tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
30static DEFINE_SPINLOCK(mmu_context_lock);
31static DEFINE_IDA(mmu_context_ida);
32
33int __init_new_context(void)
34{
35 int index;
36 int err;
37
38again:
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}
60EXPORT_SYMBOL_GPL(__init_new_context);
61static int radix__init_new_context(struct mm_struct *mm, int index)
62{
63 unsigned long rts_field;
64
65 /*
66 * set the process table entry,
67 */
68 rts_field = radix__get_tree_size();
69 process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
70 return 0;
71}
72
73int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
74{
75 int index;
76
77 index = __init_new_context();
78 if (index < 0)
79 return index;
80
81 if (radix_enabled()) {
82 radix__init_new_context(mm, index);
83 } else {
84
85 /* The old code would re-promote on fork, we don't do that
86 * when using slices as it could cause problem promoting slices
87 * that have been forced down to 4K
88 *
89 * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
90 * explicitly against context.id == 0. This ensures that we
91 * properly initialize context slice details for newly allocated
92 * mm's (which will have id == 0) and don't alter context slice
93 * inherited via fork (which will have id != 0).
94 *
95 * We should not be calling init_new_context() on init_mm. Hence a
96 * check against 0 is ok.
97 */
98 if (mm->context.id == 0)
99 slice_set_user_psize(mm, mmu_virtual_psize);
100 subpage_prot_init_new_context(mm);
101 }
102 mm->context.id = index;
103#ifdef CONFIG_PPC_ICSWX
104 mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
105 if (!mm->context.cop_lockp) {
106 __destroy_context(index);
107 subpage_prot_free(mm);
108 mm->context.id = MMU_NO_CONTEXT;
109 return -ENOMEM;
110 }
111 spin_lock_init(mm->context.cop_lockp);
112#endif /* CONFIG_PPC_ICSWX */
113
114#ifdef CONFIG_PPC_64K_PAGES
115 mm->context.pte_frag = NULL;
116#endif
117#ifdef CONFIG_SPAPR_TCE_IOMMU
118 mm_iommu_init(&mm->context);
119#endif
120 return 0;
121}
122
123void __destroy_context(int context_id)
124{
125 spin_lock(&mmu_context_lock);
126 ida_remove(&mmu_context_ida, context_id);
127 spin_unlock(&mmu_context_lock);
128}
129EXPORT_SYMBOL_GPL(__destroy_context);
130
131#ifdef CONFIG_PPC_64K_PAGES
132static void destroy_pagetable_page(struct mm_struct *mm)
133{
134 int count;
135 void *pte_frag;
136 struct page *page;
137
138 pte_frag = mm->context.pte_frag;
139 if (!pte_frag)
140 return;
141
142 page = virt_to_page(pte_frag);
143 /* drop all the pending references */
144 count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
145 /* We allow PTE_FRAG_NR fragments from a PTE page */
146 if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
147 pgtable_page_dtor(page);
148 free_hot_cold_page(page, 0);
149 }
150}
151
152#else
153static inline void destroy_pagetable_page(struct mm_struct *mm)
154{
155 return;
156}
157#endif
158
159
160void destroy_context(struct mm_struct *mm)
161{
162#ifdef CONFIG_SPAPR_TCE_IOMMU
163 mm_iommu_cleanup(&mm->context);
164#endif
165
166#ifdef CONFIG_PPC_ICSWX
167 drop_cop(mm->context.acop, mm);
168 kfree(mm->context.cop_lockp);
169 mm->context.cop_lockp = NULL;
170#endif /* CONFIG_PPC_ICSWX */
171
172 if (radix_enabled())
173 process_tb[mm->context.id].prtb1 = 0;
174 else
175 subpage_prot_free(mm);
176 destroy_pagetable_page(mm);
177 __destroy_context(mm->context.id);
178 mm->context.id = MMU_NO_CONTEXT;
179}
180
181#ifdef CONFIG_PPC_RADIX_MMU
182void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
183{
184 asm volatile("isync": : :"memory");
185 mtspr(SPRN_PID, next->context.id);
186 asm volatile("isync \n"
187 PPC_SLBIA(0x7)
188 : : :"memory");
189}
190#endif