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 <sys/random.h> 18 #include <init.h> 19 #include <os.h> 20 21 void stack_protections(unsigned long address) 22 { 23 if (mprotect((void *) address, UM_THREAD_SIZE, PROT_READ | PROT_WRITE) < 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 #if IS_ENABLED(CONFIG_UML_X86) 55 # if !IS_ENABLED(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 ssize_t os_getrandom(void *buf, size_t len, unsigned int flags) 100 { 101 return getrandom(buf, len, flags); 102 } 103 104 /* 105 * UML helper threads must not handle SIGWINCH/INT/TERM 106 */ 107 void os_fix_helper_signals(void) 108 { 109 signal(SIGWINCH, SIG_IGN); 110 signal(SIGINT, SIG_DFL); 111 signal(SIGTERM, SIG_DFL); 112 } 113 114 void os_dump_core(void) 115 { 116 int pid; 117 118 signal(SIGSEGV, SIG_DFL); 119 120 /* 121 * We are about to SIGTERM this entire process group to ensure that 122 * nothing is around to run after the kernel exits. The 123 * kernel wants to abort, not die through SIGTERM, so we 124 * ignore it here. 125 */ 126 127 signal(SIGTERM, SIG_IGN); 128 kill(0, SIGTERM); 129 /* 130 * Most of the other processes associated with this UML are 131 * likely sTopped, so give them a SIGCONT so they see the 132 * SIGTERM. 133 */ 134 kill(0, SIGCONT); 135 136 /* 137 * Now, having sent signals to everyone but us, make sure they 138 * die by ptrace. Processes can survive what's been done to 139 * them so far - the mechanism I understand is receiving a 140 * SIGSEGV and segfaulting immediately upon return. There is 141 * always a SIGSEGV pending, and (I'm guessing) signals are 142 * processed in numeric order so the SIGTERM (signal 15 vs 143 * SIGSEGV being signal 11) is never handled. 144 * 145 * Run a waitpid loop until we get some kind of error. 146 * Hopefully, it's ECHILD, but there's not a lot we can do if 147 * it's something else. Tell os_kill_ptraced_process not to 148 * wait for the child to report its death because there's 149 * nothing reasonable to do if that fails. 150 */ 151 152 while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0) 153 os_kill_ptraced_process(pid, 0); 154 155 uml_abort(); 156 } 157 158 void um_early_printk(const char *s, unsigned int n) 159 { 160 printf("%.*s", n, s); 161 } 162 163 static int quiet_info; 164 165 static int __init quiet_cmd_param(char *str, int *add) 166 { 167 quiet_info = 1; 168 return 0; 169 } 170 171 __uml_setup("quiet", quiet_cmd_param, 172 "quiet\n" 173 " Turns off information messages during boot.\n\n"); 174 175 /* 176 * The os_info/os_warn functions will be called by helper threads. These 177 * have a very limited stack size and using the libc formatting functions 178 * may overflow the stack. 179 * So pull in the kernel vscnprintf and use that instead with a fixed 180 * on-stack buffer. 181 */ 182 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args); 183 184 void os_info(const char *fmt, ...) 185 { 186 char buf[256]; 187 va_list list; 188 int len; 189 190 if (quiet_info) 191 return; 192 193 va_start(list, fmt); 194 len = vscnprintf(buf, sizeof(buf), fmt, list); 195 fwrite(buf, len, 1, stderr); 196 va_end(list); 197 } 198 199 void os_warn(const char *fmt, ...) 200 { 201 char buf[256]; 202 va_list list; 203 int len; 204 205 va_start(list, fmt); 206 len = vscnprintf(buf, sizeof(buf), fmt, list); 207 fwrite(buf, len, 1, stderr); 208 va_end(list); 209 } 210