drivers/firmware/efi/libstub/mem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/efi.h>
   4 #include <asm/efi.h>
   5
   6 #include "efistub.h"
   7
   8 static inline bool mmap_has_headroom(unsigned long buff_size,
   9                                      unsigned long map_size,
  10                                      unsigned long desc_size)
  11 {
  12         unsigned long slack = buff_size - map_size;
  13
  14         return slack / desc_size >= EFI_MMAP_NR_SLACK_SLOTS;
  15 }
  16
  17 /**
  18  * efi_get_memory_map() - get memory map
  19  * @map:        on return pointer to memory map
  20  *
  21  * Retrieve the UEFI memory map. The allocated memory leaves room for
  22  * up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries.
  23  *
  24  * Return:      status code
  25  */
  26 efi_status_t efi_get_memory_map(struct efi_boot_memmap *map)
  27 {
  28         efi_memory_desc_t *m = NULL;
  29         efi_status_t status;
  30         unsigned long key;
  31         u32 desc_version;
  32
  33         *map->desc_size =       sizeof(*m);
  34         *map->map_size =        *map->desc_size * 32;
  35         *map->buff_size =       *map->map_size;
  36 again:
  37         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
  38                              *map->map_size, (void **)&m);
  39         if (status != EFI_SUCCESS)
  40                 goto fail;
  41
  42         *map->desc_size = 0;
  43         key = 0;
  44         status = efi_bs_call(get_memory_map, map->map_size, m,
  45                              &key, map->desc_size, &desc_version);
  46         if (status == EFI_BUFFER_TOO_SMALL ||
  47             !mmap_has_headroom(*map->buff_size, *map->map_size,
  48                                *map->desc_size)) {
  49                 efi_bs_call(free_pool, m);
  50                 /*
  51                  * Make sure there is some entries of headroom so that the
  52                  * buffer can be reused for a new map after allocations are
  53                  * no longer permitted.  Its unlikely that the map will grow to
  54                  * exceed this headroom once we are ready to trigger
  55                  * ExitBootServices()
  56                  */
  57                 *map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS;
  58                 *map->buff_size = *map->map_size;
  59                 goto again;
  60         }
  61
  62         if (status == EFI_SUCCESS) {
  63                 if (map->key_ptr)
  64                         *map->key_ptr = key;
  65                 if (map->desc_ver)
  66                         *map->desc_ver = desc_version;
  67         } else {
  68                 efi_bs_call(free_pool, m);
  69         }
  70
  71 fail:
  72         *map->map = m;
  73         return status;
  74 }
  75
  76 /**
  77  * efi_allocate_pages() - Allocate memory pages
  78  * @size:       minimum number of bytes to allocate
  79  * @addr:       On return the address of the first allocated page. The first
  80  *              allocated page has alignment EFI_ALLOC_ALIGN which is an
  81  *              architecture dependent multiple of the page size.
  82  * @max:        the address that the last allocated memory page shall not
  83  *              exceed
  84  *
  85  * Allocate pages as EFI_LOADER_DATA. The allocated pages are aligned according
  86  * to EFI_ALLOC_ALIGN. The last allocated page will not exceed the address
  87  * given by @max.
  88  *
  89  * Return:      status code
  90  */
  91 efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
  92                                 unsigned long max)
  93 {
  94         efi_physical_addr_t alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
  95         int slack = EFI_ALLOC_ALIGN / EFI_PAGE_SIZE - 1;
  96         efi_status_t status;
  97
  98         size = round_up(size, EFI_ALLOC_ALIGN);
  99         status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
 100                              EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,
 101                              &alloc_addr);
 102         if (status != EFI_SUCCESS)
 103                 return status;
 104
 105         *addr = ALIGN((unsigned long)alloc_addr, EFI_ALLOC_ALIGN);
 106
 107         if (slack > 0) {
 108                 int l = (alloc_addr % EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
 109
 110                 if (l) {
 111                         efi_bs_call(free_pages, alloc_addr, slack - l + 1);
 112                         slack = l - 1;
 113                 }
 114                 if (slack)
 115                         efi_bs_call(free_pages, *addr + size, slack);
 116         }
 117         return EFI_SUCCESS;
 118 }
 119 /**
 120  * efi_low_alloc_above() - allocate pages at or above given address
 121  * @size:       size of the memory area to allocate
 122  * @align:      minimum alignment of the allocated memory area. It should
 123  *              a power of two.
 124  * @addr:       on exit the address of the allocated memory
 125  * @min:        minimum address to used for the memory allocation
 126  *
 127  * Allocate at the lowest possible address that is not below @min as
 128  * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
 129  * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
 130  * given by @min.
 131  *
 132  * Return:      status code
 133  */
 134 efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
 135                                  unsigned long *addr, unsigned long min)
 136 {
 137         unsigned long map_size, desc_size, buff_size;
 138         efi_memory_desc_t *map;
 139         efi_status_t status;
 140         unsigned long nr_pages;
 141         int i;
 142         struct efi_boot_memmap boot_map;
 143
 144         boot_map.map            = &map;
 145         boot_map.map_size       = &map_size;
 146         boot_map.desc_size      = &desc_size;
 147         boot_map.desc_ver       = NULL;
 148         boot_map.key_ptr        = NULL;
 149         boot_map.buff_size      = &buff_size;
 150
 151         status = efi_get_memory_map(&boot_map);
 152         if (status != EFI_SUCCESS)
 153                 goto fail;
 154
 155         /*
 156          * Enforce minimum alignment that EFI or Linux requires when
 157          * requesting a specific address.  We are doing page-based (or
 158          * larger) allocations, and both the address and size must meet
 159          * alignment constraints.
