1/*
  2 * EFI stub implementation that is shared by arm and arm64 architectures.
  3 * This should be #included by the EFI stub implementation files.
  4 *
  5 * Copyright (C) 2013,2014 Linaro Limited
  6 *     Roy Franz <roy.franz@linaro.org
  7 * Copyright (C) 2013 Red Hat, Inc.
  8 *     Mark Salter <msalter@redhat.com>
  9 *
 10 * This file is part of the Linux kernel, and is made available under the
 11 * terms of the GNU General Public License version 2.
 12 *
 13 */
 14
 15#include <linux/efi.h>
 16#include <linux/sort.h>
 17#include <asm/efi.h>
 18
 19#include "efistub.h"
 20
 21bool __nokaslr;
 22
 23static int efi_get_secureboot(efi_system_table_t *sys_table_arg)
 24{
 25	static efi_char16_t const sb_var_name[] = {
 26		'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
 27	static efi_char16_t const sm_var_name[] = {
 28		'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0 };
 29
 30	efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
 31	efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
 32	u8 val;
 33	unsigned long size = sizeof(val);
 34	efi_status_t status;
 35
 36	status = f_getvar((efi_char16_t *)sb_var_name, (efi_guid_t *)&var_guid,
 37			  NULL, &size, &val);
 38
 39	if (status != EFI_SUCCESS)
 40		goto out_efi_err;
 41
 42	if (val == 0)
 43		return 0;
 44
 45	status = f_getvar((efi_char16_t *)sm_var_name, (efi_guid_t *)&var_guid,
 46			  NULL, &size, &val);
 47
 48	if (status != EFI_SUCCESS)
 49		goto out_efi_err;
 50
 51	if (val == 1)
 52		return 0;
 53
 54	return 1;
 55
 56out_efi_err:
 57	switch (status) {
 58	case EFI_NOT_FOUND:
 59		return 0;
 60	case EFI_DEVICE_ERROR:
 61		return -EIO;
 62	case EFI_SECURITY_VIOLATION:
 63		return -EACCES;
 64	default:
 65		return -EINVAL;
 66	}
 67}
 68
 69efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
 70			     void *__image, void **__fh)
 71{
 72	efi_file_io_interface_t *io;
 73	efi_loaded_image_t *image = __image;
 74	efi_file_handle_t *fh;
 75	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
 76	efi_status_t status;
 77	void *handle = (void *)(unsigned long)image->device_handle;
 78
 79	status = sys_table_arg->boottime->handle_protocol(handle,
 80				 &fs_proto, (void **)&io);
 81	if (status != EFI_SUCCESS) {
 82		efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
 83		return status;
 84	}
 85
 86	status = io->open_volume(io, &fh);
 87	if (status != EFI_SUCCESS)
 88		efi_printk(sys_table_arg, "Failed to open volume\n");
 89
 90	*__fh = fh;
 91	return status;
 92}
 93
 94efi_status_t efi_file_close(void *handle)
 95{
 96	efi_file_handle_t *fh = handle;
 97
 98	return fh->close(handle);
 99}
100
101efi_status_t
102efi_file_read(void *handle, unsigned long *size, void *addr)
103{
104	efi_file_handle_t *fh = handle;
105
106	return fh->read(handle, size, addr);
107}
108
109
110efi_status_t
111efi_file_size(efi_system_table_t *sys_table_arg, void *__fh,
112	      efi_char16_t *filename_16, void **handle, u64 *file_sz)
113{
114	efi_file_handle_t *h, *fh = __fh;
115	efi_file_info_t *info;
116	efi_status_t status;
117	efi_guid_t info_guid = EFI_FILE_INFO_ID;
118	unsigned long info_sz;
119
120	status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, (u64)0);
121	if (status != EFI_SUCCESS) {
122		efi_printk(sys_table_arg, "Failed to open file: ");
123		efi_char16_printk(sys_table_arg, filename_16);
124		efi_printk(sys_table_arg, "\n");
125		return status;
126	}
127
128	*handle = h;
129
130	info_sz = 0;
131	status = h->get_info(h, &info_guid, &info_sz, NULL);
132	if (status != EFI_BUFFER_TOO_SMALL) {
