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);
61
62int 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
95void __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}
101EXPORT_SYMBOL_GPL(__destroy_context);
102
103#ifdef CONFIG_PPC_64K_PAGES
104static 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
126static inline void destroy_pagetable_page(struct mm_struct *mm)
127{
128	return;
129}
130#endif
131
132
133void 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