 160          */
 161         if (align < EFI_ALLOC_ALIGN)
 162                 align = EFI_ALLOC_ALIGN;
 163
 164         size = round_up(size, EFI_ALLOC_ALIGN);
 165         nr_pages = size / EFI_PAGE_SIZE;
 166         for (i = 0; i < map_size / desc_size; i++) {
 167                 efi_memory_desc_t *desc;
 168                 unsigned long m = (unsigned long)map;
 169                 u64 start, end;
 170
 171                 desc = efi_early_memdesc_ptr(m, desc_size, i);
 172
 173                 if (desc->type != EFI_CONVENTIONAL_MEMORY)
 174                         continue;
 175
 176                 if (efi_soft_reserve_enabled() &&
 177                     (desc->attribute & EFI_MEMORY_SP))
 178                         continue;
 179
 180                 if (desc->num_pages < nr_pages)
 181                         continue;
 182
 183                 start = desc->phys_addr;
 184                 end = start + desc->num_pages * EFI_PAGE_SIZE;
 185
 186                 if (start < min)
 187                         start = min;
 188
 189                 start = round_up(start, align);
 190                 if ((start + size) > end)
 191                         continue;
 192
 193                 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
 194                                      EFI_LOADER_DATA, nr_pages, &start);
 195                 if (status == EFI_SUCCESS) {
 196                         *addr = start;
 197                         break;
 198                 }
 199         }
 200
 201         if (i == map_size / desc_size)
 202                 status = EFI_NOT_FOUND;
 203
 204         efi_bs_call(free_pool, map);
 205 fail:
 206         return status;
 207 }
 208
 209 /**
 210  * efi_free() - free memory pages
 211  * @size:       size of the memory area to free in bytes
 212  * @addr:       start of the memory area to free (must be EFI_PAGE_SIZE
 213  *              aligned)
 214  *
 215  * @size is rounded up to a multiple of EFI_ALLOC_ALIGN which is an
 216  * architecture specific multiple of EFI_PAGE_SIZE. So this function should
 217  * only be used to return pages allocated with efi_allocate_pages() or
 218  * efi_low_alloc_above().
 219  */
 220 void efi_free(unsigned long size, unsigned long addr)
 221 {
 222         unsigned long nr_pages;
 223
 224         if (!size)
 225                 return;
 226
 227         nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
 228         efi_bs_call(free_pages, addr, nr_pages);
 229 }
 230
 231 /**
 232  * efi_relocate_kernel() - copy memory area
 233  * @image_addr:         pointer to address of memory area to copy
 234  * @image_size:         size of memory area to copy
 235  * @alloc_size:         minimum size of memory to allocate, must be greater or
 236  *                      equal to image_size
 237  * @preferred_addr:     preferred target address
 238  * @alignment:          minimum alignment of the allocated memory area. It
 239  *                      should be a power of two.
 240  * @min_addr:           minimum target address
 241  *
 242  * Copy a memory area to a newly allocated memory area aligned according
 243  * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
 244  * is not available, the allocated address will not be below @min_addr.
 245  * On exit, @image_addr is updated to the target copy address that was used.
 246  *
 247  * This function is used to copy the Linux kernel verbatim. It does not apply
 248  * any relocation changes.
 249  *
 250  * Return:              status code
 251  */
 252 efi_status_t efi_relocate_kernel(unsigned long *image_addr,
 253                                  unsigned long image_size,
 254                                  unsigned long alloc_size,
 255                                  unsigned long preferred_addr,
 256                                  unsigned long alignment,
 257                                  unsigned long min_addr)
 258 {
 259         unsigned long cur_image_addr;
 260         unsigned long new_addr = 0;
 261         efi_status_t status;
 262         unsigned long nr_pages;
 263         efi_physical_addr_t efi_addr = preferred_addr;
 264
 265         if (!image_addr || !image_size || !alloc_size)
 266                 return EFI_INVALID_PARAMETER;
 267         if (alloc_size < image_size)
 268                 return EFI_INVALID_PARAMETER;
 269
 270         cur_image_addr = *image_addr;
 271
 272         /*
 273          * The EFI firmware loader could have placed the kernel image
 274          * anywhere in memory, but the kernel has restrictions on the
 275          * max physical address it can run at.  Some architectures
 276          * also have a prefered address, so first try to relocate
 277          * to the preferred address.  If that fails, allocate as low
 278          * as possible while respecting the required alignment.
 279          */
 280         nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
 281         status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
 282                              EFI_LOADER_DATA, nr_pages, &efi_addr);
 283         new_addr = efi_addr;
 284         /*
 285          * If preferred address allocation failed allocate as low as
 286          * possible.
 287          */
 288         if (status != EFI_SUCCESS) {
 289                 status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
 290                                              min_addr);
 291         }
 292         if (status != EFI_SUCCESS) {
 293                 pr_efi_err("Failed to allocate usable memory for kernel.\n");
 294                 return status;
 295         }
 296
 297         /*
 298          * We know source/dest won't overlap since both memory ranges
 299          * have been allocated by UEFI, so we can safely use memcpy.
 300          */
 301         memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
 302
 303         /* Return the new address of the relocated image. */
 304         *image_addr = new_addr;
 305
 306         return status;
 307 }