x86/mm/fault.c

136 	 * If it was a exec (instruction fetch) fault on NX page, then
147 	 * not-present page (e.g. due to a race).  No one has ever
225  *   where it synchronizes this update with the other page-tables in the
231  *   which are not mapped in every page-table in the system, causing an
232  *   unhandled page-fault when they are accessed.
245 	 * Synchronize this task's top level page-table
246 	 * with the 'reference' page table.
274 		struct page *page;
277 		list_for_each_entry(page, &pgd_list, lru) {
281 			pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
284 			vmalloc_sync_one(page_address(page), addr);
321 	 * case if the page table is located in highmem.
415  * The OS sees this as a page fault with the upper 32bits of RIP cleared.
452  * We catch this in the page fault handler because these addresses
528 			pr_crit("kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n",
541 		pr_alert("BUG: unable to handle page fault for address: %px\n",
551 		 !(error_code & X86_PF_PROT) ? "not-present page" :
565 		 * contributory exception from user code and gets a page fault
566 		 * during delivery, the page fault can be delivered as though
604 	printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
618 	 * To avoid leaking information about the kernel page
686 	 * Buggy firmware could access regions which might page fault.  If
700 	 * Oops. The kernel tried to access some bad page. We'll have to
732 	 * AMD erratum #91 manifests as a spurious page fault on a PREFETCH
803 	 * Valid to do another page fault here because this one came
895 		 * 2. T1   : set PKRU to deny access to pkey=4, touches page
921 	/* User-space => ok to do another page fault: */
966  * permissions of a kernel page (RO -> RW or NX -> X).  Doing it
972  * fewer permission than the page table entry.  Non-present (P = 0)
976  * increasing the permissions on a page.
1041 	 * If not, then there's a bug in the page tables:
1081 	 * page.
1122 	 * On 64-bit systems, the vsyscall page is at an address above
1151 	 * 'reference' page table is init_mm.pgd.
1155 	 * only copy the information from the master page table,
1163 	 * 3. A fault caused by a page-level protection violation.
1164 	 *    (A demand fault would be on a non-present page which
1245 	 * entries in the user portion of the page tables.
1303 	 * system page faults are still user accesses.
1310 	 * Faults in the vsyscall page might need emulation.  The
1311 	 * vsyscall page is at a high address (>PAGE_OFFSET), but is
1314 	 * The vsyscall page does not have a "real" VMA, so do this
1384 	 * repeat the page fault later with a VM_FAULT_NOPAGE retval
1483 		 * User address page fault handling might have reenabled
1503 	 * KVM uses #PF vector to deliver 'page not present' events to guests
1504 	 * (asynchronous page fault mechanism). The event happens when a
1507 	 * memory is swapped out). Note, the corresponding "page ready" event
1516 	 * getting values from real and async page faults mixed up.