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