79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/*
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* MMU context allocation for 64-bit kernels.
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*
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* Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/spinlock.h>
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#include <linux/idr.h>
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#include <asm/mmu_context.h>
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static DEFINE_SPINLOCK(mmu_context_lock);
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static DEFINE_IDR(mmu_context_idr);
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/*
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* The proto-VSID space has 2^35 - 1 segments available for user mappings.
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* Each segment contains 2^28 bytes. Each context maps 2^44 bytes,
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* so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
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*/
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#define NO_CONTEXT 0
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#define MAX_CONTEXT ((1UL << 19) - 1)
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int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
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{
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int index;
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int err;
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again:
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if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL))
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return -ENOMEM;
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spin_lock(&mmu_context_lock);
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err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index);
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spin_unlock(&mmu_context_lock);
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if (err == -EAGAIN)
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goto again;
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else if (err)
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return err;
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if (index > MAX_CONTEXT) {
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spin_lock(&mmu_context_lock);
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idr_remove(&mmu_context_idr, index);
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spin_unlock(&mmu_context_lock);
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return -ENOMEM;
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}
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/* The old code would re-promote on fork, we don't do that
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* when using slices as it could cause problem promoting slices
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* that have been forced down to 4K
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*/
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if (slice_mm_new_context(mm))
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slice_set_user_psize(mm, mmu_virtual_psize);
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mm->context.id = index;
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return 0;
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}
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void destroy_context(struct mm_struct *mm)
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{
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spin_lock(&mmu_context_lock);
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idr_remove(&mmu_context_idr, mm->context.id);
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spin_unlock(&mmu_context_lock);
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mm->context.id = NO_CONTEXT;
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}
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