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 } 116