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