patch-2.2.18 linux/arch/arm/mm/fault-common.c

• Lines: 131
• Date: Fri Sep 15 23:28:37 2000
• Orig file: v2.2.17/arch/arm/mm/fault-common.c
• Orig date: Fri Apr 21 12:45:45 2000

diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/arch/arm/mm/fault-common.c linux/arch/arm/mm/fault-common.c
@@ -26,25 +26,14 @@
 	set_pmd(pmd, mk_kernel_pmd(BAD_PAGETABLE));
 }
 
-static void
-kernel_page_fault(unsigned long addr, int mode, struct pt_regs *regs,
-		  struct task_struct *tsk, struct mm_struct *mm)
+/*
+ * This is useful to dump out the page tables associated with
+ * 'addr' in mm 'mm'.
+ */
+void show_pte(struct mm_struct *mm, unsigned long addr)
 {
-	char *reason;
-	/*
-	 * Oops. The kernel tried to access some bad page. We'll have to
-	 * terminate things with extreme prejudice.
-	 */
 	pgd_t *pgd;
 
-	if (addr < PAGE_SIZE)
-		reason = "NULL pointer dereference";
-	else
-		reason = "paging request";
-
-	printk(KERN_ALERT "Unable to handle kernel %s at virtual address %08lx\n",
-		reason, addr);
-	printk(KERN_ALERT "memmap = %08lX, pgd = %p\n", tsk->tss.memmap, mm->pgd);
 	pgd = pgd_offset(mm, addr);
 	printk(KERN_ALERT "*pgd = %08lx", pgd_val(*pgd));
 
@@ -73,11 +62,34 @@
 
 		pte = pte_offset(pmd, addr);
 		printk(", *pte = %08lx", pte_val(*pte));
+#ifdef CONFIG_CPU_32
 		printk(", *ppte = %08lx", pte_val(pte[-PTRS_PER_PTE]));
+#endif
 	} while(0);
 
 	printk("\n");
-	die("Oops", regs, mode);
+}
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+static void
+kernel_page_fault(unsigned long addr, int write_access, struct pt_regs *regs,
+		  struct task_struct *tsk, struct mm_struct *mm)
+{
+	char *reason;
+
+	if (addr < PAGE_SIZE)
+		reason = "NULL pointer dereference";
+	else
+		reason = "paging request";
+
+	printk(KERN_ALERT "Unable to handle kernel %s at virtual address %08lx\n",
+		reason, addr);
+	printk(KERN_ALERT "memmap = %08lX, pgd = %p\n", tsk->tss.memmap, mm->pgd);
+	show_pte(mm, addr);
+	die("Oops", regs, write_access);
 
 	do_exit(SIGKILL);
 }
@@ -88,6 +100,7 @@
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	unsigned long fixup;
+	int fault;
 
 	tsk = current;
 	mm  = tsk->mm;
@@ -126,8 +139,12 @@
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	if (!handle_mm_fault(tsk, vma, addr & PAGE_MASK, DO_COW(mode)))
+survive:
+	fault = handle_mm_fault(tsk, vma, addr & PAGE_MASK, DO_COW(mode));
+	if (!fault)
 		goto do_sigbus;
+	if (fault < 0)
+		goto out_of_memory;
 
 	up(&mm->mmap_sem);
 	return;
@@ -140,7 +157,7 @@
 	up(&mm->mmap_sem);
 
 	/* User mode accesses just cause a SIGSEGV */
-	if (mode & FAULT_CODE_USER) {
+	if (user_mode(regs)) {
 		tsk->tss.error_code = mode;
 		tsk->tss.trap_no = 14;
 #ifdef CONFIG_DEBUG_USER
@@ -165,6 +182,23 @@
 	kernel_page_fault(addr, mode, regs, tsk, mm);
 	return;
 
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+out_of_memory:
+	if (tsk->pid == 1) {
+		tsk->policy |= SCHED_YIELD;
+		schedule();
+		goto survive;
+	}
+	up(&mm->mmap_sem);
+	if (user_mode(regs)) {
+		printk("VM: killing process %s\n", tsk->comm);
+		do_exit(SIGKILL);
+	}
+	goto no_context;
+
 do_sigbus:
 	/*
 	 * We ran out of memory, or some other thing happened to us that made
@@ -181,7 +215,7 @@
 	force_sig(SIGBUS, tsk);
 
 	/* Kernel mode? Handle exceptions or die */
-	if (!(mode & FAULT_CODE_USER))
+	if (!user_mode(regs))
 		goto no_context;
 }