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 <init.h> 18 #include <os.h> 19 20 void stack_protections(unsigned long address) 21 { 22 if (mprotect((void *) address, UM_THREAD_SIZE, 23 PROT_READ | PROT_WRITE | PROT_EXEC) < 0) 24 panic("protecting stack failed, errno = %d", errno); 25 } 26 27 int raw(int fd) 28 { 29 struct termios tt; 30 int err; 31 32 CATCH_EINTR(err = tcgetattr(fd, &tt)); 33 if (err < 0) 34 return -errno; 35 36 cfmakeraw(&tt); 37 38 CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt)); 39 if (err < 0) 40 return -errno; 41 42 /* 43 * XXX tcsetattr could have applied only some changes 44 * (and cfmakeraw() is a set of changes) 45 */ 46 return 0; 47 } 48 49 void setup_machinename(char *machine_out) 50 { 51 struct utsname host; 52 53 uname(&host); 54 #ifdef UML_CONFIG_UML_X86 55 # ifndef UML_CONFIG_64BIT 56 if (!strcmp(host.machine, "x86_64")) { 57 strcpy(machine_out, "i686"); 58 return; 59 } 60 # else 61 if (!strcmp(host.machine, "i686")) { 62 strcpy(machine_out, "x86_64"); 63 return; 64 } 65 # endif 66 #endif 67 strcpy(machine_out, host.machine); 68 } 69 70 void setup_hostinfo(char *buf, int len) 71 { 72 struct utsname host; 73 74 uname(&host); 75 snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename, 76 host.release, host.version, host.machine); 77 } 78 79 /* 80 * We cannot use glibc's abort(). It makes use of tgkill() which 81 * has no effect within UML's kernel threads. 82 * After that glibc would execute an invalid instruction to kill 83 * the calling process and UML crashes with SIGSEGV. 84 */ 85 static inline void __attribute__ ((noreturn)) uml_abort(void) 86 { 87 sigset_t sig; 88 89 fflush(NULL); 90 91 if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT)) 92 sigprocmask(SIG_UNBLOCK, &sig, 0); 93 94 for (;;) 95 if (kill(getpid(), SIGABRT) < 0) 96 exit(127); 97 } 98 99 /* 100 * UML helper threads must not handle SIGWINCH/INT/TERM 101 */ 102 void os_fix_helper_signals(void) 103 { 104 signal(SIGWINCH, SIG_IGN); 105 signal(SIGINT, SIG_DFL); 106 signal(SIGTERM, SIG_DFL); 107 } 108 109 void os_dump_core(void) 110 { 111 int pid; 112 113 signal(SIGSEGV, SIG_DFL); 114 115 /* 116 * We are about to SIGTERM this entire process group to ensure that 117 * nothing is around to run after the kernel exits. The 118 * kernel wants to abort, not die through SIGTERM, so we 119 * ignore it here. 120 */ 121 122 signal(SIGTERM, SIG_IGN); 123 kill(0, SIGTERM); 124 /* 125 * Most of the other processes associated with this UML are 126 * likely sTopped, so give them a SIGCONT so they see the 127 * SIGTERM. 128 */ 129 kill(0, SIGCONT); 130 131 /* 132 * Now, having sent signals to everyone but us, make sure they 133 * die by ptrace. Processes can survive what's been done to 134 * them so far - the mechanism I understand is receiving a 135 * SIGSEGV and segfaulting immediately upon return. There is 136 * always a SIGSEGV pending, and (I'm guessing) signals are 137 * processed in numeric order so the SIGTERM (signal 15 vs 138 * SIGSEGV being signal 11) is never handled. 139 * 140 * Run a waitpid loop until we get some kind of error. 141 * Hopefully, it's ECHILD, but there's not a lot we can do if 142 * it's something else. Tell os_kill_ptraced_process not to 143 * wait for the child to report its death because there's 144 * nothing reasonable to do if that fails. 145 */ 146 147 while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0) 148 os_kill_ptraced_process(pid, 0); 149 150 uml_abort(); 151 } 152 153 void um_early_printk(const char *s, unsigned int n) 154 { 155 printf("%.*s", n, s); 156 } 157 158 static int quiet_info; 159 160 static int __init quiet_cmd_param(char *str, int *add) 161 { 162 quiet_info = 1; 163 return 0; 164 } 165 166 __uml_setup("quiet", quiet_cmd_param, 167 "quiet\n" 168 " Turns off information messages during boot.\n\n"); 169 170 void os_info(const char *fmt, ...) 171 { 172 va_list list; 173 174 if (quiet_info) 175 return; 176 177 va_start(list, fmt); 178 vfprintf(stderr, fmt, list); 179 va_end(list); 180 } 181 182 void os_warn(const char *fmt, ...) 183 { 184 va_list list; 185 186 va_start(list, fmt); 187 vfprintf(stderr, fmt, list); 188 va_end(list); 189 } 190