1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * EFI stub implementation that is shared by arm and arm64 architectures.
4 * This should be #included by the EFI stub implementation files.
5 *
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>
10 */
11
12#include <linux/efi.h>
13#include <asm/efi.h>
14
15#include "efistub.h"
16
17/*
18 * This is the base address at which to start allocating virtual memory ranges
19 * for UEFI Runtime Services.
20 *
21 * For ARM/ARM64:
22 * This is in the low TTBR0 range so that we can use
23 * any allocation we choose, and eliminate the risk of a conflict after kexec.
24 * The value chosen is the largest non-zero power of 2 suitable for this purpose
25 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
26 * be mapped efficiently.
27 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
28 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
29 * entire footprint of the UEFI runtime services memory regions)
30 *
31 * For RISC-V:
32 * There is no specific reason for which, this address (512MB) can't be used
33 * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
34 * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
35 * as well to minimize the code churn.
36 */
37#define EFI_RT_VIRTUAL_BASE	SZ_512M
38#define EFI_RT_VIRTUAL_SIZE	SZ_512M
39
40#ifdef CONFIG_ARM64
41# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
42#elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH)
43# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_MIN
44#else
45# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
46#endif
47
48#ifndef EFI_RT_VIRTUAL_OFFSET
49#define EFI_RT_VIRTUAL_OFFSET	0
50#endif
51
52static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
53static bool flat_va_mapping = !!EFI_RT_VIRTUAL_OFFSET;
54
55const efi_system_table_t *efi_system_table;
56
57static struct screen_info *setup_graphics(void)
58{
59	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
60	efi_status_t status;
61	unsigned long size;
62	void **gop_handle = NULL;
63	struct screen_info *si = NULL;
64
65	size = 0;
66	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
67			     &gop_proto, NULL, &size, gop_handle);
68	if (status == EFI_BUFFER_TOO_SMALL) {
69		si = alloc_screen_info();
70		if (!si)
71			return NULL;
72		status = efi_setup_gop(si, &gop_proto, size);
73		if (status != EFI_SUCCESS) {
74			free_screen_info(si);
75			return NULL;
76		}
77	}
78	return si;
79}
80
81static void install_memreserve_table(void)
82{
83	struct linux_efi_memreserve *rsv;
84	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
85	efi_status_t status;
86
87	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
88			     (void **)&rsv);
89	if (status != EFI_SUCCESS) {
90		efi_err("Failed to allocate memreserve entry!\n");
91		return;
92	}
93
94	rsv->next = 0;
95	rsv->size = 0;
96	atomic_set(&rsv->count, 0);
97
98	status = efi_bs_call(install_configuration_table,
99			     &memreserve_table_guid, rsv);
100	if (status != EFI_SUCCESS)
101		efi_err("Failed to install memreserve config table!\n");
102}
103
104static u32 get_supported_rt_services(void)
105{
106	const efi_rt_properties_table_t *rt_prop_table;
107	u32 supported = EFI_RT_SUPPORTED_ALL;
108
109	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
110	if (rt_prop_table)
111		supported &= rt_prop_table->runtime_services_supported;
112
113	return supported;
114}
115
116/*
117 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
118 * that is described in the PE/COFF header.  Most of the code is the same
119 * for both archictectures, with the arch-specific code provided in the
120 * handle_kernel_image() function.
121 */
122efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
123				   efi_system_table_t *sys_table_arg)
124{
125	efi_loaded_image_t *image;
126	efi_status_t status;
127	unsigned long image_addr;
128	unsigned long image_size = 0;
129	/* addr/point and size pairs for memory management*/
130	char *cmdline_ptr = NULL;
131	int cmdline_size = 0;
132	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
133	unsigned long reserve_addr = 0;
134	unsigned long reserve_size = 0;
135	struct screen_info *si;
136	efi_properties_table_t *prop_tbl;
137	unsigned long max_addr;
138
139	efi_system_table = sys_table_arg;
140
141	/* Check if we were booted by the EFI firmware */
142	if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
143		status = EFI_INVALID_PARAMETER;
144		goto fail;
145	}
146
147	status = check_platform_features();
148	if (status != EFI_SUCCESS)
149		goto fail;
150
151	/*
152	 * Get a handle to the loaded image protocol.  This is used to get
153	 * information about the running image, such as size and the command
154	 * line.
155	 */
156	status = efi_system_table->boottime->handle_protocol(handle,
157					&loaded_image_proto, (void *)&image);
158	if (status != EFI_SUCCESS) {
159		efi_err("Failed to get loaded image protocol\n");
160		goto fail;
161	}
162
163	/*
164	 * Get the command line from EFI, using the LOADED_IMAGE
165	 * protocol. We are going to copy the command line into the
166	 * device tree, so this can be allocated anywhere.
