Linux kernel mirror (for testing)
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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) */
22static 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
48static 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
60static 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
66static 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
74static 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
104static inline void
105pmd_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
125static inline pgtable_t
126pte_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
138static inline pte_t *
139pte_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
145static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
146{
147 free_page((unsigned long)pte);
148}
149
150static 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