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
209
210
211
212
213
214
215
216
217
218
|
/* Fault-safe copy into or out of pager-backed memory.
Copyright (C) 1996,97,99, 2000,01,02 Free Software Foundation, Inc.
Written by Roland McGrath.
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, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "priv.h"
#include "pager.h"
#include <sys/mman.h>
#include <hurd/sigpreempt.h>
#include <assert.h>
#include <string.h>
/* Start using vm_copy over memcpy when we have that many page. This is
roughly the L1 cache size. (This value *cannot* be less than
vm_page_size.) */
#define VMCOPY_BETTER_THAN_MEMCPY (8*vm_page_size)
/* Try to copy *SIZE bytes between the region OTHER points to
and the region at OFFSET in the pager indicated by PAGER and MEMOBJ.
If PROT is VM_PROT_READ, copying is from the pager to OTHER;
if PROT contains VM_PROT_WRITE, copying is from OTHER into the pager.
*SIZE is always filled in the actual number of bytes successfully copied.
Returns an error code if the pager-backed memory faults;
if there is no fault, returns 0 and *SIZE will be unchanged. */
error_t
pager_memcpy (struct pager *pager, memory_object_t memobj,
vm_offset_t offset, void *other, size_t *size,
vm_prot_t prot)
{
error_t err;
size_t n = *size;
#define VMCOPY_WINDOW_DEFAULT_SIZE (32 * vm_page_size)
#define MEMCPY_WINDOW_DEFAULT_SIZE (32 * vm_page_size)
vm_address_t window;
vm_size_t window_size;
error_t do_vm_copy (void)
{
assert ((offset & (vm_page_size - 1)) == 0);
assert (((vm_address_t) other & (vm_page_size - 1)) == 0);
assert (n >= vm_page_size);
do
{
window_size =
VMCOPY_WINDOW_DEFAULT_SIZE > n
? (n - (n & (vm_page_size - 1)))
: VMCOPY_WINDOW_DEFAULT_SIZE;
assert (window_size >= VMCOPY_BETTER_THAN_MEMCPY);
assert ((window_size & (vm_page_size - 1)) == 0);
err = vm_map (mach_task_self (), &window, window_size, 0, 1,
memobj, offset, 0, prot, prot, VM_INHERIT_NONE);
if (err)
return err;
if (prot == VM_PROT_READ)
err = vm_copy (mach_task_self (), window, window_size,
(vm_address_t) other);
else
err = vm_copy (mach_task_self (), (vm_address_t) other,
window_size, window);
vm_deallocate (mach_task_self (), window, window_size);
if (err)
return err;
other += window_size;
offset += window_size;
n -= window_size;
}
while (n >= VMCOPY_BETTER_THAN_MEMCPY);
return 0;
}
error_t do_copy (struct hurd_signal_preemptor *preemptor)
{
error_t do_memcpy (size_t to_copy)
{
window_size = MEMCPY_WINDOW_DEFAULT_SIZE;
do
{
size_t pageoff = offset & (vm_page_size - 1);
size_t copy_count = window_size - pageoff;
/* Map in and copy a standard-sized window, unless that is
more than the total left to be copied. */
if (window_size >= round_page (pageoff + to_copy))
{
copy_count = to_copy;
window_size = round_page (pageoff + to_copy);
}
err = vm_map (mach_task_self (), &window, window_size, 0, 1,
memobj, offset - pageoff, 0,
prot, prot, VM_INHERIT_NONE);
if (err)
return err;
/* Realign the fault preemptor for the new mapping window. */
preemptor->first = window;
preemptor->last = window + window_size;
if (prot == VM_PROT_READ)
memcpy (other, (const void *) window + pageoff, copy_count);
else
memcpy ((void *) window + pageoff, other, copy_count);
vm_deallocate (mach_task_self (), window, window_size);
offset += copy_count;
other += copy_count;
to_copy -= copy_count;
n -= copy_count;
assert (n >= 0);
assert (to_copy >= 0);
}
while (to_copy > 0);
return 0;
}
/* Can we use vm_copy? */
if ((((vm_address_t) other & (vm_page_size - 1))
== (offset & (vm_page_size - 1)))
&& (n >= (VMCOPY_BETTER_THAN_MEMCPY + vm_page_size
- ((vm_address_t) other & (vm_page_size - 1)))))
/* 1) other and offset are aligned with repect to each other;
and 2) we have at least VMCOPY_BETTER_THAN_MEMCPY fully
aligned pages. */
{
err = do_memcpy (vm_page_size
- ((vm_address_t) other & (vm_page_size - 1)));
if (err)
return err;
assert (n >= VMCOPY_BETTER_THAN_MEMCPY);
err = do_vm_copy ();
if (err || n == 0)
/* We failed or we finished. */
return err;
assert (n < VMCOPY_BETTER_THAN_MEMCPY);
}
return do_memcpy (n);
}
jmp_buf buf;
void fault (int signo, long int sigcode, struct sigcontext *scp)
{
assert (scp->sc_error == EKERN_MEMORY_ERROR);
err = pager_get_error (pager, sigcode - window + offset);
n -= sigcode - window;
vm_deallocate (mach_task_self (), window, window_size);
longjmp (buf, 1);
}
if (n == 0)
/* Nothing to do. */
return 0;
if (((vm_address_t) other & (vm_page_size - 1)) == 0
&& (offset & (vm_page_size - 1)) == 0
&& n >= VMCOPY_BETTER_THAN_MEMCPY)
/* 1) the start address is page aligned; 2) the offset is page
aligned; and 3) we have more than VMCOPY_BETTER_THAN_MEMCPY
pages. */
{
err = do_vm_copy ();
if (err || n == 0)
/* We failed or we finished. */
{
*size -= n;
return err;
}
assert (n < VMCOPY_BETTER_THAN_MEMCPY);
}
/* Need to do it the hard way. */
window = 0;
window_size = 0;
if (setjmp (buf) == 0)
hurd_catch_signal (sigmask (SIGSEGV) | sigmask (SIGBUS),
window, window + window_size,
&do_copy, (sighandler_t) &fault);
if (! err)
assert (n == 0);
*size -= n;
return err;
}
|
