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
201
202
203
204
205
206
207
208
|
/* mmu-context.c: MMU context allocation and management
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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/mm.h>
#include <asm/tlbflush.h>
#define NR_CXN 4096
static unsigned long cxn_bitmap[NR_CXN / (sizeof(unsigned long) * 8)];
static LIST_HEAD(cxn_owners_lru);
static DEFINE_SPINLOCK(cxn_owners_lock);
int __nongpreldata cxn_pinned = -1;
/*****************************************************************************/
/*
* initialise a new context
*/
int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
memset(&mm->context, 0, sizeof(mm->context));
INIT_LIST_HEAD(&mm->context.id_link);
mm->context.itlb_cached_pge = 0xffffffffUL;
mm->context.dtlb_cached_pge = 0xffffffffUL;
return 0;
} /* end init_new_context() */
/*****************************************************************************/
/*
* make sure a kernel MMU context has a CPU context number
* - call with cxn_owners_lock held
*/
static unsigned get_cxn(mm_context_t *ctx)
{
struct list_head *_p;
mm_context_t *p;
unsigned cxn;
if (!list_empty(&ctx->id_link)) {
list_move_tail(&ctx->id_link, &cxn_owners_lru);
}
else {
/* find the first unallocated context number
* - 0 is reserved for the kernel
*/
cxn = find_next_zero_bit(cxn_bitmap, NR_CXN, 1);
if (cxn < NR_CXN) {
set_bit(cxn, cxn_bitmap);
}
else {
/* none remaining - need to steal someone else's cxn */
p = NULL;
list_for_each(_p, &cxn_owners_lru) {
p = list_entry(_p, mm_context_t, id_link);
if (!p->id_busy && p->id != cxn_pinned)
break;
}
BUG_ON(_p == &cxn_owners_lru);
cxn = p->id;
p->id = 0;
list_del_init(&p->id_link);
__flush_tlb_mm(cxn);
}
ctx->id = cxn;
list_add_tail(&ctx->id_link, &cxn_owners_lru);
}
return ctx->id;
} /* end get_cxn() */
/*****************************************************************************/
/*
* restore the current TLB miss handler mapped page tables into the MMU context and set up a
* mapping for the page directory
*/
void change_mm_context(mm_context_t *old, mm_context_t *ctx, pgd_t *pgd)
{
unsigned long _pgd;
_pgd = virt_to_phys(pgd);
/* save the state of the outgoing MMU context */
old->id_busy = 0;
asm volatile("movsg scr0,%0" : "=r"(old->itlb_cached_pge));
asm volatile("movsg dampr4,%0" : "=r"(old->itlb_ptd_mapping));
asm volatile("movsg scr1,%0" : "=r"(old->dtlb_cached_pge));
asm volatile("movsg dampr5,%0" : "=r"(old->dtlb_ptd_mapping));
/* select an MMU context number */
spin_lock(&cxn_owners_lock);
get_cxn(ctx);
ctx->id_busy = 1;
spin_unlock(&cxn_owners_lock);
asm volatile("movgs %0,cxnr" : : "r"(ctx->id));
/* restore the state of the incoming MMU context */
asm volatile("movgs %0,scr0" : : "r"(ctx->itlb_cached_pge));
asm volatile("movgs %0,dampr4" : : "r"(ctx->itlb_ptd_mapping));
asm volatile("movgs %0,scr1" : : "r"(ctx->dtlb_cached_pge));
asm volatile("movgs %0,dampr5" : : "r"(ctx->dtlb_ptd_mapping));
/* map the PGD into uncached virtual memory */
asm volatile("movgs %0,ttbr" : : "r"(_pgd));
asm volatile("movgs %0,dampr3"
:: "r"(_pgd | xAMPRx_L | xAMPRx_M | xAMPRx_SS_16Kb |
xAMPRx_S | xAMPRx_C | xAMPRx_V));
} /* end change_mm_context() */
/*****************************************************************************/
/*
* finished with an MMU context number
*/
void destroy_context(struct mm_struct *mm)
{
mm_context_t *ctx = &mm->context;
spin_lock(&cxn_owners_lock);
if (!list_empty(&ctx->id_link)) {
if (ctx->id == cxn_pinned)
cxn_pinned = -1;
list_del_init(&ctx->id_link);
clear_bit(ctx->id, cxn_bitmap);
__flush_tlb_mm(ctx->id);
ctx->id = 0;
}
spin_unlock(&cxn_owners_lock);
} /* end destroy_context() */
/*****************************************************************************/
/*
* display the MMU context currently a process is currently using
*/
#ifdef CONFIG_PROC_FS
char *proc_pid_status_frv_cxnr(struct mm_struct *mm, char *buffer)
{
spin_lock(&cxn_owners_lock);
buffer += sprintf(buffer, "CXNR: %u\n", mm->context.id);
spin_unlock(&cxn_owners_lock);
return buffer;
} /* end proc_pid_status_frv_cxnr() */
#endif
/*****************************************************************************/
/*
* (un)pin a process's mm_struct's MMU context ID
*/
int cxn_pin_by_pid(pid_t pid)
{
struct task_struct *tsk;
struct mm_struct *mm = NULL;
int ret;
/* unpin if pid is zero */
if (pid == 0) {
cxn_pinned = -1;
return 0;
}
ret = -ESRCH;
/* get a handle on the mm_struct */
read_lock(&tasklist_lock);
tsk = find_task_by_vpid(pid);
if (tsk) {
ret = -EINVAL;
task_lock(tsk);
if (tsk->mm) {
mm = tsk->mm;
mmget(mm);
ret = 0;
}
task_unlock(tsk);
}
read_unlock(&tasklist_lock);
if (ret < 0)
return ret;
/* make sure it has a CXN and pin it */
spin_lock(&cxn_owners_lock);
cxn_pinned = get_cxn(&mm->context);
spin_unlock(&cxn_owners_lock);
mmput(mm);
return 0;
} /* end cxn_pin_by_pid() */
|
