v4.19.13 snapshot.
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
new file mode 100644
index 0000000..a818cce
--- /dev/null
+++ b/arch/um/kernel/um_arch.c
@@ -0,0 +1,363 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/utsname.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/kmsg_dump.h>
+
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <as-layout.h>
+#include <arch.h>
+#include <init.h>
+#include <kern.h>
+#include <kern_util.h>
+#include <mem_user.h>
+#include <os.h>
+
+#define DEFAULT_COMMAND_LINE "root=98:0"
+
+/* Changed in add_arg and setup_arch, which run before SMP is started */
+static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };
+
+static void __init add_arg(char *arg)
+{
+ if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
+ os_warn("add_arg: Too many command line arguments!\n");
+ exit(1);
+ }
+ if (strlen(command_line) > 0)
+ strcat(command_line, " ");
+ strcat(command_line, arg);
+}
+
+/*
+ * These fields are initialized at boot time and not changed.
+ * XXX This structure is used only in the non-SMP case. Maybe this
+ * should be moved to smp.c.
+ */
+struct cpuinfo_um boot_cpu_data = {
+ .loops_per_jiffy = 0,
+ .ipi_pipe = { -1, -1 }
+};
+
+union thread_union cpu0_irqstack
+ __attribute__((__section__(".data..init_irqstack"))) =
+ { .thread_info = INIT_THREAD_INFO(init_task) };
+
+/* Changed in setup_arch, which is called in early boot */
+static char host_info[(__NEW_UTS_LEN + 1) * 5];
+
+static int show_cpuinfo(struct seq_file *m, void *v)
+{
+ int index = 0;
+
+ seq_printf(m, "processor\t: %d\n", index);
+ seq_printf(m, "vendor_id\t: User Mode Linux\n");
+ seq_printf(m, "model name\t: UML\n");
+ seq_printf(m, "mode\t\t: skas\n");
+ seq_printf(m, "host\t\t: %s\n", host_info);
+ seq_printf(m, "bogomips\t: %lu.%02lu\n\n",
+ loops_per_jiffy/(500000/HZ),
+ (loops_per_jiffy/(5000/HZ)) % 100);
+
+ return 0;
+}
+
+static void *c_start(struct seq_file *m, loff_t *pos)
+{
+ return *pos < NR_CPUS ? cpu_data + *pos : NULL;
+}
+
+static void *c_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ ++*pos;
+ return c_start(m, pos);
+}
+
+static void c_stop(struct seq_file *m, void *v)
+{
+}
+
+const struct seq_operations cpuinfo_op = {
+ .start = c_start,
+ .next = c_next,
+ .stop = c_stop,
+ .show = show_cpuinfo,
+};
+
+/* Set in linux_main */
+unsigned long uml_physmem;
+EXPORT_SYMBOL(uml_physmem);
+
+unsigned long uml_reserved; /* Also modified in mem_init */
+unsigned long start_vm;
+unsigned long end_vm;
+
+/* Set in uml_ncpus_setup */
+int ncpus = 1;
+
+/* Set in early boot */
+static int have_root __initdata = 0;
+
+/* Set in uml_mem_setup and modified in linux_main */
+long long physmem_size = 32 * 1024 * 1024;
+
+static const char *usage_string =
+"User Mode Linux v%s\n"
+" available at http://user-mode-linux.sourceforge.net/\n\n";
+
+static int __init uml_version_setup(char *line, int *add)
+{
+ /* Explicitly use printf() to show version in stdout */
+ printf("%s\n", init_utsname()->release);
+ exit(0);
+
+ return 0;
+}
+
+__uml_setup("--version", uml_version_setup,
+"--version\n"
+" Prints the version number of the kernel.\n\n"
+);
+
+static int __init uml_root_setup(char *line, int *add)
+{
+ have_root = 1;
+ return 0;
+}
+
+__uml_setup("root=", uml_root_setup,
+"root=<file containing the root fs>\n"
+" This is actually used by the generic kernel in exactly the same\n"
+" way as in any other kernel. If you configure a number of block\n"
+" devices and want to boot off something other than ubd0, you \n"
+" would use something like:\n"
+" root=/dev/ubd5\n\n"
+);
+
+static int __init no_skas_debug_setup(char *line, int *add)
+{
+ os_warn("'debug' is not necessary to gdb UML in skas mode - run\n");
+ os_warn("'gdb linux'\n");
+
+ return 0;
+}
+
+__uml_setup("debug", no_skas_debug_setup,
+"debug\n"
+" this flag is not needed to run gdb on UML in skas mode\n\n"
+);
+
+static int __init Usage(char *line, int *add)
+{
+ const char **p;
+
+ printf(usage_string, init_utsname()->release);
+ p = &__uml_help_start;
+ /* Explicitly use printf() to show help in stdout */
+ while (p < &__uml_help_end) {
+ printf("%s", *p);
+ p++;
+ }
