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