[linux-2.6-block.git] / arch / microblaze / include / asm / mmu_context_mm.h

/*
 * 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 <linux/atomic.h>
#include <linux/mm_types.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 */
Commit	Line	Data
fc34d1eb MS	1	/*
	2	* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
	3	* Copyright (C) 2008-2009 PetaLogix
	4	* Copyright (C) 2006 Atmark Techno, Inc.
	5	*
	6	* This file is subject to the terms and conditions of the GNU General Public
	7	* License. See the file "COPYING" in the main directory of this archive
	8	* for more details.
	9	*/
	10
	11	#ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H
	12	#define _ASM_MICROBLAZE_MMU_CONTEXT_H
	13
60063497	14	#include <linux/atomic.h>
589ee628 IM	15	#include <linux/mm_types.h>
589ee628 IM	16
fc34d1eb MS	17	#include <asm/bitops.h>
	18	#include <asm/mmu.h>
	19	#include <asm-generic/mm_hooks.h>
	20
	21	# ifdef __KERNEL__
	22	/*
	23	* This function defines the mapping from contexts to VSIDs (virtual
	24	* segment IDs). We use a skew on both the context and the high 4 bits
	25	* of the 32-bit virtual address (the "effective segment ID") in order
	26	* to spread out the entries in the MMU hash table.
	27	*/
	28	# define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
	29	& 0xffffff)
	30
	31	/*
	32	MicroBlaze has 256 contexts, so we can just rotate through these
	33	as a way of "switching" contexts. If the TID of the TLB is zero,
	34	the PID/TID comparison is disabled, so we can use a TID of zero
	35	to represent all kernel pages as shared among all contexts.
	36	*/
	37
	38	static inline void enter_lazy_tlb(struct mm_struct mm, struct task_struct tsk)
	39	{
	40	}
	41
	42	# define NO_CONTEXT 256
	43	# define LAST_CONTEXT 255
	44	# define FIRST_CONTEXT 1
	45
	46	/*
	47	* Set the current MMU context.
	48	* This is done byloading up the segment registers for the user part of the
	49	* address space.
	50	*
	51	* Since the PGD is immediately available, it is much faster to simply
	52	* pass this along as a second parameter, which is required for 8xx and
	53	* can be used for debugging on all processors (if you happen to have
	54	* an Abatron).
	55	*/
	56	extern void set_context(mm_context_t context, pgd_t *pgd);
	57
	58	/*
	59	* Bitmap of contexts in use.
	60	* The size of this bitmap is LAST_CONTEXT + 1 bits.
	61	*/
	62	extern unsigned long context_map[];
	63
	64	/*
	65	* This caches the next context number that we expect to be free.
	66	* Its use is an optimization only, we can't rely on this context
	67	* number to be free, but it usually will be.
	68	*/
	69	extern mm_context_t next_mmu_context;
	70
	71	/*
	72	* Since we don't have sufficient contexts to give one to every task
	73	* that could be in the system, we need to be able to steal contexts.
	74	* These variables support that.
	75	*/
	76	extern atomic_t nr_free_contexts;
	77	extern struct mm_struct *context_mm[LAST_CONTEXT+1];
	78	extern void steal_context(void);
	79
	80	/*
81	* Get a new mmu context for the address space described by `mm'.
82	*/
83	static inline void get_mmu_context(struct mm_struct *mm)
84	{
85	mm_context_t ctx;
86
87	if (mm->context != NO_CONTEXT)
88	return;
89	while (atomic_dec_if_positive(&nr_free_contexts) < 0)
90	steal_context();
91	ctx = next_mmu_context;
92	while (test_and_set_bit(ctx, context_map)) {
93	ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx);
94	if (ctx > LAST_CONTEXT)
95	ctx = 0;
96	}
97	next_mmu_context = (ctx + 1) & LAST_CONTEXT;
98	mm->context = ctx;
99	context_mm[ctx] = mm;
100	}
101
102	/*
103	* Set up the context for a new address space.
104	*/
105	# define init_new_context(tsk, mm) (((mm)->context = NO_CONTEXT), 0)
106
107	/*
108	* We're finished using the context for an address space.
109	*/
110	static inline void destroy_context(struct mm_struct *mm)
111	{
112	if (mm->context != NO_CONTEXT) {
113	clear_bit(mm->context, context_map);
114	mm->context = NO_CONTEXT;
115	atomic_inc(&nr_free_contexts);
116	}
117	}
118
119	static inline void switch_mm(struct mm_struct prev, struct mm_struct next,
120	struct task_struct *tsk)
121	{
122	tsk->thread.pgdir = next->pgd;
123	get_mmu_context(next);
124	set_context(next->context, next->pgd);
125	}
126
127	/*
128	* After we have set current->mm to a new value, this activates
129	* the context for the new mm so we see the new mappings.
130	*/
131	static inline void activate_mm(struct mm_struct *active_mm,
132	struct mm_struct *mm)
133	{
134	current->thread.pgdir = mm->pgd;
135	get_mmu_context(mm);
136	set_context(mm->context, mm->pgd);
137	}
138
139	extern void mmu_context_init(void);
140
141	# endif /* __KERNEL__ */
142	#endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */