2 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
16 #include <linux/magic.h>
20 /* Set by make_tempfile() during early boot. */
21 static char *tempdir = NULL;
23 /* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
24 static int __init check_tmpfs(const char *dir)
28 printf("Checking if %s is on tmpfs...", dir);
29 if (statfs(dir, &st) < 0) {
30 printf("%s\n", strerror(errno));
31 } else if (st.f_type != TMPFS_MAGIC) {
41 * Choose the tempdir to use. We want something on tmpfs so that our memory is
42 * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
43 * environment, we use that even if it's not on tmpfs, but we warn the user.
44 * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
45 * then we fall back to /tmp.
47 static char * __init choose_tempdir(void)
49 static const char * const vars[] = {
55 static const char fallback_dir[] = "/tmp";
56 static const char * const tmpfs_dirs[] = {
64 printf("Checking environment variables for a tempdir...");
65 for (i = 0; vars[i]; i++) {
66 dir = getenv(vars[i]);
67 if ((dir != NULL) && (*dir != '\0')) {
69 if (check_tmpfs(dir) >= 0)
75 printf("none found\n");
77 for (i = 0; tmpfs_dirs[i]; i++) {
79 if (check_tmpfs(dir) >= 0)
85 printf("Warning: tempdir %s is not on tmpfs\n", dir);
87 /* Make a copy since getenv results may not remain valid forever. */
92 * Create an unlinked tempfile in a suitable tempdir. template must be the
93 * basename part of the template with a leading '/'.
95 static int __init make_tempfile(const char *template)
100 if (tempdir == NULL) {
101 tempdir = choose_tempdir();
102 if (tempdir == NULL) {
103 fprintf(stderr, "Failed to choose tempdir: %s\n",
109 tempname = malloc(strlen(tempdir) + strlen(template) + 1);
110 if (tempname == NULL)
113 strcpy(tempname, tempdir);
114 strcat(tempname, template);
115 fd = mkstemp(tempname);
117 fprintf(stderr, "open - cannot create %s: %s\n", tempname,
121 if (unlink(tempname) < 0) {
134 #define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
136 static int __init create_tmp_file(unsigned long long len)
141 fd = make_tempfile(TEMPNAME_TEMPLATE);
145 err = fchmod(fd, 0777);
152 * Seek to len - 1 because writing a character there will
153 * increase the file size by one byte, to the desired length.
155 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
162 err = write(fd, &zero, 1);
171 int __init create_mem_file(unsigned long long len)
175 fd = create_tmp_file(len);
177 err = os_set_exec_close(fd);
180 perror("exec_close");
185 void __init check_tmpexec(void)
188 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
190 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
191 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
192 printf("Checking PROT_EXEC mmap in %s...", tempdir);
193 if (addr == MAP_FAILED) {
195 printf("%s\n", strerror(err));
198 printf("%s must be not mounted noexec\n", tempdir);
202 munmap(addr, UM_KERN_PAGE_SIZE);