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 15 #include "efistub.h" 16 17 /* 18 * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail 19 * to provide space, and fail to zero it). Check for this condition by double 20 * checking that the first and the last byte of the image are covered by the 21 * same EFI memory map entry. 22 */ 23 static bool check_image_region(u64 base, u64 size) 24 { 25 struct efi_boot_memmap *map; 26 efi_status_t status; 27 bool ret = false; 28 int map_offset; 29 30 status = efi_get_memory_map(&map, false); 31 if (status != EFI_SUCCESS) 32 return false; 33 34 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { 35 efi_memory_desc_t *md = (void *)map->map + map_offset; 36 u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; 37 38 /* 39 * Find the region that covers base, and return whether 40 * it covers base+size bytes. 41 */ 42 if (base >= md->phys_addr && base < end) { 43 ret = (base + size) <= end; 44 break; 45 } 46 } 47 48 efi_bs_call(free_pool, map); 49 50 return ret; 51 } 52 53 efi_status_t handle_kernel_image(unsigned long *image_addr, 54 unsigned long *image_size, 55 unsigned long *reserve_addr, 56 unsigned long *reserve_size, 57 efi_loaded_image_t *image, 58 efi_handle_t image_handle) 59 { 60 efi_status_t status; 61 unsigned long kernel_size, kernel_memsize = 0; 62 u32 phys_seed = 0; 63 u64 min_kimg_align = efi_get_kimg_min_align(); 64 65 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 66 efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; 67 void *p; 68 69 if (efi_nokaslr) { 70 efi_info("KASLR disabled on kernel command line\n"); 71 } else if (efi_bs_call(handle_protocol, image_handle, 72 &li_fixed_proto, &p) == EFI_SUCCESS) { 73 efi_info("Image placement fixed by loader\n"); 74 } else { 75 status = efi_get_random_bytes(sizeof(phys_seed), 76 (u8 *)&phys_seed); 77 if (status == EFI_NOT_FOUND) { 78 efi_info("EFI_RNG_PROTOCOL unavailable\n"); 79 efi_nokaslr = true; 80 } else if (status != EFI_SUCCESS) { 81 efi_err("efi_get_random_bytes() failed (0x%lx)\n", 82 status); 83 efi_nokaslr = true; 84 } 85 } 86 } 87 88 if (image->image_base != _text) 89 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); 90 91 if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN)) 92 efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n", 93 SEGMENT_ALIGN >> 10); 94 95 kernel_size = _edata - _text; 96 kernel_memsize = kernel_size + (_end - _edata); 97 *reserve_size = kernel_memsize; 98 99 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 100 /* 101 * If KASLR is enabled, and we have some randomness available, 102 * locate the kernel at a randomized offset in physical memory. 103 */ 104 status = efi_random_alloc(*reserve_size, min_kimg_align, 105 reserve_addr, phys_seed, 106 EFI_LOADER_CODE); 107 if (status != EFI_SUCCESS) 108 efi_warn("efi_random_alloc() failed: 0x%lx\n", status); 109 } else { 110 status = EFI_OUT_OF_RESOURCES; 111 } 112 113 if (status != EFI_SUCCESS) { 114 if (!check_image_region((u64)_text, kernel_memsize)) { 115 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); 116 } else if (IS_ALIGNED((u64)_text, min_kimg_align) && 117 (u64)_end < EFI_ALLOC_LIMIT) { 118 /* 119 * Just execute from wherever we were loaded by the 120 * UEFI PE/COFF loader if the placement is suitable. 121 */ 122 *image_addr = (u64)_text; 123 *reserve_size = 0; 124 goto clean_image_to_poc; 125 } 126 127 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, 128 ULONG_MAX, min_kimg_align, 129 EFI_LOADER_CODE); 130 131 if (status != EFI_SUCCESS) { 132 efi_err("Failed to relocate kernel\n"); 133 *reserve_size = 0; 134 return status; 135 } 136 } 137 138 *image_addr = *reserve_addr; 139 memcpy((void *)*image_addr, _text, kernel_size); 140 141 clean_image_to_poc: 142 /* 143 * Clean the copied Image to the PoC, and ensure it is not shadowed by 144 * stale icache entries from before relocation. 145 */ 146 dcache_clean_poc(*image_addr, *image_addr + kernel_size); 147 asm("ic ialluis"); 148 149 return EFI_SUCCESS; 150 } 151