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 * Although relocatable kernels can fix up the misalignment with respect to 39 * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of 40 * sync with those recorded in the vmlinux when kaslr is disabled but the 41 * image required relocation anyway. Therefore retain 2M alignment unless 42 * KASLR is in use. 43 */ 44 static u64 min_kimg_align(void) 45 { 46 return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; 47 } 48 49 efi_status_t handle_kernel_image(unsigned long *image_addr, 50 unsigned long *image_size, 51 unsigned long *reserve_addr, 52 unsigned long *reserve_size, 53 efi_loaded_image_t *image) 54 { 55 efi_status_t status; 56 unsigned long kernel_size, kernel_memsize = 0; 57 u32 phys_seed = 0; 58 59 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 60 if (!efi_nokaslr) { 61 status = efi_get_random_bytes(sizeof(phys_seed), 62 (u8 *)&phys_seed); 63 if (status == EFI_NOT_FOUND) { 64 efi_info("EFI_RNG_PROTOCOL unavailable\n"); 65 efi_nokaslr = true; 66 } else if (status != EFI_SUCCESS) { 67 efi_err("efi_get_random_bytes() failed (0x%lx)\n", 68 status); 69 efi_nokaslr = true; 70 } 71 } else { 72 efi_info("KASLR disabled on kernel command line\n"); 73 } 74 } 75 76 if (image->image_base != _text) 77 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); 78 79 kernel_size = _edata - _text; 80 kernel_memsize = kernel_size + (_end - _edata); 81 *reserve_size = kernel_memsize; 82 83 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 84 /* 85 * If KASLR is enabled, and we have some randomness available, 86 * locate the kernel at a randomized offset in physical memory. 87 */ 88 status = efi_random_alloc(*reserve_size, min_kimg_align(), 89 reserve_addr, phys_seed); 90 } else { 91 status = EFI_OUT_OF_RESOURCES; 92 } 93 94 if (status != EFI_SUCCESS) { 95 if (IS_ALIGNED((u64)_text, min_kimg_align())) { 96 /* 97 * Just execute from wherever we were loaded by the 98 * UEFI PE/COFF loader if the alignment is suitable. 99 */ 100 *image_addr = (u64)_text; 101 *reserve_size = 0; 102 return EFI_SUCCESS; 103 } 104 105 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, 106 ULONG_MAX, min_kimg_align()); 107 108 if (status != EFI_SUCCESS) { 109 efi_err("Failed to relocate kernel\n"); 110 *reserve_size = 0; 111 return status; 112 } 113 } 114 115 *image_addr = *reserve_addr; 116 memcpy((void *)*image_addr, _text, kernel_size); 117 118 return EFI_SUCCESS; 119 } 120