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 #define __HAVE_ARCH_PMD_ALLOC_ONE 14 #define __HAVE_ARCH_PMD_FREE 15 #define __HAVE_ARCH_PGD_FREE 16 #include <asm-generic/pgalloc.h> 17 18 /* Allocate the top level pgd (page directory) 19 * 20 * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we 21 * allocate the first pmd adjacent to the pgd. This means that we can 22 * subtract a constant offset to get to it. The pmd and pgd sizes are 23 * arranged so that a single pmd covers 4GB (giving a full 64-bit 24 * process access to 8TB) so our lookups are effectively L2 for the 25 * first 4GB of the kernel (i.e. for all ILP32 processes and all the 26 * kernel for machines with under 4GB of memory) */ 27 static inline pgd_t *pgd_alloc(struct mm_struct *mm) 28 { 29 pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 30 PGD_ALLOC_ORDER); 31 pgd_t *actual_pgd = pgd; 32 33 if (likely(pgd != NULL)) { 34 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER); 35 #if CONFIG_PGTABLE_LEVELS == 3 36 actual_pgd += PTRS_PER_PGD; 37 /* Populate first pmd with allocated memory. We mark it 38 * with PxD_FLAG_ATTACHED as a signal to the system that this 39 * pmd entry may not be cleared. */ 40 set_pgd(actual_pgd, __pgd((PxD_FLAG_PRESENT | 41 PxD_FLAG_VALID | 42 PxD_FLAG_ATTACHED) 43 + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT))); 44 /* The first pmd entry also is marked with PxD_FLAG_ATTACHED as 45 * a signal that this pmd may not be freed */ 46 set_pgd(pgd, __pgd(PxD_FLAG_ATTACHED)); 47 #endif 48 } 49 spin_lock_init(pgd_spinlock(actual_pgd)); 50 return actual_pgd; 51 } 52 53 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd) 54 { 55 #if CONFIG_PGTABLE_LEVELS == 3 56 pgd -= PTRS_PER_PGD; 57 #endif 58 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER); 59 } 60 61 #if CONFIG_PGTABLE_LEVELS == 3 62 63 /* Three Level Page Table Support for pmd's */ 64 65 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd) 66 { 67 set_pud(pud, __pud((PxD_FLAG_PRESENT | PxD_FLAG_VALID) + 68 (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT))); 69 } 70 71 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address) 72 { 73 return (pmd_t *)__get_free_pages(GFP_PGTABLE_KERNEL, PMD_ORDER); 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 #endif 92 93 static inline void 94 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte) 95 { 96 #if CONFIG_PGTABLE_LEVELS == 3 97 /* preserve the gateway marker if this is the beginning of 98 * the permanent pmd */ 99 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED) 100 set_pmd(pmd, __pmd((PxD_FLAG_PRESENT | 101 PxD_FLAG_VALID | 102 PxD_FLAG_ATTACHED) 103 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT))); 104 else 105 #endif 106 set_pmd(pmd, __pmd((PxD_FLAG_PRESENT | PxD_FLAG_VALID) 107 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT))); 108 } 109 110 #define pmd_populate(mm, pmd, pte_page) \ 111 pmd_populate_kernel(mm, pmd, page_address(pte_page)) 112 #define pmd_pgtable(pmd) pmd_page(pmd) 113 114 #endif 115