:
+            /*
+             * R_PKTDS: permission fault for insn fetched from non-Realm,
+             * for Realm EL2 or EL2&0.  The corresponding fault for EL1&0
+             * happens during any stage2 translation.
+             */
+            switch (mmu_idx) {
+            case ARMMMUIdx_E2:
+            case ARMMMUIdx_E20_0:
+            case ARMMMUIdx_E20_2:
+            case ARMMMUIdx_E20_2_PAN:
+                return prot_rw;
+            default:
+                break;
+            }
+            break;
+        case ARMSS_Secure:
+            if (env->cp15.scr_el3 & SCR_SIF) {
+                return prot_rw;
+            }
+            break;
+        default:
+            /* Input NonSecure must have output NonSecure. */
+            g_assert_not_reached();
+        }
     }
 
     /* TODO have_wxn should be replaced with
@@ -1556,12 +1595,16 @@ static bool get_phys_addr_lpae(CPUARMState *env, S1Translate *ptw,
         /*
          * R_GYNXY: For stage2 in Realm security state, bit 55 is NS.
          * The bit remains ignored for other security states.
+         * R_YMCSL: Executing an insn fetched from non-Realm causes
+         * a stage2 permission fault.
          */
         if (out_space == ARMSS_Realm && extract64(attrs, 55, 1)) {
             out_space = ARMSS_NonSecure;
+            result->f.prot = get_S2prot_noexecute(ap);
+        } else {
+            xn = extract64(attrs, 53, 2);
+            result->f.prot = get_S2prot(env, ap, xn, s1_is_el0);
         }
-        xn = extract64(attrs, 53, 2);
-        result->f.prot = get_S2prot(env, ap, xn, s1_is_el0);
     } else {
         int ns = extract32(attrs, 5, 1);
         switch (out_space) {
@@ -1613,7 +1656,14 @@ static bool get_phys_addr_lpae(CPUARMState *env, S1Translate *ptw,
         }
         xn = extract64(attrs, 54, 1);
         pxn = extract64(attrs, 53, 1);
-        result->f.prot = get_S1prot(env, mmu_idx, aarch64, ap, ns, xn, pxn);
+
+        /*
+         * Note that we modified ptw->in_space earlier for NSTable,
+         * and result->f.attrs was initialized by get_phys_addr, so
+         * that retains a copy of the original security space.
+         */
+        result->f.prot = get_S1prot(env, mmu_idx, aarch64, ap, xn, pxn,
+                                    result->f.attrs.space, out_space);
     }
 
     if (!(result->f.prot & (1 << access_type))) {
-- 
2.34.1