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/*
* 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;
}
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