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}