drivers/firmware/efi/libstub/arm64-stub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013, 2014 Linaro Ltd;  <roy.franz@linaro.org>
   4  *
   5  * This file implements the EFI boot stub for the arm64 kernel.
   6  * Adapted from ARM version by Mark Salter <msalter@redhat.com>
   7  */
   8
   9
  10 #include <linux/efi.h>
  11 #include <asm/efi.h>
  12 #include <asm/memory.h>
  13 #include <asm/sections.h>
  14 #include <asm/sysreg.h>
  15
  16 #include "efistub.h"
  17
  18 efi_status_t check_platform_features(void)
  19 {
  20         u64 tg;
  21
  22         /* UEFI mandates support for 4 KB granularity, no need to check */
  23         if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
  24                 return EFI_SUCCESS;
  25
  26         tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
  27         if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
  28                 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
  29                         efi_err("This 64 KB granular kernel is not supported by your CPU\n");
  30                 else
  31                         efi_err("This 16 KB granular kernel is not supported by your CPU\n");
  32                 return EFI_UNSUPPORTED;
  33         }
  34         return EFI_SUCCESS;
  35 }
  36
  37 /*
  38  * Relocatable kernels can fix up the misalignment with respect to
  39  * MIN_KIMG_ALIGN, so they only require a minimum alignment of EFI_KIMG_ALIGN
  40  * (which accounts for the alignment of statically allocated objects such as
  41  * the swapper stack.)
  42  */
  43 static const u64 min_kimg_align = IS_ENABLED(CONFIG_RELOCATABLE) ? EFI_KIMG_ALIGN
  44                                                                  : MIN_KIMG_ALIGN;
  45
  46 efi_status_t handle_kernel_image(unsigned long *image_addr,
  47                                  unsigned long *image_size,
  48                                  unsigned long *reserve_addr,
  49                                  unsigned long *reserve_size,
  50                                  unsigned long dram_base,
  51                                  efi_loaded_image_t *image)
  52 {
  53         efi_status_t status;
  54         unsigned long kernel_size, kernel_memsize = 0;
  55         u32 phys_seed = 0;
  56
  57         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
  58                 if (!efi_nokaslr) {
  59                         status = efi_get_random_bytes(sizeof(phys_seed),
  60                                                       (u8 *)&phys_seed);
  61                         if (status == EFI_NOT_FOUND) {
  62                                 efi_info("EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
  63                         } else if (status != EFI_SUCCESS) {
  64                                 efi_err("efi_get_random_bytes() failed\n");
  65                                 return status;
  66                         }
  67                 } else {
  68                         efi_info("KASLR disabled on kernel command line\n");
  69                 }
  70         }
  71
  72         if (image->image_base != _text)
  73                 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
  74
  75         kernel_size = _edata - _text;
  76         kernel_memsize = kernel_size + (_end - _edata);
  77         *reserve_size = kernel_memsize + TEXT_OFFSET % min_kimg_align;
  78
  79         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
  80                 /*
  81                  * If KASLR is enabled, and we have some randomness available,
  82                  * locate the kernel at a randomized offset in physical memory.
  83                  */
  84                 status = efi_random_alloc(*reserve_size, min_kimg_align,
  85                                           reserve_addr, phys_seed);
  86         } else {
  87                 status = EFI_OUT_OF_RESOURCES;
  88         }
  89
  90         if (status != EFI_SUCCESS) {
  91                 if (IS_ALIGNED((u64)_text - TEXT_OFFSET, min_kimg_align)) {
  92                         /*
  93                          * Just execute from wherever we were loaded by the
  94                          * UEFI PE/COFF loader if the alignment is suitable.
  95                          */
  96                         *image_addr = (u64)_text;
  97                         *reserve_size = 0;
  98                         return EFI_SUCCESS;
  99                 }
 100
 101                 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
 102                                                     ULONG_MAX, min_kimg_align);
 103
 104                 if (status != EFI_SUCCESS) {
 105                         efi_err("Failed to relocate kernel\n");
 106                         *reserve_size = 0;
 107                         return status;
 108                 }
 109         }
 110
 111         *image_addr = *reserve_addr + TEXT_OFFSET % min_kimg_align;
 112         memcpy((void *)*image_addr, _text, kernel_size);
 113
 114         return EFI_SUCCESS;
 115 }