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    Subject[PATCH 16/20] swsusp: do not use virt_to_page on kernel data address


    o virt_to_page() call should be used on kernel linear addresses and not
    on kernel text and data addresses. Swsusp code uses it on kernel data
    (statically allocated swsusp_header).

    o Allocate swsusp_header dynamically so that virt_to_page() can be used
    safely.

    o I am changing this because in next few patches, __pa() on x86_64 will
    no longer support kernel text and data addresses and hibernation breaks.

    Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
    ---

    kernel/power/swap.c | 42 +++++++++++++++++++++++++++---------------
    1 file changed, 27 insertions(+), 15 deletions(-)

    diff -puN kernel/power/swap.c~swsusp-do-not-use-virt_to_page-on-kernel-data-addr kernel/power/swap.c
    --- linux-2.6.21-rc2-reloc/kernel/power/swap.c~swsusp-do-not-use-virt_to_page-on-kernel-data-addr 2007-03-07 01:30:43.000000000 +0530
    +++ linux-2.6.21-rc2-reloc-root/kernel/power/swap.c 2007-03-07 01:30:43.000000000 +0530
    @@ -33,12 +33,14 @@ extern char resume_file[];

    #define SWSUSP_SIG "S1SUSPEND"

    -static struct swsusp_header {
    +struct swsusp_header {
    char reserved[PAGE_SIZE - 20 - sizeof(sector_t)];
    sector_t image;
    char orig_sig[10];
    char sig[10];
    -} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
    +} __attribute__((packed));
    +
    +static struct swsusp_header *swsusp_header;

    /*
    * General things
    @@ -141,14 +143,14 @@ static int mark_swapfiles(sector_t start
    {
    int error;

    - bio_read_page(swsusp_resume_block, &swsusp_header, NULL);
    - if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
    - !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
    - memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
    - memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
    - swsusp_header.image = start;
    + bio_read_page(swsusp_resume_block, swsusp_header, NULL);
    + if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
    + !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
    + memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
    + memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
    + swsusp_header->image = start;
    error = bio_write_page(swsusp_resume_block,
    - &swsusp_header, NULL);
    + swsusp_header, NULL);
    } else {
    printk(KERN_ERR "swsusp: Swap header not found!\n");
    error = -ENODEV;
    @@ -564,7 +566,7 @@ int swsusp_read(void)
    if (error < PAGE_SIZE)
    return error < 0 ? error : -EFAULT;
    header = (struct swsusp_info *)data_of(snapshot);
    - error = get_swap_reader(&handle, swsusp_header.image);
    + error = get_swap_reader(&handle, swsusp_header->image);
    if (!error)
    error = swap_read_page(&handle, header, NULL);
    if (!error)
    @@ -591,17 +593,17 @@ int swsusp_check(void)
    resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
    if (!IS_ERR(resume_bdev)) {
    set_blocksize(resume_bdev, PAGE_SIZE);
    - memset(&swsusp_header, 0, sizeof(swsusp_header));
    + memset(swsusp_header, 0, sizeof(PAGE_SIZE));
    error = bio_read_page(swsusp_resume_block,
    - &swsusp_header, NULL);
    + swsusp_header, NULL);
    if (error)
    return error;

    - if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
    - memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
    + if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
    + memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
    /* Reset swap signature now */
    error = bio_write_page(swsusp_resume_block,
    - &swsusp_header, NULL);
    + swsusp_header, NULL);
    } else {
    return -EINVAL;
    }
    @@ -632,3 +634,13 @@ void swsusp_close(void)

    blkdev_put(resume_bdev);
    }
    +
    +static int swsusp_header_init(void)
    +{
    + swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
    + if (!swsusp_header)
    + panic("Could not allocate memory for swsusp_header\n");
    + return 0;
    +}
    +
    +core_initcall(swsusp_header_init);
    _
    -
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