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/*
* linux/arch/arm/mm/fault-common.c
*
* Copyright (C) 1995 Linus Torvalds
* Modifications for ARM processor (c) 1995-1999 Russell King
*/
#include <linux/config.h>
extern void die(char *msg, struct pt_regs *regs, unsigned int err);
void __bad_pmd(pmd_t *pmd)
{
printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
#ifdef CONFIG_DEBUG_ERRORS
__backtrace();
#endif
set_pmd(pmd, mk_user_pmd(BAD_PAGETABLE));
}
void __bad_pmd_kernel(pmd_t *pmd)
{
printk("Bad pmd in pte_alloc_kernel: %08lx\n", pmd_val(*pmd));
#ifdef CONFIG_DEBUG_ERRORS
__backtrace();
#endif
set_pmd(pmd, mk_kernel_pmd(BAD_PAGETABLE));
}
/*
* This is useful to dump out the page tables associated with
* 'addr' in mm 'mm'.
*/
void show_pte(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pgd = pgd_offset(mm, addr);
printk(KERN_ALERT "*pgd = %08lx", pgd_val(*pgd));
do {
pmd_t *pmd;
pte_t *pte;
if (pgd_none(*pgd))
break;
if (pgd_bad(*pgd)) {
printk("(bad)\n");
break;
}
pmd = pmd_offset(pgd, addr);
printk(", *pmd = %08lx", pmd_val(*pmd));
if (pmd_none(*pmd))
break;
if (pmd_bad(*pmd)) {
printk("(bad)\n");
break;
}
pte = pte_offset(pmd, addr);
printk(", *pte = %08lx", pte_val(*pte));
printk(", *ppte = %08lx", pte_val(pte[-PTRS_PER_PTE]));
} while(0);
printk("\n");
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
static void
kernel_page_fault(unsigned long addr, int mode, struct pt_regs *regs,
struct task_struct *tsk, struct mm_struct *mm)
{
char *reason;
if (addr < PAGE_SIZE)
reason = "NULL pointer dereference";
else
reason = "paging request";
printk(KERN_ALERT "Unable to handle kernel %s at virtual address %08lx\n",
reason, addr);
printk(KERN_ALERT "memmap = %08lX, pgd = %p\n", tsk->tss.memmap, mm->pgd);
show_pte(mm, addr);
die("Oops", regs, mode);
do_exit(SIGKILL);
}
static void do_page_fault(unsigned long addr, int mode, struct pt_regs *regs)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long fixup;
tsk = current;
mm = tsk->mm;
/*
* 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;
down(&mm->mmap_sem);
vma = find_vma(mm, addr);
if (!vma)
goto bad_area;
if (vma->vm_start <= addr)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, addr))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
if (READ_FAULT(mode)) { /* read? */
if (!(vma->vm_flags & (VM_READ|VM_EXEC)))
goto bad_area;
} else {
if (!(vma->vm_flags & VM_WRITE))
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, addr & PAGE_MASK, DO_COW(mode)))
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);
/* User mode accesses just cause a SIGSEGV */
if (mode & FAULT_CODE_USER) {
tsk->tss.error_code = mode;
tsk->tss.trap_no = 14;
#ifdef CONFIG_DEBUG_USER
printk("%s: memory violation at pc=0x%08lx, lr=0x%08lx (bad address=0x%08lx, code %d)\n",
tsk->comm, regs->ARM_pc, regs->ARM_lr, addr, mode);
#endif
force_sig(SIGSEGV, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if ((fixup = search_exception_table(instruction_pointer(regs))) != 0) {
#ifdef DEBUG
printk(KERN_DEBUG "%s: Exception at [<%lx>] addr=%lx (fixup: %lx)\n",
tsk->comm, regs->ARM_pc, addr, fixup);
#endif
regs->ARM_pc = fixup;
return;
}
kernel_page_fault(addr, mode, regs, tsk, mm);
return;
do_sigbus:
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
up(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
tsk->tss.error_code = mode;
tsk->tss.trap_no = 14;
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
if (!(mode & FAULT_CODE_USER))
goto no_context;
}
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