v4.19.13 snapshot.
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
new file mode 100644
index 0000000..8cc8b26
--- /dev/null
+++ b/arch/um/os-Linux/util.c
@@ -0,0 +1,188 @@
+/*
+ * 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 <init.h>
+#include <os.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);
+}
+
+/*
+ * 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");
+
+void os_info(const char *fmt, ...)
+{
+ va_list list;
+
+ if (quiet_info)
+ return;
+
+ va_start(list, fmt);
+ vfprintf(stderr, fmt, list);
+ va_end(list);
+}
+
+void os_warn(const char *fmt, ...)
+{
+ va_list list;
+
+ va_start(list, fmt);
+ vfprintf(stderr, fmt, list);
+ va_end(list);
+}