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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 <linux/module.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 */
int send_fault_sig(struct pt_regs *regs)
{
siginfo_t siginfo = { 0, 0, 0, };
siginfo.si_signo = current->thread.signo;
siginfo.si_code = current->thread.code;
siginfo.si_addr = (void *)current->thread.faddr;
#ifdef DEBUG
printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code);
#endif
if (user_mode(regs)) {
force_sig_info(siginfo.si_signo,
&siginfo, current);
} else {
const struct exception_table_entry *fixup;
/* Are we prepared to handle this kernel fault? */
if ((fixup = search_exception_tables(regs->pc))) {
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->fixup;
tregs->sr = regs->sr;
return -1;
}
//if (siginfo.si_signo == SIGBUS)
// force_sig_info(siginfo.si_signo,
// &siginfo, current);
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if ((unsigned long)siginfo.si_addr < 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 %p\n", siginfo.si_addr);
die_if_kernel("Oops", regs, 0 /*error_code*/);
do_exit(SIGKILL);
}
return 1;
}
/*
* 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.
*/
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;
int write, fault;
#ifdef DEBUG
printk ("do page fault:\nregs->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_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto map_err;
if (vma->vm_flags & VM_IO)
goto acc_err;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto map_err;
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 map_err;
}
if (expand_stack(vma, address))
goto map_err;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
#ifdef DEBUG
printk("do_page_fault: good_area\n");
#endif
write = 0;
switch (error_code & 3) {
default: /* 3: write, present */
/* fall through */
case 2: /* write, not present */
if (!(vma->vm_flags & VM_WRITE))
goto acc_err;
write++;
break;
case 1: /* read, present */
goto acc_err;
case 0: /* read, not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto acc_err;
}
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
survive:
fault = handle_mm_fault(mm, vma, address, write);
#ifdef DEBUG
printk("handle_mm_fault returns %d\n",fault);
#endif
switch (fault) {
case VM_FAULT_MINOR:
current->min_flt++;
break;
case VM_FAULT_MAJOR:
current->maj_flt++;
break;
case VM_FAULT_SIGBUS:
goto bus_err;
default:
goto out_of_memory;
}
up_read(&mm->mmap_sem);
return 0;
/*
* 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_read(&mm->mmap_sem);
if (current->pid == 1) {
yield();
down_read(&mm->mmap_sem);
goto survive;
}
printk("VM: killing process %s\n", current->comm);
if (user_mode(regs))
do_exit(SIGKILL);
no_context:
current->thread.signo = SIGBUS;
current->thread.faddr = address;
return send_fault_sig(regs);
bus_err:
current->thread.signo = SIGBUS;
current->thread.code = BUS_ADRERR;
current->thread.faddr = address;
goto send_sig;
map_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_MAPERR;
current->thread.faddr = address;
goto send_sig;
acc_err:
current->thread.signo = SIGSEGV;
current->thread.code = SEGV_ACCERR;
current->thread.faddr = address;
send_sig:
up_read(&mm->mmap_sem);
return send_fault_sig(regs);
}
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