drivers/firmware/efi/libstub/relocate.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 /**
   9  * efi_low_alloc_above() - allocate pages at or above given address
  10  * @size:       size of the memory area to allocate
  11  * @align:      minimum alignment of the allocated memory area. It should
  12  *              a power of two.
  13  * @addr:       on exit the address of the allocated memory
  14  * @min:        minimum address to used for the memory allocation
  15  *
  16  * Allocate at the lowest possible address that is not below @min as
  17  * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
  18  * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
  19  * given by @min.
  20  *
  21  * Return:      status code
  22  */
  23 efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
  24                                  unsigned long *addr, unsigned long min)
  25 {
  26         struct efi_boot_memmap *map;
  27         efi_status_t status;
  28         unsigned long nr_pages;
  29         int i;
  30
  31         status = efi_get_memory_map(&map, false);
  32         if (status != EFI_SUCCESS)
  33                 goto fail;
  34
  35         /*
  36          * Enforce minimum alignment that EFI or Linux requires when
  37          * requesting a specific address.  We are doing page-based (or
  38          * larger) allocations, and both the address and size must meet
  39          * alignment constraints.
  40          */
  41         if (align < EFI_ALLOC_ALIGN)
  42                 align = EFI_ALLOC_ALIGN;
  43
  44         size = round_up(size, EFI_ALLOC_ALIGN);
  45         nr_pages = size / EFI_PAGE_SIZE;
  46         for (i = 0; i < map->map_size / map->desc_size; i++) {
  47                 efi_memory_desc_t *desc;
  48                 unsigned long m = (unsigned long)map->map;
  49                 u64 start, end;
  50
  51                 desc = efi_memdesc_ptr(m, map->desc_size, i);
  52
  53                 if (desc->type != EFI_CONVENTIONAL_MEMORY)
  54                         continue;
  55
  56                 if (efi_soft_reserve_enabled() &&
  57                     (desc->attribute & EFI_MEMORY_SP))
  58                         continue;
  59
  60                 if (desc->num_pages < nr_pages)
  61                         continue;
  62
  63                 start = desc->phys_addr;
  64                 end = start + desc->num_pages * EFI_PAGE_SIZE;
  65
  66                 if (start < min)
  67                         start = min;
  68
  69                 start = round_up(start, align);
  70                 if ((start + size) > end)
  71                         continue;
  72
  73                 status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
  74                                      EFI_LOADER_DATA, nr_pages, &start);
  75                 if (status == EFI_SUCCESS) {
  76                         *addr = start;
  77                         break;
  78                 }
  79         }
  80
  81         if (i == map->map_size / map->desc_size)
  82                 status = EFI_NOT_FOUND;
  83
  84         efi_bs_call(free_pool, map);
  85 fail:
  86         return status;
  87 }
  88
  89 /**
  90  * efi_relocate_kernel() - copy memory area
  91  * @image_addr:         pointer to address of memory area to copy
  92  * @image_size:         size of memory area to copy
  93  * @alloc_size:         minimum size of memory to allocate, must be greater or
  94  *                      equal to image_size
  95  * @preferred_addr:     preferred target address
  96  * @alignment:          minimum alignment of the allocated memory area. It
  97  *                      should be a power of two.
  98  * @min_addr:           minimum target address
  99  *
 100  * Copy a memory area to a newly allocated memory area aligned according
 101  * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
 102  * is not available, the allocated address will not be below @min_addr.
 103  * On exit, @image_addr is updated to the target copy address that was used.
 104  *
 105  * This function is used to copy the Linux kernel verbatim. It does not apply
 106  * any relocation changes.
 107  *
 108  * Return:              status code
 109  */
 110 efi_status_t efi_relocate_kernel(unsigned long *image_addr,
 111                                  unsigned long image_size,
 112                                  unsigned long alloc_size,
 113                                  unsigned long preferred_addr,
 114                                  unsigned long alignment,
 115                                  unsigned long min_addr)
 116 {
 117         unsigned long cur_image_addr;
 118         unsigned long new_addr = 0;
 119         efi_status_t status;
 120         unsigned long nr_pages;
 121         efi_physical_addr_t efi_addr = preferred_addr;
 122
 123         if (!image_addr || !image_size || !alloc_size)
 124                 return EFI_INVALID_PARAMETER;
 125         if (alloc_size < image_size)
 126                 return EFI_INVALID_PARAMETER;
 127
 128         cur_image_addr = *image_addr;
 129
 130         /*
 131          * The EFI firmware loader could have placed the kernel image
 132          * anywhere in memory, but the kernel has restrictions on the
 133          * max physical address it can run at.  Some architectures
 134          * also have a preferred address, so first try to relocate
 135          * to the preferred address.  If that fails, allocate as low
 136          * as possible while respecting the required alignment.
 137          */
 138         nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
 139         status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
 140                              EFI_LOADER_DATA, nr_pages, &efi_addr);
 141         new_addr = efi_addr;
 142         /*
 143          * If preferred address allocation failed allocate as low as
 144          * possible.
 145          */
 146         if (status != EFI_SUCCESS) {
 147                 status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
 148                                              min_addr);
 149         }
 150         if (status != EFI_SUCCESS) {
 151                 efi_err("Failed to allocate usable memory for kernel.\n");
 152                 return status;
 153         }
 154
 155         /*
 156          * We know source/dest won't overlap since both memory ranges
 157          * have been allocated by UEFI, so we can safely use memcpy.
 158          */
 159         memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
 160
 161         /* Return the new address of the relocated image. */
 162         *image_addr = new_addr;
 163
 164         return status;
 165 }