patch-2.3.43 linux/arch/ia64/mm/fault.c

• Lines: 165
• Date: Sun Feb 6 18:42:40 2000
• Orig file: v2.3.42/linux/arch/ia64/mm/fault.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.42/linux/arch/ia64/mm/fault.c linux/arch/ia64/mm/fault.c
@@ -0,0 +1,164 @@
+/*
+ * MMU fault handling support.
+ *
+ * Copyright (C) 1998, 1999 Hewlett-Packard Co
+ * Copyright (C) 1998, 1999 David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/hardirq.h>
+
+extern void die_if_kernel (char *, struct pt_regs *, long);
+
+/*
+ * This routine is analogous to expand_stack() but instead grows the
+ * register backing store (which grows towards higher addresses).
+ * Since the register backing store is access sequentially, we
+ * disallow growing the RBS by more than a page at a time.  Note that
+ * the VM_GROWSUP flag can be set on any VM area but that's fine
+ * because the total process size is still limited by RLIMIT_STACK and
+ * RLIMIT_AS.
+ */
+static inline long
+expand_backing_store (struct vm_area_struct *vma, unsigned long address)
+{
+	unsigned long grow;
+
+	grow = PAGE_SIZE >> PAGE_SHIFT;
+	if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur
+	    || (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur))
+		return -ENOMEM;
+	vma->vm_end += PAGE_SIZE;
+	vma->vm_mm->total_vm += grow;
+	if (vma->vm_flags & VM_LOCKED)
+		vma->vm_mm->locked_vm += grow;
+	return 0;
+}
+
+void
+ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
+{
+	struct mm_struct *mm = current->mm;
+	const struct exception_table_entry *fix;
+	struct vm_area_struct *vma, *prev_vma;
+	struct siginfo si;
+	int signal = SIGSEGV;
+	unsigned long mask;
+
+	/*
+	 * If we're in an interrupt or have no user
+	 * context, we must not take the fault..
+	 */
+	if (in_interrupt() || !mm)
+		goto no_context;
+
+	down(&mm->mmap_sem);
+
+	vma = find_vma_prev(mm, address, &prev_vma);
+	if (!vma)
+		goto bad_area;
+
+	/* find_vma_prev() returns vma such that address < vma->vm_end or NULL */
+	if (address < vma->vm_start)
+		goto check_expansion;
+
+  good_area:
+	/* OK, we've got a good vm_area for this memory area.  Check the access permissions: */
+
+#	define VM_READ_BIT	0
+#	define VM_WRITE_BIT	1
+#	define VM_EXEC_BIT	2
+
+#	if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
+	    || (1 << VM_EXEC_BIT) != VM_EXEC)
+#		error File is out of sync with <linux/mm.h>.  Pleaes update.
+#	endif
+
+	mask = (  (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
+		| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)
+		| (((isr >> IA64_ISR_R_BIT) & 1UL) << VM_READ_BIT));
+
+	if ((vma->vm_flags & mask) != mask)
+		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(current, vma, address, (isr & IA64_ISR_W) != 0)) {
+		/*
+		 * We ran out of memory, or some other thing happened
+		 * to us that made us unable to handle the page fault
+		 * gracefully.
+		 */
+		signal = SIGBUS;
+		goto bad_area;
+	}
+	up(&mm->mmap_sem);
+	return;
+
+  check_expansion:
+	if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
+		if (!(vma->vm_flags & VM_GROWSDOWN))
+			goto bad_area;
+		if (expand_stack(vma, address))
+			goto bad_area;
+	} else if (expand_backing_store(prev_vma, address))
+		goto bad_area;
+	goto good_area;
+
+  bad_area:
+	up(&mm->mmap_sem);
+	if (isr & IA64_ISR_SP) {
+		/*
+		 * This fault was due to a speculative load set the
+		 * "ed" bit in the psr to ensure forward progress
+		 * (target register will get a NaT).
+		 */
+		ia64_psr(regs)->ed = 1;
+		return;
+	}
+	if (user_mode(regs)) {
+#if 0
+printk("%s(%d): segfault accessing %lx\n", current->comm, current->pid, address);
+show_regs(regs);
+#endif
+		si.si_signo = signal;
+		si.si_errno = 0;
+		si.si_code = SI_KERNEL;
+		si.si_addr = (void *) address;
+		force_sig_info(SIGSEGV, &si, current);
+		return;
+	}
+
+  no_context:
+	fix = search_exception_table(regs->cr_iip);
+	if (fix) {
+		regs->r8 = -EFAULT;
+		if (fix->skip & 1) {
+			regs->r9 = 0;
+		}
+		regs->cr_iip += ((long) fix->skip) & ~15;
+		regs->cr_ipsr &= ~IA64_PSR_RI;	/* clear exception slot number */
+		return;
+	}
+
+	/*
+	 * Oops. The kernel tried to access some bad page. We'll have
+	 * to terminate things with extreme prejudice.
+	 */
+	printk(KERN_ALERT "Unable to handle kernel paging request at "
+	       "virtual address %016lx\n", address);
+	die_if_kernel("Oops", regs, isr);
+	do_exit(SIGKILL);
+	return;
+}