tlbex_32.c

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/*
 * TLB miss handler for SH with an MMU.
 *
 *  Copyright (C) 1999  Niibe Yutaka
 *  Copyright (C) 2003 - 2012  Paul Mundt
 *
 * 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/kprobes.h>
#include <linux/kdebug.h>
#include <asm/mmu_context.h>
#include <asm/thread_info.h>

/*
 * Called with interrupts disabled.
 */
asmlinkage int __kprobes
handle_tlbmiss(struct pt_regs *regs, unsigned long error_code,
           unsigned long address)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;
    pte_t entry;

    /*
     * 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);
    } else {
        if (unlikely(address >= TASK_SIZE || !current->mm))
            return 1;

        pgd = pgd_offset(current->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;
    pte = pte_offset_kernel(pmd, address);
    entry = *pte;
    if (unlikely(pte_none(entry) || pte_not_present(entry)))
        return 1;
    if (unlikely(error_code && !pte_write(entry)))
        return 1;

    if (error_code)
        entry = pte_mkdirty(entry);
    entry = pte_mkyoung(entry);

    set_pte(pte, entry);

#if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
    /*
     * SH-4 does not set MMUCR.RC to the corresponding TLB entry in
     * the case of an initial page write exception, so we need to
     * flush it in order to avoid potential TLB entry duplication.
     */
    if (error_code == FAULT_CODE_INITIAL)
        local_flush_tlb_one(get_asid(), address & PAGE_MASK);
#endif

    set_thread_fault_code(error_code);
    update_mmu_cache(NULL, address, pte);

    return 0;
}