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