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