1 /* Memory handling for libdw.
2 Copyright (C) 2003, 2004, 2006 Red Hat, Inc.
3 This file is part of elfutils.
4 Written by Ulrich Drepper <drepper@redhat.com>, 2003.
5
6 This file is free software; you can redistribute it and/or modify
7 it under the terms of either
8
9 * the GNU Lesser General Public License as published by the Free
10 Software Foundation; either version 3 of the License, or (at
11 your option) any later version
12
13 or
14
15 * the GNU General Public License as published by the Free
16 Software Foundation; either version 2 of the License, or (at
17 your option) any later version
18
19 or both in parallel, as here.
20
21 elfutils is distributed in the hope that it will be useful, but
22 WITHOUT ANY WARRANTY; without even the implied warranty of
23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
24 General Public License for more details.
25
26 You should have received copies of the GNU General Public License and
27 the GNU Lesser General Public License along with this program. If
28 not, see <http://www.gnu.org/licenses/>. */
29
30 #ifdef HAVE_CONFIG_H
31 # include <config.h>
32 #endif
33
34 #include <errno.h>
35 #include <stdlib.h>
36 #include "libdwP.h"
37 #include "system.h"
38 #include "atomics.h"
39 #if USE_VG_ANNOTATIONS == 1
40 #include <helgrind.h>
41 #else
42 #define ANNOTATE_HAPPENS_BEFORE(X)
43 #define ANNOTATE_HAPPENS_AFTER(X)
44 #endif
45
46 #define THREAD_ID_UNSET ((size_t) -1)
47 static __thread size_t thread_id = THREAD_ID_UNSET;
48 static atomic_size_t next_id = ATOMIC_VAR_INIT(0);
49
50 struct libdw_memblock *
__libdw_alloc_tail(Dwarf * dbg)51 __libdw_alloc_tail (Dwarf *dbg)
52 {
53 if (thread_id == THREAD_ID_UNSET)
54 thread_id = atomic_fetch_add (&next_id, 1);
55
56 pthread_rwlock_rdlock (&dbg->mem_rwl);
57 if (thread_id >= dbg->mem_stacks)
58 {
59 pthread_rwlock_unlock (&dbg->mem_rwl);
60 pthread_rwlock_wrlock (&dbg->mem_rwl);
61
62 /* Another thread may have already reallocated. In theory using an
63 atomic would be faster, but given that this only happens once per
64 thread per Dwarf, some minor slowdown should be fine. */
65 if (thread_id >= dbg->mem_stacks)
66 {
67 dbg->mem_tails = realloc (dbg->mem_tails, (thread_id+1)
68 * sizeof (struct libdw_memblock *));
69 if (dbg->mem_tails == NULL)
70 {
71 pthread_rwlock_unlock (&dbg->mem_rwl);
72 dbg->oom_handler();
73 }
74 for (size_t i = dbg->mem_stacks; i <= thread_id; i++)
75 dbg->mem_tails[i] = NULL;
76 dbg->mem_stacks = thread_id + 1;
77 ANNOTATE_HAPPENS_BEFORE (&dbg->mem_tails);
78 }
79
80 pthread_rwlock_unlock (&dbg->mem_rwl);
81 pthread_rwlock_rdlock (&dbg->mem_rwl);
82 }
83
84 /* At this point, we have an entry in the tail array. */
85 ANNOTATE_HAPPENS_AFTER (&dbg->mem_tails);
86 struct libdw_memblock *result = dbg->mem_tails[thread_id];
87 if (result == NULL)
88 {
89 result = malloc (dbg->mem_default_size);
90 result->size = dbg->mem_default_size
91 - offsetof (struct libdw_memblock, mem);
92 result->remaining = result->size;
93 result->prev = NULL;
94 dbg->mem_tails[thread_id] = result;
95 }
96 pthread_rwlock_unlock (&dbg->mem_rwl);
97 return result;
98 }
99
100 /* Can only be called after a allocation for this thread has already
101 been done, to possibly undo it. */
102 struct libdw_memblock *
__libdw_thread_tail(Dwarf * dbg)103 __libdw_thread_tail (Dwarf *dbg)
104 {
105 struct libdw_memblock *result;
106 pthread_rwlock_rdlock (&dbg->mem_rwl);
107 result = dbg->mem_tails[thread_id];
108 pthread_rwlock_unlock (&dbg->mem_rwl);
109 return result;
110 }
111
112 void *
__libdw_allocate(Dwarf * dbg,size_t minsize,size_t align)113 __libdw_allocate (Dwarf *dbg, size_t minsize, size_t align)
114 {
115 size_t size = MAX (dbg->mem_default_size,
116 (align - 1 +
117 2 * minsize + offsetof (struct libdw_memblock, mem)));
118 struct libdw_memblock *newp = malloc (size);
119 if (newp == NULL)
120 dbg->oom_handler ();
121
122 uintptr_t result = ((uintptr_t) newp->mem + align - 1) & ~(align - 1);
123
124 newp->size = size - offsetof (struct libdw_memblock, mem);
125 newp->remaining = (uintptr_t) newp + size - (result + minsize);
126
127 pthread_rwlock_rdlock (&dbg->mem_rwl);
128 newp->prev = dbg->mem_tails[thread_id];
129 dbg->mem_tails[thread_id] = newp;
130 pthread_rwlock_unlock (&dbg->mem_rwl);
131
132 return (void *) result;
133 }
134
135
136 Dwarf_OOM
dwarf_new_oom_handler(Dwarf * dbg,Dwarf_OOM handler)137 dwarf_new_oom_handler (Dwarf *dbg, Dwarf_OOM handler)
138 {
139 Dwarf_OOM old = dbg->oom_handler;
140 dbg->oom_handler = handler;
141 return old;
142 }
143
144
145 void
146 __attribute ((noreturn)) attribute_hidden
__libdw_oom(void)147 __libdw_oom (void)
148 {
149 while (1)
150 error (EXIT_FAILURE, ENOMEM, "libdw");
151 }
152