efi-stub.c

  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 <linux/screen_info.h>
 14#include <asm/efi.h>
 15
 16#include "efistub.h"
 17
 18/*
 19 * This is the base address at which to start allocating virtual memory ranges
 20 * for UEFI Runtime Services.
 21 *
 22 * For ARM/ARM64:
 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)
 31 *
 32 * For RISC-V:
 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.
 37 */
 38#define EFI_RT_VIRTUAL_BASE	SZ_512M
 39
 40/*
 41 * Some architectures map the EFI regions into the kernel's linear map using a
 42 * fixed offset.
 43 */
 44#ifndef EFI_RT_VIRTUAL_OFFSET
 45#define EFI_RT_VIRTUAL_OFFSET	0
 46#endif
 47
 48static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
 49static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
 50
 51void __weak free_screen_info(struct screen_info *si)
 52{
 53}
 54
 55static struct screen_info *setup_graphics(void)
 56{
 57	struct screen_info *si, tmp = {};
 58
 59	if (efi_setup_graphics(&tmp, NULL) != EFI_SUCCESS)
 60		return NULL;
 61
 62	si = alloc_screen_info();
 63	if (!si)
 64		return NULL;
 65
 66	*si = tmp;
 67	return si;
 68}
 69
 70static void install_memreserve_table(void)
 71{
 72	struct linux_efi_memreserve *rsv;
 73	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
 74	efi_status_t status;
 75
 76	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
 77			     (void **)&rsv);
 78	if (status != EFI_SUCCESS) {
 79		efi_err("Failed to allocate memreserve entry!\n");
 80		return;
 81	}
 82
 83	rsv->next = 0;
 84	rsv->size = 0;
 85	atomic_set(&rsv->count, 0);
 86
 87	status = efi_bs_call(install_configuration_table,
 88			     &memreserve_table_guid, rsv);
 89	if (status != EFI_SUCCESS)
 90		efi_err("Failed to install memreserve config table!\n");
 91}
 92
 93static u32 get_supported_rt_services(void)
 94{
 95	const efi_rt_properties_table_t *rt_prop_table;
 96	u32 supported = EFI_RT_SUPPORTED_ALL;
 97
 98	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
 99	if (rt_prop_table)
100		supported &= rt_prop_table->runtime_services_supported;
101
102	return supported;
103}
104
105efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
106{
107	char *cmdline __free(efi_pool) = NULL;
108	efi_status_t status;
109
110	/*
111	 * Get the command line from EFI, using the LOADED_IMAGE
112	 * protocol. We are going to copy the command line into the
113	 * device tree, so this can be allocated anywhere.
114	 */
115	cmdline = efi_convert_cmdline(image);
116	if (!cmdline) {
117		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
118		return EFI_OUT_OF_RESOURCES;
119	}
120
121	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
122		status = efi_parse_options(cmdline);
123		if (status != EFI_SUCCESS) {
124			efi_err("Failed to parse EFI load options\n");
125			return status;
126		}
127	}
128
129	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
130	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
131	    cmdline[0] == 0) {
132		status = efi_parse_options(CONFIG_CMDLINE);
133		if (status != EFI_SUCCESS) {
134			efi_err("Failed to parse built-in command line\n");
135			return status;
136		}
137	}
138
139	*cmdline_ptr = no_free_ptr(cmdline);
140	return EFI_SUCCESS;
141}
142
143efi_status_t efi_stub_common(efi_handle_t handle,
144			     efi_loaded_image_t *image,
145			     unsigned long image_addr,
146			     char *cmdline_ptr)
147{
148	struct screen_info *si;
149	efi_status_t status;
150
151	status = check_platform_features();
152	if (status != EFI_SUCCESS)
153		return status;
154
155	si = setup_graphics();
156
157	efi_retrieve_eventlog();
158
159	/* Ask the firmware to clear memory on unclean shutdown */
160	efi_enable_reset_attack_mitigation();
161
162	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
163			NULL);
164
165	efi_random_get_seed();
166
167	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
168	efi_novamap |= !(get_supported_rt_services() &
169			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
170
171	install_memreserve_table();
172
173	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
174
175	free_screen_info(si);
176	return status;
177}
178
179/*
180 * efi_allocate_virtmap() - create a pool allocation for the virtmap
181 *
182 * Create an allocation that is of sufficient size to hold all the memory
183 * descriptors that will be passed to SetVirtualAddressMap() to inform the
184 * firmware about the virtual mapping that will be used under the OS to call
185 * into the firmware.
186 */
187efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
188			       unsigned long *desc_size, u32 *desc_ver)
189{
190	unsigned long size, mmap_key;
191	efi_status_t status;
192
193	/*
194	 * Use the size of the current memory map as an upper bound for the
195	 * size of the buffer we need to pass to SetVirtualAddressMap() to
196	 * cover all EFI_MEMORY_RUNTIME regions.
197	 */
198	size = 0;
199	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
200			     desc_ver);
201	if (status != EFI_BUFFER_TOO_SMALL)
202		return EFI_LOAD_ERROR;
203
204	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
205			   (void **)virtmap);
206}
207
208/*
209 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
210 *
211 * This function populates the virt_addr fields of all memory region descriptors
212 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
213 * are also copied to @runtime_map, and their total count is returned in @count.
214 */
215void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
216		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
217		     int *count)
218{
219	u64 efi_virt_base = virtmap_base;
220	efi_memory_desc_t *in, *out = runtime_map;
221	int l;
222
223	*count = 0;
224
225	for (l = 0; l < map_size; l += desc_size) {
226		u64 paddr, size;
227
228		in = (void *)memory_map + l;
229		if (!(in->attribute & EFI_MEMORY_RUNTIME))
230			continue;
231
232		paddr = in->phys_addr;
233		size = in->num_pages * EFI_PAGE_SIZE;
234
235		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
236		if (efi_novamap) {
237			continue;
238		}
239
240		/*
241		 * Make the mapping compatible with 64k pages: this allows
242		 * a 4k page size kernel to kexec a 64k page size kernel and
243		 * vice versa.
244		 */
245		if (!flat_va_mapping) {
246
247			paddr = round_down(in->phys_addr, SZ_64K);
248			size += in->phys_addr - paddr;
249
250			/*
251			 * Avoid wasting memory on PTEs by choosing a virtual
252			 * base that is compatible with section mappings if this
253			 * region has the appropriate size and physical
254			 * alignment. (Sections are 2 MB on 4k granule kernels)
255			 */
256			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
257				efi_virt_base = round_up(efi_virt_base, SZ_2M);
258			else
259				efi_virt_base = round_up(efi_virt_base, SZ_64K);
260
261			in->virt_addr += efi_virt_base - paddr;
262			efi_virt_base += size;
263		}
264
265		memcpy(out, in, desc_size);
266		out = (void *)out + desc_size;
267		++*count;
268	}
269}