Hi!
> Use temporary page tables for the kernel text mapping during hibernation
> restore
> on x86_64.
>
> Without the patch, the original boot kernel's page tables that represent the
> kernel text mapping are used while the core of the image kernel is being
> restored. However, in principle, if the boot kernel is not identical to the
> image kernel, the location of these page tables in the image kernel need not
> be
> the same, so we should create a safe copy of the kernel text mapping prior to
> restoring the core of the image kernel.
> @@ -190,25 +190,42 @@ static int res_phys_pud_init(pud_t *pud,
> return 0;
> }
>
> +static int res_kernel_text_pud_init(pud_t *pud, unsigned long start)
> +{
> + pmd_t *pmd;
> + unsigned long paddr;
> +
> + pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
> + if (!pmd)
> + return -ENOMEM;
> + set_pud(pud + pud_index(start), __pud(__pa(pmd) | _KERNPG_TABLE));
> + for (paddr = 0; paddr < KERNEL_TEXT_SIZE; pmd++, paddr += PMD_SIZE) {
> + unsigned long pe;
> +
> + pe = __PAGE_KERNEL_LARGE_EXEC | _PAGE_GLOBAL | paddr;
> + pe &= __supported_pte_mask;
> + set_pmd(pmd, __pmd(pe));
> + }
> +
> + return 0;
> +}
> +
> static int set_up_temporary_mappings(void)
> {
> unsigned long start, end, next;
> + pud_t *pud;
> int error;
>
> temp_level4_pgt = (pgd_t *)get_safe_page(GFP_ATOMIC);
> if (!temp_level4_pgt)
> return -ENOMEM;
>
> - /* It is safe to reuse the original kernel mapping */
> - set_pgd(temp_level4_pgt + pgd_index(__START_KERNEL_map),
> - init_level4_pgt[pgd_index(__START_KERNEL_map)]);
> -
> /* Set up the direct mapping from scratch */
> start = (unsigned long)pfn_to_kaddr(0);
> end = (unsigned long)pfn_to_kaddr(end_pfn);
>
> for (; start < end; start = next) {
> - pud_t *pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> + pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> if (!pud)
> return -ENOMEM;
I believe we leak temp_level4_pgt here.
> + /* Set up the kernel text mapping from scratch */
> + pud = (pud_t *)get_safe_page(GFP_ATOMIC);
> + if (!pud)
> + return -ENOMEM;
...and some more memory here :-(.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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