arm-stub.c 12.1 KB
Newer Older
M
Mark Salter 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14
/*
 * EFI stub implementation that is shared by arm and arm64 architectures.
 * This should be #included by the EFI stub implementation files.
 *
 * Copyright (C) 2013,2014 Linaro Limited
 *     Roy Franz <roy.franz@linaro.org
 * Copyright (C) 2013 Red Hat, Inc.
 *     Mark Salter <msalter@redhat.com>
 *
 * This file is part of the Linux kernel, and is made available under the
 * terms of the GNU General Public License version 2.
 *
 */

15
#include <linux/efi.h>
16
#include <linux/sort.h>
17 18 19 20
#include <asm/efi.h>

#include "efistub.h"

21 22 23 24 25 26 27 28 29 30 31 32 33 34
/*
 * This is the base address at which to start allocating virtual memory ranges
 * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
 * any allocation we choose, and eliminate the risk of a conflict after kexec.
 * The value chosen is the largest non-zero power of 2 suitable for this purpose
 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
 * be mapped efficiently.
 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
 * entire footprint of the UEFI runtime services memory regions)
 */
#define EFI_RT_VIRTUAL_BASE	SZ_512M
#define EFI_RT_VIRTUAL_SIZE	SZ_512M

35 36 37 38 39 40
#ifdef CONFIG_ARM64
# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64
#else
# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
#endif

41 42
static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;

43 44
efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
			     void *__image, void **__fh)
M
Mark Salter 已提交
45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
{
	efi_file_io_interface_t *io;
	efi_loaded_image_t *image = __image;
	efi_file_handle_t *fh;
	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
	efi_status_t status;
	void *handle = (void *)(unsigned long)image->device_handle;

	status = sys_table_arg->boottime->handle_protocol(handle,
				 &fs_proto, (void **)&io);
	if (status != EFI_SUCCESS) {
		efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
		return status;
	}

	status = io->open_volume(io, &fh);
	if (status != EFI_SUCCESS)
		efi_printk(sys_table_arg, "Failed to open volume\n");

	*__fh = fh;
	return status;
}
67 68

void efi_char16_printk(efi_system_table_t *sys_table_arg,
M
Mark Salter 已提交
69 70 71 72 73 74 75 76
			      efi_char16_t *str)
{
	struct efi_simple_text_output_protocol *out;

	out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
	out->output_string(out, str);
}

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
{
	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
	efi_status_t status;
	unsigned long size;
	void **gop_handle = NULL;
	struct screen_info *si = NULL;

	size = 0;
	status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
				&gop_proto, NULL, &size, gop_handle);
	if (status == EFI_BUFFER_TOO_SMALL) {
		si = alloc_screen_info(sys_table_arg);
		if (!si)
			return NULL;
		efi_setup_gop(sys_table_arg, si, &gop_proto, size);
	}
	return si;
}
M
Mark Salter 已提交
96 97 98 99 100 101 102

/*
 * This function handles the architcture specific differences between arm and
 * arm64 regarding where the kernel image must be loaded and any memory that
 * must be reserved. On failure it is required to free all
 * all allocations it has made.
 */
103 104 105 106 107 108 109
efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
				 unsigned long *image_addr,
				 unsigned long *image_size,
				 unsigned long *reserve_addr,
				 unsigned long *reserve_size,
				 unsigned long dram_base,
				 efi_loaded_image_t *image);
M
Mark Salter 已提交
110 111 112 113 114 115
/*
 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 * that is described in the PE/COFF header.  Most of the code is the same
 * for both archictectures, with the arch-specific code provided in the
 * handle_kernel_image() function.
 */
116
unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
M
Mark Salter 已提交
117 118 119 120 121 122 123 124 125
			       unsigned long *image_addr)
{
	efi_loaded_image_t *image;
	efi_status_t status;
	unsigned long image_size = 0;
	unsigned long dram_base;
	/* addr/point and size pairs for memory management*/
	unsigned long initrd_addr;
	u64 initrd_size = 0;
126
	unsigned long fdt_addr = 0;  /* Original DTB */
127
	unsigned long fdt_size = 0;
M
Mark Salter 已提交
128 129 130 131 132 133
	char *cmdline_ptr = NULL;
	int cmdline_size = 0;
	unsigned long new_fdt_addr;
	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
	unsigned long reserve_addr = 0;
	unsigned long reserve_size = 0;
134
	enum efi_secureboot_mode secure_boot;
135
	struct screen_info *si;
M
Mark Salter 已提交
136 137 138 139 140

