v4.19.13 snapshot.
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
new file mode 100644
index 0000000..f02596e
--- /dev/null
+++ b/arch/um/kernel/physmem.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/module.h>
+#include <linux/bootmem.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <asm/page.h>
+#include <asm/sections.h>
+#include <as-layout.h>
+#include <init.h>
+#include <kern.h>
+#include <mem_user.h>
+#include <os.h>
+
+static int physmem_fd = -1;
+
+/* Changed during early boot */
+unsigned long high_physmem;
+EXPORT_SYMBOL(high_physmem);
+
+extern unsigned long long physmem_size;
+
+void __init mem_total_pages(unsigned long physmem, unsigned long iomem,
+ unsigned long highmem)
+{
+ unsigned long phys_pages, highmem_pages;
+ unsigned long iomem_pages, total_pages;
+
+ phys_pages = physmem >> PAGE_SHIFT;
+ iomem_pages = iomem >> PAGE_SHIFT;
+ highmem_pages = highmem >> PAGE_SHIFT;
+
+ total_pages = phys_pages + iomem_pages + highmem_pages;
+
+ max_mapnr = total_pages;
+}
+
+void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
+ int r, int w, int x)
+{
+ __u64 offset;
+ int fd, err;
+
+ fd = phys_mapping(phys, &offset);
+ err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
+ if (err) {
+ if (err == -ENOMEM)
+ printk(KERN_ERR "try increasing the host's "
+ "/proc/sys/vm/max_map_count to <physical "
+ "memory size>/4096\n");
+ panic("map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
+ "err = %d\n", virt, fd, offset, len, r, w, x, err);
+ }
+}
+
+/**
+ * setup_physmem() - Setup physical memory for UML
+ * @start: Start address of the physical kernel memory,
+ * i.e start address of the executable image.
+ * @reserve_end: end address of the physical kernel memory.
+ * @len: Length of total physical memory that should be mapped/made
+ * available, in bytes.
+ * @highmem: Number of highmem bytes that should be mapped/made available.
+ *
+ * Creates an unlinked temporary file of size (len + highmem) and memory maps
+ * it on the last executable image address (uml_reserved).
+ *
+ * The offset is needed as the length of the total physical memory
+ * (len + highmem) includes the size of the memory used be the executable image,
+ * but the mapped-to address is the last address of the executable image
+ * (uml_reserved == end address of executable image).
+ *
+ * The memory mapped memory of the temporary file is used as backing memory
+ * of all user space processes/kernel tasks.
+ */
+void __init setup_physmem(unsigned long start, unsigned long reserve_end,
+ unsigned long len, unsigned long long highmem)
+{
+ unsigned long reserve = reserve_end - start;
+ unsigned long pfn = PFN_UP(__pa(reserve_end));
+ unsigned long delta = (len - reserve) >> PAGE_SHIFT;
+ unsigned long offset, bootmap_size;
+ long map_size;
+ int err;
+
+ offset = uml_reserved - uml_physmem;
+ map_size = len - offset;
+ if(map_size <= 0) {
+ os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
+ offset, len);
+ exit(1);
+ }
+
+ physmem_fd = create_mem_file(len + highmem);
+
+ err = os_map_memory((void *) uml_reserved, physmem_fd, offset,
+ map_size, 1, 1, 1);
+ if (err < 0) {
+ os_warn("setup_physmem - mapping %ld bytes of memory at 0x%p "
+ "failed - errno = %d\n", map_size,
+ (void *) uml_reserved, err);
+ exit(1);
+ }
+
+ /*
+ * Special kludge - This page will be mapped in to userspace processes
+ * from physmem_fd, so it needs to be written out there.
+ */
+ os_seek_file(physmem_fd, __pa(__syscall_stub_start));
+ os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
+ os_fsync_file(physmem_fd);
+
+ bootmap_size = init_bootmem(pfn, pfn + delta);
+ free_bootmem(__pa(reserve_end) + bootmap_size,
+ len - bootmap_size - reserve);
+}
+
+int phys_mapping(unsigned long phys, unsigned long long *offset_out)
+{
+ int fd = -1;
+
+ if (phys < physmem_size) {
+ fd = physmem_fd;
+ *offset_out = phys;
+ }
+ else if (phys < __pa(end_iomem)) {
+ struct iomem_region *region = iomem_regions;
+
+ while (region != NULL) {
+ if ((phys >= region->phys) &&
+ (phys < region->phys + region->size)) {
+ fd = region->fd;
+ *offset_out = phys - region->phys;
+ break;
+ }
+ region = region->next;
+ }
+ }
+ else if (phys < __pa(end_iomem) + highmem) {
+ fd = physmem_fd;
+ *offset_out = phys - iomem_size;
+ }
+
+ return fd;
+}
+
+static int __init uml_mem_setup(char *line, int *add)
+{
+ char *retptr;
+ physmem_size = memparse(line,&retptr);
+ return 0;
+}
+__uml_setup("mem=", uml_mem_setup,
+"mem=<Amount of desired ram>\n"
+" This controls how much \"physical\" memory the kernel allocates\n"
+" for the system. The size is specified as a number followed by\n"
+" one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
+" This is not related to the amount of memory in the host. It can\n"
+" be more, and the excess, if it's ever used, will just be swapped out.\n"
+" Example: mem=64M\n\n"
+);
+
+extern int __init parse_iomem(char *str, int *add);
+
+__uml_setup("iomem=", parse_iomem,
+"iomem=<name>,<file>\n"
+" Configure <file> as an IO memory region named <name>.\n\n"
+);
+
+/*
+ * This list is constructed in parse_iomem and addresses filled in in
+ * setup_iomem, both of which run during early boot. Afterwards, it's
+ * unchanged.
+ */
+struct iomem_region *iomem_regions;
+
+/* Initialized in parse_iomem and unchanged thereafter */
+int iomem_size;
+
+unsigned long find_iomem(char *driver, unsigned long *len_out)
+{
+ struct iomem_region *region = iomem_regions;
+
+ while (region != NULL) {
+ if (!strcmp(region->driver, driver)) {
+ *len_out = region->size;
+ return region->virt;
+ }
+
+ region = region->next;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(find_iomem);
+
+static int setup_iomem(void)
+{
+ struct iomem_region *region = iomem_regions;
+ unsigned long iomem_start = high_physmem + PAGE_SIZE;
+ int err;
+
+ while (region != NULL) {
+ err = os_map_memory((void *) iomem_start, region->fd, 0,
+ region->size, 1, 1, 0);
+ if (err)
+ printk(KERN_ERR "Mapping iomem region for driver '%s' "
+ "failed, errno = %d\n", region->driver, -err);
+ else {
+ region->virt = iomem_start;
+ region->phys = __pa(region->virt);
+ }
+
+ iomem_start += region->size + PAGE_SIZE;
+ region = region->next;
+ }
+
+ return 0;
+}
+
+__initcall(setup_iomem);