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    Subject[PATCH][Fix][Resend] Fix Bug #4959: Page tables corrupted during resume on x86-64 (take 3)
    Date
    Hi,

    The following patch fixes Bug #4959.  For this purpose it creates temporary
    page translation tables including the kernel mapping (reused) and the direct
    mapping (created from scratch) and makes swsusp switch to these tables
    right before the image is restored.

    The code that generates the direct mapping is based on the code in
    arch/x86_64/mm/init.c.

    Please consider for applying.

    Greetings,
    Rafael


    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

    Index: linux-2.6.14-rc2-git6/arch/x86_64/kernel/suspend.c
    ===================================================================
    --- linux-2.6.14-rc2-git6.orig/arch/x86_64/kernel/suspend.c 2005-09-28 01:17:23.000000000 +0200
    +++ linux-2.6.14-rc2-git6/arch/x86_64/kernel/suspend.c 2005-09-28 10:28:05.000000000 +0200
    @@ -11,6 +11,21 @@
    #include <linux/smp.h>
    #include <linux/suspend.h>
    #include <asm/proto.h>
    +#include <asm/page.h>
    +#include <asm/pgtable.h>
    +
    +#define MAX_RESUME_PUD_ENTRIES 8
    +#define MAX_RESUME_RAM_SIZE (MAX_RESUME_PUD_ENTRIES * PTRS_PER_PMD * PMD_SIZE)
    +
    +int arch_prepare_suspend(void)
    +{
    + if (MAX_RESUME_RAM_SIZE < (end_pfn << PAGE_SHIFT)) {
    + printk(KERN_ERR "Too much RAM for suspend (%lu K), max. allowed: %lu K",
    + end_pfn << (PAGE_SHIFT - 10), MAX_RESUME_RAM_SIZE >> 10);
    + return -ENOMEM;
    + }
    + return 0;
    +}

    struct saved_context saved_context;

    @@ -140,4 +155,62 @@

    }

    +/* Defined in arch/x86_64/kernel/suspend_asm.S */
    +int restore_image(void);
    +
    +/* References to section boundaries */
    +extern const void __nosave_begin, __nosave_end;

    +pgd_t resume_level4_pgt[PTRS_PER_PGD] __nosavedata;
    +pud_t resume_level3_pgt[PTRS_PER_PUD] __nosavedata;
    +pmd_t resume_level2_pgt[MAX_RESUME_PUD_ENTRIES*PTRS_PER_PMD] __nosavedata;
    +
    +static void phys_pud_init(pud_t *pud, unsigned long end)
    +{
    + long i, j;
    + pmd_t *pmd = resume_level2_pgt;
    +
    + for (i = 0; i < PTRS_PER_PUD; pud++, i++) {
    + unsigned long paddr;
    +
    + paddr = i*PUD_SIZE;
    + if (paddr >= end) {
    + for (; i < PTRS_PER_PUD; i++, pud++)
    + set_pud(pud, __pud(0));
    + break;
    + }
    +
    + set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
    + for (j = 0; j < PTRS_PER_PMD; pmd++, j++, paddr += PMD_SIZE) {
    + unsigned long pe;
    +
    + if (paddr >= end) {
    + for (; j < PTRS_PER_PMD; j++, pmd++)
    + set_pmd(pmd, __pmd(0));
    + break;
    + }
    + pe = _PAGE_NX|_PAGE_PSE | _KERNPG_TABLE | _PAGE_GLOBAL | paddr;
    + pe &= __supported_pte_mask;
    + set_pmd(pmd, __pmd(pe));
    + }
    + }
    +}
    +
    +static void set_up_temporary_mappings(void)
    +{
    + /* It is safe to reuse the original kernel mapping */
    + set_pgd(resume_level4_pgt + pgd_index(__START_KERNEL_map),
    + init_level4_pgt[pgd_index(__START_KERNEL_map)]);
    +
    + /* Set up the direct mapping from scratch */
    + phys_pud_init(resume_level3_pgt, end_pfn << PAGE_SHIFT);
    + set_pgd(resume_level4_pgt + pgd_index(PAGE_OFFSET),
    + mk_kernel_pgd(__pa(resume_level3_pgt)));
    +}
    +
    +int swsusp_arch_resume(void)
    +{
    + set_up_temporary_mappings();
    + restore_image();
    + return 0;
    +}
    Index: linux-2.6.14-rc2-git6/arch/x86_64/kernel/suspend_asm.S
    ===================================================================
    --- linux-2.6.14-rc2-git6.orig/arch/x86_64/kernel/suspend_asm.S 2005-09-28 01:17:23.000000000 +0200
    +++ linux-2.6.14-rc2-git6/arch/x86_64/kernel/suspend_asm.S 2005-09-28 01:18:12.000000000 +0200
    @@ -39,12 +39,12 @@
    call swsusp_save
    ret

    -ENTRY(swsusp_arch_resume)
    - /* set up cr3 */
    - leaq init_level4_pgt(%rip),%rax
    - subq $__START_KERNEL_map,%rax
    - movq %rax,%cr3
    -
    +ENTRY(restore_image)
    + /* switch to temporary page tables */
    + leaq resume_level4_pgt(%rip), %rax
    + subq $__START_KERNEL_map, %rax
    + movq %rax, %cr3
    + /* Flush TLB */
    movq mmu_cr4_features(%rip), %rax
    movq %rax, %rdx
    andq $~(1<<7), %rdx # PGE
    @@ -69,6 +69,10 @@
    movq pbe_next(%rdx), %rdx
    jmp loop
    done:
    + /* go back to the original page tables */
    + leaq init_level4_pgt(%rip), %rax
    + subq $__START_KERNEL_map, %rax
    + movq %rax, %cr3
    /* Flush TLB, including "global" things (vmalloc) */
    movq mmu_cr4_features(%rip), %rax
    movq %rax, %rdx
    Index: linux-2.6.14-rc2-git6/include/asm-x86_64/suspend.h
    ===================================================================
    --- linux-2.6.14-rc2-git6.orig/include/asm-x86_64/suspend.h 2005-08-29 01:41:01.000000000 +0200
    +++ linux-2.6.14-rc2-git6/include/asm-x86_64/suspend.h 2005-09-28 01:18:12.000000000 +0200
    @@ -6,11 +6,7 @@
    #include <asm/desc.h>
    #include <asm/i387.h>

    -static inline int
    -arch_prepare_suspend(void)
    -{
    - return 0;
    -}
    +extern int arch_prepare_suspend(void);

    /* Image of the saved processor state. If you touch this, fix acpi_wakeup.S. */
    struct saved_context {
    -
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