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