v4.19.13 snapshot.
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
new file mode 100644
index 0000000..f1fee2b
--- /dev/null
+++ b/arch/um/os-Linux/main.c
@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
+ * 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 <sys/resource.h>
+#include <as-layout.h>
+#include <init.h>
+#include <kern_util.h>
+#include <os.h>
+#include <um_malloc.h>
+
+#define PGD_BOUND (4 * 1024 * 1024)
+#define STACKSIZE (8 * 1024 * 1024)
+#define THREAD_NAME_LEN (256)
+
+long elf_aux_hwcap;
+
+static void set_stklim(void)
+{
+ struct rlimit lim;
+
+ if (getrlimit(RLIMIT_STACK, &lim) < 0) {
+ perror("getrlimit");
+ exit(1);
+ }
+ if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
+ lim.rlim_cur = STACKSIZE;
+ if (setrlimit(RLIMIT_STACK, &lim) < 0) {
+ perror("setrlimit");
+ exit(1);
+ }
+ }
+}
+
+static void last_ditch_exit(int sig)
+{
+ uml_cleanup();
+ exit(1);
+}
+
+static void install_fatal_handler(int sig)
+{
+ struct sigaction action;
+
+ /* All signals are enabled in this handler ... */
+ sigemptyset(&action.sa_mask);
+
+ /*
+ * ... including the signal being handled, plus we want the
+ * handler reset to the default behavior, so that if an exit
+ * handler is hanging for some reason, the UML will just die
+ * after this signal is sent a second time.
+ */
+ action.sa_flags = SA_RESETHAND | SA_NODEFER;
+ action.sa_restorer = NULL;
+ action.sa_handler = last_ditch_exit;
+ if (sigaction(sig, &action, NULL) < 0) {
+ os_warn("failed to install handler for signal %d "
+ "- errno = %d\n", sig, errno);
+ exit(1);
+ }
+}
+
+#define UML_LIB_PATH ":" OS_LIB_PATH "/uml"
+
+static void setup_env_path(void)
+{
+ char *new_path = NULL;
+ char *old_path = NULL;
+ int path_len = 0;
+
+ old_path = getenv("PATH");
+ /*
+ * if no PATH variable is set or it has an empty value
+ * just use the default + /usr/lib/uml
+ */
+ if (!old_path || (path_len = strlen(old_path)) == 0) {
+ if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
+ perror("couldn't putenv");
+ return;
+ }
+
+ /* append /usr/lib/uml to the existing path */
+ path_len += strlen("PATH=" UML_LIB_PATH) + 1;
+ new_path = malloc(path_len);
+ if (!new_path) {
+ perror("couldn't malloc to set a new PATH");
+ return;
+ }
+ snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
+ if (putenv(new_path)) {
+ perror("couldn't putenv to set a new PATH");
+ free(new_path);
+ }
+}
+
+extern void scan_elf_aux( char **envp);
+
+int __init main(int argc, char **argv, char **envp)
+{
+ char **new_argv;
+ int ret, i, err;
+
+ set_stklim();
+
+ setup_env_path();
+
+ setsid();
+
+ new_argv = malloc((argc + 1) * sizeof(char *));
+ if (new_argv == NULL) {
+ perror("Mallocing argv");
+ exit(1);
+ }
+ for (i = 0; i < argc; i++) {
+ new_argv[i] = strdup(argv[i]);
+ if (new_argv[i] == NULL) {
+ perror("Mallocing an arg");
+ exit(1);
+ }
+ }
+ new_argv[argc] = NULL;
+
+ /*
+ * Allow these signals to bring down a UML if all other
+ * methods of control fail.
+ */
+ install_fatal_handler(SIGINT);
+ install_fatal_handler(SIGTERM);
+
+#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
+ scan_elf_aux(envp);
+#endif
+
+ change_sig(SIGPIPE, 0);
+ ret = linux_main(argc, argv);
+
+ /*
+ * Disable SIGPROF - I have no idea why libc doesn't do this or turn
+ * off the profiling time, but UML dies with a SIGPROF just before
+ * exiting when profiling is active.
+ */
+ change_sig(SIGPROF, 0);
+
+ /*
+ * This signal stuff used to be in the reboot case. However,
+ * sometimes a timer signal can come in when we're halting (reproducably
+ * when writing out gcov information, presumably because that takes
+ * some time) and cause a segfault.
+ */
+
+ /* stop timers and set timer signal to be ignored */
+ os_timer_disable();
+
+ /* disable SIGIO for the fds and set SIGIO to be ignored */
+ err = deactivate_all_fds();
+ if (err)
+ os_warn("deactivate_all_fds failed, errno = %d\n", -err);
+
+ /*
+ * Let any pending signals fire now. This ensures
+ * that they won't be delivered after the exec, when
+ * they are definitely not expected.
+ */
+ unblock_signals();
+
+ os_info("\n");
+ /* Reboot */
+ if (ret) {
+ execvp(new_argv[0], new_argv);
+ perror("Failed to exec kernel");
+ ret = 1;
+ }
+ return uml_exitcode;
+}
+
+extern void *__real_malloc(int);
+
+void *__wrap_malloc(int size)
+{
+ void *ret;
+
+ if (!kmalloc_ok)
+ return __real_malloc(size);
+ else if (size <= UM_KERN_PAGE_SIZE)
+ /* finding contiguous pages can be hard*/
+ ret = uml_kmalloc(size, UM_GFP_KERNEL);
+ else ret = vmalloc(size);
+
+ /*
+ * glibc people insist that if malloc fails, errno should be
+ * set by malloc as well. So we do.
+ */
+ if (ret == NULL)
+ errno = ENOMEM;
+
+ return ret;
+}
+
+void *__wrap_calloc(int n, int size)
+{
+ void *ptr = __wrap_malloc(n * size);
+
+ if (ptr == NULL)
+ return NULL;
+ memset(ptr, 0, n * size);
+ return ptr;
+}
+
+extern void __real_free(void *);
+
+extern unsigned long high_physmem;
+
+void __wrap_free(void *ptr)
+{
+ unsigned long addr = (unsigned long) ptr;
+
+ /*
+ * We need to know how the allocation happened, so it can be correctly
+ * freed. This is done by seeing what region of memory the pointer is
+ * in -
+ * physical memory - kmalloc/kfree
+ * kernel virtual memory - vmalloc/vfree
+ * anywhere else - malloc/free
+ * If kmalloc is not yet possible, then either high_physmem and/or
+ * end_vm are still 0 (as at startup), in which case we call free, or
+ * we have set them, but anyway addr has not been allocated from those
+ * areas. So, in both cases __real_free is called.
+ *
+ * CAN_KMALLOC is checked because it would be bad to free a buffer
+ * with kmalloc/vmalloc after they have been turned off during
+ * shutdown.
+ * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
+ * there is a possibility for memory leaks.
+ */
+
+ if ((addr >= uml_physmem) && (addr < high_physmem)) {
+ if (kmalloc_ok)
+ kfree(ptr);
+ }
+ else if ((addr >= start_vm) && (addr < end_vm)) {
+ if (kmalloc_ok)
+ vfree(ptr);
+ }
+ else __real_free(ptr);
+}