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
39/*
40 * Some architectures map the EFI regions into the kernel's linear map using a
41 * fixed offset.
42 */
43#ifndef EFI_RT_VIRTUAL_OFFSET
44#define EFI_RT_VIRTUAL_OFFSET	0
45#endif
46
47static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
48static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
49
50void __weak free_screen_info(struct screen_info *si)
51{
52}
53
54static struct screen_info *setup_graphics(void)
55{
56	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
57	efi_status_t status;
58	unsigned long size;
59	void **gop_handle = NULL;
60	struct screen_info *si = NULL;
61
62	size = 0;
63	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
64			     &gop_proto, NULL, &size, gop_handle);
65	if (status == EFI_BUFFER_TOO_SMALL) {
66		si = alloc_screen_info();
67		if (!si)
68			return NULL;
69		status = efi_setup_gop(si, &gop_proto, size);
70		if (status != EFI_SUCCESS) {
71			free_screen_info(si);
72			return NULL;
73		}
74	}
75	return si;
76}
77
78static void install_memreserve_table(void)
79{
80	struct linux_efi_memreserve *rsv;
81	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
82	efi_status_t status;
83
84	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
85			     (void **)&rsv);
86	if (status != EFI_SUCCESS) {
87		efi_err("Failed to allocate memreserve entry!\n");
88		return;
89	}
90
91	rsv->next = 0;
92	rsv->size = 0;
93	atomic_set(&rsv->count, 0);
94
95	status = efi_bs_call(install_configuration_table,
96			     &memreserve_table_guid, rsv);
97	if (status != EFI_SUCCESS)
98		efi_err("Failed to install memreserve config table!\n");
99}
100
101static u32 get_supported_rt_services(void)
102{
103	const efi_rt_properties_table_t *rt_prop_table;
104	u32 supported = EFI_RT_SUPPORTED_ALL;
105
106	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
107	if (rt_prop_table)
108		supported &= rt_prop_table->runtime_services_supported;
109
110	return supported;
111}
112
113efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
114{
115	int cmdline_size = 0;
116	efi_status_t status;
117	char *cmdline;
118
119	/*
120	 * Get the command line from EFI, using the LOADED_IMAGE
121	 * protocol. We are going to copy the command line into the
122	 * device tree, so this can be allocated anywhere.
123	 */
124	cmdline = efi_convert_cmdline(image, &cmdline_size);
125	if (!cmdline) {
126		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
127		return EFI_OUT_OF_RESOURCES;
128	}
129
130	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
131	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
132	    cmdline_size == 0) {
133		status = efi_parse_options(CONFIG_CMDLINE);
134		if (status != EFI_SUCCESS) {
135			efi_err("Failed to parse options\n");
136			goto fail_free_cmdline;
137		}
138	}
139
140	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
141		status = efi_parse_options(cmdline);
142		if (status != EFI_SUCCESS) {
143			efi_err("Failed to parse options\n");
144			goto fail_free_cmdline;
145		}
146	}
147
148	*cmdline_ptr = cmdline;
149	return EFI_SUCCESS;
150
151fail_free_cmdline:
152	efi_bs_call(free_pool, cmdline_ptr);
153	return status;
154}
155
156efi_status_t efi_stub_common(efi_handle_t handle,
157			     efi_loaded_image_t *image,
158			     unsigned long image_addr,
159			     char *cmdline_ptr)
160{
161	struct screen_info *si;
162	efi_status_t status;
163
164	status = check_platform_features();
165	if (status != EFI_SUCCESS)
166		return status;
167
168	si = setup_graphics();
169
170	efi_retrieve_eventlog();
171
172	/* Ask the firmware to clear memory on unclean shutdown */
173	efi_enable_reset_attack_mitigation();
174
175	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
176			NULL);
177
178	efi_random_get_seed();
179
180	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
181	efi_novamap |= !(get_supported_rt_services() &
182			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
183
184	install_memreserve_table();
185
186	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
187
188	free_screen_info(si);
189	return status;
190}
191
192/*
193 * efi_allocate_virtmap() - create a pool allocation for the virtmap
194 *
195 * Create an allocation that is of sufficient size to hold all the memory
196 * descriptors that will be passed to SetVirtualAddressMap() to inform the
197 * firmware about the virtual mapping that will be used under the OS to call
198 * into the firmware.
199 */
200efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
201			       unsigned long *desc_size, u32 *desc_ver)
202{
203	unsigned long size, mmap_key;
204	efi_status_t status;
205
206	/*
207	 * Use the size of the current memory map as an upper bound for the
208	 * size of the buffer we need to pass to SetVirtualAddressMap() to
209	 * cover all EFI_MEMORY_RUNTIME regions.
210	 */
211	size = 0;
212	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
213			     desc_ver);
214	if (status != EFI_BUFFER_TOO_SMALL)
215		return EFI_LOAD_ERROR;
216
217	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
218			   (void **)virtmap);
219}
220
221/*
222 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
223 *
224 * This function populates the virt_addr fields of all memory region descriptors
225 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
226 * are also copied to @runtime_map, and their total count is returned in @count.
227 */
228void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
229		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
230		     int *count)
231{
232	u64 efi_virt_base = virtmap_base;
233	efi_memory_desc_t *in, *out = runtime_map;
234	int l;
235
236	*count = 0;
237
238	for (l = 0; l < map_size; l += desc_size) {
239		u64 paddr, size;
240
241		in = (void *)memory_map + l;
242		if (!(in->attribute & EFI_MEMORY_RUNTIME))
243			continue;
244
245		paddr = in->phys_addr;
246		size = in->num_pages * EFI_PAGE_SIZE;
247
248		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
249		if (efi_novamap) {
250			continue;
251		}
252
253		/*
254		 * Make the mapping compatible with 64k pages: this allows
255		 * a 4k page size kernel to kexec a 64k page size kernel and
256		 * vice versa.
257		 */
258		if (!flat_va_mapping) {
259
260			paddr = round_down(in->phys_addr, SZ_64K);
261			size += in->phys_addr - paddr;
262
263			/*
264			 * Avoid wasting memory on PTEs by choosing a virtual
265			 * base that is compatible with section mappings if this
266			 * region has the appropriate size and physical
267			 * alignment. (Sections are 2 MB on 4k granule kernels)
268			 */
269			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
270				efi_virt_base = round_up(efi_virt_base, SZ_2M);
271			else
272				efi_virt_base = round_up(efi_virt_base, SZ_64K);
273
274			in->virt_addr += efi_virt_base - paddr;
275			efi_virt_base += size;
276		}
277
278		memcpy(out, in, desc_size);
279		out = (void *)out + desc_size;
280		++*count;
281	}
282}
283