133		efi_printk(sys_table_arg, "Failed to get file info size\n");
134		return status;
135	}
136
137grow:
138	status = sys_table_arg->boottime->allocate_pool(EFI_LOADER_DATA,
139				 info_sz, (void **)&info);
140	if (status != EFI_SUCCESS) {
141		efi_printk(sys_table_arg, "Failed to alloc mem for file info\n");
142		return status;
143	}
144
145	status = h->get_info(h, &info_guid, &info_sz,
146						   info);
147	if (status == EFI_BUFFER_TOO_SMALL) {
148		sys_table_arg->boottime->free_pool(info);
149		goto grow;
150	}
151
152	*file_sz = info->file_size;
153	sys_table_arg->boottime->free_pool(info);
154
155	if (status != EFI_SUCCESS)
156		efi_printk(sys_table_arg, "Failed to get initrd info\n");
157
158	return status;
159}
160
161
162
163void efi_char16_printk(efi_system_table_t *sys_table_arg,
164			      efi_char16_t *str)
165{
166	struct efi_simple_text_output_protocol *out;
167
168	out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
169	out->output_string(out, str);
170}
171
172static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
173{
174	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
175	efi_status_t status;
176	unsigned long size;
177	void **gop_handle = NULL;
178	struct screen_info *si = NULL;
179
180	size = 0;
181	status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
182				&gop_proto, NULL, &size, gop_handle);
183	if (status == EFI_BUFFER_TOO_SMALL) {
184		si = alloc_screen_info(sys_table_arg);
185		if (!si)
186			return NULL;
187		efi_setup_gop(sys_table_arg, si, &gop_proto, size);
188	}
189	return si;
190}
191
192/*
193 * This function handles the architcture specific differences between arm and
194 * arm64 regarding where the kernel image must be loaded and any memory that
195 * must be reserved. On failure it is required to free all
196 * all allocations it has made.
197 */
198efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
199				 unsigned long *image_addr,
200				 unsigned long *image_size,
201				 unsigned long *reserve_addr,
202				 unsigned long *reserve_size,
203				 unsigned long dram_base,
204				 efi_loaded_image_t *image);
205/*
206 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
207 * that is described in the PE/COFF header.  Most of the code is the same
208 * for both archictectures, with the arch-specific code provided in the
209 * handle_kernel_image() function.
210 */
211unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
212			       unsigned long *image_addr)
213{
214	efi_loaded_image_t *image;
215	efi_status_t status;
216	unsigned long image_size = 0;
217	unsigned long dram_base;
218	/* addr/point and size pairs for memory management*/
219	unsigned long initrd_addr;
220	u64 initrd_size = 0;
221	unsigned long fdt_addr = 0;  /* Original DTB */
222	unsigned long fdt_size = 0;
223	char *cmdline_ptr = NULL;
224	int cmdline_size = 0;
225	unsigned long new_fdt_addr;
226	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
227	unsigned long reserve_addr = 0;
228	unsigned long reserve_size = 0;
229	int secure_boot = 0;
230	struct screen_info *si;
231
232	/* Check if we were booted by the EFI firmware */
233	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
234		goto fail;
235
236	pr_efi(sys_table, "Booting Linux Kernel...\n");
237
238	status = check_platform_features(sys_table);
239	if (status != EFI_SUCCESS)
240		goto fail;
241
242	/*
243	 * Get a handle to the loaded image protocol.  This is used to get
244	 * information about the running image, such as size and the command
245	 * line.
