arch/arm64/kernel/efi-stub.c

   1 /*
   2  * Copyright (C) 2013, 2014 Linaro Ltd;  <roy.franz@linaro.org>
   3  *
   4  * This file implements the EFI boot stub for the arm64 kernel.
   5  * Adapted from ARM version by Mark Salter <msalter@redhat.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12 #include <linux/efi.h>
  13 #include <asm/efi.h>
  14 #include <asm/sections.h>
  15
  16 efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
  17                                         unsigned long *image_addr,
  18                                         unsigned long *image_size,
  19                                         unsigned long *reserve_addr,
  20                                         unsigned long *reserve_size,
  21                                         unsigned long dram_base,
  22                                         efi_loaded_image_t *image)
  23 {
  24         efi_status_t status;
  25         unsigned long kernel_size, kernel_memsize = 0;
  26         unsigned long nr_pages;
  27         void *old_image_addr = (void *)*image_addr;
  28         unsigned long preferred_offset;
  29
  30         /*
  31          * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
  32          * a 2 MB aligned base, which itself may be lower than dram_base, as
  33          * long as the resulting offset equals or exceeds it.
  34          */
  35         preferred_offset = round_down(dram_base, SZ_2M) + TEXT_OFFSET;
  36         if (preferred_offset < dram_base)
  37                 preferred_offset += SZ_2M;
  38
  39         /* Relocate the image, if required. */
  40         kernel_size = _edata - _text;
  41         if (*image_addr != preferred_offset) {
  42                 kernel_memsize = kernel_size + (_end - _edata);
  43
  44                 /*
  45                  * First, try a straight allocation at the preferred offset.
  46                  * This will work around the issue where, if dram_base == 0x0,
  47                  * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
  48                  * address of the allocation to be mistaken for a FAIL return
  49                  * value or a NULL pointer). It will also ensure that, on
  50                  * platforms where the [dram_base, dram_base + TEXT_OFFSET)
  51                  * interval is partially occupied by the firmware (like on APM
  52                  * Mustang), we can still place the kernel at the address
  53                  * 'dram_base + TEXT_OFFSET'.
  54                  */
  55                 *image_addr = *reserve_addr = preferred_offset;
  56                 nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
  57                            EFI_PAGE_SIZE;
  58                 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
  59                                         EFI_LOADER_DATA, nr_pages,
  60                                         (efi_physical_addr_t *)reserve_addr);
  61                 if (status != EFI_SUCCESS) {
  62                         kernel_memsize += TEXT_OFFSET;
  63                         status = efi_low_alloc(sys_table_arg, kernel_memsize,
  64                                                SZ_2M, reserve_addr);
  65
  66                         if (status != EFI_SUCCESS) {
  67                                 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
  68                                 return status;
  69                         }
  70                         *image_addr = *reserve_addr + TEXT_OFFSET;
  71                 }
  72                 memcpy((void *)*image_addr, old_image_addr, kernel_size);
  73                 *reserve_size = kernel_memsize;
  74         }
  75
  76
  77         return EFI_SUCCESS;
  78 }