arm-stub.c 11.6 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 35 36
/*
 * 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

static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;

37 38
efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
			     void *__image, void **__fh)
M
Mark Salter 已提交
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
{
	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;
}
61 62

void efi_char16_printk(efi_system_table_t *sys_table_arg,
M
Mark Salter 已提交
63 64 65 66 67 68 69 70
			      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);
}

71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89
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
90 91 92 93 94 95 96

/*
 * 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.
 */
97 98 99 100 101 102 103
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
104 105 106 107 108 109
/*
 * 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.
 */
110
unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
M
Mark Salter 已提交
111 112 113 114 115 116 117 118 119
			       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;
120
	unsigned long fdt_addr = 0;  /* Original DTB */
121
	unsigned long fdt_size = 0;
M
Mark Salter 已提交
122 123 124 125 126 127
	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;
128
	enum efi_secureboot_mode secure_boot;
129
	struct screen_info *si;
M
Mark Salter 已提交
130 131 132 133 134

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

135 136 137 138
	status = check_platform_features(sys_table);
	if (status != EFI_SUCCESS)
		goto fail;

M
Mark Salter 已提交
139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164
	/*
	 * 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");
165 166 167
		goto fail;
	}

168 169 170 171 172 173 174 175 176 177
	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");

178 179
	si = setup_graphics(sys_table);

180 181 182 183 184 185 186
	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
187 188
	}

189 190
	secure_boot = efi_get_secureboot(sys_table);

191
	/*
192 193 194
	 * 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.
195
	 */
196 197
	if (secure_boot != efi_secureboot_mode_disabled &&
	    strstr(cmdline_ptr, "dtb=")) {
198
		pr_efi(sys_table, "Ignoring DTB from command line.\n");
199
	} else {
M
Mark Salter 已提交
200 201
		status = handle_cmdline_files(sys_table, image, cmdline_ptr,
					      "dtb=",
202
					      ~0UL, &fdt_addr, &fdt_size);
M
Mark Salter 已提交
203 204 205

		if (status != EFI_SUCCESS) {
			pr_efi_err(sys_table, "Failed to load device tree!\n");
206
			goto fail_free_image;
M
Mark Salter 已提交
207 208
		}
	}
209 210 211 212

	if (fdt_addr) {
		pr_efi(sys_table, "Using DTB from command line\n");
	} else {
213
		/* Look for a device tree configuration table entry. */
214
		fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
215 216 217 218 219 220
		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
221

222 223 224
	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
225 226 227 228 229
				      (unsigned long *)&initrd_addr,
				      (unsigned long *)&initrd_size);
	if (status != EFI_SUCCESS)
		pr_efi_err(sys_table, "Failed initrd from command line!\n");

230 231
	efi_random_get_seed(sys_table);

232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250
	if (!nokaslr()) {
		/*
		 * 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.
		 */
		u64 headroom = TASK_SIZE - EFI_RT_VIRTUAL_BASE -
			       EFI_RT_VIRTUAL_SIZE;
		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
251 252
	new_fdt_addr = fdt_addr;
	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
253
				&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
M
Mark Salter 已提交
254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272
				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);
273
fail_free_cmdline:
274
	free_screen_info(sys_table, si);
275
	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
M
Mark Salter 已提交
276 277 278
fail:
	return EFI_ERROR;
}
279

280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317
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;
}

318 319 320 321 322 323 324 325 326 327 328
/*
 * 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)
{
329
	u64 efi_virt_base = virtmap_base;
330
	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
331 332
	int l;

333 334 335 336 337 338 339 340 341 342 343 344
	/*
	 * 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.
	 */
	sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);

	for (l = 0; l < map_size; l += desc_size, prev = in) {
345 346
		u64 paddr, size;

347
		in = (void *)memory_map + l;
348 349 350
		if (!(in->attribute & EFI_MEMORY_RUNTIME))
			continue;

351 352 353
		paddr = in->phys_addr;
		size = in->num_pages * EFI_PAGE_SIZE;

354 355 356 357 358
		/*
		 * Make the mapping compatible with 64k pages: this allows
		 * a 4k page size kernel to kexec a 64k page size kernel and
		 * vice versa.
		 */
359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375
		if (!regions_are_adjacent(prev, in) ||
		    !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);
		}
376 377 378 379 380 381 382 383 384

		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;
	}
}