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/*
* 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 <linux/interrupt.h>
#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
extern void die_if_kernel(char *, struct pt_regs *, long);
extern const int frame_extra_sizes[]; /* in m68k/kernel/signal.c */
/*
* 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 mm_struct *mm = current->mm;
struct vm_area_struct * vma;
unsigned long fixup;
int write, fault;
#ifdef DEBUG
printk ("regs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
regs->sr, regs->pc, address, error_code,
current->mm->pgd);
#endif
/*
* 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(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_flags & VM_IO)
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:
write = 0;
switch (error_code & 3) {
default: /* 3: write, present */
/* fall through */
case 2: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
write++;
break;
case 1: /* read, present */
goto bad_area;
case 0: /* read, not present */
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.
*/
fault = handle_mm_fault(mm, vma, address, write);
if (fault < 0)
goto out_of_memory;
if (!fault)
goto do_sigbus;
/* 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).
*/
if (CPU_IS_040_OR_060)
flush_tlb_page(vma, address);
up(&mm->mmap_sem);
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:
up(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
siginfo_t info;
info.si_signo = SIGSEGV;
info.si_code = SEGV_MAPERR;
info.si_addr = (void *)address;
force_sig_info(SIGSEGV, &info, current);
return 1;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if ((fixup = search_exception_table(regs->pc)) != 0) {
struct pt_regs *tregs;
/* Create a new four word stack frame, discarding the old
one. */
regs->stkadj = frame_extra_sizes[regs->format];
tregs = (struct pt_regs *)((ulong)regs + regs->stkadj);
tregs->vector = regs->vector;
tregs->format = 0;
tregs->pc = fixup;
tregs->sr = regs->sr;
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);
/*
* 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:
up(&mm->mmap_sem);
printk("VM: killing process %s\n", current->comm);
if (error_code & 4)
do_exit(SIGKILL);
goto no_context;
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))
goto no_context;
return 1;
}
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