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 spin_lock_init(pgd_spinlock(actual_pgd)); 45 return actual_pgd; 46 } 47 48 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd) 49 { 50 #if CONFIG_PGTABLE_LEVELS == 3 51 pgd -= PTRS_PER_PGD; 52 #endif 53 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER); 54 } 55 56 #if CONFIG_PGTABLE_LEVELS == 3 57 58 /* Three Level Page Table Support for pmd's */ 59 60 static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd) 61 { 62 __pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) + 63 (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT)); 64 } 65 66 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address) 67 { 68 pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER); 69 if (pmd) 70 memset(pmd, 0, PAGE_SIZE<<PMD_ORDER); 71 return pmd; 72 } 73 74 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd) 75 { 76 if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) { 77 /* 78 * This is the permanent pmd attached to the pgd; 79 * cannot free it. 80 * Increment the counter to compensate for the decrement 81 * done by generic mm code. 82 */ 83 mm_inc_nr_pmds(mm); 84 return; 85 } 86 free_pages((unsigned long)pmd, PMD_ORDER); 87 } 88 89 #else 90 91 /* Two Level Page Table Support for pmd's */ 92 93 /* 94 * allocating and freeing a pmd is trivial: the 1-entry pmd is 95 * inside the pgd, so has no extra memory associated with it. 96 */ 97 98 #define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); }) 99 #define pmd_free(mm, x) do { } while (0) 100 #define pgd_populate(mm, pmd, pte) BUG() 101 102 #endif 103 104 static inline void 105 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte) 106 { 107 #if CONFIG_PGTABLE_LEVELS == 3 108 /* preserve the gateway marker if this is the beginning of 109 * the permanent pmd */ 110 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED) 111 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | 112 PxD_FLAG_VALID | 113 PxD_FLAG_ATTACHED) 114 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 115 else 116 #endif 117 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) 118 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)); 119 } 120 121 #define pmd_populate(mm, pmd, pte_page) \ 122 pmd_populate_kernel(mm, pmd, page_address(pte_page)) 123 #define pmd_pgtable(pmd) pmd_page(pmd) 124 125 static inline pgtable_t 126 pte_alloc_one(struct mm_struct *mm) 127 { 128 struct page *page = alloc_page(GFP_KERNEL|__GFP_ZERO); 129 if (!page) 130 return NULL; 131 if (!pgtable_page_ctor(page)) { 132 __free_page(page); 133 return NULL; 134 } 135 return page; 136 } 137 138 static inline pte_t * 139 pte_alloc_one_kernel(struct mm_struct *mm) 140 { 141 pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO); 142 return pte; 143 } 144 145 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte) 146 { 147 free_page((unsigned long)pte); 148 } 149 150 static inline void pte_free(struct mm_struct *mm, struct page *pte) 151 { 152 pgtable_page_dtor(pte); 153 pte_free_kernel(mm, page_address(pte)); 154 } 155 156 #define check_pgt_cache() do { } while (0) 157 158 #endif 159