target/arm: Fixed Privileged Access Never (PAN) for aarch32

Commit Message

Timofey Kutergin Oct. 19, 2022, 12:03 p.m. UTC

- synchronize PSTATE.PAN with changes in CPSR.PAN in aarch32 mode
- set PAN bit automatically on exception entry if SCTLR_SPAN bit
  is set
- throw permission fault during address translation when PAN is
  enabled and kernel tries to access user acessible page
- ignore SCTLR_XP bit for armv7 and armv8 (conflicts with SCTLR_SPAN).
---
 target/arm/helper.c |  6 ++++++
 target/arm/ptw.c    | 11 ++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

Patch

diff --git a/target/arm/helper.c b/target/arm/helper.c
index dde64a487a..5299f67e3f 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -9052,6 +9052,11 @@  void cpsr_write(CPUARMState *env, uint32_t val, uint32_t mask,
     }
     mask &= ~CACHED_CPSR_BITS;
     env->uncached_cpsr = (env->uncached_cpsr & ~mask) | (val & mask);
+    if (env->uncached_cpsr & CPSR_PAN) {
+        env->pstate |= PSTATE_PAN;
+    } else {
+        env->pstate &= ~PSTATE_PAN;
+    }
     if (rebuild_hflags) {
         arm_rebuild_hflags(env);
     }
@@ -9592,6 +9597,7 @@  static void take_aarch32_exception(CPUARMState *env, int new_mode,
                 /* ... the target is EL1 and SCTLR.SPAN is 0.  */
                 if (!(env->cp15.sctlr_el[new_el] & SCTLR_SPAN)) {
                     env->uncached_cpsr |= CPSR_PAN;
+                    env->pstate |= PSTATE_PAN;
                 }
                 break;
             }
diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index 23f16f4ff7..204a73350f 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -659,6 +659,13 @@  static bool get_phys_addr_v6(CPUARMState *env, uint32_t address,
             goto do_fault;
         }
 
+        if (regime_is_pan(env, mmu_idx) && !regime_is_user(env, mmu_idx) &&
+            simple_ap_to_rw_prot_is_user(ap >> 1, 1) &&
+            access_type != MMU_INST_FETCH) {
+            fi->type = ARMFault_Permission;
+            goto do_fault;
+        }
+
         if (arm_feature(env, ARM_FEATURE_V6K) &&
                 (regime_sctlr(env, mmu_idx) & SCTLR_AFE)) {
             /* The simplified model uses AP[0] as an access control bit.  */
@@ -2506,7 +2513,9 @@  bool get_phys_addr_with_secure(CPUARMState *env, target_ulong address,
     if (regime_using_lpae_format(env, mmu_idx)) {
         return get_phys_addr_lpae(env, address, access_type, mmu_idx,
                                   is_secure, false, result, fi);
-    } else if (regime_sctlr(env, mmu_idx) & SCTLR_XP) {
+    } else if (arm_feature(env, ARM_FEATURE_V7) ||
+               arm_feature(env, ARM_FEATURE_V8) || (
+               regime_sctlr(env, mmu_idx) & SCTLR_XP)) {
         return get_phys_addr_v6(env, address, access_type, mmu_idx,
                                 is_secure, result, fi);
     } else {