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
97 /*
98 * UML helper threads must not handle SIGWINCH/INT/TERM
99 */
os_fix_helper_signals(void)100 void os_fix_helper_signals(void)
101 {
102 signal(SIGWINCH, SIG_IGN);
103 signal(SIGINT, SIG_DFL);
104 signal(SIGTERM, SIG_DFL);
105 }
106
os_dump_core(void)107 void os_dump_core(void)
108 {
109 int pid;
110
111 signal(SIGSEGV, SIG_DFL);
112
113 /*
114 * We are about to SIGTERM this entire process group to ensure that
115 * nothing is around to run after the kernel exits. The
116 * kernel wants to abort, not die through SIGTERM, so we
117 * ignore it here.
118 */
119
120 signal(SIGTERM, SIG_IGN);
121 kill(0, SIGTERM);
122 /*
123 * Most of the other processes associated with this UML are
124 * likely sTopped, so give them a SIGCONT so they see the
125 * SIGTERM.
126 */
127 kill(0, SIGCONT);
128
129 /*
130 * Now, having sent signals to everyone but us, make sure they
131 * die by ptrace. Processes can survive what's been done to
132 * them so far - the mechanism I understand is receiving a
133 * SIGSEGV and segfaulting immediately upon return. There is
134 * always a SIGSEGV pending, and (I'm guessing) signals are
135 * processed in numeric order so the SIGTERM (signal 15 vs
136 * SIGSEGV being signal 11) is never handled.
137 *
138 * Run a waitpid loop until we get some kind of error.
139 * Hopefully, it's ECHILD, but there's not a lot we can do if
140 * it's something else. Tell os_kill_ptraced_process not to
141 * wait for the child to report its death because there's
142 * nothing reasonable to do if that fails.
143 */
144
145 while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
146 os_kill_ptraced_process(pid, 0);
147
148 uml_abort();
149 }
150
um_early_printk(const char * s,unsigned int n)151 void um_early_printk(const char *s, unsigned int n)
152 {
153 printf("%.*s", n, s);
154 }
155