1 // SPDX-License-Identifier: GPL-2.0-only
3 * EFI stub implementation that is shared by arm and arm64 architectures.
4 * This should be #included by the EFI stub implementation files.
6 * Copyright (C) 2013,2014 Linaro Limited
7 * Roy Franz <roy.franz@linaro.org
8 * Copyright (C) 2013 Red Hat, Inc.
9 * Mark Salter <msalter@redhat.com>
12 #include <linux/efi.h>
13 #include <linux/libfdt.h>
19 * This is the base address at which to start allocating virtual memory ranges
20 * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
21 * any allocation we choose, and eliminate the risk of a conflict after kexec.
22 * The value chosen is the largest non-zero power of 2 suitable for this purpose
23 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
24 * be mapped efficiently.
25 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
26 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
27 * entire footprint of the UEFI runtime services memory regions)
29 #define EFI_RT_VIRTUAL_BASE SZ_512M
30 #define EFI_RT_VIRTUAL_SIZE SZ_512M
33 # define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64
35 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE
38 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
39 static bool __efistub_global flat_va_mapping;
41 static efi_system_table_t *__efistub_global sys_table;
43 __pure efi_system_table_t *efi_system_table(void)
48 static struct screen_info *setup_graphics(void)
50 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
53 void **gop_handle = NULL;
54 struct screen_info *si = NULL;
57 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
58 &gop_proto, NULL, &size, gop_handle);
59 if (status == EFI_BUFFER_TOO_SMALL) {
60 si = alloc_screen_info();
63 efi_setup_gop(si, &gop_proto, size);
68 void install_memreserve_table(void)
70 struct linux_efi_memreserve *rsv;
71 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
74 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
76 if (status != EFI_SUCCESS) {
77 pr_efi_err("Failed to allocate memreserve entry!\n");
83 atomic_set(&rsv->count, 0);
85 status = efi_bs_call(install_configuration_table,
86 &memreserve_table_guid, rsv);
87 if (status != EFI_SUCCESS)
88 pr_efi_err("Failed to install memreserve config table!\n");
93 * This function handles the architcture specific differences between arm and
94 * arm64 regarding where the kernel image must be loaded and any memory that
95 * must be reserved. On failure it is required to free all
96 * all allocations it has made.
98 efi_status_t handle_kernel_image(unsigned long *image_addr,
99 unsigned long *image_size,
100 unsigned long *reserve_addr,
101 unsigned long *reserve_size,
102 unsigned long dram_base,
103 efi_loaded_image_t *image);
105 asmlinkage void __noreturn efi_enter_kernel(unsigned long entrypoint,
106 unsigned long fdt_addr,
107 unsigned long fdt_size);
110 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
111 * that is described in the PE/COFF header. Most of the code is the same
112 * for both archictectures, with the arch-specific code provided in the
113 * handle_kernel_image() function.
115 efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
117 efi_loaded_image_t *image;
119 unsigned long image_addr;
120 unsigned long image_size = 0;
121 unsigned long dram_base;
122 /* addr/point and size pairs for memory management*/
123 unsigned long initrd_addr;
125 unsigned long fdt_addr = 0; /* Original DTB */
126 unsigned long fdt_size = 0;
127 char *cmdline_ptr = NULL;
128 int cmdline_size = 0;
129 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
130 unsigned long reserve_addr = 0;
131 unsigned long reserve_size = 0;
132 enum efi_secureboot_mode secure_boot;
133 struct screen_info *si;
134 efi_properties_table_t *prop_tbl;
136 sys_table = sys_table_arg;
138 /* Check if we were booted by the EFI firmware */
139 if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
140 status = EFI_INVALID_PARAMETER;
144 status = check_platform_features();
145 if (status != EFI_SUCCESS)
149 * Get a handle to the loaded image protocol. This is used to get
150 * information about the running image, such as size and the command
153 status = sys_table->boottime->handle_protocol(handle,
154 &loaded_image_proto, (void *)&image);
155 if (status != EFI_SUCCESS) {
156 pr_efi_err("Failed to get loaded image protocol\n");
160 dram_base = get_dram_base();
161 if (dram_base == EFI_ERROR) {
162 pr_efi_err("Failed to find DRAM base\n");
163 status = EFI_LOAD_ERROR;
168 * Get the command line from EFI, using the LOADED_IMAGE
169 * protocol. We are going to copy the command line into the
170 * device tree, so this can be allocated anywhere.
