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> /* for pte_{alloc,free}_one */
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 pgd_free(struct mm_struct *mm, pgd_t *pgd)
45 {
46 free_page((unsigned long) pgd);
47 }
48
49 static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
50 pgtable_t pte)
51 {
52 /*
53 * Conveniently, zero in 3 LSB means indirect 4K page table.
54 * Not so convenient when you're trying to vary the page size.
55 */
56 set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) |
57 HEXAGON_L1_PTE_SIZE));
58 }
59
60 /*
61 * Other architectures seem to have ways of making all processes
62 * share the same pmd's for their kernel mappings, but the v0.3
63 * Hexagon VM spec has a "monolithic" L1 table for user and kernel
64 * segments. We track "generations" of the kernel map to minimize
65 * overhead, and update the "slave" copies of the kernel mappings
66 * as part of switch_mm. However, we still need to update the
67 * kernel map of the active thread who's calling pmd_populate_kernel...
68 */
69 static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
70 pte_t *pte)
71 {
72 extern spinlock_t kmap_gen_lock;
73 pmd_t *ppmd;
74 int pmdindex;
75
76 spin_lock(&kmap_gen_lock);
77 kmap_generation++;
78 mm->context.generation = kmap_generation;
79 current->active_mm->context.generation = kmap_generation;
80 spin_unlock(&kmap_gen_lock);
81
82 set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
83
84 /*
85 * Now the "slave" copy of the current thread.
86 * This is pointer arithmetic, not byte addresses!
87 */
88 pmdindex = (pgd_t *)pmd - mm->pgd;
89 ppmd = (pmd_t *)current->active_mm->pgd + pmdindex;
90 set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
91 if (pmdindex > max_kernel_seg)
92 max_kernel_seg = pmdindex;
93 }
94
95 #define __pte_free_tlb(tlb, pte, addr) \
96 do { \
97 pgtable_pte_page_dtor((pte)); \
98 tlb_remove_page((tlb), (pte)); \
99 } while (0)
100
101 #endif