Cleanup XN/PXN handling in get_phys_addr_lpae, and implement all but
EL2 support of the following ARMv8 sections
D4.5.1 Memory access control: Access permissions for instruction
execution
G4.7.2 Execute-never restrictions on instruction fetching
G4.7.2 matches the ARMv7 section B3.7.2 when long-descriptors are used.
Signed-off-by: Andrew Jones <drjo...@redhat.com>
---
I didn't test this with secure mode (I didn't even check if that's
currently possible), but I did test all other EL1&0 XN controls with
both tcg-arm (cortex-a15) and tcg-aarch64 (cortex-a57) by hacking up
some tests with kvm-unit-tests/arm[64]. I also booted Linux (just
up to looking for a rootfs) with both.
---
target-arm/helper.c | 99 ++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 79 insertions(+), 20 deletions(-)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 3ef0f1f38eda5..48a83cff957fb 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -4516,6 +4516,69 @@ static inline int check_ap(CPUARMState *env, int ap, int
domain_prot,
}
}
+/* Check section/page execution permission.
+ *
+ * Returns PAGE_EXEC if execution is permitted, otherwise zero.
+ *
+ * Supports AArch64, AArch32, and v7-LPAE. Doesn't yet support
+ * EL2. Actually, for v7-LPAE, we'd also need to emulate Virt
+ * Extensions to truly have WXN/UWXN. We don't support checking
+ * for that yet, so we just assume we have them.
+ *
+ * @env : CPUARMState
+ * @is_user : 0 for privileged access, 1 for user
+ * @ap : Access permissions (AP[2:1]) from descriptor
+ * @ns : (NSTable || NS) from descriptors
+ * @xn : ([U]XNTable || [U]XN) descriptors
+ * @pxn : (PXNTable || PXN) descriptors
+ */
+static int check_xn_lpae(CPUARMState *env, int is_user, int ap,
+ int ns, int xn, int pxn)
+{
+ int wxn;
+
+ switch (arm_current_el(env)) {
+ case 0:
+ case 1:
+ if (is_user && !(ap & 1)) {
+ return 0;
+ }
+ wxn = env->cp15.sctlr_el[1] & SCTLR_WXN;
+ if (arm_el_is_aa64(env, 1)) {
+ pxn = pxn || ((ap & 1) && !(ap & 2));
+ xn = is_user ? xn : pxn;
+ } else {
+ int uwxn = env->cp15.sctlr_el[1] & SCTLR_UWXN;
+ pxn = pxn || (uwxn && (ap & 1) && !(ap & 2));
+ xn = xn || (!is_user && pxn);
+ }
+ if (arm_is_secure(env)) {
+ xn = xn || (ns && (env->cp15.scr_el3 & SCR_SIF));
+ }
+ break;
+ case 2:
+ /* TODO actually support EL2 */
+ assert(true);
+
+ if (arm_el_is_aa64(env, 2)) {
+ wxn = env->cp15.sctlr_el[2] & SCTLR_WXN;
+ } else {
+ /* wxn = HSCTLR.WXN */
+ }
+ break;
+ case 3:
+ if (arm_el_is_aa64(env, 3)) {
+ wxn = env->cp15.sctlr_el[3] & SCTLR_WXN;
+ } else {
+ wxn = 0;
+ }
+ xn = xn || (ns && (env->cp15.scr_el3 & SCR_SIF));
+ break;
+ }
+
+ return xn || (!(ap & 2) && wxn) ? 0 : PAGE_EXEC;
+}
+
static bool get_level1_table_address(CPUARMState *env, uint32_t *table,
uint32_t address)
{
@@ -4787,7 +4850,7 @@ static int get_phys_addr_lpae(CPUARMState *env,
target_ulong address,
hwaddr descaddr, descmask;
uint32_t tableattrs;
target_ulong page_size;
- uint32_t attrs;
+ uint32_t attrs, ap;
int32_t granule_sz = 9;
int32_t va_size = 32;
int32_t tbi = 0;
@@ -4941,7 +5004,7 @@ static int get_phys_addr_lpae(CPUARMState *env,
target_ulong address,
if (extract32(tableattrs, 2, 1)) {
attrs &= ~(1 << 4);
}
- /* Since we're always in the Non-secure state, NSTable is ignored. */
+ attrs |= extract32(tableattrs, 4, 1) << 3; /* NS */
break;
}
/* Here descaddr is the final physical address, and attributes
@@ -4952,29 +5015,25 @@ static int get_phys_addr_lpae(CPUARMState *env,
target_ulong address,
/* Access flag */
goto do_fault;
}
+
fault_type = permission_fault;
- if (is_user && !(attrs & (1 << 4))) {
+ ap = extract32(attrs, 4, 2); /* AP[2:1] */
+
+ if (is_user && !(ap & 1)) {
/* Unprivileged access not enabled */
goto do_fault;
}
- *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
- if ((arm_feature(env, ARM_FEATURE_V8) && is_user && (attrs & (1 << 12))) ||
- (!arm_feature(env, ARM_FEATURE_V8) && (attrs & (1 << 12))) ||
- (!is_user && (attrs & (1 << 11)))) {
- /* XN/UXN or PXN. Since we only implement EL0/EL1 we unconditionally
- * treat XN/UXN as UXN for v8.
- */
- if (access_type == 2) {
- goto do_fault;
- }
- *prot &= ~PAGE_EXEC;
+
+ *prot = PAGE_READ;
+ *prot |= check_xn_lpae(env, is_user, ap, extract32(attrs, 3, 1),
+ extract32(attrs, 12, 1), extract32(attrs, 11, 1));
+ if (!(*prot & PAGE_EXEC) && access_type == 2) {
+ goto do_fault;
}
- if (attrs & (1 << 5)) {
- /* Write access forbidden */
- if (access_type == 1) {
- goto do_fault;
- }
- *prot &= ~PAGE_WRITE;
+
+ *prot |= !(ap & 2) ? PAGE_WRITE : 0;
+ if (!(*prot & PAGE_WRITE) && access_type == 1) {
+ goto do_fault;
}
*phys_ptr = descaddr;
--
1.9.3
