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/* $Id: fault.c,v 1.10 1999/08/09 19:43:16 harald Exp $
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/version.h>
#include <asm/hardirq.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/softirq.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define development_version (LINUX_VERSION_CODE & 0x100)
extern void die(char *, struct pt_regs *, unsigned long write);
unsigned long asid_cache = ASID_FIRST_VERSION;
/*
* Macro for exception fixup code to access integer registers.
*/
#define dpf_reg(r) (regs->regs[r])
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
unsigned long address)
{
struct vm_area_struct * vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
unsigned long fixup;
/*
* 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;
#if 0
printk("[%s:%d:%08lx:%ld:%08lx]\n", current->comm, current->pid,
address, writeaccess, regs->cp0_epc);
#endif
down(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
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:
if (writeaccess) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
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, address, writeaccess))
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);
if (user_mode(regs)) {
tsk->tss.cp0_badvaddr = address;
tsk->tss.error_code = writeaccess;
#if 0
printk("do_page_fault() #2: sending SIGSEGV to %s for illegal %s\n"
"%08lx (epc == %08lx, ra == %08lx)\n",
tsk->comm,
writeaccess ? "writeaccess to" : "readaccess from",
address,
(unsigned long) regs->cp0_epc,
(unsigned long) regs->regs[31]);
#endif
force_sig(SIGSEGV, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
fixup = search_exception_table(regs->cp0_epc);
if (fixup) {
long new_epc;
tsk->tss.cp0_baduaddr = address;
new_epc = fixup_exception(dpf_reg, fixup, regs->cp0_epc);
if (development_version)
printk(KERN_DEBUG "%s: Exception at [<%lx>] (%lx)\n",
tsk->comm, regs->cp0_epc, new_epc);
regs->cp0_epc = new_epc;
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 %08lx, epc == %08lx, ra == %08lx\n",
address, regs->cp0_epc, regs->regs[31]);
die("Oops", regs, writeaccess);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
do_sigbus:
up(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->tss.cp0_badvaddr = address;
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
}
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