aboutsummaryrefslogtreecommitdiff
path: root/arch/um/os-Linux/util.c
blob: 42827cafa6af3ac72f4c57d62e08968b81360faa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <termios.h>
#include <wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include "kern_constants.h"
#include "os.h"
#include "user.h"

void stack_protections(unsigned long address)
{
	if (mprotect((void *) address, UM_THREAD_SIZE,
		    PROT_READ | PROT_WRITE | PROT_EXEC) < 0)
		panic("protecting stack failed, errno = %d", errno);
}

int raw(int fd)
{
	struct termios tt;
	int err;

	CATCH_EINTR(err = tcgetattr(fd, &tt));
	if (err < 0)
		return -errno;

	cfmakeraw(&tt);

	CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt));
	if (err < 0)
		return -errno;

	/*
	 * XXX tcsetattr could have applied only some changes
	 * (and cfmakeraw() is a set of changes)
	 */
	return 0;
}

void setup_machinename(char *machine_out)
{
	struct utsname host;

	uname(&host);
#ifdef UML_CONFIG_UML_X86
# ifndef UML_CONFIG_64BIT
	if (!strcmp(host.machine, "x86_64")) {
		strcpy(machine_out, "i686");
		return;
	}
# else
	if (!strcmp(host.machine, "i686")) {
		strcpy(machine_out, "x86_64");
		return;
	}
# endif
#endif
	strcpy(machine_out, host.machine);
}

void setup_hostinfo(char *buf, int len)
{
	struct utsname host;

	uname(&host);
	snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename,
		 host.release, host.version, host.machine);
}

/*
 * We cannot use glibc's abort(). It makes use of tgkill() which
 * has no effect within UML's kernel threads.
 * After that glibc would execute an invalid instruction to kill
 * the calling process and UML crashes with SIGSEGV.
 */
static inline void __attribute__ ((noreturn)) uml_abort(void)
{
	sigset_t sig;

	fflush(NULL);

	if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT))
		sigprocmask(SIG_UNBLOCK, &sig, 0);

	for (;;)
		if (kill(getpid(), SIGABRT) < 0)
			exit(127);
}

void os_dump_core(void)
{
	int pid;

	signal(SIGSEGV, SIG_DFL);

	/*
	 * We are about to SIGTERM this entire process group to ensure that
	 * nothing is around to run after the kernel exits.  The
	 * kernel wants to abort, not die through SIGTERM, so we
	 * ignore it here.
	 */

	signal(SIGTERM, SIG_IGN);
	kill(0, SIGTERM);
	/*
	 * Most of the other processes associated with this UML are
	 * likely sTopped, so give them a SIGCONT so they see the
	 * SIGTERM.
	 */
	kill(0, SIGCONT);

	/*
	 * Now, having sent signals to everyone but us, make sure they
	 * die by ptrace.  Processes can survive what's been done to
	 * them so far - the mechanism I understand is receiving a
	 * SIGSEGV and segfaulting immediately upon return.  There is
	 * always a SIGSEGV pending, and (I'm guessing) signals are
	 * processed in numeric order so the SIGTERM (signal 15 vs
	 * SIGSEGV being signal 11) is never handled.
	 *
	 * Run a waitpid loop until we get some kind of error.
	 * Hopefully, it's ECHILD, but there's not a lot we can do if
	 * it's something else.  Tell os_kill_ptraced_process not to
	 * wait for the child to report its death because there's
	 * nothing reasonable to do if that fails.
	 */

	while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0)
		os_kill_ptraced_process(pid, 0);

	uml_abort();
}