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