linux/arch/powerpc/mm/mmu_context_hash64.c
<<
>>
Prefs
   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
  27#include "icswx.h"
  28
  29static DEFINE_SPINLOCK(mmu_context_lock);
  30static DEFINE_IDA(mmu_context_ida);
  31
  32/*
  33 * The proto-VSID space has 2^35 - 1 segments available for user mappings.
  34 * Each segment contains 2^28 bytes.  Each context maps 2^44 bytes,
  35 * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
  36 */
  37#define MAX_CONTEXT     ((1UL << 19) - 1)
  38
  39int __init_new_context(void)
  40{
  41        int index;
  42        int err;
  43
  44again:
  45        if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  46                return -ENOMEM;
  47
  48        spin_lock(&mmu_context_lock);
  49        err = ida_get_new_above(&mmu_context_ida, 1, &index);
  50        spin_unlock(&mmu_context_lock);
  51
  52        if (err == -EAGAIN)
  53                goto again;
  54        else if (err)
  55                return err;
  56
  57        if (index > MAX_CONTEXT) {
  58                spin_lock(&mmu_context_lock);
  59                ida_remove(&mmu_context_ida, index);
  60                spin_unlock(&mmu_context_lock);
  61                return -ENOMEM;
  62        }
  63
  64        return index;
  65}
  66EXPORT_SYMBOL_GPL(__init_new_context);
  67
  68int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  69{
  70        int index;
  71
  72        index = __init_new_context();
  73        if (index < 0)
  74                return index;
  75
  76        /* The old code would re-promote on fork, we don't do that
  77         * when using slices as it could cause problem promoting slices
  78         * that have been forced down to 4K
  79         */
  80        if (slice_mm_new_context(mm))
  81                slice_set_user_psize(mm, mmu_virtual_psize);
  82        subpage_prot_init_new_context(mm);
  83        mm->context.id = index;
  84#ifdef CONFIG_PPC_ICSWX
  85        mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
  86        if (!mm->context.cop_lockp) {
  87                __destroy_context(index);
  88                subpage_prot_free(mm);
  89                mm->context.id = MMU_NO_CONTEXT;
  90                return -ENOMEM;
  91        }
  92        spin_lock_init(mm->context.cop_lockp);
  93#endif /* CONFIG_PPC_ICSWX */
  94
  95        return 0;
  96}
  97
  98void __destroy_context(int context_id)
  99{
 100        spin_lock(&mmu_context_lock);
 101        ida_remove(&mmu_context_ida, context_id);
 102        spin_unlock(&mmu_context_lock);
 103}
 104EXPORT_SYMBOL_GPL(__destroy_context);
 105
 106void destroy_context(struct mm_struct *mm)
 107{
 108#ifdef CONFIG_PPC_ICSWX
 109        drop_cop(mm->context.acop, mm);
 110        kfree(mm->context.cop_lockp);
 111        mm->context.cop_lockp = NULL;
 112#endif /* CONFIG_PPC_ICSWX */
 113        __destroy_context(mm->context.id);
 114        subpage_prot_free(mm);
 115        mm->context.id = MMU_NO_CONTEXT;
 116}
 117