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 <wait.h> 14 #include <sys/mman.h> 15 #include <sys/utsname.h> 16 #include <init.h> 17 #include <os.h> 18 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 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 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 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 */ 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 */ 101 void os_fix_helper_signals(void) 102 { 103 signal(SIGWINCH, SIG_IGN); 104 signal(SIGINT, SIG_DFL); 105 signal(SIGTERM, SIG_DFL); 106 } 107 108 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 } 151 152 void um_early_printk(const char *s, unsigned int n) 153 { 154 printf("%.*s", n, s); 155 } 156 157 static int quiet_info; 158 159 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"); 168 169 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 } 180 181 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