patch-2.2.15 linux/arch/ppc/mm/fault.c

• Lines: 161
• Date: Fri Apr 21 12:45:47 2000
• Orig file: v2.2.14/arch/ppc/mm/fault.c
• Orig date: Sat Aug 14 02:26:47 1999

diff -u --new-file --recursive --exclude-from ../../exclude v2.2.14/arch/ppc/mm/fault.c linux/arch/ppc/mm/fault.c
@@ -48,7 +48,7 @@
 unsigned int probingmem = 0;
 
 extern void die_if_kernel(char *, struct pt_regs *, long);
-void bad_page_fault(struct pt_regs *, unsigned long);
+void bad_page_fault(struct pt_regs *, unsigned long, unsigned long);
 void do_page_fault(struct pt_regs *, unsigned long, unsigned long);
 
 /*
@@ -60,6 +60,7 @@
 {
 	struct vm_area_struct * vma;
 	struct mm_struct *mm = current->mm;
+	int fault;
 
 	/*printk("address: %08lx nip:%08lx code: %08lx %s%s%s%s%s%s\n",
 	       address,regs->nip,error_code,
@@ -82,23 +83,11 @@
 			return;
 	}
 #endif
-	if (in_interrupt()) {
-		static int complained;
-		if (complained < 20) {
-			++complained;
-			printk("page fault in interrupt handler, addr=%lx\n",
-			       address);
-			show_regs(regs);
-#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
-			if (debugger_kernel_faults)
-				debugger(regs);
-#endif
-		}
-	}
-	if (current == NULL) {
-		bad_page_fault(regs, address);
+	if (in_interrupt() || mm == &init_mm) {
+		bad_page_fault(regs, address, error_code);
 		return;
 	}
+
 	down(&mm->mmap_sem);
 	vma = find_vma(mm, address);
 	if (!vma)
@@ -115,6 +104,7 @@
 	if (error_code & 0x95700000)
 		/* an error such as lwarx to I/O controller space,
 		   address matching DABR, eciwx, etc. */
+		goto bad_area;
 #endif /* CONFIG_6xx */
 #ifdef CONFIG_8xx
         /* The MPC8xx seems to always set 0x80000000, which is
@@ -123,10 +113,9 @@
          */
 	if (error_code & 0x10000000)
                 /* Guarded storage error. */
-#endif /* CONFIG_8xx */
 		goto bad_area;
-	
-	
+#endif /* CONFIG_8xx */
+
 	/* a write */
 	if (error_code & 0x02000000) {
 		if (!(vma->vm_flags & VM_WRITE))
@@ -139,8 +128,13 @@
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}
-	if (!handle_mm_fault(current, vma, address, error_code & 0x02000000))
-		goto bad_area;
+
+ survive:
+	fault = handle_mm_fault(current, vma, address, error_code & 0x2000000);
+	if (!fault)
+		goto do_sigbus;
+	if (fault < 0)
+		goto out_of_memory;
 	up(&mm->mmap_sem);
 	/*
 	 * keep track of tlb+htab misses that are good addrs but
@@ -151,36 +145,72 @@
 	return;
 
 bad_area:
-
 	up(&mm->mmap_sem);
 	pte_errors++;	
-	bad_page_fault(regs, address);
+	bad_page_fault(regs, address, error_code);
+	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 (current->pid == 1) {
+		current->policy |= SCHED_YIELD;
+		schedule();
+		goto survive;
+	}
+	up(&mm->mmap_sem);
+	if (user_mode(regs)) {
+		printk("VM: killing process %s\n", current->comm);
+		do_exit(SIGKILL);
+	}
+	bad_page_fault(regs, address, error_code);
+	return;
+
+do_sigbus:
+	up(&mm->mmap_sem);
+
+	/*
+	 * Send a sigbus, regardless of whether we were in kernel
+	 * or user mode.
+	 */
+	force_sig(SIGBUS, current);
+
+	/* Kernel mode? Handle exceptions or die */
+	if (!user_mode(regs))
+		bad_page_fault(regs, address, error_code);
 }
 
 void
-bad_page_fault(struct pt_regs *regs, unsigned long address)
+bad_page_fault(struct pt_regs *regs, unsigned long address, unsigned long err)
 {
 	unsigned long fixup;
 	if (user_mode(regs)) {
 		force_sig(SIGSEGV, current);
 		return;
 	}
-	
+
 	/* Are we prepared to handle this fault?  */
 	if ((fixup = search_exception_table(regs->nip)) != 0) {
 		regs->nip = fixup;
 		return;
 	}
 
-	/* kernel has accessed a bad area */
+	/* kernel has accessed a bad address */
+	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 (error %lx)\n", address, err);
 	show_regs(regs);
-	print_backtrace( (unsigned long *)regs->gpr[1] );
 #if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
 	if (debugger_kernel_faults)
 		debugger(regs);
 #endif
+	print_backtrace((unsigned long *)regs->gpr[1]);
 	panic("kernel access of bad area pc %lx lr %lx address %lX tsk %s/%d",
-	      regs->nip,regs->link,address,current->comm,current->pid);
+	      regs->nip, regs->link, address, current->comm, current->pid);
 }
 
 #ifdef CONFIG_8xx