1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6 #include <stdarg.h>
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 <termios.h>
14 #include <sys/wait.h>
15 #include <sys/mman.h>
16 #include <sys/utsname.h>
17 #include <sys/random.h>
18 #include <init.h>
19 #include <os.h>
20
21 void stack_protections(unsigned long address)
22 {
23 if (mprotect((void *) address, UM_THREAD_SIZE,
24 PROT_READ | PROT_WRITE | PROT_EXEC) < 0)
25 panic("protecting stack failed, errno = %d", errno);
26 }
27
28 int raw(int fd)
29 {
30 struct termios tt;
31 int err;
32
33 CATCH_EINTR(err = tcgetattr(fd, &tt));
34 if (err < 0)
35 return -errno;
36
37 cfmakeraw(&tt);
38
39 CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt));
40 if (err < 0)
41 return -errno;
42
43 /*
44 * XXX tcsetattr could have applied only some changes
45 * (and cfmakeraw() is a set of changes)
46 */
47 return 0;
48 }
49
50 void setup_machinename(char *machine_out)
51 {
52 struct utsname host;
53
54 uname(&host);
55 #ifdef UML_CONFIG_UML_X86
56 # ifndef UML_CONFIG_64BIT
57 if (!strcmp(host.machine, "x86_64")) {
58 strcpy(machine_out, "i686");
59 return;
60 }
61 # else
62 if (!strcmp(host.machine, "i686")) {
63 strcpy(machine_out, "x86_64");
64 return;
65 }
66 # endif
67 #endif
68 strcpy(machine_out, host.machine);
69 }
70
71 void setup_hostinfo(char *buf, int len)
72 {
73 struct utsname host;
74
75 uname(&host);
76 snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename,
77 host.release, host.version, host.machine);
78 }
79
80 /*
81 * We cannot use glibc's abort(). It makes use of tgkill() which
82 * has no effect within UML's kernel threads.
83 * After that glibc would execute an invalid instruction to kill
84 * the calling process and UML crashes with SIGSEGV.
85 */
86 static inline void __attribute__ ((noreturn)) uml_abort(void)
87 {
88 sigset_t sig;
89
90 fflush(NULL);
91
92 if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT))
93 sigprocmask(SIG_UNBLOCK, &sig, 0);
94
95 for (;;)
96 if (kill(getpid(), SIGABRT) < 0)
97 exit(127);
98 }
99
100 ssize_t os_getrandom(void *buf, size_t len, unsigned int flags)
101 {
102 return getrandom(buf, len, flags);
103 }
104
105 /*
106 * UML helper threads must not handle SIGWINCH/INT/TERM
107 */
108 void os_fix_helper_signals(void)
109 {
110 signal(SIGWINCH, SIG_IGN);
111 signal(SIGINT, SIG_DFL);
112 signal(SIGTERM, SIG_DFL);
113 }
114
115 void os_dump_core(void)
116 {
117 int pid;
118
119 signal(SIGSEGV, SIG_DFL);
120
121 /*
122 * We are about to SIGTERM this entire process group to ensure that
123 * nothing is around to run after the kernel exits. The
124 * kernel wants to abort, not die through SIGTERM, so we
125 * ignore it here.
126 */
127
128 signal(SIGTERM, SIG_IGN);
129 kill(0, SIGTERM);
130 /*
131 * Most of the other processes associated with this UML are
132 * likely sTopped, so give them a SIGCONT so they see the
133 * SIGTERM.
134 */
135 kill(0, SIGCONT);
136
137 /*
138 * Now, having sent signals to everyone but us, make sure they
139 * die by ptrace. Processes can survive what's been done to
140 * them so far - the mechanism I understand is receiving a
141 * SIGSEGV and segfaulting immediately upon return. There is
142 * always a SIGSEGV pending, and (I'm guessing) signals are
143 * processed in numeric order so the SIGTERM (signal 15 vs
144 * SIGSEGV being signal 11) is never handled.
145 *
146 * Run a waitpid loop until we get some kind of error.
147 * Hopefully, it's ECHILD, but there's not a lot we can do if
148 * it's something else. Tell os_kill_ptraced_process not to
149 * wait for the child to report its death because there's
150 * nothing reasonable to do if that fails.
151 */
152
153 while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
154 os_kill_ptraced_process(pid, 0);
155
156 uml_abort();
157 }
158
159 void um_early_printk(const char *s, unsigned int n)
160 {
161 printf("%.*s", n, s);
162 }
163
164 static int quiet_info;
165
166 static int __init quiet_cmd_param(char *str, int *add)
167 {
168 quiet_info = 1;
169 return 0;
170 }
171
172 __uml_setup("quiet", quiet_cmd_param,
173 "quiet\n"
174 " Turns off information messages during boot.\n\n");
175
176 /*
177 * The os_info/os_warn functions will be called by helper threads. These
178 * have a very limited stack size and using the libc formatting functions
179 * may overflow the stack.
180 * So pull in the kernel vscnprintf and use that instead with a fixed
181 * on-stack buffer.
182 */
183 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
184
185 void os_info(const char *fmt, ...)
186 {
187 char buf[256];
188 va_list list;
189 int len;
190
191 if (quiet_info)
192 return;
193
194 va_start(list, fmt);
195 len = vscnprintf(buf, sizeof(buf), fmt, list);
196 fwrite(buf, len, 1, stderr);
197 va_end(list);
198 }
199
200 void os_warn(const char *fmt, ...)
201 {
202 char buf[256];
203 va_list list;
204 int len;
205
206 va_start(list, fmt);
207 len = vscnprintf(buf, sizeof(buf), fmt, list);
208 fwrite(buf, len, 1, stderr);
209 va_end(list);
210 }
211
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