init.c

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#include <linux/gfp.h>
#include <linux/initrd.h>
#include <linux/ioport.h>
#include <linux/swap.h>
#include <linux/memblock.h>
#include <linux/bootmem.h>  /* for max_low_pfn */

#include <asm/cacheflush.h>
#include <asm/e820.h>
#include <asm/init.h>
#include <asm/page.h>
#include <asm/page_types.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/proto.h>
#include <asm/dma.h>        /* for MAX_DMA_PFN */

unsigned long __initdata pgt_buf_start;
unsigned long __meminitdata pgt_buf_end;
unsigned long __meminitdata pgt_buf_top;

int after_bootmem;

int direct_gbpages
#ifdef CONFIG_DIRECT_GBPAGES
                = 1
#endif
;

struct map_range {
    unsigned long start;
    unsigned long end;
    unsigned page_size_mask;
};

/*
 * First calculate space needed for kernel direct mapping page tables to cover
 * mr[0].start to mr[nr_range - 1].end, while accounting for possible 2M and 1GB
 * pages. Then find enough contiguous space for those page tables.
 */
static void __init find_early_table_space(struct map_range *mr, int nr_range)
{
    int i;
    unsigned long puds = 0, pmds = 0, ptes = 0, tables;
    unsigned long start = 0, good_end;
    phys_addr_t base;

    for (i = 0; i < nr_range; i++) {
        unsigned long range, extra;

        range = mr[i].end - mr[i].start;
        puds += (range + PUD_SIZE - 1) >> PUD_SHIFT;

        if (mr[i].page_size_mask & (1 << PG_LEVEL_1G)) {
            extra = range - ((range >> PUD_SHIFT) << PUD_SHIFT);
            pmds += (extra + PMD_SIZE - 1) >> PMD_SHIFT;
        } else {
            pmds += (range + PMD_SIZE - 1) >> PMD_SHIFT;
        }

        if (mr[i].page_size_mask & (1 << PG_LEVEL_2M)) {
            extra = range - ((range >> PMD_SHIFT) << PMD_SHIFT);
#ifdef CONFIG_X86_32
            extra += PMD_SIZE;
#endif
            ptes += (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
        } else {
            ptes += (range + PAGE_SIZE - 1) >> PAGE_SHIFT;
        }
    }

    tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
    tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
    tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);

#ifdef CONFIG_X86_32
    /* for fixmap */
    tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
#endif
    good_end = max_pfn_mapped << PAGE_SHIFT;

    base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
    if (!base)
        panic("Cannot find space for the kernel page tables");

    pgt_buf_start = base >> PAGE_SHIFT;
    pgt_buf_end = pgt_buf_start;
    pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);

    printk(KERN_DEBUG "kernel direct mapping tables up to %#lx @ [mem %#010lx-%#010lx]\n",
        mr[nr_range - 1].end - 1, pgt_buf_start << PAGE_SHIFT,
        (pgt_buf_top << PAGE_SHIFT) - 1);
}

void __init native_pagetable_reserve(u64 start, u64 end)
{
    memblock_reserve(start, end - start);
}

#ifdef CONFIG_X86_32
#define NR_RANGE_MR 3
#else /* CONFIG_X86_64 */
#define NR_RANGE_MR 5
#endif

static int __meminit save_mr(struct map_range *mr, int nr_range,
                 unsigned long start_pfn, unsigned long end_pfn,
                 unsigned long page_size_mask)
{
    if (start_pfn < end_pfn) {
        if (nr_range >= NR_RANGE_MR)
            panic("run out of range for init_memory_mapping\n");
        mr[nr_range].start = start_pfn<<PAGE_SHIFT;
        mr[nr_range].end   = end_pfn<<PAGE_SHIFT;
        mr[nr_range].page_size_mask = page_size_mask;
        nr_range++;
    }

    return nr_range;
}

/*
 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
 * This runs before bootmem is initialized and gets pages directly from
 * the physical memory. To access them they are temporarily mapped.
 */
unsigned long __init_refok init_memory_mapping(unsigned long start,
                           unsigned long end)
{
    unsigned long page_size_mask = 0;
    unsigned long start_pfn, end_pfn;
    unsigned long ret = 0;
    unsigned long pos;

    struct map_range mr[NR_RANGE_MR];
    int nr_range, i;
    int use_pse, use_gbpages;

    printk(KERN_INFO "init_memory_mapping: [mem %#010lx-%#010lx]\n",
           start, end - 1);

