+ /* Faults from writes to non-writable pages */
+ u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0;
+ /* Faults from user mode accesses to supervisor pages */
+ u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0;
+ /* Faults from fetches of non-executable pages*/
+ u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0;
+ /* Faults from kernel mode fetches of user pages */
+ u8 smepf = 0;
+ /* Faults from kernel mode accesses of user pages */
+ u8 smapf = 0;
+
+ if (!ept) {
+ /* Faults from kernel mode accesses to user pages */
+ u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u;
+
+ /* Not really needed: !nx will cause pte.nx to fault */
+ if (!mmu->nx)
+ ff = 0;
+
+ /* Allow supervisor writes if !cr0.wp */
+ if (!cr0_wp)
+ wf = (pfec & PFERR_USER_MASK) ? wf : 0;
+
+ /* Disallow supervisor fetches of user code if cr4.smep */
+ if (cr4_smep)
+ smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0;
+
+ /*
+ * SMAP:kernel-mode data accesses from user-mode
+ * mappings should fault. A fault is considered
+ * as a SMAP violation if all of the following
+ * conditions are ture:
+ * - X86_CR4_SMAP is set in CR4
+ * - A user page is accessed
+ * - The access is not a fetch
+ * - Page fault in kernel mode
+ * - if CPL = 3 or X86_EFLAGS_AC is clear
+ *
+ * Here, we cover the first three conditions.
+ * The fourth is computed dynamically in permission_fault();
+ * PFERR_RSVD_MASK bit will be set in PFEC if the access is
+ * *not* subject to SMAP restrictions.
+ */
+ if (cr4_smap)
+ smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf;