1 /*
2 * MMU context allocation for 64-bit kernels.
3 *
4 * Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 */
12
13 #include <linux/sched.h>
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/string.h>
17 #include <linux/types.h>
18 #include <linux/mm.h>
19 #include <linux/spinlock.h>
20 #include <linux/idr.h>
21 #include <linux/export.h>
22 #include <linux/gfp.h>
23 #include <linux/slab.h>
24
25 #include <asm/mmu_context.h>
26 #include <asm/pgalloc.h>
27
28 #include "icswx.h"
29
30 static DEFINE_SPINLOCK(mmu_context_lock);
31 static DEFINE_IDA(mmu_context_ida);
32
__init_new_context(void)33 int __init_new_context(void)
34 {
35 int index;
36 int err;
37
38 again:
39 if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
40 return -ENOMEM;
41
42 spin_lock(&mmu_context_lock);
43 err = ida_get_new_above(&mmu_context_ida, 1, &index);
44 spin_unlock(&mmu_context_lock);
45
46 if (err == -EAGAIN)
47 goto again;
48 else if (err)
49 return err;
50
51 if (index > MAX_USER_CONTEXT) {
52 spin_lock(&mmu_context_lock);
53 ida_remove(&mmu_context_ida, index);
54 spin_unlock(&mmu_context_lock);
55 return -ENOMEM;
56 }
57
58 return index;
59 }
60 EXPORT_SYMBOL_GPL(__init_new_context);
61
init_new_context(struct task_struct * tsk,struct mm_struct * mm)62 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
63 {
64 int index;
65
66 index = __init_new_context();
67 if (index < 0)
68 return index;
69
70 /* The old code would re-promote on fork, we don't do that
71 * when using slices as it could cause problem promoting slices
72 * that have been forced down to 4K
73 */
74 if (slice_mm_new_context(mm))
75 slice_set_user_psize(mm, mmu_virtual_psize);
76 subpage_prot_init_new_context(mm);
77 mm->context.id = index;
78 #ifdef CONFIG_PPC_ICSWX
79 mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
80 if (!mm->context.cop_lockp) {
81 __destroy_context(index);
82 subpage_prot_free(mm);
83 mm->context.id = MMU_NO_CONTEXT;
84 return -ENOMEM;
85 }
86 spin_lock_init(mm->context.cop_lockp);
87 #endif /* CONFIG_PPC_ICSWX */
88
89 #ifdef CONFIG_PPC_64K_PAGES
90 mm->context.pte_frag = NULL;
91 #endif
92 return 0;
93 }
94
__destroy_context(int context_id)95 void __destroy_context(int context_id)
96 {
97 spin_lock(&mmu_context_lock);
98 ida_remove(&mmu_context_ida, context_id);
99 spin_unlock(&mmu_context_lock);
100 }
101 EXPORT_SYMBOL_GPL(__destroy_context);
102
103 #ifdef CONFIG_PPC_64K_PAGES
destroy_pagetable_page(struct mm_struct * mm)104 static void destroy_pagetable_page(struct mm_struct *mm)
105 {
106 int count;
107 void *pte_frag;
108 struct page *page;
109
110 pte_frag = mm->context.pte_frag;
111 if (!pte_frag)
112 return;
113
114 page = virt_to_page(pte_frag);
115 /* drop all the pending references */
116 count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
117 /* We allow PTE_FRAG_NR fragments from a PTE page */
118 count = atomic_sub_return(PTE_FRAG_NR - count, &page->_count);
119 if (!count) {
120 pgtable_page_dtor(page);
121 free_hot_cold_page(page, 0);
122 }
123 }
124
125 #else
destroy_pagetable_page(struct mm_struct * mm)126 static inline void destroy_pagetable_page(struct mm_struct *mm)
127 {
128 return;
129 }
130 #endif
131
132
destroy_context(struct mm_struct * mm)133 void destroy_context(struct mm_struct *mm)
134 {
135
136 #ifdef CONFIG_PPC_ICSWX
137 drop_cop(mm->context.acop, mm);
138 kfree(mm->context.cop_lockp);
139 mm->context.cop_lockp = NULL;
140 #endif /* CONFIG_PPC_ICSWX */
141
142 destroy_pagetable_page(mm);
143 __destroy_context(mm->context.id);
144 subpage_prot_free(mm);
145 mm->context.id = MMU_NO_CONTEXT;
146 }
147