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/*
* MMU fault handling support.
*
* Copyright (C) 1998-2000 Hewlett-Packard Co
* Copyright (C) 1998-2000 David Mosberger-Tang <davidm@hpl.hp.com>
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/hardirq.h>
extern void die_if_kernel (char *, struct pt_regs *, long);
/*
* This routine is analogous to expand_stack() but instead grows the
* register backing store (which grows towards higher addresses).
* Since the register backing store is access sequentially, we
* disallow growing the RBS by more than a page at a time. Note that
* the VM_GROWSUP flag can be set on any VM area but that's fine
* because the total process size is still limited by RLIMIT_STACK and
* RLIMIT_AS.
*/
static inline long
expand_backing_store (struct vm_area_struct *vma, unsigned long address)
{
unsigned long grow;
grow = PAGE_SIZE >> PAGE_SHIFT;
if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur
|| (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur))
return -ENOMEM;
vma->vm_end += PAGE_SIZE;
vma->vm_mm->total_vm += grow;
if (vma->vm_flags & VM_LOCKED)
vma->vm_mm->locked_vm += grow;
return 0;
}
void
ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
{
struct mm_struct *mm = current->mm;
struct exception_fixup fix;
struct vm_area_struct *vma, *prev_vma;
struct siginfo si;
int signal = SIGSEGV;
unsigned long mask;
/*
* 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_prev(mm, address, &prev_vma);
if (!vma)
goto bad_area;
/* find_vma_prev() returns vma such that address < vma->vm_end or NULL */
if (address < vma->vm_start)
goto check_expansion;
good_area:
/* OK, we've got a good vm_area for this memory area. Check the access permissions: */
# define VM_READ_BIT 0
# define VM_WRITE_BIT 1
# define VM_EXEC_BIT 2
# if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
|| (1 << VM_EXEC_BIT) != VM_EXEC)
# error File is out of sync with <linux/mm.h>. Pleaes update.
# endif
mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)
| (((isr >> IA64_ISR_R_BIT) & 1UL) << VM_READ_BIT));
if ((vma->vm_flags & mask) != mask)
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.
*/
switch (handle_mm_fault(mm, vma, address, mask) != 0) {
case 1:
++current->min_flt;
break;
case 2:
++current->maj_flt;
break;
case 0:
/*
* We ran out of memory, or some other thing happened
* to us that made us unable to handle the page fault
* gracefully.
*/
signal = SIGBUS;
goto bad_area;
default:
goto out_of_memory;
}
up_read(&mm->mmap_sem);
return;
check_expansion:
if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (rgn_index(address) != rgn_index(vma->vm_start)
|| rgn_offset(address) >= RGN_MAP_LIMIT)
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
} else {
vma = prev_vma;
if (rgn_index(address) != rgn_index(vma->vm_start)
|| rgn_offset(address) >= RGN_MAP_LIMIT)
goto bad_area;
if (expand_backing_store(vma, address))
goto bad_area;
}
goto good_area;
bad_area:
up_read(&mm->mmap_sem);
if (isr & IA64_ISR_SP) {
/*
* This fault was due to a speculative load set the "ed" bit in the psr to
* ensure forward progress (target register will get a NaT).
*/
ia64_psr(regs)->ed = 1;
return;
}
if (user_mode(regs)) {
si.si_signo = signal;
si.si_errno = 0;
si.si_code = SI_KERNEL;
si.si_addr = (void *) address;
force_sig_info(signal, &si, current);
return;
}
no_context:
if (isr & IA64_ISR_SP) {
/*
* This fault was due to a speculative load set the "ed" bit in the psr to
* ensure forward progress (target register will get a NaT).
*/
ia64_psr(regs)->ed = 1;
return;
}
#ifdef GAS_HAS_LOCAL_TAGS
fix = search_exception_table(regs->cr_iip + ia64_psr(regs)->ri);
#else
fix = search_exception_table(regs->cr_iip);
#endif
if (fix.cont) {
handle_exception(regs, fix);
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 %016lx\n", address);
die_if_kernel("Oops", regs, isr);
do_exit(SIGKILL);
return;
out_of_memory:
up_read(&mm->mmap_sem);
printk("VM: killing process %s\n", current->comm);
if (user_mode(regs))
do_exit(SIGKILL);
goto no_context;
}
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