xref: /openbmc/linux/arch/um/os-Linux/util.c (revision a4378abc)
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 
stack_protections(unsigned long address)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 
raw(int fd)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 
setup_machinename(char * machine_out)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 
setup_hostinfo(char * buf,int len)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  */
uml_abort(void)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 
os_getrandom(void * buf,size_t len,unsigned int flags)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  */
os_fix_helper_signals(void)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 
os_dump_core(void)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 
um_early_printk(const char * s,unsigned int n)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 
quiet_cmd_param(char * str,int * add)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 
os_info(const char * fmt,...)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 
os_warn(const char * fmt,...)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