1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) 4 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 5 */ 6 7 #include <stdio.h> 8 #include <stdlib.h> 9 #include <unistd.h> 10 #include <errno.h> 11 #include <signal.h> 12 #include <string.h> 13 #include <sys/resource.h> 14 #include <as-layout.h> 15 #include <init.h> 16 #include <kern_util.h> 17 #include <os.h> 18 #include <um_malloc.h> 19 #include "internal.h" 20 21 #define PGD_BOUND (4 * 1024 * 1024) 22 #define STACKSIZE (8 * 1024 * 1024) 23 #define THREAD_NAME_LEN (256) 24 25 long elf_aux_hwcap; 26 27 static void set_stklim(void) 28 { 29 struct rlimit lim; 30 31 if (getrlimit(RLIMIT_STACK, &lim) < 0) { 32 perror("getrlimit"); 33 exit(1); 34 } 35 if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) { 36 lim.rlim_cur = STACKSIZE; 37 if (setrlimit(RLIMIT_STACK, &lim) < 0) { 38 perror("setrlimit"); 39 exit(1); 40 } 41 } 42 } 43 44 static void last_ditch_exit(int sig) 45 { 46 uml_cleanup(); 47 exit(1); 48 } 49 50 static void install_fatal_handler(int sig) 51 { 52 struct sigaction action; 53 54 /* All signals are enabled in this handler ... */ 55 sigemptyset(&action.sa_mask); 56 57 /* 58 * ... including the signal being handled, plus we want the 59 * handler reset to the default behavior, so that if an exit 60 * handler is hanging for some reason, the UML will just die 61 * after this signal is sent a second time. 62 */ 63 action.sa_flags = SA_RESETHAND | SA_NODEFER; 64 action.sa_restorer = NULL; 65 action.sa_handler = last_ditch_exit; 66 if (sigaction(sig, &action, NULL) < 0) { 67 os_warn("failed to install handler for signal %d " 68 "- errno = %d\n", sig, errno); 69 exit(1); 70 } 71 } 72 73 #define UML_LIB_PATH ":" OS_LIB_PATH "/uml" 74 75 static void setup_env_path(void) 76 { 77 char *new_path = NULL; 78 char *old_path = NULL; 79 int path_len = 0; 80 81 old_path = getenv("PATH"); 82 /* 83 * if no PATH variable is set or it has an empty value 84 * just use the default + /usr/lib/uml 85 */ 86 if (!old_path || (path_len = strlen(old_path)) == 0) { 87 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH)) 88 perror("couldn't putenv"); 89 return; 90 } 91 92 /* append /usr/lib/uml to the existing path */ 93 path_len += strlen("PATH=" UML_LIB_PATH) + 1; 94 new_path = malloc(path_len); 95 if (!new_path) { 96 perror("couldn't malloc to set a new PATH"); 97 return; 98 } 99 snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path); 100 if (putenv(new_path)) { 101 perror("couldn't putenv to set a new PATH"); 102 free(new_path); 103 } 104 } 105 106 int __init main(int argc, char **argv, char **envp) 107 { 108 char **new_argv; 109 int ret, i, err; 110 111 set_stklim(); 112 113 setup_env_path(); 114 115 setsid(); 116 117 new_argv = malloc((argc + 1) * sizeof(char *)); 118 if (new_argv == NULL) { 119 perror("Mallocing argv"); 120 exit(1); 121 } 122 for (i = 0; i < argc; i++) { 123 new_argv[i] = strdup(argv[i]); 124 if (new_argv[i] == NULL) { 125 perror("Mallocing an arg"); 126 exit(1); 127 } 128 } 129 new_argv[argc] = NULL; 130 131 /* 132 * Allow these signals to bring down a UML if all other 133 * methods of control fail. 134 */ 135 install_fatal_handler(SIGINT); 136 install_fatal_handler(SIGTERM); 137 138 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA 139 scan_elf_aux(envp); 140 #endif 141 142 change_sig(SIGPIPE, 0); 143 ret = linux_main(argc, argv); 144 145 /* 146 * Disable SIGPROF - I have no idea why libc doesn't do this or turn 147 * off the profiling time, but UML dies with a SIGPROF just before 148 * exiting when profiling is active. 149 */ 150 change_sig(SIGPROF, 0); 151 152 /* 153 * This signal stuff used to be in the reboot case. However, 154 * sometimes a timer signal can come in when we're halting (reproducably 155 * when writing out gcov information, presumably because that takes 156 * some time) and cause a segfault. 157 */ 158 159 /* stop timers and set timer signal to be ignored */ 160 os_timer_disable(); 161 162 /* disable SIGIO for the fds and set SIGIO to be ignored */ 163 err = deactivate_all_fds(); 164 if (err) 165 os_warn("deactivate_all_fds failed, errno = %d\n", -err); 166 167 /* 168 * Let any pending signals fire now. This ensures 169 * that they won't be delivered after the exec, when 170 * they are definitely not expected. 171 */ 172 unblock_signals(); 173 174 os_info("\n"); 175 /* Reboot */ 176 if (ret) { 177 execvp(new_argv[0], new_argv); 178 perror("Failed to exec kernel"); 179 ret = 1; 180 } 181 return uml_exitcode; 182 } 183 184 extern void *__real_malloc(int); 185 186 /* workaround for -Wmissing-prototypes warnings */ 187 void *__wrap_malloc(int size); 188 void *__wrap_calloc(int n, int size); 189 void __wrap_free(void *ptr); 190 191 void *__wrap_malloc(int size) 192 { 193 void *ret; 194 195 if (!kmalloc_ok) 196 return __real_malloc(size); 197 else if (size <= UM_KERN_PAGE_SIZE) 198 /* finding contiguous pages can be hard*/ 199 ret = uml_kmalloc(size, UM_GFP_KERNEL); 200 else ret = vmalloc(size); 201 202 /* 203 * glibc people insist that if malloc fails, errno should be 204 * set by malloc as well. So we do. 205 */ 206 if (ret == NULL) 207 errno = ENOMEM; 208 209 return ret; 210 } 211 212 void *__wrap_calloc(int n, int size) 213 { 214 void *ptr = __wrap_malloc(n * size); 215 216 if (ptr == NULL) 217 return NULL; 218 memset(ptr, 0, n * size); 219 return ptr; 220 } 221 222 extern void __real_free(void *); 223 224 extern unsigned long high_physmem; 225 226 void __wrap_free(void *ptr) 227 { 228 unsigned long addr = (unsigned long) ptr; 229 230 /* 231 * We need to know how the allocation happened, so it can be correctly 232 * freed. This is done by seeing what region of memory the pointer is 233 * in - 234 * physical memory - kmalloc/kfree 235 * kernel virtual memory - vmalloc/vfree 236 * anywhere else - malloc/free 237 * If kmalloc is not yet possible, then either high_physmem and/or 238 * end_vm are still 0 (as at startup), in which case we call free, or 239 * we have set them, but anyway addr has not been allocated from those 240 * areas. So, in both cases __real_free is called. 241 * 242 * CAN_KMALLOC is checked because it would be bad to free a buffer 243 * with kmalloc/vmalloc after they have been turned off during 244 * shutdown. 245 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so 246 * there is a possibility for memory leaks. 247 */ 248 249 if ((addr >= uml_physmem) && (addr < high_physmem)) { 250 if (kmalloc_ok) 251 kfree(ptr); 252 } 253 else if ((addr >= start_vm) && (addr < end_vm)) { 254 if (kmalloc_ok) 255 vfree(ptr); 256 } 257 else __real_free(ptr); 258 } 259