1 /* Memory allocation aligned to system page boundaries.
3 Copyright (C) 2005 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public
16 License along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
20 /* Written by Derek R. Price <derek@ximbiot.com>. */
26 #include "pagealign_alloc.h"
40 # include <sys/mman.h>
45 #include "getpagesize.h"
49 #define _(str) gettext (str)
52 #if HAVE_MMAP || ! HAVE_POSIX_MEMALIGN
55 /* For each memory region, we store its size. */
56 typedef size_t info_t;
58 /* For each memory region, we store the original pointer returned by
60 typedef void * info_t;
63 /* A simple linked list of allocated memory regions. It is probably not the
64 most efficient way to store these, but anyway... */
65 typedef struct memnode_s memnode_t;
73 /* The list of currently allocated memory regions. */
74 static memnode_t *memnode_table = NULL;
78 new_memnode (void *aligned_ptr, info_t info)
80 memnode_t *new_node = (memnode_t *) xmalloc (sizeof (memnode_t));
81 new_node->aligned_ptr = aligned_ptr;
82 new_node->info = info;
83 new_node->next = memnode_table;
84 memnode_table = new_node;
88 /* Dispose of the memnode containing a map for the ALIGNED_PTR in question
89 and return the content of the node's INFO field. */
91 get_memnode (void *aligned_ptr)
95 memnode_t **p_next = &memnode_table;
97 for (c = *p_next; c != NULL; p_next = &c->next, c = c->next)
98 if (c->aligned_ptr == aligned_ptr)
102 /* An attempt to free untracked memory. A wrong pointer was passed
103 to pagealign_free(). */
106 /* Remove this entry from the list, save the return value, and free it. */
114 #endif /* HAVE_MMAP || !HAVE_POSIX_MEMALIGN */
118 pagealign_alloc (size_t size)
122 # ifdef HAVE_MAP_ANONYMOUS
124 const int flags = MAP_ANONYMOUS | MAP_PRIVATE;
125 # else /* !HAVE_MAP_ANONYMOUS */
126 static int fd = -1; /* Only open /dev/zero once in order to avoid limiting
127 the amount of memory we may allocate based on the
128 number of open file descriptors. */
129 const int flags = MAP_FILE | MAP_PRIVATE;
132 fd = open ("/dev/zero", O_RDONLY, 0666);
134 error (EXIT_FAILURE, errno, _("Failed to open /dev/zero for read"));
136 # endif /* HAVE_MAP_ANONYMOUS */
137 ret = mmap (NULL, size, PROT_READ | PROT_WRITE, flags, fd, 0);
138 if (ret == MAP_FAILED)
140 new_memnode (ret, size);
141 #elif HAVE_POSIX_MEMALIGN
142 int status = posix_memalign (&ret, getpagesize (), size);
148 #else /* !HAVE_MMAP && !HAVE_POSIX_MEMALIGN */
149 size_t pagesize = getpagesize ();
150 void *unaligned_ptr = malloc (size + pagesize - 1);
151 if (unaligned_ptr == NULL)
153 ret = (char *) unaligned_ptr
154 + ((- (unsigned long) unaligned_ptr) & (pagesize - 1));
155 new_memnode (ret, unaligned_ptr);
156 #endif /* HAVE_MMAP && HAVE_POSIX_MEMALIGN */
162 pagealign_xalloc (size_t size)
166 ret = pagealign_alloc (size);
174 pagealign_free (void *aligned_ptr)
177 if (munmap (aligned_ptr, get_memnode (aligned_ptr)) < 0)
178 error (EXIT_FAILURE, errno, "Failed to unmap memory");
179 #elif HAVE_POSIX_MEMALIGN
182 free (get_memnode (aligned_ptr));