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.
23 * This is in the low TTBR0 range so that we can use
24 * any allocation we choose, and eliminate the risk of a conflict after kexec.
25 * The value chosen is the largest non-zero power of 2 suitable for this purpose
26 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
27 * be mapped efficiently.
28 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
29 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
30 * entire footprint of the UEFI runtime services memory regions)
33 * There is no specific reason for which, this address (512MB) can't be used
34 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
35 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
36 * as well to minimize the code churn.
38 #define EFI_RT_VIRTUAL_BASE SZ_512M
39 #define EFI_RT_VIRTUAL_SIZE SZ_512M
42 # define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64
44 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE
47 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
48 static bool flat_va_mapping;
50 const efi_system_table_t *efi_system_table;
52 static struct screen_info *setup_graphics(void)
54 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
57 void **gop_handle = NULL;
58 struct screen_info *si = NULL;
61 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
62 &gop_proto, NULL, &size, gop_handle);
63 if (status == EFI_BUFFER_TOO_SMALL) {
64 si = alloc_screen_info();
67 status = efi_setup_gop(si, &gop_proto, size);
68 if (status != EFI_SUCCESS) {
76 static void install_memreserve_table(void)
78 struct linux_efi_memreserve *rsv;
79 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
82 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
84 if (status != EFI_SUCCESS) {
85 efi_err("Failed to allocate memreserve entry!\n");
91 atomic_set(&rsv->count, 0);
93 status = efi_bs_call(install_configuration_table,
94 &memreserve_table_guid, rsv);
95 if (status != EFI_SUCCESS)
96 efi_err("Failed to install memreserve config table!\n");
100 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
101 * that is described in the PE/COFF header. Most of the code is the same
102 * for both archictectures, with the arch-specific code provided in the
103 * handle_kernel_image() function.
105 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
106 efi_system_table_t *sys_table_arg)
108 efi_loaded_image_t *image;
110 unsigned long image_addr;
111 unsigned long image_size = 0;
112 /* addr/point and size pairs for memory management*/
113 unsigned long initrd_addr = 0;
114 unsigned long initrd_size = 0;
115 unsigned long fdt_addr = 0; /* Original DTB */
116 unsigned long fdt_size = 0;
117 char *cmdline_ptr = NULL;
118 int cmdline_size = 0;
119 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
120 unsigned long reserve_addr = 0;
121 unsigned long reserve_size = 0;
122 enum efi_secureboot_mode secure_boot;
123 struct screen_info *si;
124 efi_properties_table_t *prop_tbl;
125 unsigned long max_addr;
127 efi_system_table = sys_table_arg;
129 /* Check if we were booted by the EFI firmware */
130 if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
131 status = EFI_INVALID_PARAMETER;
135 status = check_platform_features();
136 if (status != EFI_SUCCESS)
140 * Get a handle to the loaded image protocol. This is used to get
141 * information about the running image, such as size and the command
144 status = efi_system_table->boottime->handle_protocol(handle,
145 &loaded_image_proto, (void *)&image);
146 if (status != EFI_SUCCESS) {
147 efi_err("Failed to get loaded image protocol\n");
152 * Get the command line from EFI, using the LOADED_IMAGE
153 * protocol. We are going to copy the command line into the
154 * device tree, so this can be allocated anywhere.
156 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
158 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
159 status = EFI_OUT_OF_RESOURCES;
163 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
164 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
166 status = efi_parse_options(CONFIG_CMDLINE);
167 if (status != EFI_SUCCESS) {
168 efi_err("Failed to parse options\n");
169 goto fail_free_cmdline;
173 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
174 status = efi_parse_options(cmdline_ptr);
175 if (status != EFI_SUCCESS) {
176 efi_err("Failed to parse options\n");
177 goto fail_free_cmdline;
181 efi_info("Booting Linux Kernel...\n");
183 si = setup_graphics();
185 status = handle_kernel_image(&image_addr, &image_size,
189 if (status != EFI_SUCCESS) {
190 efi_err("Failed to relocate kernel\n");
191 goto fail_free_screeninfo;
194 efi_retrieve_tpm2_eventlog();
196 /* Ask the firmware to clear memory on unclean shutdown */
197 efi_enable_reset_attack_mitigation();
199 secure_boot = efi_get_secureboot();
202 * Unauthenticated device tree data is a security hazard, so ignore
203 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
204 * boot is enabled if we can't determine its state.
