1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
4  * Copyright (C) 2002 - 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 <fcntl.h>
13 #include <sys/mman.h>
14 #include <sys/ptrace.h>
15 #include <sys/wait.h>
16 #include <asm/unistd.h>
17 #include <init.h>
18 #include <longjmp.h>
19 #include <os.h>
20 
21 #define ARBITRARY_ADDR -1
22 #define FAILURE_PID    -1
23 
24 #define STAT_PATH_LEN sizeof("/proc/#######/stat\0")
25 #define COMM_SCANF "%*[^)])"
26 
os_process_pc(int pid)27 unsigned long os_process_pc(int pid)
28 {
29 	char proc_stat[STAT_PATH_LEN], buf[256];
30 	unsigned long pc = ARBITRARY_ADDR;
31 	int fd, err;
32 
33 	sprintf(proc_stat, "/proc/%d/stat", pid);
34 	fd = open(proc_stat, O_RDONLY, 0);
35 	if (fd < 0) {
36 		printk(UM_KERN_ERR "os_process_pc - couldn't open '%s', "
37 		       "errno = %d\n", proc_stat, errno);
38 		goto out;
39 	}
40 	CATCH_EINTR(err = read(fd, buf, sizeof(buf)));
41 	if (err < 0) {
42 		printk(UM_KERN_ERR "os_process_pc - couldn't read '%s', "
43 		       "err = %d\n", proc_stat, errno);
44 		goto out_close;
45 	}
46 	os_close_file(fd);
47 	pc = ARBITRARY_ADDR;
48 	if (sscanf(buf, "%*d " COMM_SCANF " %*c %*d %*d %*d %*d %*d %*d %*d "
49 		   "%*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d "
50 		   "%*d %*d %*d %*d %*d %lu", &pc) != 1)
51 		printk(UM_KERN_ERR "os_process_pc - couldn't find pc in '%s'\n",
52 		       buf);
53  out_close:
54 	close(fd);
55  out:
56 	return pc;
57 }
58 
os_process_parent(int pid)59 int os_process_parent(int pid)
60 {
61 	char stat[STAT_PATH_LEN];
62 	char data[256];
63 	int parent = FAILURE_PID, n, fd;
64 
65 	if (pid == -1)
66 		return parent;
67 
68 	snprintf(stat, sizeof(stat), "/proc/%d/stat", pid);
69 	fd = open(stat, O_RDONLY, 0);
70 	if (fd < 0) {
71 		printk(UM_KERN_ERR "Couldn't open '%s', errno = %d\n", stat,
72 		       errno);
73 		return parent;
74 	}
75 
76 	CATCH_EINTR(n = read(fd, data, sizeof(data)));
77 	close(fd);
78 
79 	if (n < 0) {
80 		printk(UM_KERN_ERR "Couldn't read '%s', errno = %d\n", stat,
81 		       errno);
82 		return parent;
83 	}
84 
85 	parent = FAILURE_PID;
86 	n = sscanf(data, "%*d " COMM_SCANF " %*c %d", &parent);
87 	if (n != 1)
88 		printk(UM_KERN_ERR "Failed to scan '%s'\n", data);
89 
90 	return parent;
91 }
92 
os_alarm_process(int pid)93 void os_alarm_process(int pid)
94 {
95 	kill(pid, SIGALRM);
96 }
97 
os_stop_process(int pid)98 void os_stop_process(int pid)
99 {
100 	kill(pid, SIGSTOP);
101 }
102 
os_kill_process(int pid,int reap_child)103 void os_kill_process(int pid, int reap_child)
104 {
105 	kill(pid, SIGKILL);
106 	if (reap_child)
107 		CATCH_EINTR(waitpid(pid, NULL, __WALL));
108 }
109 
110 /* Kill off a ptraced child by all means available.  kill it normally first,
111  * then PTRACE_KILL it, then PTRACE_CONT it in case it's in a run state from
112  * which it can't exit directly.
113  */
114 
os_kill_ptraced_process(int pid,int reap_child)115 void os_kill_ptraced_process(int pid, int reap_child)
116 {
117 	kill(pid, SIGKILL);
118 	ptrace(PTRACE_KILL, pid);
119 	ptrace(PTRACE_CONT, pid);
120 	if (reap_child)
121 		CATCH_EINTR(waitpid(pid, NULL, __WALL));
122 }
123 
124 /* Don't use the glibc version, which caches the result in TLS. It misses some
125  * syscalls, and also breaks with clone(), which does not unshare the TLS.
