1 // -*- C++ -*- Allocate exception objects.
2 // Copyright (C) 2001-2014 Free Software Foundation, Inc.
3 //
4 // This file is part of GCC.
5 //
6 // GCC is free software; you can redistribute it and/or modify
7 // it under the terms of the GNU General Public License as published by
8 // the Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 //
11 // GCC is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 //
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 // This is derived from the C++ ABI for IA-64. Where we diverge
26 // for cross-architecture compatibility are noted with "@@@".
27
28 #include <bits/c++config.h>
29 #include <cstdlib>
30 #if _GLIBCXX_HOSTED
31 #include <cstring>
32 #endif
33 #include <climits>
34 #include <exception>
35 #include "unwind-cxx.h"
36 #include <ext/concurrence.h>
37
38 #if _GLIBCXX_HOSTED
39 using std::free;
40 using std::malloc;
41 using std::memset;
42 #else
43 // In a freestanding environment, these functions may not be available
44 // -- but for now, we assume that they are.
45 extern "C" void *malloc (std::size_t);
46 extern "C" void free(void *);
47 extern "C" void *memset (void *, int, std::size_t);
48 #endif
49
50 using namespace __cxxabiv1;
51
52 // ??? How to control these parameters.
53
54 // Guess from the size of basic types how large a buffer is reasonable.
55 // Note that the basic c++ exception header has 13 pointers and 2 ints,
56 // so on a system with PSImode pointers we're talking about 56 bytes
57 // just for overhead.
58
59 #if INT_MAX == 32767
60 # define EMERGENCY_OBJ_SIZE 128
61 # define EMERGENCY_OBJ_COUNT 16
62 #elif !defined (_GLIBCXX_LLP64) && LONG_MAX == 2147483647
63 # define EMERGENCY_OBJ_SIZE 512
64 # define EMERGENCY_OBJ_COUNT 32
65 #else
66 # define EMERGENCY_OBJ_SIZE 1024
67 # define EMERGENCY_OBJ_COUNT 64
68 #endif
69
70 #ifndef __GTHREADS
71 # undef EMERGENCY_OBJ_COUNT
72 # define EMERGENCY_OBJ_COUNT 4
73 #endif
74
75 #if INT_MAX == 32767 || EMERGENCY_OBJ_COUNT <= 32
76 typedef unsigned int bitmask_type;
77 #else
78 #if defined (_GLIBCXX_LLP64)
79 typedef unsigned long long bitmask_type;
80 #else
81 typedef unsigned long bitmask_type;
82 #endif
83 #endif
84
85
86 typedef char one_buffer[EMERGENCY_OBJ_SIZE] __attribute__((aligned));
87 static one_buffer emergency_buffer[EMERGENCY_OBJ_COUNT];
88 static bitmask_type emergency_used;
89
90 static __cxa_dependent_exception dependents_buffer[EMERGENCY_OBJ_COUNT];
91 static bitmask_type dependents_used;
92
93 namespace
94 {
95 // A single mutex controlling emergency allocations.
96 __gnu_cxx::__mutex emergency_mutex;
97 }
98
99 extern "C" void *
__cxa_allocate_exception(std::size_t thrown_size)100 __cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) _GLIBCXX_NOTHROW
101 {
102 void *ret;
103
104 thrown_size += sizeof (__cxa_refcounted_exception);
105 ret = malloc (thrown_size);
106
107 if (! ret)
108 {
109 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
110
111 bitmask_type used = emergency_used;
112 unsigned int which = 0;
113
114 if (thrown_size > EMERGENCY_OBJ_SIZE)
115 goto failed;
116 while (used & 1)
117 {
118 used >>= 1;
119 if (++which >= EMERGENCY_OBJ_COUNT)
120 goto failed;
121 }
122
123 emergency_used |= (bitmask_type)1 << which;
124 ret = &emergency_buffer[which][0];
125
126 failed:;
127
128 if (!ret)
129 std::terminate ();
130 }
131
132 memset (ret, 0, sizeof (__cxa_refcounted_exception));
133
134 return (void *)((char *)ret + sizeof (__cxa_refcounted_exception));
135 }
136
137
138 extern "C" void
__cxa_free_exception(void * vptr)139 __cxxabiv1::__cxa_free_exception(void *vptr) _GLIBCXX_NOTHROW
140 {
141 char *base = (char *) emergency_buffer;
142 char *ptr = (char *) vptr;
143 if (ptr >= base
144 && ptr < base + sizeof (emergency_buffer))
145 {
146 const unsigned int which
147 = (unsigned) (ptr - base) / EMERGENCY_OBJ_SIZE;
148
149 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
150 emergency_used &= ~((bitmask_type)1 << which);
151 }
152 else
153 free (ptr - sizeof (__cxa_refcounted_exception));
154 }
155
156
157 extern "C" __cxa_dependent_exception*
__cxa_allocate_dependent_exception()158 __cxxabiv1::__cxa_allocate_dependent_exception() _GLIBCXX_NOTHROW
159 {
160 __cxa_dependent_exception *ret;
161
162 ret = static_cast<__cxa_dependent_exception*>
163 (malloc (sizeof (__cxa_dependent_exception)));
164
165 if (!ret)
166 {
167 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
168
169 bitmask_type used = dependents_used;
170 unsigned int which = 0;
171
172 while (used & 1)
173 {
174 used >>= 1;
175 if (++which >= EMERGENCY_OBJ_COUNT)
176 goto failed;
177 }
178
179 dependents_used |= (bitmask_type)1 << which;
180 ret = &dependents_buffer[which];
181
182 failed:;
183
184 if (!ret)
185 std::terminate ();
186 }
187
188 memset (ret, 0, sizeof (__cxa_dependent_exception));
189
190 return ret;
191 }
192
193
194 extern "C" void
__cxa_free_dependent_exception(__cxa_dependent_exception * vptr)195 __cxxabiv1::__cxa_free_dependent_exception
196 (__cxa_dependent_exception *vptr) _GLIBCXX_NOTHROW
197 {
198 char *base = (char *) dependents_buffer;
199 char *ptr = (char *) vptr;
200 if (ptr >= base
201 && ptr < base + sizeof (dependents_buffer))
202 {
203 const unsigned int which
204 = (unsigned) (ptr - base) / sizeof (__cxa_dependent_exception);
205
206 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
207 dependents_used &= ~((bitmask_type)1 << which);
208 }
209 else
210 free (vptr);
211 }
212