Messages in this thread | | | Date | Mon, 26 Sep 2005 00:07:38 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH][Fix] Prevent swsusp from corrupting page translation tables during resume on x86-64 |
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Hi!
> The following patch fixes Bug #4959. It creates temporary page translation > tables located in the page frames that are not overwritten by swsusp while copying > the image. > > The temporary page translation tables are generally based on the existing ones > with the exception that the mappings using 4KB pages are replaced with the > equivalent mappings that use 2MB pages only. The temporary page tables are > only used for copying the image.
Would not it be simpler to create them from scratch? mm/init.c has some handy functions, they should be applicable. [init_memory_mapping, phys_pud_init]. Perhaps even initialize only simple direct mapping, and place virt_to_phys() at strategic places? Pavel
> +static int __duplicate_page_tables(pgd_t *src_pgd, pgd_t *pgd, unsigned long map_offset) > +{ > + pud_t *src_pud, *pud; > + pmd_t *src_pmd, *pmd; > + pte_t *src_pte; > + int i, j, k; > + > + pr_debug("Duplicating pagetables for the map 0x%016lx at 0x%016lx\n", > + map_offset, (unsigned long)src_pgd); > + i = pgd_index(map_offset); > + j = pud_index(map_offset); > + k = pmd_index(map_offset); > + src_pgd += i; > + pgd += i; > + for (; pgd_val(*src_pgd) && i < PTRS_PER_PGD; i++, src_pgd++, pgd++) { > + pud = (pud_t *)get_usable_page(GFP_ATOMIC); > + if (!pud) > + return -ENOMEM; > + pgd_val(*pgd) = (pgd_val(*src_pgd) & ~__PGTABLE_MASK) | > + __pa((unsigned long)pud); > + pud += j; > + src_pud = (pud_t *)__va(pgd_val(*src_pgd) & __PGTABLE_MASK) + j; > + for (; pud_val(*src_pud) && j < PTRS_PER_PUD; j++, src_pud++, pud++) { > + pmd = (pmd_t *)get_usable_page(GFP_ATOMIC); > + if (!pmd) > + return -ENOMEM; > + pud_val(*pud) = (pud_val(*src_pud) & ~__PGTABLE_MASK) | > + __pa((unsigned long)pmd); > + pmd += k; > + src_pmd = (pmd_t *)__va(pud_val(*src_pud) & __PGTABLE_MASK) + k; > + for (; pmd_val(*src_pmd) && k < PTRS_PER_PMD; k++, src_pmd++, pmd++) > + if (pmd_val(*src_pmd) & _PAGE_PSE) /* 2MB page */ > + pmd_val(*pmd) = pmd_val(*src_pmd); > + else { /* 4KB page table -> 2MB page */ > + src_pte = __va(pmd_val(*src_pmd) & __PGTABLE_MASK); > + pmd_val(*pmd) = ((pmd_val(*src_pmd) & ~__PGTABLE_MASK) | > + _PAGE_PSE) | > + (pte_val(*src_pte) & __PGTABLE_PSE_MASK); > + } > + k = 0; > + } > + j = 0; > + } > + return 0; > +}
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