126  */
127 
os_getpid(void)128 int os_getpid(void)
129 {
130 	return syscall(__NR_getpid);
131 }
132 
os_getpgrp(void)133 int os_getpgrp(void)
134 {
135 	return getpgrp();
136 }
137 
os_map_memory(void * virt,int fd,unsigned long long off,unsigned long len,int r,int w,int x)138 int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
139 		  int r, int w, int x)
140 {
141 	void *loc;
142 	int prot;
143 
144 	prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
145 		(x ? PROT_EXEC : 0);
146 
147 	loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED,
148 		     fd, off);
149 	if (loc == MAP_FAILED)
150 		return -errno;
151 	return 0;
152 }
153 
os_protect_memory(void * addr,unsigned long len,int r,int w,int x)154 int os_protect_memory(void *addr, unsigned long len, int r, int w, int x)
155 {
156 	int prot = ((r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
157 		    (x ? PROT_EXEC : 0));
158 
159 	if (mprotect(addr, len, prot) < 0)
160 		return -errno;
161 
162 	return 0;
163 }
164 
os_unmap_memory(void * addr,int len)165 int os_unmap_memory(void *addr, int len)
166 {
167 	int err;
168 
169 	err = munmap(addr, len);
170 	if (err < 0)
171 		return -errno;
172 	return 0;
173 }
174 
175 #ifndef MADV_REMOVE
176 #define MADV_REMOVE KERNEL_MADV_REMOVE
177 #endif
178 
os_drop_memory(void * addr,int length)179 int os_drop_memory(void *addr, int length)
180 {
181 	int err;
182 
183 	err = madvise(addr, length, MADV_REMOVE);
184 	if (err < 0)
185 		err = -errno;
186 	return err;
187 }
188 
can_drop_memory(void)189 int __init can_drop_memory(void)
190 {
191 	void *addr;
192 	int fd, ok = 0;
193 
194 	printk(UM_KERN_INFO "Checking host MADV_REMOVE support...");
195 	fd = create_mem_file(UM_KERN_PAGE_SIZE);
196 	if (fd < 0) {
197 		printk(UM_KERN_ERR "Creating test memory file failed, "
198 		       "err = %d\n", -fd);
199 		goto out;
200 	}
201 
202 	addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
203 		      MAP_SHARED, fd, 0);
204 	if (addr == MAP_FAILED) {
205 		printk(UM_KERN_ERR "Mapping test memory file failed, "
206 		       "err = %d\n", -errno);
207 		goto out_close;
208 	}
209 
210 	if (madvise(addr, UM_KERN_PAGE_SIZE, MADV_REMOVE) != 0) {
211 		printk(UM_KERN_ERR "MADV_REMOVE failed, err = %d\n", -errno);
212 		goto out_unmap;
213 	}
214 
215 	printk(UM_KERN_CONT "OK\n");
216 	ok = 1;
217 
218 out_unmap:
219 	munmap(addr, UM_KERN_PAGE_SIZE);
220 out_close:
221 	close(fd);
222 out:
223 	return ok;
224 }
225 
os_page_mincore(void * addr)226 static int os_page_mincore(void *addr)
227 {
228 	char vec[2];
229 	int ret;
230 
231 	ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
232 	if (ret < 0) {
233 		if (errno == ENOMEM || errno == EINVAL)
234 			return 0;
235 		else
236 			return -errno;
237 	}
238 
239 	return vec[0] & 1;
240 }
241 
os_mincore(void * addr,unsigned long len)242 int os_mincore(void *addr, unsigned long len)
243 {
244 	char *vec;
245 	int ret, i;
246 
247 	if (len <= UM_KERN_PAGE_SIZE)
248 		return os_page_mincore(addr);
249 
250 	vec = calloc(1, (len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE);
251 	if (!vec)
252 		return -ENOMEM;
253 
254 	ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
255 	if (ret < 0) {
256 		if (errno == ENOMEM || errno == EINVAL)
257 			ret = 0;
258 		else
259 			ret = -errno;
260 
261 		goto out;
262 	}
263 
264 	for (i = 0; i < ((len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE); i++) {
265 		if (!(vec[i] & 1)) {
266 			ret = 0;
267 			goto out;
268 		}
269 	}
270 
271 	ret = 1;
272 out:
273 	free(vec);
274 	return ret;
275 }
276 
init_new_thread_signals(void)277 void init_new_thread_signals(void)
278 {
279 	set_handler(SIGSEGV);
280 	set_handler(SIGTRAP);
281 	set_handler(SIGFPE);
282 	set_handler(SIGILL);
283 	set_handler(SIGBUS);
284 	signal(SIGHUP, SIG_IGN);
285 	set_handler(SIGIO);
286 	signal(SIGWINCH, SIG_IGN);
287 }
288