// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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); #if IS_ENABLED(CONFIG_UML_X86) # if !IS_ENABLED(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); } ssize_t os_getrandom(void *buf, size_t len, unsigned int flags) { return getrandom(buf, len, flags); } /* * UML helper threads must not handle SIGWINCH/INT/TERM */ void os_fix_helper_signals(void) { signal(SIGWINCH, SIG_IGN); signal(SIGINT, SIG_DFL); signal(SIGTERM, SIG_DFL); } 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(); } void um_early_printk(const char *s, unsigned int n) { printf("%.*s", n, s); } static int quiet_info; static int __init quiet_cmd_param(char *str, int *add) { quiet_info = 1; return 0; } __uml_setup("quiet", quiet_cmd_param, "quiet\n" " Turns off information messages during boot.\n\n"); /* * The os_info/os_warn functions will be called by helper threads. These * have a very limited stack size and using the libc formatting functions * may overflow the stack. * So pull in the kernel vscnprintf and use that instead with a fixed * on-stack buffer. */ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args); void os_info(const char *fmt, ...) { char buf[256]; va_list list; int len; if (quiet_info) return; va_start(list, fmt); len = vscnprintf(buf, sizeof(buf), fmt, list); fwrite(buf, len, 1, stderr); va_end(list); } void os_warn(const char *fmt, ...) { char buf[256]; va_list list; int len; va_start(list, fmt); len = vscnprintf(buf, sizeof(buf), fmt, list); fwrite(buf, len, 1, stderr); va_end(list); }