1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_PGALLOC_H 3 #define _ASM_PGALLOC_H 4 5 #include <linux/gfp.h> 6 #include <linux/mm.h> 7 #include <linux/threads.h> 8 #include <asm/processor.h> 9 #include <asm/fixmap.h> 10 11 #include <asm/cache.h> 12 13 /* Allocate the top level pgd (page directory) 14 * 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 64-bit 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) 23 { 24 pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 25 PGD_ALLOC_ORDER); 26 pgd_t *actual_pgd = pgd; 27 28 if (likely(pgd != NULL)) { 29 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER); 30 #if CONFIG_PGTABLE_LEVELS == 3 31 actual_pgd += PTRS_PER_PGD; 32 /* Populate first pmd with allocated memory. We mark it 33 * with PxD_FLAG_ATTACHED as a signal to the system that this 34 * pmd entry may not be cleared. */ 35 __pgd_val_set(*actual_pgd, (PxD_FLAG_PRESENT | 36 PxD_FLAG_VALID | 37 PxD_FLAG_ATTACHED) 38 + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT)); 39 /* The first pmd entry also is marked with PxD_FLAG_ATTACHED as 40 * a signal that this pmd may not be freed */ 41 __pgd_val_set(*pgd, PxD_FLAG_ATTACHED); 42 #endif 43 } 44 return actual_pgd; 45 } 46 47 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd) 48 { 49 #if CONFIG_PGTABLE_LEVELS == 3 50 pgd -= PTRS_PER_PGD; 51 #endif 52 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER); 53 } 54 55 #if CONFIG_PGTABLE_LEVELS == 3 56 57 /* Three Level Page Table Support for pmd's */ 58 59 static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd) 60 { 61 __pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) + 62 (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT)); 63 } 64 65 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address) 66 { 67 pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER); 68 if (pmd) 69 memset(pmd, 0, PAGE_SIZE<<PMD_ORDER); 70 return pmd; 71 } 72 73 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd) 74 { 75 if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) { 76 /* 77 * This is the permanent pmd attached to the pgd; 78 * cannot free it. 79 * Increment the counter to compensate for the decrement 80 * done by generic mm code. 81 */ 82 mm_inc_nr_pmds(mm); 83 return; 84 } 85 free_pages((unsigned long)pmd, PMD_ORDER); 86 } 87 88 #else 89 90 /* Two Level Page Table Support for pmd's */ 91 92 /* 93 * allocating and freeing a pmd is trivial: the 1-entry pmd is 94 * inside the pgd, so has no extra memory associated with it. 95 */ 96 97 #define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); }) 98 #define pmd_free(mm, x) do { } while (0) 99 #define pgd_populate(mm, pmd, pte) BUG() 100 101 #endif 102 103 static inline void 104 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte) 105 { 106 #if CONFIG_PGTABLE_LEVELS == 3 107 /* preserve the gateway marker if this is the beginning of 108 * the permanent pmd */ 109 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED) 110 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | 111 PxD_FLAG_VALID | 112 PxD_FLAG_ATTACHED) 113 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 114 else 115 #endif 116 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) 117 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 118 } 119 120 #define pmd_populate(mm, pmd, pte_page) \ 121 pmd_populate_kernel(mm, pmd, page_address(pte_page)) 122 #define pmd_pgtable(pmd) pmd_page(pmd) 123 124 static inline pgtable_t 125 pte_alloc_one(struct mm_struct *mm, unsigned long address) 126 { 127 struct page *page = alloc_page(GFP_KERNEL|__GFP_ZERO); 128 if (!page) 129 return NULL; 130 if (!pgtable_page_ctor(page)) { 131 __free_page(page); 132 return NULL; 133 } 134 return page; 135 } 136 137 static inline pte_t * 138 pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr) 139 { 140 pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO); 141 return pte; 142 } 143 144 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte) 145 { 146 free_page((unsigned long)pte); 147 } 148 149 static inline void pte_free(struct mm_struct *mm, struct page *pte) 150 { 151 pgtable_page_dtor(pte); 152 pte_free_kernel(mm, page_address(pte)); 153 } 154 155 #define check_pgt_cache() do { } while (0) 156 157 #endif 158