1 /* 2 * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org> 3 * 4 * This file implements the EFI boot stub for the arm64 kernel. 5 * Adapted from ARM version by Mark Salter <msalter@redhat.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 */ 12 13 /* 14 * To prevent the compiler from emitting GOT-indirected (and thus absolute) 15 * references to the section markers, override their visibility as 'hidden' 16 */ 17 #pragma GCC visibility push(hidden) 18 #include <asm/sections.h> 19 #pragma GCC visibility pop 20 21 #include <linux/efi.h> 22 #include <asm/efi.h> 23 #include <asm/memory.h> 24 #include <asm/sysreg.h> 25 26 #include "efistub.h" 27 28 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg) 29 { 30 u64 tg; 31 32 /* UEFI mandates support for 4 KB granularity, no need to check */ 33 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES)) 34 return EFI_SUCCESS; 35 36 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf; 37 if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) { 38 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) 39 pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n"); 40 else 41 pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n"); 42 return EFI_UNSUPPORTED; 43 } 44 return EFI_SUCCESS; 45 } 46 47 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg, 48 unsigned long *image_addr, 49 unsigned long *image_size, 50 unsigned long *reserve_addr, 51 unsigned long *reserve_size, 52 unsigned long dram_base, 53 efi_loaded_image_t *image) 54 { 55 efi_status_t status; 56 unsigned long kernel_size, kernel_memsize = 0; 57 void *old_image_addr = (void *)*image_addr; 58 unsigned long preferred_offset; 59 u64 phys_seed = 0; 60 61 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 62 if (!nokaslr()) { 63 status = efi_get_random_bytes(sys_table_arg, 64 sizeof(phys_seed), 65 (u8 *)&phys_seed); 66 if (status == EFI_NOT_FOUND) { 67 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n"); 68 } else if (status != EFI_SUCCESS) { 69 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n"); 70 return status; 71 } 72 } else { 73 pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n"); 74 } 75 } 76 77 /* 78 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond 79 * a 2 MB aligned base, which itself may be lower than dram_base, as 80 * long as the resulting offset equals or exceeds it. 81 */ 82 preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET; 83 if (preferred_offset < dram_base) 84 preferred_offset += MIN_KIMG_ALIGN; 85 86 kernel_size = _edata - _text; 87 kernel_memsize = kernel_size + (_end - _edata); 88 89 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 90 /* 91 * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a 92 * displacement in the interval [0, MIN_KIMG_ALIGN) that 93 * doesn't violate this kernel's de-facto alignment 94 * constraints. 95 */ 96 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(EFI_KIMG_ALIGN - 1); 97 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ? 98 (phys_seed >> 32) & mask : TEXT_OFFSET; 99 100 /* 101 * With CONFIG_RANDOMIZE_TEXT_OFFSET=y, TEXT_OFFSET may not 102 * be a multiple of EFI_KIMG_ALIGN, and we must ensure that 103 * we preserve the misalignment of 'offset' relative to 104 * EFI_KIMG_ALIGN so that statically allocated objects whose 105 * alignment exceeds PAGE_SIZE appear correctly aligned in 106 * memory. 107 */ 108 offset |= TEXT_OFFSET % EFI_KIMG_ALIGN; 109 110 /* 111 * If KASLR is enabled, and we have some randomness available, 112 * locate the kernel at a randomized offset in physical memory. 113 */ 114 *reserve_size = kernel_memsize + offset; 115 status = efi_random_alloc(sys_table_arg, *reserve_size, 116 MIN_KIMG_ALIGN, reserve_addr, 117 (u32)phys_seed); 118 119 *image_addr = *reserve_addr + offset; 120 } else { 121 /* 122 * Else, try a straight allocation at the preferred offset. 123 * This will work around the issue where, if dram_base == 0x0, 124 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the 125 * address of the allocation to be mistaken for a FAIL return 126 * value or a NULL pointer). It will also ensure that, on 127 * platforms where the [dram_base, dram_base + TEXT_OFFSET) 128 * interval is partially occupied by the firmware (like on APM 129 * Mustang), we can still place the kernel at the address 130 * 'dram_base + TEXT_OFFSET'. 131 */ 132 if (*image_addr == preferred_offset) 133 return EFI_SUCCESS; 134 135 *image_addr = *reserve_addr = preferred_offset; 136 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); 137 138 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 139 EFI_LOADER_DATA, 140 *reserve_size / EFI_PAGE_SIZE, 141 (efi_physical_addr_t *)reserve_addr); 142 } 143 144 if (status != EFI_SUCCESS) { 145 *reserve_size = kernel_memsize + TEXT_OFFSET; 146 status = efi_low_alloc(sys_table_arg, *reserve_size, 147 MIN_KIMG_ALIGN, reserve_addr); 148 149 if (status != EFI_SUCCESS) { 150 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n"); 151 *reserve_size = 0; 152 return status; 153 } 154 *image_addr = *reserve_addr + TEXT_OFFSET; 155 } 156 memcpy((void *)*image_addr, old_image_addr, kernel_size); 157 158 return EFI_SUCCESS; 159 } 160