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_MIN || tg > ID_AA64MMFR0_TGRAN_SUPPORTED_MAX) { 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 * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail 39 * to provide space, and fail to zero it). Check for this condition by double 40 * checking that the first and the last byte of the image are covered by the 41 * same EFI memory map entry. 42 */ 43 static bool check_image_region(u64 base, u64 size) 44 { 45 unsigned long map_size, desc_size, buff_size; 46 efi_memory_desc_t *memory_map; 47 struct efi_boot_memmap map; 48 efi_status_t status; 49 bool ret = false; 50 int map_offset; 51 52 map.map = &memory_map; 53 map.map_size = &map_size; 54 map.desc_size = &desc_size; 55 map.desc_ver = NULL; 56 map.key_ptr = NULL; 57 map.buff_size = &buff_size; 58 59 status = efi_get_memory_map(&map); 60 if (status != EFI_SUCCESS) 61 return false; 62 63 for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { 64 efi_memory_desc_t *md = (void *)memory_map + map_offset; 65 u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; 66 67 /* 68 * Find the region that covers base, and return whether 69 * it covers base+size bytes. 70 */ 71 if (base >= md->phys_addr && base < end) { 72 ret = (base + size) <= end; 73 break; 74 } 75 } 76 77 efi_bs_call(free_pool, memory_map); 78 79 return ret; 80 } 81 82 efi_status_t handle_kernel_image(unsigned long *image_addr, 83 unsigned long *image_size, 84 unsigned long *reserve_addr, 85 unsigned long *reserve_size, 86 efi_loaded_image_t *image) 87 { 88 efi_status_t status; 89 unsigned long kernel_size, kernel_memsize = 0; 90 u32 phys_seed = 0; 91 92 /* 93 * Although relocatable kernels can fix up the misalignment with 94 * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are 95 * subtly out of sync with those recorded in the vmlinux when kaslr is 96 * disabled but the image required relocation anyway. Therefore retain 97 * 2M alignment if KASLR was explicitly disabled, even if it was not 98 * going to be activated to begin with. 99 */ 100 u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; 101 102 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 103 if (!efi_nokaslr) { 104 status = efi_get_random_bytes(sizeof(phys_seed), 105 (u8 *)&phys_seed); 106 if (status == EFI_NOT_FOUND) { 107 efi_info("EFI_RNG_PROTOCOL unavailable\n"); 108 efi_nokaslr = true; 109 } else if (status != EFI_SUCCESS) { 110 efi_err("efi_get_random_bytes() failed (0x%lx)\n", 111 status); 112 efi_nokaslr = true; 113 } 114 } else { 115 efi_info("KASLR disabled on kernel command line\n"); 116 } 117 } 118 119 if (image->image_base != _text) 120 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); 121 122 if (!IS_ALIGNED((u64)_text, EFI_KIMG_ALIGN)) 123 efi_err("FIRMWARE BUG: kernel image not aligned on %ldk boundary\n", 124 EFI_KIMG_ALIGN >> 10); 125 126 kernel_size = _edata - _text; 127 kernel_memsize = kernel_size + (_end - _edata); 128 *reserve_size = kernel_memsize; 129 130 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 131 /* 132 * If KASLR is enabled, and we have some randomness available, 133 * locate the kernel at a randomized offset in physical memory. 134 */ 135 status = efi_random_alloc(*reserve_size, min_kimg_align, 136 reserve_addr, phys_seed); 137 if (status != EFI_SUCCESS) 138 efi_warn("efi_random_alloc() failed: 0x%lx\n", status); 139 } else { 140 status = EFI_OUT_OF_RESOURCES; 141 } 142 143 if (status != EFI_SUCCESS) { 144 if (!check_image_region((u64)_text, kernel_memsize)) { 145 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); 146 } else if (IS_ALIGNED((u64)_text, min_kimg_align)) { 147 /* 148 * Just execute from wherever we were loaded by the 149 * UEFI PE/COFF loader if the alignment is suitable. 150 */ 151 *image_addr = (u64)_text; 152 *reserve_size = 0; 153 return EFI_SUCCESS; 154 } 155 156 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, 157 ULONG_MAX, min_kimg_align); 158 159 if (status != EFI_SUCCESS) { 160 efi_err("Failed to relocate kernel\n"); 161 *reserve_size = 0; 162 return status; 163 } 164 } 165 166 *image_addr = *reserve_addr; 167 memcpy((void *)*image_addr, _text, kernel_size); 168 169 return EFI_SUCCESS; 170 } 171