304 lines
6.8 KiB
C
304 lines
6.8 KiB
C
/*
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* Page fault handler for SH with an MMU.
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*
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* Copyright (C) 1999 Niibe Yutaka
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* Copyright (C) 2003 - 2007 Paul Mundt
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*
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* Based on linux/arch/i386/mm/fault.c:
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* Copyright (C) 1995 Linus Torvalds
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <asm/system.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#include <asm/kgdb.h>
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*/
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asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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unsigned long writeaccess,
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unsigned long address)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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int si_code;
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int fault;
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siginfo_t info;
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trace_hardirqs_on();
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local_irq_enable();
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#ifdef CONFIG_SH_KGDB
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if (kgdb_nofault && kgdb_bus_err_hook)
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kgdb_bus_err_hook();
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#endif
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tsk = current;
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mm = tsk->mm;
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si_code = SEGV_MAPERR;
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if (unlikely(address >= TASK_SIZE)) {
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*
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* Do _not_ use "tsk" here. We might be inside
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* an interrupt in the middle of a task switch..
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*/
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int offset = pgd_index(address);
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pgd_t *pgd, *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pgd = get_TTB() + offset;
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pgd_k = swapper_pg_dir + offset;
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/* This will never happen with the folded page table. */
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if (!pgd_present(*pgd)) {
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if (!pgd_present(*pgd_k))
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goto bad_area_nosemaphore;
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set_pgd(pgd, *pgd_k);
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return;
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}
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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_k, address);
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if (pud_present(*pud) || !pud_present(*pud_k))
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goto bad_area_nosemaphore;
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set_pud(pud, *pud_k);
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pmd = pmd_offset(pud, address);
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pmd_k = pmd_offset(pud_k, address);
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if (pmd_present(*pmd) || !pmd_present(*pmd_k))
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goto bad_area_nosemaphore;
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set_pmd(pmd, *pmd_k);
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return;
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}
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (in_atomic() || !mm)
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goto no_context;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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si_code = SEGV_ACCERR;
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if (writeaccess) {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto bad_area;
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}
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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survive:
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fault = handle_mm_fault(mm, vma, address, writeaccess);
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGBUS)
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goto do_sigbus;
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BUG();
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}
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if (fault & VM_FAULT_MAJOR)
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tsk->maj_flt++;
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else
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tsk->min_flt++;
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up_read(&mm->mmap_sem);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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bad_area_nosemaphore:
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if (user_mode(regs)) {
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info.si_signo = SIGSEGV;
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void *) address;
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force_sig_info(SIGSEGV, &info, tsk);
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return;
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}
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no_context:
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/* Are we prepared to handle this kernel fault? */
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if (fixup_exception(regs))
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return;
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*
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*/
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bust_spinlocks(1);
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if (oops_may_print()) {
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__typeof__(pte_val(__pte(0))) page;
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if (address < PAGE_SIZE)
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printk(KERN_ALERT "Unable to handle kernel NULL "
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"pointer dereference");
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else
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printk(KERN_ALERT "Unable to handle kernel paging "
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"request");
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printk(" at virtual address %08lx\n", address);
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printk(KERN_ALERT "pc = %08lx\n", regs->pc);
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page = (unsigned long)get_TTB();
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if (page) {
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page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
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printk(KERN_ALERT "*pde = %08lx\n", page);
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if (page & _PAGE_PRESENT) {
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page &= PAGE_MASK;
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address &= 0x003ff000;
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page = ((__typeof__(page) *)
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__va(page))[address >>
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PAGE_SHIFT];
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printk(KERN_ALERT "*pte = %08lx\n", page);
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}
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}
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}
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die("Oops", regs, writeaccess);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (is_global_init(current)) {
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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}
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printk("VM: killing process %s\n", tsk->comm);
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if (user_mode(regs))
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do_group_exit(SIGKILL);
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goto no_context;
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do_sigbus:
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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info.si_signo = SIGBUS;
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info.si_errno = 0;
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info.si_code = BUS_ADRERR;
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info.si_addr = (void *)address;
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force_sig_info(SIGBUS, &info, tsk);
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/* Kernel mode? Handle exceptions or die */
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if (!user_mode(regs))
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goto no_context;
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}
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#ifdef CONFIG_SH_STORE_QUEUES
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/*
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* This is a special case for the SH-4 store queues, as pages for this
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* space still need to be faulted in before it's possible to flush the
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* store queue cache for writeout to the remapped region.
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*/
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#define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000)
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#else
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#define P3_ADDR_MAX P4SEG
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#endif
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/*
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* Called with interrupts disabled.
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*/
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asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
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unsigned long writeaccess,
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unsigned long address)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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pte_t entry;
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#ifdef CONFIG_SH_KGDB
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if (kgdb_nofault && kgdb_bus_err_hook)
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kgdb_bus_err_hook();
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#endif
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/*
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* We don't take page faults for P1, P2, and parts of P4, these
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* are always mapped, whether it be due to legacy behaviour in
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* 29-bit mode, or due to PMB configuration in 32-bit mode.
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*/
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if (address >= P3SEG && address < P3_ADDR_MAX) {
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pgd = pgd_offset_k(address);
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} else {
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if (unlikely(address >= TASK_SIZE || !current->mm))
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return 1;
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pgd = pgd_offset(current->mm, address);
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}
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pud = pud_offset(pgd, address);
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if (pud_none_or_clear_bad(pud))
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return 1;
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pmd = pmd_offset(pud, address);
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if (pmd_none_or_clear_bad(pmd))
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return 1;
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pte = pte_offset_kernel(pmd, address);
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entry = *pte;
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if (unlikely(pte_none(entry) || pte_not_present(entry)))
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return 1;
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if (unlikely(writeaccess && !pte_write(entry)))
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return 1;
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if (writeaccess)
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entry = pte_mkdirty(entry);
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entry = pte_mkyoung(entry);
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set_pte(pte, entry);
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update_mmu_cache(NULL, address, entry);
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return 0;
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}
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