patch-1.3.94 linux/arch/m68k/mm/fault.c

• Lines: 114
• Date: Thu Apr 18 02:59:59 1996
• Orig file: v1.3.93/linux/arch/m68k/mm/fault.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.93/linux/arch/m68k/mm/fault.c linux/arch/m68k/mm/fault.c
@@ -0,0 +1,113 @@
+/*
+ *  linux/arch/m68k/mm/fault.c
+ *
+ *  Copyright (C) 1995  Hamish Macdonald
+ */
+
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+
+extern void die_if_kernel(char *, struct pt_regs *, long);
+
+/*
+ * This routine handles page faults.  It determines the problem, and
+ * then passes it off to one of the appropriate routines.
+ *
+ * error_code:
+ *	bit 0 == 0 means no page found, 1 means protection fault
+ *	bit 1 == 0 means read, 1 means write
+ *
+ * If this routine detects a bad access, it returns 1, otherwise it
+ * returns 0.
+ */
+asmlinkage int do_page_fault(struct pt_regs *regs, unsigned long address,
+			      unsigned long error_code)
+{
+	struct vm_area_struct * vma;
+
+#ifdef DEBUG
+	printk ("regs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
+		regs->sr, regs->pc, address, error_code,
+		current->tss.pagedir_v);
+#endif
+
+	vma = find_vma(current, address);
+	if (!vma)
+	  goto bad_area;
+	if (vma->vm_start <= address)
+		goto good_area;
+	if (!(vma->vm_flags & VM_GROWSDOWN))
+		goto bad_area;
+	if (user_mode(regs)) {
+		/* Accessing the stack below usp is always a bug.  The
+		   "+ 256" is there due to some instructions doing
+		   pre-decrement on the stack and that doesn't show up
+		   until later.  */
+		if (address + 256 < rdusp())
+			goto bad_area;
+	}
+	if (expand_stack(vma, address))
+		goto bad_area;
+
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+	/*
+	 * was it a write?
+	 */
+	if (error_code & 2) {
+	  if (!(vma->vm_flags & VM_WRITE))
+	    goto bad_area;
+	} else {
+		/* read with protection fault? */
+	  if (error_code & 1)
+	    goto bad_area;
+	  if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+	    goto bad_area;
+	}
+	if (error_code & 1) {
+		do_wp_page(current, vma, address, error_code & 2);
+		return 0;
+	}
+	do_no_page(current, vma, address, error_code & 2);
+
+	/* There seems to be a missing invalidate somewhere in do_no_page.
+	 * Until I found it, this one cures the problem and makes
+	 * 1.2 run on the 68040 (Martin Apel).
+	 */
+	flush_tlb_all();
+
+	return 0;
+
+/*
+ * 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:
+	if (user_mode(regs)) {
+		/* User memory access */
+		send_sig (SIGSEGV, current, 1);
+		return 1;
+	}
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+	if ((unsigned long) address < PAGE_SIZE) {
+		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
+	} else
+		printk(KERN_ALERT "Unable to handle kernel access");
+	printk(" at virtual address %08lx\n",address);
+	die_if_kernel("Oops", regs, error_code);
+	do_exit(SIGKILL);
+
+	return 1;
+}