1 #ifndef _ASM_PGALLOC_H 2 #define _ASM_PGALLOC_H 3 4 #include <linux/gfp.h> 5 #include <linux/mm.h> 6 #include <linux/threads.h> 7 #include <asm/processor.h> 8 #include <asm/fixmap.h> 9 10 #include <asm/cache.h> 11 12 /* Allocate the top level pgd (page directory) 13 * 14 * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we 15 * allocate the first pmd adjacent to the pgd. This means that we can 16 * subtract a constant offset to get to it. The pmd and pgd sizes are 17 * arranged so that a single pmd covers 4GB (giving a full 64-bit 18 * process access to 8TB) so our lookups are effectively L2 for the 19 * first 4GB of the kernel (i.e. for all ILP32 processes and all the 20 * kernel for machines with under 4GB of memory) */ 21 static inline pgd_t *pgd_alloc(struct mm_struct *mm) 22 { 23 pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 24 PGD_ALLOC_ORDER); 25 pgd_t *actual_pgd = pgd; 26 27 if (likely(pgd != NULL)) { 28 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER); 29 #if CONFIG_PGTABLE_LEVELS == 3 30 actual_pgd += PTRS_PER_PGD; 31 /* Populate first pmd with allocated memory. We mark it 32 * with PxD_FLAG_ATTACHED as a signal to the system that this 33 * pmd entry may not be cleared. */ 34 __pgd_val_set(*actual_pgd, (PxD_FLAG_PRESENT | 35 PxD_FLAG_VALID | 36 PxD_FLAG_ATTACHED) 37 + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT)); 38 /* The first pmd entry also is marked with PxD_FLAG_ATTACHED as 39 * a signal that this pmd may not be freed */ 40 __pgd_val_set(*pgd, PxD_FLAG_ATTACHED); 41 #endif 42 } 43 return actual_pgd; 44 } 45 46 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd) 47 { 48 #if CONFIG_PGTABLE_LEVELS == 3 49 pgd -= PTRS_PER_PGD; 50 #endif 51 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER); 52 } 53 54 #if CONFIG_PGTABLE_LEVELS == 3 55 56 /* Three Level Page Table Support for pmd's */ 57 58 static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd) 59 { 60 __pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) + 61 (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT)); 62 } 63 64 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address) 65 { 66 pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER); 67 if (pmd) 68 memset(pmd, 0, PAGE_SIZE<<PMD_ORDER); 69 return pmd; 70 } 71 72 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd) 73 { 74 if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) { 75 /* 76 * This is the permanent pmd attached to the pgd; 77 * cannot free it. 78 * Increment the counter to compensate for the decrement 79 * done by generic mm code. 80 */ 81 mm_inc_nr_pmds(mm); 82 return; 83 } 84 free_pages((unsigned long)pmd, PMD_ORDER); 85 } 86 87 #else 88 89 /* Two Level Page Table Support for pmd's */ 90 91 /* 92 * allocating and freeing a pmd is trivial: the 1-entry pmd is 93 * inside the pgd, so has no extra memory associated with it. 94 */ 95 96 #define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); }) 97 #define pmd_free(mm, x) do { } while (0) 98 #define pgd_populate(mm, pmd, pte) BUG() 99 100 #endif 101 102 static inline void 103 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte) 104 { 105 #if CONFIG_PGTABLE_LEVELS == 3 106 /* preserve the gateway marker if this is the beginning of 107 * the permanent pmd */ 108 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED) 109 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | 110 PxD_FLAG_VALID | 111 PxD_FLAG_ATTACHED) 112 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 113 else 114 #endif 115 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) 116 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 117 } 118 119 #define pmd_populate(mm, pmd, pte_page) \ 120 pmd_populate_kernel(mm, pmd, page_address(pte_page)) 121 #define pmd_pgtable(pmd) pmd_page(pmd) 122 123 static inline pgtable_t 124 pte_alloc_one(struct mm_struct *mm, unsigned long address) 125 { 126 struct page *page = alloc_page(GFP_KERNEL|__GFP_ZERO); 127 if (!page) 128 return NULL; 129 if (!pgtable_page_ctor(page)) { 130 __free_page(page); 131 return NULL; 132 } 133 return page; 134 } 135 136 static inline pte_t * 137 pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr) 138 { 139 pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO); 140 return pte; 141 } 142 143 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte) 144 { 145 free_page((unsigned long)pte); 146 } 147 148 static inline void pte_free(struct mm_struct *mm, struct page *pte) 149 { 150 pgtable_page_dtor(pte); 151 pte_free_kernel(mm, page_address(pte)); 152 } 153 154 #define check_pgt_cache() do { } while (0) 155 156 #endif 157