167	 */
168	cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
169	if (!cmdline_ptr) {
170		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
171		status = EFI_OUT_OF_RESOURCES;
172		goto fail;
173	}
174
175	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
176	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
177	    cmdline_size == 0) {
178		status = efi_parse_options(CONFIG_CMDLINE);
179		if (status != EFI_SUCCESS) {
180			efi_err("Failed to parse options\n");
181			goto fail_free_cmdline;
182		}
183	}
184
185	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
186		status = efi_parse_options(cmdline_ptr);
187		if (status != EFI_SUCCESS) {
188			efi_err("Failed to parse options\n");
189			goto fail_free_cmdline;
190		}
191	}
192
193	efi_info("Booting Linux Kernel...\n");
194
195	si = setup_graphics();
196
197	status = handle_kernel_image(&image_addr, &image_size,
198				     &reserve_addr,
199				     &reserve_size,
200				     image);
201	if (status != EFI_SUCCESS) {
202		efi_err("Failed to relocate kernel\n");
203		goto fail_free_screeninfo;
204	}
205
206	efi_retrieve_tpm2_eventlog();
207
208	/* Ask the firmware to clear memory on unclean shutdown */
209	efi_enable_reset_attack_mitigation();
210
211	if (!efi_noinitrd) {
212		max_addr = efi_get_max_initrd_addr(image_addr);
213		efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
214				NULL);
215		if (status != EFI_SUCCESS)
216			efi_err("Failed to load initrd!\n");
217	}
218
219	efi_random_get_seed();
220
221	/*
222	 * If the NX PE data feature is enabled in the properties table, we
223	 * should take care not to create a virtual mapping that changes the
224	 * relative placement of runtime services code and data regions, as
225	 * they may belong to the same PE/COFF executable image in memory.
226	 * The easiest way to achieve that is to simply use a 1:1 mapping.
227	 */
228	prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
229	flat_va_mapping |= prop_tbl &&
230			   (prop_tbl->memory_protection_attribute &
231			   EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
232
233	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
234	efi_novamap |= !(get_supported_rt_services() &
235			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
236
237	/* hibernation expects the runtime regions to stay in the same place */
238	if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
239		/*
240		 * Randomize the base of the UEFI runtime services region.
241		 * Preserve the 2 MB alignment of the region by taking a
242		 * shift of 21 bit positions into account when scaling
243		 * the headroom value using a 32-bit random value.
244		 */
245		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
246					    EFI_RT_VIRTUAL_BASE -
247					    EFI_RT_VIRTUAL_SIZE;
248		u32 rnd;
249
250		status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
251		if (status == EFI_SUCCESS) {
252			virtmap_base = EFI_RT_VIRTUAL_BASE +
253				       (((headroom >> 21) * rnd) >> (32 - 21));
254		}
255	}
256
257	install_memreserve_table();
258
259	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
260
261	efi_free(image_size, image_addr);
262	efi_free(reserve_size, reserve_addr);
263fail_free_screeninfo:
264	free_screen_info(si);
265fail_free_cmdline:
266	efi_bs_call(free_pool, cmdline_ptr);
267fail:
268	return status;
269}
270
271/*
272 * efi_allocate_virtmap() - create a pool allocation for the virtmap
273 *
274 * Create an allocation that is of sufficient size to hold all the memory
275 * descriptors that will be passed to SetVirtualAddressMap() to inform the
276 * firmware about the virtual mapping that will be used under the OS to call
277 * into the firmware.
278 */
279efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
280			       unsigned long *desc_size, u32 *desc_ver)
281{
282	unsigned long size, mmap_key;
283	efi_status_t status;
284
285	/*
286	 * Use the size of the current memory map as an upper bound for the
287	 * size of the buffer we need to pass to SetVirtualAddressMap() to
288	 * cover all EFI_MEMORY_RUNTIME regions.
289	 */
290	size = 0;
291	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
292			     desc_ver);
293	if (status != EFI_BUFFER_TOO_SMALL)
294		return EFI_LOAD_ERROR;
295
296	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
297			   (void **)virtmap);
298}
299
300/*
301 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
302 *
303 * This function populates the virt_addr fields of all memory region descriptors
304 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
305 * are also copied to @runtime_map, and their total count is returned in @count.
306 */
307void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
308		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
309		     int *count)
310{
311	u64 efi_virt_base = virtmap_base;
312	efi_memory_desc_t *in, *out = runtime_map;
313	int l;
314
315	*count = 0;
316
317	for (l = 0; l < map_size; l += desc_size) {
318		u64 paddr, size;
319
320		in = (void *)memory_map + l;
321		if (!(in->attribute & EFI_MEMORY_RUNTIME))
322			continue;
323
324		paddr = in->phys_addr;
325		size = in->num_pages * EFI_PAGE_SIZE;
326
327		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
328		if (efi_novamap) {
329			continue;
330		}
331
332		/*
333		 * Make the mapping compatible with 64k pages: this allows
334		 * a 4k page size kernel to kexec a 64k page size kernel and
335		 * vice versa.
336		 */
337		if (!flat_va_mapping) {
338
339			paddr = round_down(in->phys_addr, SZ_64K);
340			size += in->phys_addr - paddr;
341
342			/*
343			 * Avoid wasting memory on PTEs by choosing a virtual
344			 * base that is compatible with section mappings if this
345			 * region has the appropriate size and physical
346			 * alignment. (Sections are 2 MB on 4k granule kernels)
347			 */
348			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
349				efi_virt_base = round_up(efi_virt_base, SZ_2M);
350			else
351				efi_virt_base = round_up(efi_virt_base, SZ_64K);
352
353			in->virt_addr += efi_virt_base - paddr;
354			efi_virt_base += size;
355		}
356
357		memcpy(out, in, desc_size);
358		out = (void *)out + desc_size;
359		++*count;
360	}
361}
362