#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
    /*
     * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
     * This will simplify cpa(), which otherwise needs to support splitting
     * large pages into small in interrupt context, etc.
     */
    use_pse = use_gbpages = 0;
#else
    use_pse = cpu_has_pse;
    use_gbpages = direct_gbpages;
#endif

    /* Enable PSE if available */
    if (cpu_has_pse)
        set_in_cr4(X86_CR4_PSE);

    /* Enable PGE if available */
    if (cpu_has_pge) {
        set_in_cr4(X86_CR4_PGE);
        __supported_pte_mask |= _PAGE_GLOBAL;
    }

    if (use_gbpages)
        page_size_mask |= 1 << PG_LEVEL_1G;
    if (use_pse)
        page_size_mask |= 1 << PG_LEVEL_2M;

    memset(mr, 0, sizeof(mr));
    nr_range = 0;

    /* head if not big page alignment ? */
    start_pfn = start >> PAGE_SHIFT;
    pos = start_pfn << PAGE_SHIFT;
#ifdef CONFIG_X86_32
    /*
     * Don't use a large page for the first 2/4MB of memory
     * because there are often fixed size MTRRs in there
     * and overlapping MTRRs into large pages can cause
     * slowdowns.
     */
    if (pos == 0)
        end_pfn = 1<<(PMD_SHIFT - PAGE_SHIFT);
    else
        end_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
                 << (PMD_SHIFT - PAGE_SHIFT);
#else /* CONFIG_X86_64 */
    end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
            << (PMD_SHIFT - PAGE_SHIFT);
#endif
    if (end_pfn > (end >> PAGE_SHIFT))
        end_pfn = end >> PAGE_SHIFT;
    if (start_pfn < end_pfn) {
        nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
        pos = end_pfn << PAGE_SHIFT;
    }

    /* big page (2M) range */
    start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
             << (PMD_SHIFT - PAGE_SHIFT);
#ifdef CONFIG_X86_32
    end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
#else /* CONFIG_X86_64 */
    end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
             << (PUD_SHIFT - PAGE_SHIFT);
    if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
        end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
#endif

    if (start_pfn < end_pfn) {
        nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
                page_size_mask & (1<<PG_LEVEL_2M));
        pos = end_pfn << PAGE_SHIFT;
    }

#ifdef CONFIG_X86_64
    /* big page (1G) range */
    start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
             << (PUD_SHIFT - PAGE_SHIFT);
    end_pfn = (end >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
    if (start_pfn < end_pfn) {
        nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
                page_size_mask &
                 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
        pos = end_pfn << PAGE_SHIFT;
    }

    /* tail is not big page (1G) alignment */
    start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
             << (PMD_SHIFT - PAGE_SHIFT);
    end_pfn = (end >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
    if (start_pfn < end_pfn) {
        nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
                page_size_mask & (1<<PG_LEVEL_2M));
        pos = end_pfn << PAGE_SHIFT;
    }
#endif

    /* tail is not big page (2M) alignment */
    start_pfn = pos>>PAGE_SHIFT;
    end_pfn = end>>PAGE_SHIFT;
    nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);

    /* try to merge same page size and continuous */
    for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
        unsigned long old_start;
        if (mr[i].end != mr[i+1].start ||
            mr[i].page_size_mask != mr[i+1].page_size_mask)
            continue;
        /* move it */
        old_start = mr[i].start;
        memmove(&mr[i], &mr[i+1],
            (nr_range - 1 - i) * sizeof(struct map_range));
        mr[i--].start = old_start;
        nr_range--;
    }

    for (i = 0; i < nr_range; i++)
        printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n",
                mr[i].start, mr[i].end - 1,
            (mr[i].page_size_mask & (1<<PG_LEVEL_1G))?"1G":(
             (mr[i].page_size_mask & (1<<PG_LEVEL_2M))?"2M":"4k"));

    /*
     * Find space for the kernel direct mapping tables.
     *
     * Later we should allocate these tables in the local node of the
     * memory mapped. Unfortunately this is done currently before the
     * nodes are discovered.
     */
    if (!after_bootmem)
        find_early_table_space(mr, nr_range);

    for (i = 0; i < nr_range; i++)
        ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
                           mr[i].page_size_mask);

