projects/linux·blob v2.6.21 · refs

142 lines · 3.8 KiB

1#ifndef _ASM_PGALLOC_H
2#define _ASM_PGALLOC_H
3
4#include <linux/gfp.h>
5#include <linux/mm.h>
6#include <linux/threads.h>
7#include <asm/processor.h>
8#include <asm/fixmap.h>
9
10#include <asm/cache.h>
11
12/* Allocate the top level pgd (page directory)
13 *
14 * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we
15 * allocate the first pmd adjacent to the pgd. This means that we can
16 * subtract a constant offset to get to it. The pmd and pgd sizes are
17 * arranged so that a single pmd covers 4GB (giving a full 64-bit
18 * process access to 8TB) so our lookups are effectively L2 for the
19 * first 4GB of the kernel (i.e. for all ILP32 processes and all the
20 * kernel for machines with under 4GB of memory) */
21static inline pgd_t *pgd_alloc(struct mm_struct *mm)
22{
23 pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL,
24 PGD_ALLOC_ORDER);
25 pgd_t *actual_pgd = pgd;
26
27 if (likely(pgd != NULL)) {
28 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER);
29#ifdef CONFIG_64BIT
30 actual_pgd += PTRS_PER_PGD;
31 /* Populate first pmd with allocated memory. We mark it
32 * with PxD_FLAG_ATTACHED as a signal to the system that this
33 * pmd entry may not be cleared. */
34 __pgd_val_set(*actual_pgd, (PxD_FLAG_PRESENT |
35 PxD_FLAG_VALID |
36 PxD_FLAG_ATTACHED)
37 + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT));
38 /* The first pmd entry also is marked with _PAGE_GATEWAY as
39 * a signal that this pmd may not be freed */
40 __pgd_val_set(*pgd, PxD_FLAG_ATTACHED);
41#endif
42 }
43 return actual_pgd;
44}
45
46static inline void pgd_free(pgd_t *pgd)
47{
48#ifdef CONFIG_64BIT
49 pgd -= PTRS_PER_PGD;
50#endif
51 free_pages((unsigned long)pgd, PGD_ALLOC_ORDER);
52}
53
54#if PT_NLEVELS == 3
55
56/* Three Level Page Table Support for pmd's */
57
58static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
59{
60 __pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) +
61 (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT));
62}
63
64static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
65{
66 pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL|__GFP_REPEAT,
67 PMD_ORDER);
68 if (pmd)
69 memset(pmd, 0, PAGE_SIZE<<PMD_ORDER);
70 return pmd;
71}
72
73static inline void pmd_free(pmd_t *pmd)
74{
75#ifdef CONFIG_64BIT
76 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
77 /* This is the permanent pmd attached to the pgd;
78 * cannot free it */
79 return;
80#endif
81 free_pages((unsigned long)pmd, PMD_ORDER);
82}
83
84#else
85
86/* Two Level Page Table Support for pmd's */
87
88/*
89 * allocating and freeing a pmd is trivial: the 1-entry pmd is
90 * inside the pgd, so has no extra memory associated with it.
91 */
92
93#define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); })
94#define pmd_free(x) do { } while (0)
95#define pgd_populate(mm, pmd, pte) BUG()
96
97#endif
98
99static inline void
100pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
101{
102#ifdef CONFIG_64BIT
103 /* preserve the gateway marker if this is the beginning of
104 * the permanent pmd */
105 if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
106 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT |
107 PxD_FLAG_VALID |
108 PxD_FLAG_ATTACHED)
109 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
110 else
111#endif
112 __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID)
113 + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
114}
115
116#define pmd_populate(mm, pmd, pte_page) \
117 pmd_populate_kernel(mm, pmd, page_address(pte_page))
118
119static inline struct page *
120pte_alloc_one(struct mm_struct *mm, unsigned long address)
121{
122 struct page *page = alloc_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
123 return page;
124}
125
126static inline pte_t *
127pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
128{
129 pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
130 return pte;
131}
132
133static inline void pte_free_kernel(pte_t *pte)
134{
135 free_page((unsigned long)pte);
136}
137
138#define pte_free(page) pte_free_kernel(page_address(page))
139
140#define check_pgt_cache() do { } while (0)
141
142#endif