summaryrefslogtreecommitdiff
path: root/arch/ia64/include/asm/mmu_context.h
blob: 2da0e2eb036b99c73a6375804fb8f01db27d075b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_IA64_MMU_CONTEXT_H
#define _ASM_IA64_MMU_CONTEXT_H

/*
 * Copyright (C) 1998-2002 Hewlett-Packard Co
 *	David Mosberger-Tang <davidm@hpl.hp.com>
 */

/*
 * Routines to manage the allocation of task context numbers.  Task context
 * numbers are used to reduce or eliminate the need to perform TLB flushes
 * due to context switches.  Context numbers are implemented using ia-64
 * region ids.  Since the IA-64 TLB does not consider the region number when
 * performing a TLB lookup, we need to assign a unique region id to each
 * region in a process.  We use the least significant three bits in aregion
 * id for this purpose.
 */

#define IA64_REGION_ID_KERNEL	0 /* the kernel's region id (tlb.c depends on this being 0) */

#define ia64_rid(ctx,addr)	(((ctx) << 3) | (addr >> 61))

# include <asm/page.h>
# ifndef __ASSEMBLY__

#include <linux/compiler.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/spinlock.h>

#include <asm/processor.h>
#include <asm-generic/mm_hooks.h>

struct ia64_ctx {
	spinlock_t lock;
	unsigned int next;	/* next context number to use */
	unsigned int limit;     /* available free range */
	unsigned int max_ctx;   /* max. context value supported by all CPUs */
				/* call wrap_mmu_context when next >= max */
	unsigned long *bitmap;  /* bitmap size is max_ctx+1 */
	unsigned long *flushmap;/* pending rid to be flushed */
};

extern struct ia64_ctx ia64_ctx;
DECLARE_PER_CPU(u8, ia64_need_tlb_flush);

extern void mmu_context_init (void);
extern void wrap_mmu_context (struct mm_struct *mm);

static inline void
enter_lazy_tlb (struct mm_struct *mm, struct task_struct *tsk)
{
}

/*
 * When the context counter wraps around all TLBs need to be flushed because
 * an old context number might have been reused. This is signalled by the
 * ia64_need_tlb_flush per-CPU variable, which is checked in the routine
 * below. Called by activate_mm(). <efocht@ess.nec.de>
 */
static inline void
delayed_tlb_flush (void)
{
	extern void local_flush_tlb_all (void);
	unsigned long flags;

	if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
		spin_lock_irqsave(&ia64_ctx.lock, flags);
		if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
			local_flush_tlb_all();
			__ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
		}
		spin_unlock_irqrestore(&ia64_ctx.lock, flags);
	}
}

static inline nv_mm_context_t
get_mmu_context (struct mm_struct *mm)
{
	unsigned long flags;
	nv_mm_context_t context = mm->context;

	if (likely(context))
		goto out;

	spin_lock_irqsave(&ia64_ctx.lock, flags);
	/* re-check, now that we've got the lock: */
	context = mm->context;
	if (context == 0) {
		cpumask_clear(mm_cpumask(mm));
		if (ia64_ctx.next >= ia64_ctx.limit) {
			ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
					ia64_ctx.max_ctx, ia64_ctx.next);
			ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
					ia64_ctx.max_ctx, ia64_ctx.next);
			if (ia64_ctx.next >= ia64_ctx.max_ctx)
				wrap_mmu_context(mm);
		}
		mm->context = context = ia64_ctx.next++;
		__set_bit(context, ia64_ctx.bitmap);
	}
	spin_unlock_irqrestore(&ia64_ctx.lock, flags);
out:
	/*
	 * Ensure we're not starting to use "context" before any old
	 * uses of it are gone from our TLB.
	 */
	delayed_tlb_flush();

	return context;
}

/*
 * Initialize context number to some sane value.  MM is guaranteed to be a
 * brand-new address-space, so no TLB flushing is needed, ever.
 */
static inline int
init_new_context (struct task_struct *p, struct mm_struct *mm)
{
	mm->context = 0;
	return 0;
}

static inline void
destroy_context (struct mm_struct *mm)
{
	/* Nothing to do.  */
}

static inline void
reload_context (nv_mm_context_t context)
{
	unsigned long rid;
	unsigned long rid_incr = 0;
	unsigned long rr0, rr1, rr2, rr3, rr4, old_rr4;

	old_rr4 = ia64_get_rr(RGN_BASE(RGN_HPAGE));
	rid = context << 3;	/* make space for encoding the region number */
	rid_incr = 1 << 8;

	/* encode the region id, preferred page size, and VHPT enable bit: */
	rr0 = (rid << 8) | (PAGE_SHIFT << 2) | 1;
	rr1 = rr0 + 1*rid_incr;
	rr2 = rr0 + 2*rid_incr;
	rr3 = rr0 + 3*rid_incr;
	rr4 = rr0 + 4*rid_incr;
#ifdef  CONFIG_HUGETLB_PAGE
	rr4 = (rr4 & (~(0xfcUL))) | (old_rr4 & 0xfc);

#  if RGN_HPAGE != 4
#    error "reload_context assumes RGN_HPAGE is 4"
#  endif
#endif

	ia64_set_rr0_to_rr4(rr0, rr1, rr2, rr3, rr4);
	ia64_srlz_i();			/* srlz.i implies srlz.d */
}

/*
 * Must be called with preemption off
 */
static inline void
activate_context (struct mm_struct *mm)
{
	nv_mm_context_t context;

	do {
		context = get_mmu_context(mm);
		if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm)))
			cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
		reload_context(context);
		/*
		 * in the unlikely event of a TLB-flush by another thread,
		 * redo the load.
		 */
	} while (unlikely(context != mm->context));
}

#define deactivate_mm(tsk,mm)	do { } while (0)

/*
 * Switch from address space PREV to address space NEXT.
 */
static inline void
activate_mm (struct mm_struct *prev, struct mm_struct *next)
{
	/*
	 * We may get interrupts here, but that's OK because interrupt
	 * handlers cannot touch user-space.
	 */
	ia64_set_kr(IA64_KR_PT_BASE, __pa(next->pgd));
	activate_context(next);
}

#define switch_mm(prev_mm,next_mm,next_task)	activate_mm(prev_mm, next_mm)

# endif /* ! __ASSEMBLY__ */
#endif /* _ASM_IA64_MMU_CONTEXT_H */