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 * To prevent the compiler from emitting GOT-indirected (and thus absolute) 11 * references to the section markers, override their visibility as 'hidden' 12 */ 13 #pragma GCC visibility push(hidden) 14 #include <asm/sections.h> 15 #pragma GCC visibility pop 16 17 #include <linux/efi.h> 18 #include <asm/efi.h> 19 #include <asm/memory.h> 20 #include <asm/sysreg.h> 21 22 #include "efistub.h" 23 24 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg) 25 { 26 u64 tg; 27 28 /* UEFI mandates support for 4 KB granularity, no need to check */ 29 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES)) 30 return EFI_SUCCESS; 31 32 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf; 33 if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) { 34 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) 35 pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n"); 36 else 37 pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n"); 38 return EFI_UNSUPPORTED; 39 } 40 return EFI_SUCCESS; 41 } 42 43 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg, 44 unsigned long *image_addr, 45 unsigned long *image_size, 46 unsigned long *reserve_addr, 47 unsigned long *reserve_size, 48 unsigned long dram_base, 49 efi_loaded_image_t *image) 50 { 51 efi_status_t status; 52 unsigned long kernel_size, kernel_memsize = 0; 53 void *old_image_addr = (void *)*image_addr; 54 unsigned long preferred_offset; 55 u64 phys_seed = 0; 56 57 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 58 if (!nokaslr()) { 59 status = efi_get_random_bytes(sys_table_arg, 60 sizeof(phys_seed), 61 (u8 *)&phys_seed); 62 if (status == EFI_NOT_FOUND) { 63 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n"); 64 } else if (status != EFI_SUCCESS) { 65 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n"); 66 return status; 67 } 68 } else { 69 pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n"); 70 } 71 } 72 73 /* 74 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond 75 * a 2 MB aligned base, which itself may be lower than dram_base, as 76 * long as the resulting offset equals or exceeds it. 77 */ 78 preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET; 79 if (preferred_offset < dram_base) 80 preferred_offset += MIN_KIMG_ALIGN; 81 82 kernel_size = _edata - _text; 83 kernel_memsize = kernel_size + (_end - _edata); 84 85 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 86 /* 87 * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a 88 * displacement in the interval [0, MIN_KIMG_ALIGN) that 89 * doesn't violate this kernel's de-facto alignment 90 * constraints. 91 */ 92 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(EFI_KIMG_ALIGN - 1); 93 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ? 94 (phys_seed >> 32) & mask : TEXT_OFFSET; 95 96 /* 97 * With CONFIG_RANDOMIZE_TEXT_OFFSET=y, TEXT_OFFSET may not 98 * be a multiple of EFI_KIMG_ALIGN, and we must ensure that 99 * we preserve the misalignment of 'offset' relative to 100 * EFI_KIMG_ALIGN so that statically allocated objects whose 101 * alignment exceeds PAGE_SIZE appear correctly aligned in 102 * memory. 103 */ 104 offset |= TEXT_OFFSET % EFI_KIMG_ALIGN; 105 106 /* 107 * If KASLR is enabled, and we have some randomness available, 108 * locate the kernel at a randomized offset in physical memory. 109 */ 110 *reserve_size = kernel_memsize + offset; 111 status = efi_random_alloc(sys_table_arg, *reserve_size, 112 MIN_KIMG_ALIGN, reserve_addr, 113 (u32)phys_seed); 114 115 *image_addr = *reserve_addr + offset; 116 } else { 117 /* 118 * Else, try a straight allocation at the preferred offset. 119 * This will work around the issue where, if dram_base == 0x0, 120 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the 121 * address of the allocation to be mistaken for a FAIL return 122 * value or a NULL pointer). It will also ensure that, on 123 * platforms where the [dram_base, dram_base + TEXT_OFFSET) 124 * interval is partially occupied by the firmware (like on APM 125 * Mustang), we can still place the kernel at the address 126 * 'dram_base + TEXT_OFFSET'. 127 */ 128 if (*image_addr == preferred_offset) 129 return EFI_SUCCESS; 130 131 *image_addr = *reserve_addr = preferred_offset; 132 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); 133 134 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 135 EFI_LOADER_DATA, 136 *reserve_size / EFI_PAGE_SIZE, 137 (efi_physical_addr_t *)reserve_addr); 138 } 139 140 if (status != EFI_SUCCESS) { 141 *reserve_size = kernel_memsize + TEXT_OFFSET; 142 status = efi_low_alloc(sys_table_arg, *reserve_size, 143 MIN_KIMG_ALIGN, reserve_addr); 144 145 if (status != EFI_SUCCESS) { 146 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n"); 147 *reserve_size = 0; 148 return status; 149 } 150 *image_addr = *reserve_addr + TEXT_OFFSET; 151 } 152 memcpy((void *)*image_addr, old_image_addr, kernel_size); 153 154 return EFI_SUCCESS; 155 } 156