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 16 #include "efistub.h" 17 18 extern bool __nokaslr; 19 20 efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg, 21 unsigned long *image_addr, 22 unsigned long *image_size, 23 unsigned long *reserve_addr, 24 unsigned long *reserve_size, 25 unsigned long dram_base, 26 efi_loaded_image_t *image) 27 { 28 efi_status_t status; 29 unsigned long kernel_size, kernel_memsize = 0; 30 void *old_image_addr = (void *)*image_addr; 31 unsigned long preferred_offset; 32 u64 phys_seed = 0; 33 34 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 35 if (!__nokaslr) { 36 status = efi_get_random_bytes(sys_table_arg, 37 sizeof(phys_seed), 38 (u8 *)&phys_seed); 39 if (status == EFI_NOT_FOUND) { 40 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n"); 41 } else if (status != EFI_SUCCESS) { 42 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n"); 43 return status; 44 } 45 } else { 46 pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n"); 47 } 48 } 49 50 /* 51 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond 52 * a 2 MB aligned base, which itself may be lower than dram_base, as 53 * long as the resulting offset equals or exceeds it. 54 */ 55 preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET; 56 if (preferred_offset < dram_base) 57 preferred_offset += MIN_KIMG_ALIGN; 58 59 kernel_size = _edata - _text; 60 kernel_memsize = kernel_size + (_end - _edata); 61 62 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { 63 /* 64 * If KASLR is enabled, and we have some randomness available, 65 * locate the kernel at a randomized offset in physical memory. 66 */ 67 *reserve_size = kernel_memsize + TEXT_OFFSET; 68 status = efi_random_alloc(sys_table_arg, *reserve_size, 69 MIN_KIMG_ALIGN, reserve_addr, 70 phys_seed); 71 72 *image_addr = *reserve_addr + TEXT_OFFSET; 73 } else { 74 /* 75 * Else, try a straight allocation at the preferred offset. 76 * This will work around the issue where, if dram_base == 0x0, 77 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the 78 * address of the allocation to be mistaken for a FAIL return 79 * value or a NULL pointer). It will also ensure that, on 80 * platforms where the [dram_base, dram_base + TEXT_OFFSET) 81 * interval is partially occupied by the firmware (like on APM 82 * Mustang), we can still place the kernel at the address 83 * 'dram_base + TEXT_OFFSET'. 84 */ 85 if (*image_addr == preferred_offset) 86 return EFI_SUCCESS; 87 88 *image_addr = *reserve_addr = preferred_offset; 89 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); 90 91 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 92 EFI_LOADER_DATA, 93 *reserve_size / EFI_PAGE_SIZE, 94 (efi_physical_addr_t *)reserve_addr); 95 } 96 97 if (status != EFI_SUCCESS) { 98 *reserve_size = kernel_memsize + TEXT_OFFSET; 99 status = efi_low_alloc(sys_table_arg, *reserve_size, 100 MIN_KIMG_ALIGN, reserve_addr); 101 102 if (status != EFI_SUCCESS) { 103 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n"); 104 *reserve_size = 0; 105 return status; 106 } 107 *image_addr = *reserve_addr + TEXT_OFFSET; 108 } 109 memcpy((void *)*image_addr, old_image_addr, kernel_size); 110 111 return EFI_SUCCESS; 112 } 113