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microblaze_mmu_v2: Context handling - mmu_context.c/h

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Signed-off-by: Michal Simek <monstr@monstr.eu>
This commit is contained in:
Michal Simek 2009-05-26 16:30:14 +02:00
parent 5de9612100
commit fc34d1eb1c
4 changed files with 238 additions and 21 deletions
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26
arch/microblaze/include/asm/mmu_context.h
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/*
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
#define _ASM_MICROBLAZE_MMU_CONTEXT_H
# define init_new_context(tsk, mm) ({ 0; })
# define enter_lazy_tlb(mm, tsk) do {} while (0)
# define change_mm_context(old, ctx, _pml4) do {} while (0)
# define destroy_context(mm) do {} while (0)
# define deactivate_mm(tsk, mm) do {} while (0)
# define switch_mm(prev, next, tsk) do {} while (0)
# define activate_mm(prev, next) do {} while (0)
#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */
#ifdef CONFIG_MMU
# include "mmu_context_mm.h"
#else
# include "mmu_context_no.h"
#endif

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arch/microblaze/include/asm/mmu_context_mm.h Normal file
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/*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
#define _ASM_MICROBLAZE_MMU_CONTEXT_H
#include <asm/atomic.h>
#include <asm/bitops.h>
#include <asm/mmu.h>
#include <asm-generic/mm_hooks.h>
# ifdef __KERNEL__
/*
* This function defines the mapping from contexts to VSIDs (virtual
* segment IDs). We use a skew on both the context and the high 4 bits
* of the 32-bit virtual address (the "effective segment ID") in order
* to spread out the entries in the MMU hash table.
*/
# define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
& 0xffffff)
/*
MicroBlaze has 256 contexts, so we can just rotate through these
as a way of "switching" contexts. If the TID of the TLB is zero,
the PID/TID comparison is disabled, so we can use a TID of zero
to represent all kernel pages as shared among all contexts.
*/
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}
# define NO_CONTEXT 256
# define LAST_CONTEXT 255
# define FIRST_CONTEXT 1
/*
* Set the current MMU context.
* This is done byloading up the segment registers for the user part of the
* address space.
*
* Since the PGD is immediately available, it is much faster to simply
* pass this along as a second parameter, which is required for 8xx and
* can be used for debugging on all processors (if you happen to have
* an Abatron).
*/
extern void set_context(mm_context_t context, pgd_t *pgd);
/*
* Bitmap of contexts in use.
* The size of this bitmap is LAST_CONTEXT + 1 bits.
*/
extern unsigned long context_map[];
/*
* This caches the next context number that we expect to be free.
* Its use is an optimization only, we can't rely on this context
* number to be free, but it usually will be.
*/
extern mm_context_t next_mmu_context;
/*
* Since we don't have sufficient contexts to give one to every task
* that could be in the system, we need to be able to steal contexts.
* These variables support that.
*/
extern atomic_t nr_free_contexts;
extern struct mm_struct *context_mm[LAST_CONTEXT+1];
extern void steal_context(void);
/*
* Get a new mmu context for the address space described by `mm'.
*/
static inline void get_mmu_context(struct mm_struct *mm)
{
mm_context_t ctx;
if (mm->context != NO_CONTEXT)
return;
while (atomic_dec_if_positive(&nr_free_contexts) < 0)
steal_context();
ctx = next_mmu_context;
while (test_and_set_bit(ctx, context_map)) {
ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
if (ctx > LAST_CONTEXT)
ctx = 0;
}
next_mmu_context = (ctx + 1) & LAST_CONTEXT;
mm->context = ctx;
context_mm[ctx] = mm;
}
/*
* Set up the context for a new address space.
*/
# define init_new_context(tsk, mm) (((mm)->context = NO_CONTEXT), 0)
/*
* We're finished using the context for an address space.
*/
static inline void destroy_context(struct mm_struct *mm)
{
if (mm->context != NO_CONTEXT) {
clear_bit(mm->context, context_map);
mm->context = NO_CONTEXT;
atomic_inc(&nr_free_contexts);
}
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
tsk->thread.pgdir = next->pgd;
get_mmu_context(next);
set_context(next->context, next->pgd);
}
/*
* After we have set current->mm to a new value, this activates
* the context for the new mm so we see the new mappings.
*/
static inline void activate_mm(struct mm_struct *active_mm,
struct mm_struct *mm)
{
current->thread.pgdir = mm->pgd;
get_mmu_context(mm);
set_context(mm->context, mm->pgd);
}
extern void mmu_context_init(void);
# endif /* __KERNEL__ */
#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */

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arch/microblaze/include/asm/mmu_context_no.h Normal file
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/*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
#define _ASM_MICROBLAZE_MMU_CONTEXT_H
# define init_new_context(tsk, mm) ({ 0; })
# define enter_lazy_tlb(mm, tsk) do {} while (0)
# define change_mm_context(old, ctx, _pml4) do {} while (0)
# define destroy_context(mm) do {} while (0)
# define deactivate_mm(tsk, mm) do {} while (0)
# define switch_mm(prev, next, tsk) do {} while (0)
# define activate_mm(prev, next) do {} while (0)
#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */

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arch/microblaze/mm/mmu_context.c Normal file
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/*
* This file contains the routines for handling the MMU.
*
* Copyright (C) 2007 Xilinx, Inc. All rights reserved.
*
* Derived from arch/ppc/mm/4xx_mmu.c:
* -- paulus
*
* Derived from arch/ppc/mm/init.c:
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
* Copyright (C) 1996 Paul Mackerras
* Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
*
* Derived from "arch/i386/mm/init.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* 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/mm.h>
#include <linux/init.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
mm_context_t next_mmu_context;
unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
atomic_t nr_free_contexts;
struct mm_struct *context_mm[LAST_CONTEXT+1];
/*
* Initialize the context management stuff.
*/
void __init mmu_context_init(void)
{
/*
* The use of context zero is reserved for the kernel.
* This code assumes FIRST_CONTEXT < 32.
*/
context_map[0] = (1 << FIRST_CONTEXT) - 1;
next_mmu_context = FIRST_CONTEXT;
atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
}
/*
* Steal a context from a task that has one at the moment.
*
* This isn't an LRU system, it just frees up each context in
* turn (sort-of pseudo-random replacement :). This would be the
* place to implement an LRU scheme if anyone were motivated to do it.
*/
void steal_context(void)
{
struct mm_struct *mm;
/* free up context `next_mmu_context' */
/* if we shouldn't free context 0, don't... */
if (next_mmu_context < FIRST_CONTEXT)
next_mmu_context = FIRST_CONTEXT;
mm = context_mm[next_mmu_context];
flush_tlb_mm(mm);
destroy_context(mm);
}