172 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size, ULONG_MAX);
174 pr_efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
175 status = EFI_OUT_OF_RESOURCES;
179 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
180 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
182 efi_parse_options(CONFIG_CMDLINE);
184 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
185 efi_parse_options(cmdline_ptr);
187 pr_efi("Booting Linux Kernel...\n");
189 si = setup_graphics();
191 status = handle_kernel_image(&image_addr, &image_size,
195 if (status != EFI_SUCCESS) {
196 pr_efi_err("Failed to relocate kernel\n");
197 goto fail_free_cmdline;
200 efi_retrieve_tpm2_eventlog();
202 /* Ask the firmware to clear memory on unclean shutdown */
203 efi_enable_reset_attack_mitigation();
205 secure_boot = efi_get_secureboot();
208 * Unauthenticated device tree data is a security hazard, so ignore
209 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
210 * boot is enabled if we can't determine its state.
212 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
213 secure_boot != efi_secureboot_mode_disabled) {
214 if (strstr(cmdline_ptr, "dtb="))
215 pr_efi("Ignoring DTB from command line.\n");
217 status = handle_cmdline_files(image, cmdline_ptr, "dtb=",
218 ~0UL, &fdt_addr, &fdt_size);
220 if (status != EFI_SUCCESS) {
221 pr_efi_err("Failed to load device tree!\n");
222 goto fail_free_image;
227 pr_efi("Using DTB from command line\n");
229 /* Look for a device tree configuration table entry. */
230 fdt_addr = (uintptr_t)get_fdt(&fdt_size);
232 pr_efi("Using DTB from configuration table\n");
236 pr_efi("Generating empty DTB\n");
238 status = handle_cmdline_files(image, cmdline_ptr, "initrd=",
239 efi_get_max_initrd_addr(dram_base,
241 (unsigned long *)&initrd_addr,
242 (unsigned long *)&initrd_size);
243 if (status != EFI_SUCCESS)
244 pr_efi_err("Failed initrd from command line!\n");
246 efi_random_get_seed();
249 * If the NX PE data feature is enabled in the properties table, we
250 * should take care not to create a virtual mapping that changes the
251 * relative placement of runtime services code and data regions, as
252 * they may belong to the same PE/COFF executable image in memory.
253 * The easiest way to achieve that is to simply use a 1:1 mapping.
255 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
256 flat_va_mapping = prop_tbl &&
257 (prop_tbl->memory_protection_attribute &
258 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
260 /* hibernation expects the runtime regions to stay in the same place */
261 if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr() && !flat_va_mapping) {
263 * Randomize the base of the UEFI runtime services region.
264 * Preserve the 2 MB alignment of the region by taking a
265 * shift of 21 bit positions into account when scaling
266 * the headroom value using a 32-bit random value.
268 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
269 EFI_RT_VIRTUAL_BASE -
273 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
274 if (status == EFI_SUCCESS) {
275 virtmap_base = EFI_RT_VIRTUAL_BASE +
276 (((headroom >> 21) * rnd) >> (32 - 21));
280 install_memreserve_table();
282 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
283 efi_get_max_fdt_addr(dram_base),
284 initrd_addr, initrd_size,
285 cmdline_ptr, fdt_addr, fdt_size);
286 if (status != EFI_SUCCESS)
287 goto fail_free_initrd;
289 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
293 pr_efi_err("Failed to update FDT and exit boot services\n");
295 efi_free(initrd_size, initrd_addr);
296 efi_free(fdt_size, fdt_addr);
299 efi_free(image_size, image_addr);
300 efi_free(reserve_size, reserve_addr);
302 free_screen_info(si);
303 efi_free(cmdline_size, (unsigned long)cmdline_ptr);
309 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
311 * This function populates the virt_addr fields of all memory region descriptors
312 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
313 * are also copied to @runtime_map, and their total count is returned in @count.
315 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
316 unsigned long desc_size, efi_memory_desc_t *runtime_map,
319 u64 efi_virt_base = virtmap_base;
320 efi_memory_desc_t *in, *out = runtime_map;
323 for (l = 0; l < map_size; l += desc_size) {
326 in = (void *)memory_map + l;
327 if (!(in->attribute & EFI_MEMORY_RUNTIME))
330 paddr = in->phys_addr;
331 size = in->num_pages * EFI_PAGE_SIZE;
333 in->virt_addr = in->phys_addr;
339 * Make the mapping compatible with 64k pages: this allows
340 * a 4k page size kernel to kexec a 64k page size kernel and
343 if (!flat_va_mapping) {
345 paddr = round_down(in->phys_addr, SZ_64K);
346 size += in->phys_addr - paddr;
349 * Avoid wasting memory on PTEs by choosing a virtual
350 * base that is compatible with section mappings if this
351 * region has the appropriate size and physical
352 * alignment. (Sections are 2 MB on 4k granule kernels)
354 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
355 efi_virt_base = round_up(efi_virt_base, SZ_2M);
357 efi_virt_base = round_up(efi_virt_base, SZ_64K);
359 in->virt_addr += efi_virt_base - paddr;
360 efi_virt_base += size;
363 memcpy(out, in, desc_size);
364 out = (void *)out + desc_size;