1 files changed, 146 insertions, 80 deletions

diff --git a/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c b/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c
index 4939ab106e..7b620769f5 100644
--- a/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c
+++ b/linux-2.6-xen-sparse/arch/i386/mm/fault-xen.c
@@ -252,8 +252,9 @@ static void dump_fault_path(unsigned long address)
 
 	page = read_cr3();
 	page = ((unsigned long *) __va(page))[address >> 22];
-	printk(KERN_ALERT "*pde = ma %08lx pa %08lx\n", page,
-	       machine_to_phys(page));
+	if (oops_may_print())
+		printk(KERN_ALERT "*pde = ma %08lx pa %08lx\n", page,
+		       machine_to_phys(page));
 	/*
 	 * We must not directly access the pte in the highpte
 	 * case, the page table might be allocated in highmem.
@@ -261,7 +262,7 @@ static void dump_fault_path(unsigned long address)
 	 * it's allocated already.
 	 */
 #ifndef CONFIG_HIGHPTE
-	if (page & 1) {
+	if ((page & 1) && oops_may_print()) {
 		page &= PAGE_MASK;
 		address &= 0x003ff000;
 		page = machine_to_phys(page);
@@ -311,6 +312,76 @@ static int spurious_fault(struct pt_regs *regs,
 	return 1;
 }
 
+static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
+{
+	unsigned index = pgd_index(address);
+	pgd_t *pgd_k;
+	pud_t *pud, *pud_k;
+	pmd_t *pmd, *pmd_k;
+
+	pgd += index;
+	pgd_k = init_mm.pgd + index;
+
+	if (!pgd_present(*pgd_k))
+		return NULL;
+
+	/*
+	 * set_pgd(pgd, *pgd_k); here would be useless on PAE
+	 * and redundant with the set_pmd() on non-PAE. As would
+	 * set_pud.
+	 */
+
+	pud = pud_offset(pgd, address);
+	pud_k = pud_offset(pgd_k, address);
+	if (!pud_present(*pud_k))
+		return NULL;
+
+	pmd = pmd_offset(pud, address);
+	pmd_k = pmd_offset(pud_k, address);
+	if (!pmd_present(*pmd_k))
+		return NULL;
+	if (!pmd_present(*pmd))
+#ifndef CONFIG_XEN
+		set_pmd(pmd, *pmd_k);
+#else
+		/*
+		 * When running on Xen we must launder *pmd_k through
+		 * pmd_val() to ensure that _PAGE_PRESENT is correctly set.
+		 */
+		set_pmd(pmd, __pmd(pmd_val(*pmd_k)));
+#endif
+	else
+		BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
+	return pmd_k;
+}
+
+/*
+ * Handle a fault on the vmalloc or module mapping area
+ *
+ * This assumes no large pages in there.
+ */
+static inline int vmalloc_fault(unsigned long address)
+{
+	unsigned long pgd_paddr;
+	pmd_t *pmd_k;
+	pte_t *pte_k;
+	/*
+	 * Synchronize this task's top level page-table
+	 * with the 'reference' page table.
+	 *
+	 * Do _not_ use "current" here. We might be inside
+	 * an interrupt in the middle of a task switch..
+	 */
+	pgd_paddr = read_cr3();
+	pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
+	if (!pmd_k)
+		return -1;
+	pte_k = pte_offset_kernel(pmd_k, address);
+	if (!pte_present(*pte_k))
+		return -1;
+	return 0;
+}
+
 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
@@ -320,6 +391,8 @@ static int spurious_fault(struct pt_regs *regs,
  *	bit 0 == 0 means no page found, 1 means protection fault
  *	bit 1 == 0 means read, 1 means write
  *	bit 2 == 0 means kernel, 1 means user-mode
+ *	bit 3 == 1 means use of reserved bit detected
+ *	bit 4 == 1 means fault was an instruction fetch
  */
 fastcall void __kprobes do_page_fault(struct pt_regs *regs,
 				      unsigned long error_code)
@@ -339,13 +412,6 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
 	if (regs->eflags & X86_EFLAGS_VM)
 		error_code |= 4;
 
-	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
-					SIGSEGV) == NOTIFY_STOP)
-		return;
-	/* It's safe to allow irq's after cr2 has been saved */
-	if (regs->eflags & (X86_EFLAGS_IF|VM_MASK))
-		local_irq_enable();
-
 	tsk = current;
 
 	si_code = SEGV_MAPERR;
@@ -361,25 +427,37 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
 	 *
 	 * This verifies that the fault happens in kernel space
 	 * (error_code & 4) == 0, and that the fault was not a
-	 * protection error (error_code & 1) == 0.
+	 * protection error (error_code & 9) == 0.
 	 */
-	if (unlikely(address >= TASK_SIZE)) { 
+	if (unlikely(address >= TASK_SIZE)) {
 #ifdef CONFIG_XEN
 		/* Faults in hypervisor area can never be patched up. */
 		if (address >= hypervisor_virt_start)
 			goto bad_area_nosemaphore;
 #endif
-		if (!(error_code & 5))
-			goto vmalloc_fault;
+		if (!(error_code & 0x0000000d) && vmalloc_fault(address) >= 0)
+			return;
 		/* Can take a spurious fault if mapping changes R/O -> R/W. */
 		if (spurious_fault(regs, address, error_code))
 			return;
+		if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+						SIGSEGV) == NOTIFY_STOP)
+			return;
 		/* 
 		 * Don't take the mm semaphore here. If we fixup a prefetch
 		 * fault we could otherwise deadlock.
 		 */
 		goto bad_area_nosemaphore;
-	} 
+	}
+
+	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+					SIGSEGV) == NOTIFY_STOP)
+		return;
+
+	/* It's safe to allow irq's after cr2 has been saved and the vmalloc
+	   fault has been handled. */
+	if (regs->eflags & (X86_EFLAGS_IF|VM_MASK))
+		local_irq_enable();
 
 	mm = tsk->mm;
 