+ exit(0);
+ return 0;
+}
+
+__uml_setup("--help", Usage,
+"--help\n"
+" Prints this message.\n\n"
+);
+
+static void __init uml_checksetup(char *line, int *add)
+{
+ struct uml_param *p;
+
+ p = &__uml_setup_start;
+ while (p < &__uml_setup_end) {
+ size_t n;
+
+ n = strlen(p->str);
+ if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
+ return;
+ p++;
+ }
+}
+
+static void __init uml_postsetup(void)
+{
+ initcall_t *p;
+
+ p = &__uml_postsetup_start;
+ while (p < &__uml_postsetup_end) {
+ (*p)();
+ p++;
+ }
+ return;
+}
+
+static int panic_exit(struct notifier_block *self, unsigned long unused1,
+ void *unused2)
+{
+ kmsg_dump(KMSG_DUMP_PANIC);
+ bust_spinlocks(1);
+ bust_spinlocks(0);
+ uml_exitcode = 1;
+ os_dump_core();
+ return 0;
+}
+
+static struct notifier_block panic_exit_notifier = {
+ .notifier_call = panic_exit,
+ .next = NULL,
+ .priority = 0
+};
+
+void uml_finishsetup(void)
+{
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &panic_exit_notifier);
+
+ uml_postsetup();
+
+ new_thread_handler();
+}
+
+/* Set during early boot */
+unsigned long task_size;
+EXPORT_SYMBOL(task_size);
+
+unsigned long host_task_size;
+
+unsigned long brk_start;
+unsigned long end_iomem;
+EXPORT_SYMBOL(end_iomem);
+
+#define MIN_VMALLOC (32 * 1024 * 1024)
+
+int __init linux_main(int argc, char **argv)
+{
+ unsigned long avail, diff;
+ unsigned long virtmem_size, max_physmem;
+ unsigned long stack;
+ unsigned int i;
+ int add;
+
+ for (i = 1; i < argc; i++) {
+ if ((i == 1) && (argv[i][0] == ' '))
+ continue;
+ add = 1;
+ uml_checksetup(argv[i], &add);
+ if (add)
+ add_arg(argv[i]);
+ }
+ if (have_root == 0)
+ add_arg(DEFAULT_COMMAND_LINE);
+
+ host_task_size = os_get_top_address();
+ /*
+ * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
+ * out
+ */
+ task_size = host_task_size & PGDIR_MASK;
+
+ /* OS sanity checks that need to happen before the kernel runs */
+ os_early_checks();
+
+ brk_start = (unsigned long) sbrk(0);
+
+ /*
+ * Increase physical memory size for exec-shield users
+ * so they actually get what they asked for. This should
+ * add zero for non-exec shield users
+ */
+
+ diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
+ if (diff > 1024 * 1024) {
+ os_info("Adding %ld bytes to physical memory to account for "
+ "exec-shield gap\n", diff);
+ physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
+ }
+
+ uml_physmem = (unsigned long) __binary_start & PAGE_MASK;
+
+ /* Reserve up to 4M after the current brk */
+ uml_reserved = ROUND_4M(brk_start) + (1 << 22);
+
+ setup_machinename(init_utsname()->machine);
+
+ highmem = 0;
+ iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
+ max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
+
+ /*
+ * Zones have to begin on a 1 << MAX_ORDER page boundary,
+ * so this makes sure that's true for highmem
+ */
+ max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
+ if (physmem_size + iomem_size > max_physmem) {
+ highmem = physmem_size + iomem_size - max_physmem;
+ physmem_size -= highmem;
+ }
+
+ high_physmem = uml_physmem + physmem_size;
+ end_iomem = high_physmem + iomem_size;
+ high_memory = (void *) end_iomem;
+
+ start_vm = VMALLOC_START;
+
+ virtmem_size = physmem_size;
+ stack = (unsigned long) argv;
+ stack &= ~(1024 * 1024 - 1);
+ avail = stack - start_vm;
+ if (physmem_size > avail)
+ virtmem_size = avail;
+ end_vm = start_vm + virtmem_size;
+
+ if (virtmem_size < physmem_size)
+ os_info("Kernel virtual memory size shrunk to %lu bytes\n",
+ virtmem_size);
+
+ os_flush_stdout();
+
+ return start_uml();
+}
+
+int __init __weak read_initrd(void)
+{
+ return 0;
+}
+
+void __init setup_arch(char **cmdline_p)
+{
+ stack_protections((unsigned long) &init_thread_info);
+ setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
+ mem_total_pages(physmem_size, iomem_size, highmem);
+ read_initrd();
+
+ paging_init();
+ strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
+ *cmdline_p = command_line;
+ setup_hostinfo(host_info, sizeof host_info);
+}
+
+void __init check_bugs(void)
+{
+ arch_check_bugs();
+ os_check_bugs();
+}
+
+void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
+{
+}