	/* Check if we were booted by the EFI firmware */
	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
		goto fail;

141 142 143 144
	status = check_platform_features(sys_table);
	if (status != EFI_SUCCESS)
		goto fail;

M
Mark Salter 已提交
145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170
	/*
	 * Get a handle to the loaded image protocol.  This is used to get
	 * information about the running image, such as size and the command
	 * line.
	 */
	status = sys_table->boottime->handle_protocol(handle,
					&loaded_image_proto, (void *)&image);
	if (status != EFI_SUCCESS) {
		pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
		goto fail;
	}

	dram_base = get_dram_base(sys_table);
	if (dram_base == EFI_ERROR) {
		pr_efi_err(sys_table, "Failed to find DRAM base\n");
		goto fail;
	}

	/*
	 * Get the command line from EFI, using the LOADED_IMAGE
	 * protocol. We are going to copy the command line into the
	 * device tree, so this can be allocated anywhere.
	 */
	cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
	if (!cmdline_ptr) {
		pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
171 172 173
		goto fail;
	}

174 175 176 177 178 179 180 181 182 183
	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
	    cmdline_size == 0)
		efi_parse_options(CONFIG_CMDLINE);

	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
		efi_parse_options(cmdline_ptr);

	pr_efi(sys_table, "Booting Linux Kernel...\n");

184 185
	si = setup_graphics(sys_table);

186 187 188 189 190 191 192
	status = handle_kernel_image(sys_table, image_addr, &image_size,
				     &reserve_addr,
				     &reserve_size,
				     dram_base, image);
	if (status != EFI_SUCCESS) {
		pr_efi_err(sys_table, "Failed to relocate kernel\n");
		goto fail_free_cmdline;
M
Mark Salter 已提交
193 194
	}

195 196 197
	/* Ask the firmware to clear memory on unclean shutdown */
	efi_enable_reset_attack_mitigation(sys_table);

198 199
	secure_boot = efi_get_secureboot(sys_table);

200
	/*
201 202 203
	 * Unauthenticated device tree data is a security hazard, so ignore
	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
	 * boot is enabled if we can't determine its state.
204
	 */
205 206
	if (secure_boot != efi_secureboot_mode_disabled &&
	    strstr(cmdline_ptr, "dtb=")) {
207
		pr_efi(sys_table, "Ignoring DTB from command line.\n");
208
	} else {
M
Mark Salter 已提交
209 210
		status = handle_cmdline_files(sys_table, image, cmdline_ptr,
					      "dtb=",
211
					      ~0UL, &fdt_addr, &fdt_size);
M
Mark Salter 已提交
212 213 214

		if (status != EFI_SUCCESS) {
			pr_efi_err(sys_table, "Failed to load device tree!\n");
215
			goto fail_free_image;
M
Mark Salter 已提交
216 217
		}
	}
218 219 220 221

	if (fdt_addr) {
		pr_efi(sys_table, "Using DTB from command line\n");
	} else {
222
		/* Look for a device tree configuration table entry. */
223
		fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
224 225 226 227 228 229
		if (fdt_addr)
			pr_efi(sys_table, "Using DTB from configuration table\n");
	}

	if (!fdt_addr)
		pr_efi(sys_table, "Generating empty DTB\n");
M
Mark Salter 已提交
230

231 232 233
	status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
				      efi_get_max_initrd_addr(dram_base,
							      *image_addr),
M
Mark Salter 已提交
234 235 236 237 238
				      (unsigned long *)&initrd_addr,
				      (unsigned long *)&initrd_size);
	if (status != EFI_SUCCESS)
		pr_efi_err(sys_table, "Failed initrd from command line!\n");

239 240
	efi_random_get_seed(sys_table);

241 242
	/* hibernation expects the runtime regions to stay in the same place */
	if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) {
243 244 245 246 247 248
		/*
		 * Randomize the base of the UEFI runtime services region.
		 * Preserve the 2 MB alignment of the region by taking a
		 * shift of 21 bit positions into account when scaling
		 * the headroom value using a 32-bit random value.
		 */
249 250 251
		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
					    EFI_RT_VIRTUAL_BASE -
					    EFI_RT_VIRTUAL_SIZE;
252 253 254 255 256 257 258 259 260 261
		u32 rnd;

		status = efi_get_random_bytes(sys_table, sizeof(rnd),
					      (u8 *)&rnd);
		if (status == EFI_SUCCESS) {
			virtmap_base = EFI_RT_VIRTUAL_BASE +
				       (((headroom >> 21) * rnd) >> (32 - 21));
		}
	}

