main.c revision 77bf4400319db9d2a8af6b00c2be6faa0f3d07cb 
1/*
2 * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
4 */
5
6#include <unistd.h>
7#include <stdio.h>
8#include <stdlib.h>
9#include <string.h>
10#include <signal.h>
11#include <errno.h>
12#include <sys/resource.h>
13#include <sys/mman.h>
14#include <sys/user.h>
15#include "kern_util.h"
16#include "as-layout.h"
17#include "mem_user.h"
18#include "irq_user.h"
19#include "user.h"
20#include "init.h"
21#include "uml-config.h"
22#include "os.h"
23#include "um_malloc.h"
24#include "kern_constants.h"
25
26#define PGD_BOUND (4 * 1024 * 1024)
27#define STACKSIZE (8 * 1024 * 1024)
28#define THREAD_NAME_LEN (256)
29
30static void set_stklim(void)
31{
32	struct rlimit lim;
33
34	if(getrlimit(RLIMIT_STACK, &lim) < 0){
35		perror("getrlimit");
36		exit(1);
37	}
38	if((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)){
39		lim.rlim_cur = STACKSIZE;
40		if(setrlimit(RLIMIT_STACK, &lim) < 0){
41			perror("setrlimit");
42			exit(1);
43		}
44	}
45}
46
47static __init void do_uml_initcalls(void)
48{
49	initcall_t *call;
50
51	call = &__uml_initcall_start;
52	while (call < &__uml_initcall_end){
53		(*call)();
54		call++;
55	}
56}
57
58static void last_ditch_exit(int sig)
59{
60	uml_cleanup();
61	exit(1);
62}
63
64static void install_fatal_handler(int sig)
65{
66	struct sigaction action;
67
68	/* All signals are enabled in this handler ... */
69	sigemptyset(&action.sa_mask);
70
71	/* ... including the signal being handled, plus we want the
72	 * handler reset to the default behavior, so that if an exit
73	 * handler is hanging for some reason, the UML will just die
74	 * after this signal is sent a second time.
75	 */
76	action.sa_flags = SA_RESETHAND | SA_NODEFER;
77	action.sa_restorer = NULL;
78	action.sa_handler = last_ditch_exit;
79	if(sigaction(sig, &action, NULL) < 0){
80		printf("failed to install handler for signal %d - errno = %d\n",
81		       errno);
82		exit(1);
83	}
84}
85
86#define UML_LIB_PATH	":/usr/lib/uml"
87
88static void setup_env_path(void)
89{
90	char *new_path = NULL;
91	char *old_path = NULL;
92	int path_len = 0;
93
94	old_path = getenv("PATH");
95	/* if no PATH variable is set or it has an empty value
96	 * just use the default + /usr/lib/uml
97	 */
98	if (!old_path || (path_len = strlen(old_path)) == 0) {
99		putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH);
100		return;
101	}
102
103	/* append /usr/lib/uml to the existing path */
104	path_len += strlen("PATH=" UML_LIB_PATH) + 1;
105	new_path = malloc(path_len);
106	if (!new_path) {
107		perror("coudn't malloc to set a new PATH");
108		return;
109	}
110	snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
111	putenv(new_path);
112}
113
114extern int uml_exitcode;
115
116extern void scan_elf_aux( char **envp);
117
118int __init main(int argc, char **argv, char **envp)
119{
120	char **new_argv;
121	int ret, i, err;
122
123	set_stklim();
124
125	setup_env_path();
126
127	new_argv = malloc((argc + 1) * sizeof(char *));
128	if(new_argv == NULL){
129		perror("Mallocing argv");
130		exit(1);
131	}
132	for(i=0;i<argc;i++){
133		new_argv[i] = strdup(argv[i]);
134		if(new_argv[i] == NULL){
135			perror("Mallocing an arg");
136			exit(1);
137		}
138	}
139	new_argv[argc] = NULL;
140
141	/* Allow these signals to bring down a UML if all other
142	 * methods of control fail.
143	 */
144	install_fatal_handler(SIGINT);
145	install_fatal_handler(SIGTERM);
146	install_fatal_handler(SIGHUP);
147
148	scan_elf_aux( envp);
149
150	do_uml_initcalls();
151	ret = linux_main(argc, argv);
152
153	/* Disable SIGPROF - I have no idea why libc doesn't do this or turn
154	 * off the profiling time, but UML dies with a SIGPROF just before
155	 * exiting when profiling is active.
156	 */
157	change_sig(SIGPROF, 0);
158
159	/* This signal stuff used to be in the reboot case.  However,
160	 * sometimes a SIGVTALRM can come in when we're halting (reproducably
161	 * when writing out gcov information, presumably because that takes
162	 * some time) and cause a segfault.
163	 */
164
165	/* stop timers and set SIG*ALRM to be ignored */
166	disable_timer();
167
168	/* disable SIGIO for the fds and set SIGIO to be ignored */
169	err = deactivate_all_fds();
170	if(err)
171		printf("deactivate_all_fds failed, errno = %d\n", -err);
172
173	/* Let any pending signals fire now.  This ensures
174	 * that they won't be delivered after the exec, when
175	 * they are definitely not expected.
176	 */
177	unblock_signals();
178
179	/* Reboot */
180	if(ret){
181		printf("\n");
182		execvp(new_argv[0], new_argv);
183		perror("Failed to exec kernel");
184		ret = 1;
185	}
186	printf("\n");
187	return uml_exitcode;
188}
189
190extern void *__real_malloc(int);
191
192void *__wrap_malloc(int size)
193{
194	void *ret;
195
196	if(!kmalloc_ok)
197		return __real_malloc(size);
198	else if(size <= UM_KERN_PAGE_SIZE)
199		/* finding contiguous pages can be hard*/
200		ret = kmalloc(size, UM_GFP_KERNEL);
201	else ret = vmalloc(size);
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
212void *__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
222extern void __real_free(void *);
223
224extern unsigned long high_physmem;
225
226void __wrap_free(void *ptr)
227{
228	unsigned long addr = (unsigned long) ptr;
229
230	/* We need to know how the allocation happened, so it can be correctly
231	 * freed.  This is done by seeing what region of memory the pointer is
232	 * in -
233	 * 	physical memory - kmalloc/kfree
234	 *	kernel virtual memory - vmalloc/vfree
235	 * 	anywhere else - malloc/free
236	 * If kmalloc is not yet possible, then either high_physmem and/or
237	 * end_vm are still 0 (as at startup), in which case we call free, or
238	 * we have set them, but anyway addr has not been allocated from those
239	 * areas. So, in both cases __real_free is called.
240	 *
241	 * CAN_KMALLOC is checked because it would be bad to free a buffer
242	 * with kmalloc/vmalloc after they have been turned off during
243	 * shutdown.
244	 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
245	 * there is a possibility for memory leaks.
246	 */
247
248	if((addr >= uml_physmem) && (addr < high_physmem)){
249		if(kmalloc_ok)
250			kfree(ptr);
251	}
252	else if((addr >= start_vm) && (addr < end_vm)){
253		if(kmalloc_ok)
254			vfree(ptr);
255	}
256	else __real_free(ptr);
257}
258