6 #include <linux/threads.h>
7 #include <asm/processor.h>
8 #include <asm/fixmap.h>
10 #include <asm/pgtable.h>
11 #include <asm/cache.h>
13 /* Allocate the top level pgd (page directory)
15 * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we
16 * allocate the first pmd adjacent to the pgd. This means that we can
17 * subtract a constant offset to get to it. The pmd and pgd sizes are
18 * arranged so that a single pmd covers 4GB (giving a full LP64
19 * process access to 8TB) so our lookups are effectively L2 for the
20 * first 4GB of the kernel (i.e. for all ILP32 processes and all the
21 * kernel for machines with under 4GB of memory) */
22 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
24 pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL|GFP_DMA,
26 pgd_t *actual_pgd = pgd;
28 if (likely(pgd != NULL)) {
29 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER);
31 actual_pgd += PTRS_PER_PGD;
32 /* Populate first pmd with allocated memory. We mark it
33 * with _PAGE_GATEWAY as a signal to the system that this
34 * pmd entry may not be cleared. */
35 pgd_val(*actual_pgd) = (_PAGE_TABLE | _PAGE_GATEWAY) +
36 (__u32)__pa((unsigned long)pgd);
37 /* The first pmd entry also is marked with _PAGE_GATEWAY as
38 * a signal that this pmd may not be freed */
39 pgd_val(*pgd) = _PAGE_GATEWAY;
45 static inline void pgd_free(pgd_t *pgd)
50 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER);
55 /* Three Level Page Table Support for pmd's */
57 static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
59 pgd_val(*pgd) = _PAGE_TABLE + (__u32)__pa((unsigned long)pmd);
62 /* NOTE: pmd must be in ZONE_DMA (<4GB) so the pgd pointer can be
63 * housed in 32 bits */
64 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
66 pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL|__GFP_REPEAT|GFP_DMA,
69 memset(pmd, 0, PAGE_SIZE<<PMD_ORDER);
73 static inline void pmd_free(pmd_t *pmd)
76 if(pmd_val(*pmd) & _PAGE_GATEWAY)
77 /* This is the permanent pmd attached to the pgd;
81 free_pages((unsigned long)pmd, PMD_ORDER);
86 /* Two Level Page Table Support for pmd's */
89 * allocating and freeing a pmd is trivial: the 1-entry pmd is
90 * inside the pgd, so has no extra memory associated with it.
93 #define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); })
94 #define pmd_free(x) do { } while (0)
95 #define pgd_populate(mm, pmd, pte) BUG()
100 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
103 /* preserve the gateway marker if this is the beginning of
104 * the permanent pmd */
105 if(pmd_val(*pmd) & _PAGE_GATEWAY)
106 pmd_val(*pmd) = (_PAGE_TABLE | _PAGE_GATEWAY)
107 + (__u32)__pa((unsigned long)pte);
110 pmd_val(*pmd) = _PAGE_TABLE + (__u32)__pa((unsigned long)pte);
113 #define pmd_populate(mm, pmd, pte_page) \
114 pmd_populate_kernel(mm, pmd, page_address(pte_page))
116 /* NOTE: pte must be in ZONE_DMA (<4GB) so that the pmd pointer
117 * can be housed in 32 bits */
118 static inline struct page *
119 pte_alloc_one(struct mm_struct *mm, unsigned long address)
121 struct page *page = alloc_page(GFP_KERNEL|__GFP_REPEAT|GFP_DMA);
122 if (likely(page != NULL))
123 clear_page(page_address(page));
127 static inline pte_t *
128 pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
130 pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|GFP_DMA);
131 if (likely(pte != NULL))
136 static inline void pte_free_kernel(pte_t *pte)
138 free_page((unsigned long)pte);
141 #define pte_free(page) pte_free_kernel(page_address(page))
143 extern int do_check_pgt_cache(int, int);
144 #define check_pgt_cache() do { } while (0)