patch-2.2.8 linux/arch/arm/mm/fault-common.c

• Lines: 189
• Date: Sat May 8 11:06:56 1999
• Orig file: v2.2.7/linux/arch/arm/mm/fault-common.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.2.7/linux/arch/arm/mm/fault-common.c linux/arch/arm/mm/fault-common.c
@@ -0,0 +1,188 @@
+/*
+ *  linux/arch/arm/mm/fault-common.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-1999 Russell King
+ */
+#include <linux/config.h>
+
+extern void die(char *msg, struct pt_regs *regs, unsigned int err);
+
+void __bad_pmd(pmd_t *pmd)
+{
+	printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
+#ifdef CONFIG_DEBUG_ERRORS
+	__backtrace();
+#endif
+	set_pmd(pmd, mk_user_pmd(BAD_PAGETABLE));
+}
+
+void __bad_pmd_kernel(pmd_t *pmd)
+{
+	printk("Bad pmd in pte_alloc_kernel: %08lx\n", pmd_val(*pmd));
+#ifdef CONFIG_DEBUG_ERRORS
+	__backtrace();
+#endif
+	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)
+{
+	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));
+
+	do {
+		pmd_t *pmd;
+		pte_t *pte;
+
+		if (pgd_none(*pgd))
+			break;
+
+		if (pgd_bad(*pgd)) {
+			printk("(bad)\n");
+			break;
+		}
+
+		pmd = pmd_offset(pgd, addr);
+		printk(", *pmd = %08lx", pmd_val(*pmd));
+
+		if (pmd_none(*pmd))
+			break;
+
+		if (pmd_bad(*pmd)) {
+			printk("(bad)\n");
+			break;
+		}
+
+		pte = pte_offset(pmd, addr);
+		printk(", *pte = %08lx", pte_val(*pte));
+		printk(", *ppte = %08lx", pte_val(pte[-PTRS_PER_PTE]));
+	} while(0);
+
+	printk("\n");
+	die("Oops", regs, mode);
+
+	do_exit(SIGKILL);
+}
+
+static void do_page_fault(unsigned long addr, int mode, struct pt_regs *regs)
+{
+	struct task_struct *tsk;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	unsigned long fixup;
+
+	tsk = current;
+	mm  = tsk->mm;
+
+	/*
+	 * If we're in an interrupt or have no user
+	 * context, we must not take the fault..
+	 */
+	if (in_interrupt() || mm == &init_mm)
+		goto no_context;
+
+	down(&mm->mmap_sem);
+	vma = find_vma(mm, addr);
+	if (!vma)
+		goto bad_area;
+	if (vma->vm_start <= addr)
+		goto good_area;
+	if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, addr))
+		goto bad_area;
+
+	/*
+	 * Ok, we have a good vm_area for this memory access, so
+	 * we can handle it..
+	 */
+good_area:
+	if (READ_FAULT(mode)) { /* read? */
+		if (!(vma->vm_flags & (VM_READ|VM_EXEC)))
+			goto bad_area;
+	} else {
+		if (!(vma->vm_flags & VM_WRITE))
+			goto bad_area;
+	}
+
+	/*
+	 * If for any reason at all we couldn't handle the fault,
+	 * make sure we exit gracefully rather than endlessly redo
+	 * the fault.
+	 */
+	if (!handle_mm_fault(tsk, vma, addr & PAGE_MASK, DO_COW(mode)))
+		goto do_sigbus;
+
+	up(&mm->mmap_sem);
+	return;
+
+	/*
+	 * Something tried to access memory that isn't in our memory map..
+	 * Fix it, but check if it's kernel or user first..
+	 */
+bad_area:
+	up(&mm->mmap_sem);
+
+	/* User mode accesses just cause a SIGSEGV */
+	if (mode & FAULT_CODE_USER) {
+		tsk->tss.error_code = mode;
+		tsk->tss.trap_no = 14;
+#ifdef CONFIG_DEBUG_USER
+		printk("%s: memory violation at pc=0x%08lx, lr=0x%08lx (bad address=0x%08lx, code %d)\n",
+			tsk->comm, regs->ARM_pc, regs->ARM_lr, addr, mode);
+#endif
+		force_sig(SIGSEGV, tsk);
+		return;
+	}
+
+no_context:
+	/* Are we prepared to handle this kernel fault?  */
+	if ((fixup = search_exception_table(instruction_pointer(regs))) != 0) {
+#ifdef DEBUG
+		printk(KERN_DEBUG "%s: Exception at [<%lx>] addr=%lx (fixup: %lx)\n",
+			tsk->comm, regs->ARM_pc, addr, fixup);
+#endif
+		regs->ARM_pc = fixup;
+		return;
+	}
+
+	kernel_page_fault(addr, mode, regs, tsk, mm);
+	return;
+
+do_sigbus:
+	/*
+	 * We ran out of memory, or some other thing happened to us that made
+	 * us unable to handle the page fault gracefully.
+	 */
+	up(&mm->mmap_sem);
+
+	/*
+	 * Send a sigbus, regardless of whether we were in kernel
+	 * or user mode.
+	 */
+	tsk->tss.error_code = mode;
+	tsk->tss.trap_no = 14;
+	force_sig(SIGBUS, tsk);
+
+	/* Kernel mode? Handle exceptions or die */
+	if (!(mode & FAULT_CODE_USER))
+		goto no_context;
+}
+
+