@@ -550,21 +628,27 @@ no_context:
 
 	bust_spinlocks(1);
 
-#ifdef CONFIG_X86_PAE
-	if (error_code & 16) {
-		pte_t *pte = lookup_address(address);
+	if (oops_may_print()) {
+	#ifdef CONFIG_X86_PAE
+		if (error_code & 16) {
+			pte_t *pte = lookup_address(address);
 
-		if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
-			printk(KERN_CRIT "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n", current->uid);
+			if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
+				printk(KERN_CRIT "kernel tried to execute "
+					"NX-protected page - exploit attempt? "
+					"(uid: %d)\n", current->uid);
+		}
+	#endif
+		if (address < PAGE_SIZE)
+			printk(KERN_ALERT "BUG: unable to handle kernel NULL "
+					"pointer dereference");
+		else
+			printk(KERN_ALERT "BUG: unable to handle kernel paging"
+					" request");
+		printk(" at virtual address %08lx\n",address);
+		printk(KERN_ALERT " printing eip:\n");
+		printk("%08lx\n", regs->eip);
 	}
-#endif
-	if (address < PAGE_SIZE)
-		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
-	else
-		printk(KERN_ALERT "Unable to handle kernel paging request");
-	printk(" at virtual address %08lx\n",address);
-	printk(KERN_ALERT " printing eip:\n");
-	printk("%08lx\n", regs->eip);
 	dump_fault_path(address);
 	tsk->thread.cr2 = address;
 	tsk->thread.trap_no = 14;
@@ -604,59 +688,41 @@ do_sigbus:
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = 14;
 	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
-	return;
-
-vmalloc_fault:
-	{
-		/*
-		 * Synchronize this task's top level page-table
-		 * with the 'reference' page table.
-		 *
-		 * Do _not_ use "tsk" here. We might be inside
-		 * an interrupt in the middle of a task switch..
-		 */
-		int index = pgd_index(address);
-		unsigned long pgd_paddr;
-		pgd_t *pgd, *pgd_k;
-		pud_t *pud, *pud_k;
-		pmd_t *pmd, *pmd_k;
-		pte_t *pte_k;
-
-		pgd_paddr = read_cr3();
-		pgd = index + (pgd_t *)__va(pgd_paddr);
-		pgd_k = init_mm.pgd + index;
-
-		if (!pgd_present(*pgd_k))
-			goto no_context;
-
-		/*
-		 * set_pgd(pgd, *pgd_k); here would be useless on PAE
-		 * and redundant with the set_pmd() on non-PAE. As would
-		 * set_pud.
-		 */
+}
 
-		pud = pud_offset(pgd, address);
-		pud_k = pud_offset(pgd_k, address);
-		if (!pud_present(*pud_k))
-			goto no_context;
-		
-		pmd = pmd_offset(pud, address);
-		pmd_k = pmd_offset(pud_k, address);
-		if (!pmd_present(*pmd_k))
-			goto no_context;
-#ifndef CONFIG_XEN
-		set_pmd(pmd, *pmd_k);
-#else
-		/*
-		 * When running on Xen we must launder *pmd_k through
-		 * pmd_val() to ensure that _PAGE_PRESENT is correctly set.
-		 */
-		set_pmd(pmd, __pmd(pmd_val(*pmd_k)));
-#endif
+#ifndef CONFIG_X86_PAE
+void vmalloc_sync_all(void)
+{
+	/*
+	 * Note that races in the updates of insync and start aren't
+	 * problematic: insync can only get set bits added, and updates to
+	 * start are only improving performance (without affecting correctness
+	 * if undone).
+	 */
+	static DECLARE_BITMAP(insync, PTRS_PER_PGD);
+	static unsigned long start = TASK_SIZE;
+	unsigned long address;
 
-		pte_k = pte_offset_kernel(pmd_k, address);
-		if (!pte_present(*pte_k))
-			goto no_context;
-		return;
+	BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
+	for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
+		if (!test_bit(pgd_index(address), insync)) {
+			unsigned long flags;
+			struct page *page;
+
+			spin_lock_irqsave(&pgd_lock, flags);
+			for (page = pgd_list; page; page =
+					(struct page *)page->index)
+				if (!vmalloc_sync_one(page_address(page),
+								address)) {
+					BUG_ON(page != pgd_list);
+					break;
+				}
+			spin_unlock_irqrestore(&pgd_lock, flags);
+			if (!page)
+				set_bit(pgd_index(address), insync);
+		}
+		if (address == start && test_bit(pgd_index(address), insync))
+			start = address + PGDIR_SIZE;
 	}
 }
+#endif