1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * EFI_DT_FIXUP_PROTOCOL 4 * 5 * Copyright (c) 2020 Heinrich Schuchardt 6 */ 7 8#include <efi_dt_fixup.h> 9#include <efi_loader.h> 10#include <efi_rng.h> 11#include <fdtdec.h> 12#include <mapmem.h> 13 14const efi_guid_t efi_guid_dt_fixup_protocol = EFI_DT_FIXUP_PROTOCOL_GUID; 15 16/** 17 * efi_reserve_memory() - add reserved memory to memory map 18 * 19 * @addr: start address of the reserved memory range 20 * @size: size of the reserved memory range 21 * @nomap: indicates that the memory range shall not be accessed by the 22 * UEFI payload 23 */ 24static void efi_reserve_memory(u64 addr, u64 size, bool nomap) 25{ 26 int type; 27 efi_uintn_t ret; 28 29 /* Convert from sandbox address space. */ 30 addr = (uintptr_t)map_sysmem(addr, 0); 31 32 if (nomap) 33 type = EFI_RESERVED_MEMORY_TYPE; 34 else 35 type = EFI_BOOT_SERVICES_DATA; 36 37 ret = efi_add_memory_map(addr, size, type); 38 if (ret != EFI_SUCCESS) 39 log_err("Reserved memory mapping failed addr %llx size %llx\n", 40 addr, size); 41} 42 43/** 44 * efi_try_purge_kaslr_seed() - Remove unused kaslr-seed 45 * 46 * Kernel's EFI STUB only relies on EFI_RNG_PROTOCOL for randomization 47 * and completely ignores the kaslr-seed for its own randomness needs 48 * (i.e the randomization of the physical placement of the kernel). 49 * Weed it out from the DTB we hand over, which would mess up our DTB 50 * TPM measurements as well. 51 * 52 * @fdt: Pointer to device tree 53 */ 54void efi_try_purge_kaslr_seed(void *fdt) 55{ 56 const efi_guid_t efi_guid_rng_protocol = EFI_RNG_PROTOCOL_GUID; 57 struct efi_handler *handler; 58 efi_status_t ret; 59 int nodeoff = 0; 60 int err = 0; 61 62 ret = efi_search_protocol(efi_root, &efi_guid_rng_protocol, &handler); 63 if (ret != EFI_SUCCESS) 64 return; 65 66 nodeoff = fdt_path_offset(fdt, "/chosen"); 67 if (nodeoff < 0) 68 return; 69 70 err = fdt_delprop(fdt, nodeoff, "kaslr-seed"); 71 if (err < 0 && err != -FDT_ERR_NOTFOUND) 72 log_err("Error deleting kaslr-seed\n"); 73} 74 75/** 76 * efi_carve_out_dt_rsv() - Carve out DT reserved memory ranges 77 * 78 * The mem_rsv entries of the FDT are added to the memory map. Any failures are 79 * ignored because this is not critical and we would rather continue to try to 80 * boot. 81 * 82 * @fdt: Pointer to device tree 83 */ 84void efi_carve_out_dt_rsv(void *fdt) 85{ 86 int nr_rsv, i; 87 u64 addr, size; 88 int nodeoffset, subnode; 89 90 nr_rsv = fdt_num_mem_rsv(fdt); 91 92 /* Look for an existing entry and add it to the efi mem map. */ 93 for (i = 0; i < nr_rsv; i++) { 94 if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0) 95 continue; 96 efi_reserve_memory(addr, size, true); 97 } 98 99 /* process reserved-memory */ 100 nodeoffset = fdt_subnode_offset(fdt, 0, "reserved-memory"); 101 if (nodeoffset >= 0) { 102 subnode = fdt_first_subnode(fdt, nodeoffset); 103 while (subnode >= 0) { 104 fdt_addr_t fdt_addr; 105 fdt_size_t fdt_size; 106 107 /* check if this subnode has a reg property */ 108 fdt_addr = fdtdec_get_addr_size_auto_parent( 109 fdt, nodeoffset, subnode, 110 "reg", 0, &fdt_size, false); 111 /* 112 * The /reserved-memory node may have children with 113 * a size instead of a reg property. 114 */ 115 if (fdt_addr != FDT_ADDR_T_NONE && 116 fdtdec_get_is_enabled(fdt, subnode)) { 117 bool nomap; 118 119 nomap = !!fdt_getprop(fdt, subnode, "no-map", 120 NULL); 121 efi_reserve_memory(fdt_addr, fdt_size, nomap); 122 } 123 subnode = fdt_next_subnode(fdt, subnode); 124 } 125 } 126} 127 128/** 129 * efi_dt_fixup() - fix up device tree 130 * 131 * This function implements the Fixup() service of the 132 * EFI Device Tree Fixup Protocol. 133 * 134 * @this: instance of the protocol 135 * @dtb: device tree provided by caller 136 * @buffer_size: size of buffer for the device tree including free space 137 * @flags: bit field designating action to be performed 138 * Return: status code 139 */ 140static efi_status_t __maybe_unused EFIAPI 141efi_dt_fixup(struct efi_dt_fixup_protocol *this, void *dtb, 142 efi_uintn_t *buffer_size, u32 flags) 143{ 144 efi_status_t ret; 145 size_t required_size; 146 size_t total_size; 147 struct bootm_headers img = { 0 }; 148 149 EFI_ENTRY("%p, %p, %p, %d", this, dtb, buffer_size, flags); 150 151 if (this != &efi_dt_fixup_prot || !dtb || !buffer_size || 152 !flags || (flags & ~EFI_DT_ALL)) { 153 ret = EFI_INVALID_PARAMETER; 154 goto out; 155 } 156 if (fdt_check_header(dtb)) { 157 ret = EFI_INVALID_PARAMETER; 158 goto out; 159 } 160 if (flags & EFI_DT_APPLY_FIXUPS) { 161 /* Check size */ 162 required_size = fdt_off_dt_strings(dtb) + 163 fdt_size_dt_strings(dtb) + 164 0x3000; 165 total_size = fdt_totalsize(dtb); 166 if (required_size < total_size) 167 required_size = total_size; 168 if (required_size > *buffer_size) { 169 *buffer_size = required_size; 170 ret = EFI_BUFFER_TOO_SMALL; 171 goto out; 172 } 173 174 fdt_set_totalsize(dtb, *buffer_size); 175 if (image_setup_libfdt(&img, dtb, NULL)) { 176 log_err("failed to process device tree\n"); 177 ret = EFI_INVALID_PARAMETER; 178 goto out; 179 } 180 } 181 if (flags & EFI_DT_RESERVE_MEMORY) 182 efi_carve_out_dt_rsv(dtb); 183 184 if (flags & EFI_DT_INSTALL_TABLE) { 185 ret = efi_install_configuration_table(&efi_guid_fdt, dtb); 186 if (ret != EFI_SUCCESS) { 187 log_err("failed to install device tree\n"); 188 goto out; 189 } 190 } 191 192 ret = EFI_SUCCESS; 193out: 194 return EFI_EXIT(ret); 195} 196 197struct efi_dt_fixup_protocol efi_dt_fixup_prot = { 198 .revision = EFI_DT_FIXUP_PROTOCOL_REVISION, 199 .fixup = efi_dt_fixup 200}; 201