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Linux/arch/um/os-Linux/main.c

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  1 /*
  2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  3  * Licensed under the GPL
  4  */
  5 
  6 #include <stdio.h>
  7 #include <stdlib.h>
  8 #include <unistd.h>
  9 #include <errno.h>
 10 #include <signal.h>
 11 #include <string.h>
 12 #include <sys/resource.h>
 13 #include <as-layout.h>
 14 #include <init.h>
 15 #include <kern_util.h>
 16 #include <os.h>
 17 #include <um_malloc.h>
 18 
 19 #define PGD_BOUND (4 * 1024 * 1024)
 20 #define STACKSIZE (8 * 1024 * 1024)
 21 #define THREAD_NAME_LEN (256)
 22 
 23 long elf_aux_hwcap;
 24 
 25 static void set_stklim(void)
 26 {
 27         struct rlimit lim;
 28 
 29         if (getrlimit(RLIMIT_STACK, &lim) < 0) {
 30                 perror("getrlimit");
 31                 exit(1);
 32         }
 33         if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
 34                 lim.rlim_cur = STACKSIZE;
 35                 if (setrlimit(RLIMIT_STACK, &lim) < 0) {
 36                         perror("setrlimit");
 37                         exit(1);
 38                 }
 39         }
 40 }
 41 
 42 static __init void do_uml_initcalls(void)
 43 {
 44         initcall_t *call;
 45 
 46         call = &__uml_initcall_start;
 47         while (call < &__uml_initcall_end) {
 48                 (*call)();
 49                 call++;
 50         }
 51 }
 52 
 53 static void last_ditch_exit(int sig)
 54 {
 55         uml_cleanup();
 56         exit(1);
 57 }
 58 
 59 static void install_fatal_handler(int sig)
 60 {
 61         struct sigaction action;
 62 
 63         /* All signals are enabled in this handler ... */
 64         sigemptyset(&action.sa_mask);
 65 
 66         /*
 67          * ... including the signal being handled, plus we want the
 68          * handler reset to the default behavior, so that if an exit
 69          * handler is hanging for some reason, the UML will just die
 70          * after this signal is sent a second time.
 71          */
 72         action.sa_flags = SA_RESETHAND | SA_NODEFER;
 73         action.sa_restorer = NULL;
 74         action.sa_handler = last_ditch_exit;
 75         if (sigaction(sig, &action, NULL) < 0) {
 76                 printf("failed to install handler for signal %d - errno = %d\n",
 77                        sig, errno);
 78                 exit(1);
 79         }
 80 }
 81 
 82 #define UML_LIB_PATH    ":" OS_LIB_PATH "/uml"
 83 
 84 static void setup_env_path(void)
 85 {
 86         char *new_path = NULL;
 87         char *old_path = NULL;
 88         int path_len = 0;
 89 
 90         old_path = getenv("PATH");
 91         /*
 92          * if no PATH variable is set or it has an empty value
 93          * just use the default + /usr/lib/uml
 94          */
 95         if (!old_path || (path_len = strlen(old_path)) == 0) {
 96                 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
 97                         perror("couldn't putenv");
 98                 return;
 99         }
100 
101         /* append /usr/lib/uml to the existing path */
102         path_len += strlen("PATH=" UML_LIB_PATH) + 1;
103         new_path = malloc(path_len);
104         if (!new_path) {
105                 perror("couldn't malloc to set a new PATH");
106                 return;
107         }
108         snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
109         if (putenv(new_path)) {
110                 perror("couldn't putenv to set a new PATH");
111                 free(new_path);
112         }
113 }
114 
115 extern void scan_elf_aux( char **envp);
116 
117 int __init main(int argc, char **argv, char **envp)
118 {
119         char **new_argv;
120         int ret, i, err;
121 
122         set_stklim();
123 
124         setup_env_path();
125 
126         setsid();
127 
128         new_argv = malloc((argc + 1) * sizeof(char *));
129         if (new_argv == NULL) {
130                 perror("Mallocing argv");
131                 exit(1);
132         }
133         for (i = 0; i < argc; i++) {
134                 new_argv[i] = strdup(argv[i]);
135                 if (new_argv[i] == NULL) {
136                         perror("Mallocing an arg");
137                         exit(1);
138                 }
139         }
140         new_argv[argc] = NULL;
141 
142         /*
143          * Allow these signals to bring down a UML if all other
144          * methods of control fail.
