arch/um/kernel/physmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/memblock.h>
   8 #include <linux/mm.h>
   9 #include <linux/pfn.h>
  10 #include <asm/page.h>
  11 #include <asm/sections.h>
  12 #include <as-layout.h>
  13 #include <init.h>
  14 #include <kern.h>
  15 #include <mem_user.h>
  16 #include <os.h>
  17
  18 static int physmem_fd = -1;
  19
  20 /* Changed during early boot */
  21 unsigned long high_physmem;
  22 EXPORT_SYMBOL(high_physmem);
  23
  24 extern unsigned long long physmem_size;
  25
  26 void __init mem_total_pages(unsigned long physmem, unsigned long iomem,
  27                      unsigned long highmem)
  28 {
  29         unsigned long phys_pages, highmem_pages;
  30         unsigned long iomem_pages, total_pages;
  31
  32         phys_pages    = physmem >> PAGE_SHIFT;
  33         iomem_pages   = iomem   >> PAGE_SHIFT;
  34         highmem_pages = highmem >> PAGE_SHIFT;
  35
  36         total_pages   = phys_pages + iomem_pages + highmem_pages;
  37
  38         max_mapnr = total_pages;
  39 }
  40
  41 void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
  42                 int r, int w, int x)
  43 {
  44         __u64 offset;
  45         int fd, err;
  46
  47         fd = phys_mapping(phys, &offset);
  48         err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
  49         if (err) {
  50                 if (err == -ENOMEM)
  51                         printk(KERN_ERR "try increasing the host's "
  52                                "/proc/sys/vm/max_map_count to <physical "
  53                                "memory size>/4096\n");
  54                 panic("map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
  55                       "err = %d\n", virt, fd, offset, len, r, w, x, err);
  56         }
  57 }
  58
  59 /**
  60  * setup_physmem() - Setup physical memory for UML
  61  * @start:      Start address of the physical kernel memory,
  62  *              i.e start address of the executable image.
  63  * @reserve_end:        end address of the physical kernel memory.
  64  * @len:        Length of total physical memory that should be mapped/made
  65  *              available, in bytes.
  66  * @highmem:    Number of highmem bytes that should be mapped/made available.
  67  *
  68  * Creates an unlinked temporary file of size (len + highmem) and memory maps
  69  * it on the last executable image address (uml_reserved).
  70  *
  71  * The offset is needed as the length of the total physical memory
  72  * (len + highmem) includes the size of the memory used be the executable image,
  73  * but the mapped-to address is the last address of the executable image
  74  * (uml_reserved == end address of executable image).
  75  *
  76  * The memory mapped memory of the temporary file is used as backing memory
  77  * of all user space processes/kernel tasks.
  78  */
  79 void __init setup_physmem(unsigned long start, unsigned long reserve_end,
  80                           unsigned long len, unsigned long long highmem)
  81 {
  82         unsigned long reserve = reserve_end - start;
  83         long map_size = len - reserve;
  84         int err;
  85
  86         if(map_size <= 0) {
  87                 os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
  88                         reserve, len);
  89                 exit(1);
  90         }
  91
  92         physmem_fd = create_mem_file(len + highmem);
  93
  94         err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
  95                             map_size, 1, 1, 1);
  96         if (err < 0) {
  97                 os_warn("setup_physmem - mapping %ld bytes of memory at 0x%p "
  98                         "failed - errno = %d\n", map_size,
  99                         (void *) reserve_end, err);
 100                 exit(1);
 101         }
 102
 103         /*
 104          * Special kludge - This page will be mapped in to userspace processes
 105          * from physmem_fd, so it needs to be written out there.
 106          */
 107         os_seek_file(physmem_fd, __pa(__syscall_stub_start));
 108         os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
 109         os_fsync_file(physmem_fd);
 110
 111         memblock_add(__pa(start), len + highmem);
 112         memblock_reserve(__pa(start), reserve);
 113
 114         min_low_pfn = PFN_UP(__pa(reserve_end));
 115         max_low_pfn = min_low_pfn + (map_size >> PAGE_SHIFT);
 116 }
 117
 118 int phys_mapping(unsigned long phys, unsigned long long *offset_out)
 119 {
 120         int fd = -1;
 121
 122         if (phys < physmem_size) {
 123                 fd = physmem_fd;
 124                 *offset_out = phys;
 125         }
 126         else if (phys < __pa(end_iomem)) {
 127                 struct iomem_region *region = iomem_regions;
 128
 129                 while (region != NULL) {
 130                         if ((phys >= region->phys) &&
 131                             (phys < region->phys + region->size)) {
 132                                 fd = region->fd;
 133                                 *offset_out = phys - region->phys;
 134                                 break;
 135                         }
 136                         region = region->next;
 137                 }
 138         }
 139         else if (phys < __pa(end_iomem) + highmem) {
 140                 fd = physmem_fd;
 141                 *offset_out = phys - iomem_size;
 142         }
 143
 144         return fd;
 145 }
 146 EXPORT_SYMBOL(phys_mapping);
 147
 148 static int __init uml_mem_setup(char *line, int *add)
 149 {
 150         char *retptr;
 151         physmem_size = memparse(line,&retptr);
 152         return 0;
 153 }
 154 __uml_setup("mem=", uml_mem_setup,
 155 "mem=<Amount of desired ram>\n"
 156 "    This controls how much \"physical\" memory the kernel allocates\n"
 157 "    for the system. The size is specified as a number followed by\n"
 158 "    one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
 159 "    This is not related to the amount of memory in the host.  It can\n"
 160 "    be more, and the excess, if it's ever used, will just be swapped out.\n"
 161 "       Example: mem=64M\n\n"
 162 );
 163
 164 extern int __init parse_iomem(char *str, int *add);
 165
 166 __uml_setup("iomem=", parse_iomem,
 167 "iomem=<name>,<file>\n"
 168 "    Configure <file> as an IO memory region named <name>.\n\n"
 169 );
 170
 171 /*
 172  * This list is constructed in parse_iomem and addresses filled in in
 173  * setup_iomem, both of which run during early boot.  Afterwards, it's
 174  * unchanged.
 175  */
 176 struct iomem_region *iomem_regions;
 177
 178 /* Initialized in parse_iomem and unchanged thereafter */
 179 int iomem_size;
 180
 181 unsigned long find_iomem(char *driver, unsigned long *len_out)
 182 {
 183         struct iomem_region *region = iomem_regions;
 184
 185         while (region != NULL) {
 186                 if (!strcmp(region->driver, driver)) {
 187                         *len_out = region->size;
 188                         return region->virt;
 189                 }
 190
 191                 region = region->next;
 192         }
 193
 194         return 0;
 195 }
 196 EXPORT_SYMBOL(find_iomem);
 197
 198 static int setup_iomem(void)
 199 {
 200         struct iomem_region *region = iomem_regions;
 201         unsigned long iomem_start = high_physmem + PAGE_SIZE;
 202         int err;
 203
 204         while (region != NULL) {
 205                 err = os_map_memory((void *) iomem_start, region->fd, 0,
 206                                     region->size, 1, 1, 0);
 207                 if (err)
 208                         printk(KERN_ERR "Mapping iomem region for driver '%s' "
 209                                "failed, errno = %d\n", region->driver, -err);
 210                 else {
 211                         region->virt = iomem_start;
 212                         region->phys = __pa(region->virt);
 213                 }
 214
 215                 iomem_start += region->size + PAGE_SIZE;
 216                 region = region->next;
 217         }
 218
 219         return 0;
 220 }
 221
 222 __initcall(setup_iomem);