physmem.c

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/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/module.h>
#include <linux/bootmem.h>
#include <linux/mm.h>
#include <linux/pfn.h>
#include <asm/page.h>
#include <as-layout.h>
#include <init.h>
#include <kern.h>
#include <mem_user.h>
#include <os.h>

static int physmem_fd = -1;

/* Changed during early boot */
unsigned long high_physmem;
EXPORT_SYMBOL(high_physmem);

extern unsigned long long physmem_size;

int __init init_maps(unsigned long physmem, unsigned long iomem,
             unsigned long highmem)
{
    struct page *p, *map;
    unsigned long phys_len, phys_pages, highmem_len, highmem_pages;
    unsigned long iomem_len, iomem_pages, total_len, total_pages;
    int i;

    phys_pages = physmem >> PAGE_SHIFT;
    phys_len = phys_pages * sizeof(struct page);

    iomem_pages = iomem >> PAGE_SHIFT;
    iomem_len = iomem_pages * sizeof(struct page);

    highmem_pages = highmem >> PAGE_SHIFT;
    highmem_len = highmem_pages * sizeof(struct page);

    total_pages = phys_pages + iomem_pages + highmem_pages;
    total_len = phys_len + iomem_len + highmem_len;

    map = alloc_bootmem_low_pages(total_len);
    if (map == NULL)
        return -ENOMEM;

    for (i = 0; i < total_pages; i++) {
        p = &map[i];
        memset(p, 0, sizeof(struct page));
        SetPageReserved(p);
        INIT_LIST_HEAD(&p->lru);
    }

    max_mapnr = total_pages;
    return 0;
}

void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
        int r, int w, int x)
{
    __u64 offset;
    int fd, err;

    fd = phys_mapping(phys, &offset);
    err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
    if (err) {
        if (err == -ENOMEM)
            printk(KERN_ERR "try increasing the host's "
                   "/proc/sys/vm/max_map_count to <physical "
                   "memory size>/4096\n");
        panic("map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
              "err = %d\n", virt, fd, offset, len, r, w, x, err);
    }
}

extern int __syscall_stub_start;

void __init setup_physmem(unsigned long start, unsigned long reserve_end,
              unsigned long len, unsigned long long highmem)
{
    unsigned long reserve = reserve_end - start;
    int pfn = PFN_UP(__pa(reserve_end));
    int delta = (len - reserve) >> PAGE_SHIFT;
    int err, offset, bootmap_size;

    physmem_fd = create_mem_file(len + highmem);

    offset = uml_reserved - uml_physmem;
    err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
                len - offset, 1, 1, 1);
    if (err < 0) {
        printf("setup_physmem - mapping %ld bytes of memory at 0x%p "
               "failed - errno = %d\n", len - offset,
               (void *) uml_reserved, err);
        exit(1);
    }

    /*
     * Special kludge - This page will be mapped in to userspace processes
     * from physmem_fd, so it needs to be written out there.
     */
    os_seek_file(physmem_fd, __pa(&__syscall_stub_start));
    os_write_file(physmem_fd, &__syscall_stub_start, PAGE_SIZE);

    bootmap_size = init_bootmem(pfn, pfn + delta);
    free_bootmem(__pa(reserve_end) + bootmap_size,
             len - bootmap_size - reserve);
}

int phys_mapping(unsigned long phys, unsigned long long *offset_out)
{
    int fd = -1;

    if (phys < physmem_size) {
        fd = physmem_fd;
        *offset_out = phys;
    }
    else if (phys < __pa(end_iomem)) {
        struct iomem_region *region = iomem_regions;

        while (region != NULL) {
            if ((phys >= region->phys) &&
                (phys < region->phys + region->size)) {
                fd = region->fd;
                *offset_out = phys - region->phys;
                break;
            }
            region = region->next;
        }
    }
    else if (phys < __pa(end_iomem) + highmem) {
        fd = physmem_fd;
        *offset_out = phys - iomem_size;
    }

    return fd;
}

static int __init uml_mem_setup(char *line, int *add)
{
    char *retptr;
    physmem_size = memparse(line,&retptr);
    return 0;
}
__uml_setup("mem=", uml_mem_setup,
"mem=<Amount of desired ram>\n"
"    This controls how much \"physical\" memory the kernel allocates\n"
"    for the system. The size is specified as a number followed by\n"
"    one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
"    This is not related to the amount of memory in the host.  It can\n"
"    be more, and the excess, if it's ever used, will just be swapped out.\n"
"   Example: mem=64M\n\n"
);

extern int __init parse_iomem(char *str, int *add);

__uml_setup("iomem=", parse_iomem,
"iomem=<name>,<file>\n"
"    Configure <file> as an IO memory region named <name>.\n\n"
);

/*
 * This list is constructed in parse_iomem and addresses filled in in
 * setup_iomem, both of which run during early boot.  Afterwards, it's
 * unchanged.
 */
struct iomem_region *iomem_regions;

/* Initialized in parse_iomem and unchanged thereafter */
int iomem_size;

unsigned long find_iomem(char *driver, unsigned long *len_out)
{
    struct iomem_region *region = iomem_regions;

    while (region != NULL) {
        if (!strcmp(region->driver, driver)) {
            *len_out = region->size;
            return region->virt;
        }

        region = region->next;
    }

    return 0;
}
EXPORT_SYMBOL(find_iomem);

static int setup_iomem(void)
{
    struct iomem_region *region = iomem_regions;
    unsigned long iomem_start = high_physmem + PAGE_SIZE;
    int err;

    while (region != NULL) {
        err = os_map_memory((void *) iomem_start, region->fd, 0,
                    region->size, 1, 1, 0);
        if (err)
            printk(KERN_ERR "Mapping iomem region for driver '%s' "
                   "failed, errno = %d\n", region->driver, -err);
        else {
            region->virt = iomem_start;
            region->phys = __pa(region->virt);
        }

        iomem_start += region->size + PAGE_SIZE;
        region = region->next;
    }

    return 0;
}

__initcall(setup_iomem);