pgtable.c

Go to the documentation of this file.

/*
 *  This file contains the routines setting up the linux page tables.
 *
 * Copyright (C) 2008 Michal Simek
 * Copyright (C) 2008 PetaLogix
 *
 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
 *
 *  Derived from arch/ppc/mm/pgtable.c:
 *    -- paulus
 *
 *  Derived from arch/ppc/mm/init.c:
 *    Copyright (C) 1995-1996 Gary Thomas ([email protected])
 *
 *  Modifications by Paul Mackerras (PowerMac) ([email protected])
 *  and Cort Dougan (PReP) ([email protected])
 *    Copyright (C) 1996 Paul Mackerras
 *  Amiga/APUS changes by Jesper Skov ([email protected]).
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  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/module.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/init.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <linux/io.h>
#include <asm/mmu.h>
#include <asm/sections.h>
#include <asm/fixmap.h>

#define flush_HPTE(X, va, pg)   _tlbie(va)

unsigned long ioremap_base;
unsigned long ioremap_bot;
EXPORT_SYMBOL(ioremap_bot);

#ifndef CONFIG_SMP
struct pgtable_cache_struct quicklists;
#endif

static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
        unsigned long flags)
{
    unsigned long v, i;
    phys_addr_t p;
    int err;

    /*
     * Choose an address to map it to.
     * Once the vmalloc system is running, we use it.
     * Before then, we use space going down from ioremap_base
     * (ioremap_bot records where we're up to).
     */
    p = addr & PAGE_MASK;
    size = PAGE_ALIGN(addr + size) - p;

    /*
     * Don't allow anybody to remap normal RAM that we're using.
     * mem_init() sets high_memory so only do the check after that.
     *
     * However, allow remap of rootfs: TBD
     */
    if (mem_init_done &&
        p >= memory_start && p < virt_to_phys(high_memory) &&
        !(p >= virt_to_phys((unsigned long)&__bss_stop) &&
        p < virt_to_phys((unsigned long)__bss_stop))) {
        printk(KERN_WARNING "__ioremap(): phys addr "PTE_FMT
            " is RAM lr %pf\n", (unsigned long)p,
            __builtin_return_address(0));
        return NULL;
    }

    if (size == 0)
        return NULL;

    /*
     * Is it already mapped? If the whole area is mapped then we're
     * done, otherwise remap it since we want to keep the virt addrs for
     * each request contiguous.
     *
     * We make the assumption here that if the bottom and top
     * of the range we want are mapped then it's mapped to the
     * same virt address (and this is contiguous).
     *  -- Cort
     */

    if (mem_init_done) {
        struct vm_struct *area;
        area = get_vm_area(size, VM_IOREMAP);
        if (area == NULL)
            return NULL;
        v = (unsigned long) area->addr;
    } else {
        v = (ioremap_bot -= size);
    }

    if ((flags & _PAGE_PRESENT) == 0)
        flags |= _PAGE_KERNEL;
    if (flags & _PAGE_NO_CACHE)
        flags |= _PAGE_GUARDED;

    err = 0;
    for (i = 0; i < size && err == 0; i += PAGE_SIZE)
        err = map_page(v + i, p + i, flags);
    if (err) {
        if (mem_init_done)
            vfree((void *)v);
        return NULL;
    }

    return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
}

void __iomem *ioremap(phys_addr_t addr, unsigned long size)
{
    return __ioremap(addr, size, _PAGE_NO_CACHE);
}
EXPORT_SYMBOL(ioremap);

void iounmap(void *addr)
{
    if (addr > high_memory && (unsigned long) addr < ioremap_bot)
        vfree((void *) (PAGE_MASK & (unsigned long) addr));
}
EXPORT_SYMBOL(iounmap);


int map_page(unsigned long va, phys_addr_t pa, int flags)
{
    pmd_t *pd;
    pte_t *pg;
    int err = -ENOMEM;
    /* Use upper 10 bits of VA to index the first level map */
    pd = pmd_offset(pgd_offset_k(va), va);
    /* Use middle 10 bits of VA to index the second-level map */
    pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
    /* pg = pte_alloc_kernel(&init_mm, pd, va); */

    if (pg != NULL) {
        err = 0;
        set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
                __pgprot(flags)));
        if (unlikely(mem_init_done))
            flush_HPTE(0, va, pmd_val(*pd));
            /* flush_HPTE(0, va, pg); */
    }
    return err;
}

/*
 * Map in all of physical memory starting at CONFIG_KERNEL_START.
 */
void __init mapin_ram(void)
{
    unsigned long v, p, s, f;

    v = CONFIG_KERNEL_START;
    p = memory_start;
    for (s = 0; s < lowmem_size; s += PAGE_SIZE) {
        f = _PAGE_PRESENT | _PAGE_ACCESSED |
                _PAGE_SHARED | _PAGE_HWEXEC;
        if ((char *) v < _stext || (char *) v >= _etext)
            f |= _PAGE_WRENABLE;
        else
            /* On the MicroBlaze, no user access
               forces R/W kernel access */
            f |= _PAGE_USER;
        map_page(v, p, f);
        v += PAGE_SIZE;
        p += PAGE_SIZE;
    }
}

/* is x a power of 2? */
#define is_power_of_2(x)    ((x) != 0 && (((x) & ((x) - 1)) == 0))

/* Scan the real Linux page tables and return a PTE pointer for
 * a virtual address in a context.
 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 * the PTE pointer is unmodified if PTE is not found.
 */
static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
{
    pgd_t   *pgd;
    pmd_t   *pmd;
    pte_t   *pte;
    int     retval = 0;

    pgd = pgd_offset(mm, addr & PAGE_MASK);
    if (pgd) {
        pmd = pmd_offset(pgd, addr & PAGE_MASK);
        if (pmd_present(*pmd)) {
            pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
            if (pte) {
                retval = 1;
                *ptep = pte;
            }
        }
    }
    return retval;
}

/* Find physical address for this virtual address.  Normally used by
 * I/O functions, but anyone can call it.
 */
unsigned long iopa(unsigned long addr)
{
    unsigned long pa;

    pte_t *pte;
    struct mm_struct *mm;

    /* Allow mapping of user addresses (within the thread)
     * for DMA if necessary.
     */
    if (addr < TASK_SIZE)
        mm = current->mm;
    else
        mm = &init_mm;

    pa = 0;
    if (get_pteptr(mm, addr, &pte))
        pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);

    return pa;
}

__init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
        unsigned long address)
{
    pte_t *pte;
    if (mem_init_done) {
        pte = (pte_t *)__get_free_page(GFP_KERNEL |
                    __GFP_REPEAT | __GFP_ZERO);
    } else {
        pte = (pte_t *)early_get_page();
        if (pte)
            clear_page(pte);
    }
    return pte;
}

void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
{
    unsigned long address = __fix_to_virt(idx);

    if (idx >= __end_of_fixed_addresses)
        BUG();

    map_page(address, phys, pgprot_val(flags));
}