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
27unsigned 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
59int 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
93void os_alarm_process(int pid)
94{
95	kill(pid, SIGALRM);
96}
97
98void os_stop_process(int pid)
99{
100	kill(pid, SIGSTOP);
101}
102
103void 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
115void 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
128int os_getpid(void)
129{
130	return syscall(__NR_getpid);
131}
132
133int os_getpgrp(void)
134{
135	return getpgrp();
136}
137
138int 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
154int 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
165int 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
179int 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
189int __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
218out_unmap:
219	munmap(addr, UM_KERN_PAGE_SIZE);
220out_close:
221	close(fd);
222out:
223	return ok;
224}
225
226static 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
242int 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;
272out:
273	free(vec);
274	return ret;
275}
276
277void 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