[linux-2.6-block.git] / arch / powerpc / mm / mmu_context_hash64.c

/*
 *  MMU context allocation for 64-bit kernels.
 *
 *  Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/gfp.h>

#include <asm/mmu_context.h>

static DEFINE_SPINLOCK(mmu_context_lock);
static DEFINE_IDA(mmu_context_ida);

/*
 * The proto-VSID space has 2^35 - 1 segments available for user mappings.
 * Each segment contains 2^28 bytes.  Each context maps 2^44 bytes,
 * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
 */
#define NO_CONTEXT	0
#define MAX_CONTEXT	((1UL << 19) - 1)

int __init_new_context(void)
{
	int index;
	int err;

again:
	if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
		return -ENOMEM;

	spin_lock(&mmu_context_lock);
	err = ida_get_new_above(&mmu_context_ida, 1, &index);
	spin_unlock(&mmu_context_lock);

	if (err == -EAGAIN)
		goto again;
	else if (err)
		return err;

	if (index > MAX_CONTEXT) {
		spin_lock(&mmu_context_lock);
		ida_remove(&mmu_context_ida, index);
		spin_unlock(&mmu_context_lock);
		return -ENOMEM;
	}

	return index;
}
EXPORT_SYMBOL_GPL(__init_new_context);

int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
	int index;

	index = __init_new_context();
	if (index < 0)
		return index;

	/* The old code would re-promote on fork, we don't do that
	 * when using slices as it could cause problem promoting slices
	 * that have been forced down to 4K
	 */
	if (slice_mm_new_context(mm))
		slice_set_user_psize(mm, mmu_virtual_psize);
	subpage_prot_init_new_context(mm);
	mm->context.id = index;

	return 0;
}

void __destroy_context(int context_id)
{
	spin_lock(&mmu_context_lock);
	ida_remove(&mmu_context_ida, context_id);
	spin_unlock(&mmu_context_lock);
}
EXPORT_SYMBOL_GPL(__destroy_context);

void destroy_context(struct mm_struct *mm)
{
	__destroy_context(mm->context.id);
	subpage_prot_free(mm);
	mm->context.id = NO_CONTEXT;
}
Commit	Line	Data
14cf11af PM	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
14cf11af PM	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>
e85a4710	21	#include <linux/module.h>
5a0e3ad6	22	#include <linux/gfp.h>
14cf11af PM	23
	24	#include <asm/mmu_context.h>
	25
	26	static DEFINE_SPINLOCK(mmu_context_lock);
7317ac87	27	static DEFINE_IDA(mmu_context_ida);
14cf11af	28
5e696617 BH	29	/*
	30	* The proto-VSID space has 2^35 - 1 segments available for user mappings.
	31	* Each segment contains 2^28 bytes. Each context maps 2^44 bytes,
	32	* so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
	33	*/
	34	#define NO_CONTEXT 0
	35	#define MAX_CONTEXT ((1UL << 19) - 1)
	36
e85a4710	37	int __init_new_context(void)
14cf11af PM	38	{
	39	int index;
	40	int err;
	41
	42	again:
7317ac87	43	if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
14cf11af PM	44	return -ENOMEM;
	45
	46	spin_lock(&mmu_context_lock);
7317ac87	47	err = ida_get_new_above(&mmu_context_ida, 1, &index);
14cf11af PM	48	spin_unlock(&mmu_context_lock);
	49
	50	if (err == -EAGAIN)
	51	goto again;
	52	else if (err)
	53	return err;
	54
	55	if (index > MAX_CONTEXT) {
f86c9747	56	spin_lock(&mmu_context_lock);
7317ac87	57	ida_remove(&mmu_context_ida, index);
f86c9747	58	spin_unlock(&mmu_context_lock);
14cf11af PM	59	return -ENOMEM;
	60	}
	61
e85a4710 AG	62	return index;
	63	}
	64	EXPORT_SYMBOL_GPL(__init_new_context);
	65
	66	int init_new_context(struct task_struct tsk, struct mm_struct mm)
	67	{
	68	int index;
	69
	70	index = __init_new_context();
	71	if (index < 0)
	72	return index;
	73
d0f13e3c BH	74	/* The old code would re-promote on fork, we don't do that
	75	* when using slices as it could cause problem promoting slices
	76	* that have been forced down to 4K
	77	*/
e8ff0646	78	if (slice_mm_new_context(mm))
d0f13e3c	79	slice_set_user_psize(mm, mmu_virtual_psize);
d28513bc	80	subpage_prot_init_new_context(mm);
9dfe5c53	81	mm->context.id = index;
14cf11af PM	82
	83	return 0;
	84	}
	85
e85a4710	86	void __destroy_context(int context_id)
14cf11af PM	87	{
14cf11af PM	88	spin_lock(&mmu_context_lock);
7317ac87	89	ida_remove(&mmu_context_ida, context_id);
14cf11af	90	spin_unlock(&mmu_context_lock);
e85a4710 AG	91	}
e85a4710 AG	92	EXPORT_SYMBOL_GPL(__destroy_context);
14cf11af	93
e85a4710 AG	94	void destroy_context(struct mm_struct *mm)
	95	{
	96	__destroy_context(mm->context.id);
d28513bc	97	subpage_prot_free(mm);
14cf11af PM	98	mm->context.id = NO_CONTEXT;
14cf11af PM	99	}