1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Page table support for the Hexagon architecture 4 * 5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 6 */ 7 8 #ifndef _ASM_PGALLOC_H 9 #define _ASM_PGALLOC_H 10 11 #include <asm/mem-layout.h> 12 #include <asm/atomic.h> 13 14 #include <asm-generic/pgalloc.h> 15 16 extern unsigned long long kmap_generation; 17 18 /* 19 * Page table creation interface 20 */ 21 static inline pgd_t *pgd_alloc(struct mm_struct *mm) 22 { 23 pgd_t *pgd; 24 25 pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 26 27 /* 28 * There may be better ways to do this, but to ensure 29 * that new address spaces always contain the kernel 30 * base mapping, and to ensure that the user area is 31 * initially marked invalid, initialize the new map 32 * map with a copy of the kernel's persistent map. 33 */ 34 35 memcpy(pgd, swapper_pg_dir, PTRS_PER_PGD*sizeof(pgd_t)); 36 mm->context.generation = kmap_generation; 37 38 /* Physical version is what is passed to virtual machine on switch */ 39 mm->context.ptbase = __pa(pgd); 40 41 return pgd; 42 } 43 44 static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, 45 pgtable_t pte) 46 { 47 /* 48 * Conveniently, zero in 3 LSB means indirect 4K page table. 49 * Not so convenient when you're trying to vary the page size. 50 */ 51 set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) | 52 HEXAGON_L1_PTE_SIZE)); 53 } 54 55 /* 56 * Other architectures seem to have ways of making all processes 57 * share the same pmd's for their kernel mappings, but the v0.3 58 * Hexagon VM spec has a "monolithic" L1 table for user and kernel 59 * segments. We track "generations" of the kernel map to minimize 60 * overhead, and update the "slave" copies of the kernel mappings 61 * as part of switch_mm. However, we still need to update the 62 * kernel map of the active thread who's calling pmd_populate_kernel... 63 */ 64 static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, 65 pte_t *pte) 66 { 67 extern spinlock_t kmap_gen_lock; 68 pmd_t *ppmd; 69 int pmdindex; 70 71 spin_lock(&kmap_gen_lock); 72 kmap_generation++; 73 mm->context.generation = kmap_generation; 74 current->active_mm->context.generation = kmap_generation; 75 spin_unlock(&kmap_gen_lock); 76 77 set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE)); 78 79 /* 80 * Now the "slave" copy of the current thread. 81 * This is pointer arithmetic, not byte addresses! 82 */ 83 pmdindex = (pgd_t *)pmd - mm->pgd; 84 ppmd = (pmd_t *)current->active_mm->pgd + pmdindex; 85 set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE)); 86 if (pmdindex > max_kernel_seg) 87 max_kernel_seg = pmdindex; 88 } 89 90 #define __pte_free_tlb(tlb, pte, addr) \ 91 do { \ 92 pagetable_pte_dtor((page_ptdesc(pte))); \ 93 tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte))); \ 94 } while (0) 95 96 #endif 97