M
Mark Salter 已提交
262 263
	new_fdt_addr = fdt_addr;
	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
264
				&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
M
Mark Salter 已提交
265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283
				initrd_addr, initrd_size, cmdline_ptr,
				fdt_addr, fdt_size);

	/*
	 * If all went well, we need to return the FDT address to the
	 * calling function so it can be passed to kernel as part of
	 * the kernel boot protocol.
	 */
	if (status == EFI_SUCCESS)
		return new_fdt_addr;

	pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");

	efi_free(sys_table, initrd_size, initrd_addr);
	efi_free(sys_table, fdt_size, fdt_addr);

fail_free_image:
	efi_free(sys_table, image_size, *image_addr);
	efi_free(sys_table, reserve_size, reserve_addr);
284
fail_free_cmdline:
285
	free_screen_info(sys_table, si);
286
	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
M
Mark Salter 已提交
287 288 289
fail:
	return EFI_ERROR;
}
290

291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328
static int cmp_mem_desc(const void *l, const void *r)
{
	const efi_memory_desc_t *left = l, *right = r;

	return (left->phys_addr > right->phys_addr) ? 1 : -1;
}

/*
 * Returns whether region @left ends exactly where region @right starts,
 * or false if either argument is NULL.
 */
static bool regions_are_adjacent(efi_memory_desc_t *left,
				 efi_memory_desc_t *right)
{
	u64 left_end;

	if (left == NULL || right == NULL)
		return false;

	left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;

	return left_end == right->phys_addr;
}

/*
 * Returns whether region @left and region @right have compatible memory type
 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 */
static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
						      efi_memory_desc_t *right)
{
	static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
					 EFI_MEMORY_WC | EFI_MEMORY_UC |
					 EFI_MEMORY_RUNTIME;

	return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
}

329 330 331 332 333 334 335 336 337 338 339
/*
 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 *
 * This function populates the virt_addr fields of all memory region descriptors
 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 * are also copied to @runtime_map, and their total count is returned in @count.
 */
void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
		     int *count)
{
340
	u64 efi_virt_base = virtmap_base;
341
	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
342 343
	int l;

344 345 346 347 348 349 350 351 352
	/*
	 * To work around potential issues with the Properties Table feature
	 * introduced in UEFI 2.5, which may split PE/COFF executable images
	 * in memory into several RuntimeServicesCode and RuntimeServicesData
	 * regions, we need to preserve the relative offsets between adjacent
	 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
	 * The easiest way to find adjacent regions is to sort the memory map
	 * before traversing it.
	 */
353 354 355
	if (IS_ENABLED(CONFIG_ARM64))
		sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc,
		     NULL);
356 357

	for (l = 0; l < map_size; l += desc_size, prev = in) {
358 359
		u64 paddr, size;

360
		in = (void *)memory_map + l;
361 362 363
		if (!(in->attribute & EFI_MEMORY_RUNTIME))
			continue;

364 365 366
		paddr = in->phys_addr;
		size = in->num_pages * EFI_PAGE_SIZE;

367 368 369 370 371
		/*
		 * Make the mapping compatible with 64k pages: this allows
		 * a 4k page size kernel to kexec a 64k page size kernel and
		 * vice versa.
		 */
372 373
		if ((IS_ENABLED(CONFIG_ARM64) &&
		     !regions_are_adjacent(prev, in)) ||
374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389
		    !regions_have_compatible_memory_type_attrs(prev, in)) {

			paddr = round_down(in->phys_addr, SZ_64K);
			size += in->phys_addr - paddr;

			/*
			 * Avoid wasting memory on PTEs by choosing a virtual
			 * base that is compatible with section mappings if this
			 * region has the appropriate size and physical
			 * alignment. (Sections are 2 MB on 4k granule kernels)
			 */
			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
				efi_virt_base = round_up(efi_virt_base, SZ_2M);
			else
				efi_virt_base = round_up(efi_virt_base, SZ_64K);
		}
390 391 392 393 394 395 396 397 398

		in->virt_addr = efi_virt_base + in->phys_addr - paddr;
		efi_virt_base += size;

		memcpy(out, in, desc_size);
		out = (void *)out + desc_size;
		++*count;
	}
}