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
|
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is the Netscape security libraries.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998-2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License Version 2 or later (the
* "GPL"), in which case the provisions of the GPL are applicable
* instead of those above. If you wish to allow use of your
* version of this file only under the terms of the GPL and not to
* allow others to use your version of this file under the MPL,
* indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by
* the GPL. If you do not delete the provisions above, a recipient
* may use your version of this file under either the MPL or the
* GPL.
*/
#include "primpl.h"
/* List of free stack virtual memory chunks */
PRLock *_pr_stackLock;
PRCList _pr_freeStacks = PR_INIT_STATIC_CLIST(&_pr_freeStacks);
PRIntn _pr_numFreeStacks;
PRIntn _pr_maxFreeStacks = 4;
#ifdef DEBUG
/*
** A variable that can be set via the debugger...
*/
PRBool _pr_debugStacks = PR_FALSE;
#endif
/* How much space to leave between the stacks, at each end */
#define REDZONE (2 << _pr_pageShift)
#define _PR_THREAD_STACK_PTR(_qp) \
((PRThreadStack*) ((char*) (_qp) - offsetof(PRThreadStack,links)))
void _PR_InitStacks(void)
{
_pr_stackLock = PR_NewLock();
}
/*
** Allocate a stack for a thread.
*/
PRThreadStack *_PR_NewStack(PRUint32 stackSize)
{
PRCList *qp;
PRThreadStack *ts;
PRThread *thr;
/*
** Trim the list of free stacks. Trim it backwards, tossing out the
** oldest stack found first (this way more recent stacks have a
** chance of being present in the data cache).
*/
PR_Lock(_pr_stackLock);
qp = _pr_freeStacks.prev;
while ((_pr_numFreeStacks > _pr_maxFreeStacks) && (qp != &_pr_freeStacks)) {
ts = _PR_THREAD_STACK_PTR(qp);
thr = _PR_THREAD_STACK_TO_PTR(ts);
qp = qp->prev;
/*
* skip stacks which are still being used
*/
if (thr->no_sched)
continue;
PR_REMOVE_LINK(&ts->links);
/* Give platform OS to clear out the stack for debugging */
_PR_MD_CLEAR_STACK(ts);
_pr_numFreeStacks--;
_PR_DestroySegment(ts->seg);
PR_DELETE(ts);
}
/*
** Find a free thread stack. This searches the list of free'd up
** virtually mapped thread stacks.
*/
qp = _pr_freeStacks.next;
ts = 0;
while (qp != &_pr_freeStacks) {
ts = _PR_THREAD_STACK_PTR(qp);
thr = _PR_THREAD_STACK_TO_PTR(ts);
qp = qp->next;
/*
* skip stacks which are still being used
*/
if ((!(thr->no_sched)) && ((ts->allocSize - 2*REDZONE) >= stackSize)) {
/*
** Found a stack that is not in use and is big enough. Change
** stackSize to fit it.
*/
stackSize = ts->allocSize - 2*REDZONE;
PR_REMOVE_LINK(&ts->links);
_pr_numFreeStacks--;
ts->links.next = 0;
ts->links.prev = 0;
PR_Unlock(_pr_stackLock);
goto done;
}
ts = 0;
}
PR_Unlock(_pr_stackLock);
if (!ts) {
/* Make a new thread stack object. */
ts = PR_NEWZAP(PRThreadStack);
if (!ts) {
return NULL;
}
/*
** Assign some of the virtual space to the new stack object. We
** may not get that piece of VM, but if nothing else we will
** advance the pointer so we don't collide (unless the OS screws
** up).
*/
ts->allocSize = stackSize + 2*REDZONE;
ts->seg = _PR_NewSegment(ts->allocSize, 0);
if (!ts->seg) {
PR_DELETE(ts);
return NULL;
}
}
done:
ts->allocBase = (char*)ts->seg->vaddr;
ts->flags = _PR_STACK_MAPPED;
ts->stackSize = stackSize;
#ifdef HAVE_STACK_GROWING_UP
ts->stackTop = ts->allocBase + REDZONE;
ts->stackBottom = ts->stackTop + stackSize;
#else
ts->stackBottom = ts->allocBase + REDZONE;
ts->stackTop = ts->stackBottom + stackSize;
#endif
PR_LOG(_pr_thread_lm, PR_LOG_NOTICE,
("thread stack: base=0x%x limit=0x%x bottom=0x%x top=0x%x\n",
ts->allocBase, ts->allocBase + ts->allocSize - 1,
ts->allocBase + REDZONE,
ts->allocBase + REDZONE + stackSize - 1));
_PR_MD_INIT_STACK(ts,REDZONE);
return ts;
}
/*
** Free the stack for the current thread
*/
void _PR_FreeStack(PRThreadStack *ts)
{
if (!ts) {
return;
}
if (ts->flags & _PR_STACK_PRIMORDIAL) {
PR_DELETE(ts);
return;
}
/*
** Put the stack on the free list. This is done because we are still
** using the stack. Next time a thread is created we will trim the
** list down; it's safe to do it then because we will have had to
** context switch to a live stack before another thread can be
** created.
*/
PR_Lock(_pr_stackLock);
PR_APPEND_LINK(&ts->links, _pr_freeStacks.prev);
_pr_numFreeStacks++;
PR_Unlock(_pr_stackLock);
}
|