206 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
207 secure_boot != efi_secureboot_mode_disabled) {
208 if (strstr(cmdline_ptr, "dtb="))
209 efi_err("Ignoring DTB from command line.\n");
211 status = efi_load_dtb(image, &fdt_addr, &fdt_size);
213 if (status != EFI_SUCCESS) {
214 efi_err("Failed to load device tree!\n");
215 goto fail_free_image;
220 efi_info("Using DTB from command line\n");
222 /* Look for a device tree configuration table entry. */
223 fdt_addr = (uintptr_t)get_fdt(&fdt_size);
225 efi_info("Using DTB from configuration table\n");
229 efi_info("Generating empty DTB\n");
232 max_addr = efi_get_max_initrd_addr(image_addr);
233 status = efi_load_initrd(image, &initrd_addr, &initrd_size,
234 ULONG_MAX, max_addr);
235 if (status != EFI_SUCCESS)
236 efi_err("Failed to load initrd!\n");
239 efi_random_get_seed();
242 * If the NX PE data feature is enabled in the properties table, we
243 * should take care not to create a virtual mapping that changes the
244 * relative placement of runtime services code and data regions, as
245 * they may belong to the same PE/COFF executable image in memory.
246 * The easiest way to achieve that is to simply use a 1:1 mapping.
248 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
249 flat_va_mapping = prop_tbl &&
250 (prop_tbl->memory_protection_attribute &
251 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
253 /* hibernation expects the runtime regions to stay in the same place */
254 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
256 * Randomize the base of the UEFI runtime services region.
257 * Preserve the 2 MB alignment of the region by taking a
258 * shift of 21 bit positions into account when scaling
259 * the headroom value using a 32-bit random value.
261 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
262 EFI_RT_VIRTUAL_BASE -
266 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
267 if (status == EFI_SUCCESS) {
268 virtmap_base = EFI_RT_VIRTUAL_BASE +
269 (((headroom >> 21) * rnd) >> (32 - 21));
273 install_memreserve_table();
275 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
276 initrd_addr, initrd_size,
277 cmdline_ptr, fdt_addr, fdt_size);
278 if (status != EFI_SUCCESS)
279 goto fail_free_initrd;
281 if (IS_ENABLED(CONFIG_ARM))
282 efi_handle_post_ebs_state();
284 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
288 efi_err("Failed to update FDT and exit boot services\n");
290 efi_free(initrd_size, initrd_addr);
291 efi_free(fdt_size, fdt_addr);
294 efi_free(image_size, image_addr);
295 efi_free(reserve_size, reserve_addr);
296 fail_free_screeninfo:
297 free_screen_info(si);
299 efi_bs_call(free_pool, cmdline_ptr);
305 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
307 * This function populates the virt_addr fields of all memory region descriptors
308 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
309 * are also copied to @runtime_map, and their total count is returned in @count.
311 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
312 unsigned long desc_size, efi_memory_desc_t *runtime_map,
315 u64 efi_virt_base = virtmap_base;
316 efi_memory_desc_t *in, *out = runtime_map;
319 for (l = 0; l < map_size; l += desc_size) {
322 in = (void *)memory_map + l;
323 if (!(in->attribute & EFI_MEMORY_RUNTIME))
326 paddr = in->phys_addr;
327 size = in->num_pages * EFI_PAGE_SIZE;
329 in->virt_addr = in->phys_addr;
335 * Make the mapping compatible with 64k pages: this allows
336 * a 4k page size kernel to kexec a 64k page size kernel and
339 if (!flat_va_mapping) {
341 paddr = round_down(in->phys_addr, SZ_64K);
342 size += in->phys_addr - paddr;
345 * Avoid wasting memory on PTEs by choosing a virtual
346 * base that is compatible with section mappings if this
347 * region has the appropriate size and physical
348 * alignment. (Sections are 2 MB on 4k granule kernels)
350 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
351 efi_virt_base = round_up(efi_virt_base, SZ_2M);
353 efi_virt_base = round_up(efi_virt_base, SZ_64K);
355 in->virt_addr += efi_virt_base - paddr;
356 efi_virt_base += size;
359 memcpy(out, in, desc_size);
360 out = (void *)out + desc_size;