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 #include <linux/efi.h> 13 #include <asm/efi.h> 14 #include <asm/sections.h> 15 #include <asm/sysreg.h> 16 17 #include "efistub.h" 18 19 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg) 20 { 21 u64 tg; 22 23 /* UEFI mandates support for 4 KB granularity, no need to check */ 24 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES)) 25 return EFI_SUCCESS; 26 27 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf; 28 if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) { 29 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) 30 pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n"); 31 else 32 pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n"); 33 return EFI_UNSUPPORTED; 34 } 35 return EFI_SUCCESS; 36 } 37 38 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg, 39 unsigned long *image_addr, 40 unsigned long *image_size, 41 unsigned long *reserve_addr, 42 unsigned long *reserve_size, 43 unsigned long dram_base, 44 efi_loaded_image_t *image) 45 { 46 efi_status_t status; 47 unsigned long kernel_size, kernel_memsize = 0; 48 void *old_image_addr = (void *)*image_addr; 49 unsigned long preferred_offset; 50 u64 phys_seed = 0; 51 52 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 53 if (!nokaslr()) { 54 status = efi_get_random_bytes(sys_table_arg, 55 sizeof(phys_seed), 56 (u8 *)&phys_seed); 57 if (status == EFI_NOT_FOUND) { 58 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n"); 59 } else if (status != EFI_SUCCESS) { 60 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n"); 61 return status; 62 } 63 } else { 64 pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n"); 65 } 66 } 67 68 /* 69 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond 70 * a 2 MB aligned base, which itself may be lower than dram_base, as 71 * long as the resulting offset equals or exceeds it. 72 */ 73 preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET; 74 if (preferred_offset < dram_base) 75 preferred_offset += MIN_KIMG_ALIGN; 76 77 kernel_size = _edata - _text; 78 kernel_memsize = kernel_size + (_end - _edata); 79 80 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 81 /* 82 * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a 83 * displacement in the interval [0, MIN_KIMG_ALIGN) that 84 * is a multiple of the minimal segment alignment (SZ_64K) 85 */ 86 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(SZ_64K - 1); 87 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ? 88 (phys_seed >> 32) & mask : TEXT_OFFSET; 89 90 /* 91 * If KASLR is enabled, and we have some randomness available, 92 * locate the kernel at a randomized offset in physical memory. 93 */ 94 *reserve_size = kernel_memsize + offset; 95 status = efi_random_alloc(sys_table_arg, *reserve_size, 96 MIN_KIMG_ALIGN, reserve_addr, 97 (u32)phys_seed); 98 99 *image_addr = *reserve_addr + offset; 100 } else { 101 /* 102 * Else, try a straight allocation at the preferred offset. 103 * This will work around the issue where, if dram_base == 0x0, 104 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the 105 * address of the allocation to be mistaken for a FAIL return 106 * value or a NULL pointer). It will also ensure that, on 107 * platforms where the [dram_base, dram_base + TEXT_OFFSET) 108 * interval is partially occupied by the firmware (like on APM 109 * Mustang), we can still place the kernel at the address 110 * 'dram_base + TEXT_OFFSET'. 111 */ 112 if (*image_addr == preferred_offset) 113 return EFI_SUCCESS; 114 115 *image_addr = *reserve_addr = preferred_offset; 116 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); 117 118 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 119 EFI_LOADER_DATA, 120 *reserve_size / EFI_PAGE_SIZE, 121 (efi_physical_addr_t *)reserve_addr); 122 } 123 124 if (status != EFI_SUCCESS) { 125 *reserve_size = kernel_memsize + TEXT_OFFSET; 126 status = efi_low_alloc(sys_table_arg, *reserve_size, 127 MIN_KIMG_ALIGN, reserve_addr); 128 129 if (status != EFI_SUCCESS) { 130 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n"); 131 *reserve_size = 0; 132 return status; 133 } 134 *image_addr = *reserve_addr + TEXT_OFFSET; 135 } 136 memcpy((void *)*image_addr, old_image_addr, kernel_size); 137 138 return EFI_SUCCESS; 139 } 140