145          */
146         install_fatal_handler(SIGINT);
147         install_fatal_handler(SIGTERM);
148 
149 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
150         scan_elf_aux(envp);
151 #endif
152 
153         do_uml_initcalls();
154         change_sig(SIGPIPE, 0);
155         ret = linux_main(argc, argv);
156 
157         /*
158          * Disable SIGPROF - I have no idea why libc doesn't do this or turn
159          * off the profiling time, but UML dies with a SIGPROF just before
160          * exiting when profiling is active.
161          */
162         change_sig(SIGPROF, 0);
163 
164         /*
165          * This signal stuff used to be in the reboot case.  However,
166          * sometimes a SIGVTALRM can come in when we're halting (reproducably
167          * when writing out gcov information, presumably because that takes
168          * some time) and cause a segfault.
169          */
170 
171         /* stop timers and set SIGVTALRM to be ignored */
172         disable_timer();
173 
174         /* disable SIGIO for the fds and set SIGIO to be ignored */
175         err = deactivate_all_fds();
176         if (err)
177                 printf("deactivate_all_fds failed, errno = %d\n", -err);
178 
179         /*
180          * Let any pending signals fire now.  This ensures
181          * that they won't be delivered after the exec, when
182          * they are definitely not expected.
183          */
184         unblock_signals();
185 
186         /* Reboot */
187         if (ret) {
188                 printf("\n");
189                 execvp(new_argv[0], new_argv);
190                 perror("Failed to exec kernel");
191                 ret = 1;
192         }
193         printf("\n");
194         return uml_exitcode;
195 }
196 
197 extern void *__real_malloc(int);
198 
199 void *__wrap_malloc(int size)
200 {
201         void *ret;
202 
203         if (!kmalloc_ok)
204                 return __real_malloc(size);
205         else if (size <= UM_KERN_PAGE_SIZE)
206                 /* finding contiguous pages can be hard*/
207                 ret = uml_kmalloc(size, UM_GFP_KERNEL);
208         else ret = vmalloc(size);
209 
210         /*
211          * glibc people insist that if malloc fails, errno should be
212          * set by malloc as well. So we do.
213          */
214         if (ret == NULL)
215                 errno = ENOMEM;
216 
217         return ret;
218 }
219 
220 void *__wrap_calloc(int n, int size)
221 {
222         void *ptr = __wrap_malloc(n * size);
223 
224         if (ptr == NULL)
225                 return NULL;
226         memset(ptr, 0, n * size);
227         return ptr;
228 }
229 
230 extern void __real_free(void *);
231 
232 extern unsigned long high_physmem;
233 
234 void __wrap_free(void *ptr)
235 {
236         unsigned long addr = (unsigned long) ptr;
237 
238         /*
239          * We need to know how the allocation happened, so it can be correctly
240          * freed.  This is done by seeing what region of memory the pointer is
241          * in -
242          *      physical memory - kmalloc/kfree
243          *      kernel virtual memory - vmalloc/vfree
244          *      anywhere else - malloc/free
245          * If kmalloc is not yet possible, then either high_physmem and/or
246          * end_vm are still 0 (as at startup), in which case we call free, or
247          * we have set them, but anyway addr has not been allocated from those
248          * areas. So, in both cases __real_free is called.
249          *
250          * CAN_KMALLOC is checked because it would be bad to free a buffer
251          * with kmalloc/vmalloc after they have been turned off during
252          * shutdown.
253          * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
254          * there is a possibility for memory leaks.
255          */
256 
257         if ((addr >= uml_physmem) && (addr < high_physmem)) {
258                 if (kmalloc_ok)
259                         kfree(ptr);
260         }
261         else if ((addr >= start_vm) && (addr < end_vm)) {
262                 if (kmalloc_ok)
263                         vfree(ptr);
264         }
265         else __real_free(ptr);
266 }
267 

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