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/*
* Page fault handler for SH with an MMU.
*
* Copyright (C) 1999 Niibe Yutaka
* Copyright (C) 2003 Paul Mundt
*
* Based on linux/arch/i386/mm/fault.c:
* Copyright (C) 1995 Linus Torvalds
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/hardirq.h>
#include <linux/kprobes.h>
#include <asm/system.h>
#include <asm/mmu_context.h>
#include <asm/kgdb.h>
extern void die(const char *,struct pt_regs *,long);
/*
* 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 task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long page;
#ifdef CONFIG_SH_KGDB
if (kgdb_nofault && kgdb_bus_err_hook)
kgdb_bus_err_hook();
#endif
tsk = current;
mm = tsk->mm;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_atomic() || !mm)
goto no_context;
down_read(&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.
*/
survive:
switch (handle_mm_fault(mm, vma, address, writeaccess)) {
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case VM_FAULT_SIGBUS:
goto do_sigbus;
case VM_FAULT_OOM:
goto out_of_memory;
default:
BUG();
}
up_read(&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_read(&mm->mmap_sem);
if (user_mode(regs)) {
tsk->thread.address = address;
tsk->thread.error_code = writeaccess;
force_sig(SIGSEGV, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs))
return;
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*
*/
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\n", address);
printk(KERN_ALERT "pc = %08lx\n", regs->pc);
asm volatile("mov.l %1, %0"
: "=r" (page)
: "m" (__m(MMU_TTB)));
if (page) {
page = ((unsigned long *) page)[address >> 22];
printk(KERN_ALERT "*pde = %08lx\n", page);
if (page & _PAGE_PRESENT) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
printk(KERN_ALERT "*pte = %08lx\n", page);
}
}
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.
*/
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", tsk->comm);
if (user_mode(regs))
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->thread.address = address;
tsk->thread.error_code = writeaccess;
tsk->thread.trap_no = 14;
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
}
#ifdef CONFIG_SH_STORE_QUEUES
/*
* This is a special case for the SH-4 store queues, as pages for this
* space still need to be faulted in before it's possible to flush the
* store queue cache for writeout to the remapped region.
*/
#define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000)
#else
#define P3_ADDR_MAX P4SEG
#endif
/*
* Called with interrupts disabled.
*/
asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pte_t entry;
struct mm_struct *mm = current->mm;
spinlock_t *ptl;
int ret = 1;
#ifdef CONFIG_SH_KGDB
if (kgdb_nofault && kgdb_bus_err_hook)
kgdb_bus_err_hook();
#endif
/*
* We don't take page faults for P1, P2, and parts of P4, these
* are always mapped, whether it be due to legacy behaviour in
* 29-bit mode, or due to PMB configuration in 32-bit mode.
*/
if (address >= P3SEG && address < P3_ADDR_MAX) {
pgd = pgd_offset_k(address);
mm = NULL;
} else {
if (unlikely(address >= TASK_SIZE || !mm))
return 1;
pgd = pgd_offset(mm, address);
}
pud = pud_offset(pgd, address);
if (pud_none_or_clear_bad(pud))
return 1;
pmd = pmd_offset(pud, address);
if (pmd_none_or_clear_bad(pmd))
return 1;
if (mm)
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
else
pte = pte_offset_kernel(pmd, address);
entry = *pte;
if (unlikely(pte_none(entry) || pte_not_present(entry)))
goto unlock;
if (unlikely(writeaccess && !pte_write(entry)))
goto unlock;
if (writeaccess)
entry = pte_mkdirty(entry);
entry = pte_mkyoung(entry);
#ifdef CONFIG_CPU_SH4
/*
* ITLB is not affected by "ldtlb" instruction.
* So, we need to flush the entry by ourselves.
*/
__flush_tlb_page(get_asid(), address & PAGE_MASK);
#endif
set_pte(pte, entry);
update_mmu_cache(NULL, address, entry);
ret = 0;
unlock:
if (mm)
pte_unmap_unlock(pte, ptl);
return ret;
}
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