#ifdef CONFIG_X86_32
    early_ioremap_page_table_range_init();

    load_cr3(swapper_pg_dir);
#endif

    __flush_tlb_all();

    /*
     * Reserve the kernel pagetable pages we used (pgt_buf_start -
     * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
     * so that they can be reused for other purposes.
     *
     * On native it just means calling memblock_reserve, on Xen it also
     * means marking RW the pagetable pages that we allocated before
     * but that haven't been used.
     *
     * In fact on xen we mark RO the whole range pgt_buf_start -
     * pgt_buf_top, because we have to make sure that when
     * init_memory_mapping reaches the pagetable pages area, it maps
     * RO all the pagetable pages, including the ones that are beyond
     * pgt_buf_end at that time.
     */
    if (!after_bootmem && pgt_buf_end > pgt_buf_start)
        x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
                PFN_PHYS(pgt_buf_end));

    if (!after_bootmem)
        early_memtest(start, end);

    return ret >> PAGE_SHIFT;
}


/*
 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
 * is valid. The argument is a physical page number.
 *
 *
 * On x86, access has to be given to the first megabyte of ram because that area
 * contains bios code and data regions used by X and dosemu and similar apps.
 * Access has to be given to non-kernel-ram areas as well, these contain the PCI
 * mmio resources as well as potential bios/acpi data regions.
 */
int devmem_is_allowed(unsigned long pagenr)
{
    if (pagenr < 256)
        return 1;
    if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
        return 0;
    if (!page_is_ram(pagenr))
        return 1;
    return 0;
}

void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
    unsigned long addr;
    unsigned long begin_aligned, end_aligned;

    /* Make sure boundaries are page aligned */
    begin_aligned = PAGE_ALIGN(begin);
    end_aligned   = end & PAGE_MASK;

    if (WARN_ON(begin_aligned != begin || end_aligned != end)) {
        begin = begin_aligned;
        end   = end_aligned;
    }

    if (begin >= end)
        return;

    addr = begin;

    /*
     * If debugging page accesses then do not free this memory but
     * mark them not present - any buggy init-section access will
     * create a kernel page fault:
     */
#ifdef CONFIG_DEBUG_PAGEALLOC
    printk(KERN_INFO "debug: unmapping init [mem %#010lx-%#010lx]\n",
        begin, end - 1);
    set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
#else
    /*
     * We just marked the kernel text read only above, now that
     * we are going to free part of that, we need to make that
     * writeable and non-executable first.
     */
    set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
    set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);

    printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);

    for (; addr < end; addr += PAGE_SIZE) {
        ClearPageReserved(virt_to_page(addr));
        init_page_count(virt_to_page(addr));
        memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
        free_page(addr);
        totalram_pages++;
    }
#endif
}

void free_initmem(void)
{
    free_init_pages("unused kernel memory",
            (unsigned long)(&__init_begin),
            (unsigned long)(&__init_end));
}

#ifdef CONFIG_BLK_DEV_INITRD
void __init free_initrd_mem(unsigned long start, unsigned long end)
{
    /*
     * end could be not aligned, and We can not align that,
     * decompresser could be confused by aligned initrd_end
     * We already reserve the end partial page before in
     *   - i386_start_kernel()
     *   - x86_64_start_kernel()
     *   - relocate_initrd()
     * So here We can do PAGE_ALIGN() safely to get partial page to be freed
     */
    free_init_pages("initrd memory", start, PAGE_ALIGN(end));
}
#endif

void __init zone_sizes_init(void)
{
    unsigned long max_zone_pfns[MAX_NR_ZONES];

    memset(max_zone_pfns, 0, sizeof(max_zone_pfns));

#ifdef CONFIG_ZONE_DMA
    max_zone_pfns[ZONE_DMA]     = MAX_DMA_PFN;
#endif
#ifdef CONFIG_ZONE_DMA32
    max_zone_pfns[ZONE_DMA32]   = MAX_DMA32_PFN;
#endif
    max_zone_pfns[ZONE_NORMAL]  = max_low_pfn;
#ifdef CONFIG_HIGHMEM
    max_zone_pfns[ZONE_HIGHMEM] = max_pfn;
#endif

    free_area_init_nodes(max_zone_pfns);
}