246	 */
247	status = sys_table->boottime->handle_protocol(handle,
248					&loaded_image_proto, (void *)&image);
249	if (status != EFI_SUCCESS) {
250		pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
251		goto fail;
252	}
253
254	dram_base = get_dram_base(sys_table);
255	if (dram_base == EFI_ERROR) {
256		pr_efi_err(sys_table, "Failed to find DRAM base\n");
257		goto fail;
258	}
259
260	/*
261	 * Get the command line from EFI, using the LOADED_IMAGE
262	 * protocol. We are going to copy the command line into the
263	 * device tree, so this can be allocated anywhere.
264	 */
265	cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
266	if (!cmdline_ptr) {
267		pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
268		goto fail;
269	}
270
271	/* check whether 'nokaslr' was passed on the command line */
272	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
273		static const u8 default_cmdline[] = CONFIG_CMDLINE;
274		const u8 *str, *cmdline = cmdline_ptr;
275
276		if (IS_ENABLED(CONFIG_CMDLINE_FORCE))
277			cmdline = default_cmdline;
278		str = strstr(cmdline, "nokaslr");
279		if (str == cmdline || (str > cmdline && *(str - 1) == ' '))
280			__nokaslr = true;
281	}
282
283	si = setup_graphics(sys_table);
284
285	status = handle_kernel_image(sys_table, image_addr, &image_size,
286				     &reserve_addr,
287				     &reserve_size,
288				     dram_base, image);
289	if (status != EFI_SUCCESS) {
290		pr_efi_err(sys_table, "Failed to relocate kernel\n");
291		goto fail_free_cmdline;
292	}
293
294	status = efi_parse_options(cmdline_ptr);
295	if (status != EFI_SUCCESS)
296		pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n");
297
298	secure_boot = efi_get_secureboot(sys_table);
299	if (secure_boot > 0)
300		pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
301
302	if (secure_boot < 0) {
303		pr_efi_err(sys_table,
304			"could not determine UEFI Secure Boot status.\n");
305	}
306
307	/*
308	 * Unauthenticated device tree data is a security hazard, so
309	 * ignore 'dtb=' unless UEFI Secure Boot is disabled.
310	 */
311	if (secure_boot != 0 && strstr(cmdline_ptr, "dtb=")) {
312		pr_efi(sys_table, "Ignoring DTB from command line.\n");
313	} else {
314		status = handle_cmdline_files(sys_table, image, cmdline_ptr,
315					      "dtb=",
316					      ~0UL, &fdt_addr, &fdt_size);
317
318		if (status != EFI_SUCCESS) {
319			pr_efi_err(sys_table, "Failed to load device tree!\n");
320			goto fail_free_image;
321		}
322	}
323
324	if (fdt_addr) {
325		pr_efi(sys_table, "Using DTB from command line\n");
326	} else {
327		/* Look for a device tree configuration table entry. */
328		fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
329		if (fdt_addr)
330			pr_efi(sys_table, "Using DTB from configuration table\n");
331	}
332
333	if (!fdt_addr)
334		pr_efi(sys_table, "Generating empty DTB\n");
335
336	status = handle_cmdline_files(sys_table, image, cmdline_ptr,
337				      "initrd=", dram_base + SZ_512M,
338				      (unsigned long *)&initrd_addr,
339				      (unsigned long *)&initrd_size);
340	if (status != EFI_SUCCESS)
341		pr_efi_err(sys_table, "Failed initrd from command line!\n");
342
343	efi_random_get_seed(sys_table);
344
345	new_fdt_addr = fdt_addr;
346	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
347				&new_fdt_addr, dram_base + MAX_FDT_OFFSET,
348				initrd_addr, initrd_size, cmdline_ptr,
349				fdt_addr, fdt_size);
350
351	/*
352	 * If all went well, we need to return the FDT address to the
353	 * calling function so it can be passed to kernel as part of
354	 * the kernel boot protocol.
355	 */
356	if (status == EFI_SUCCESS)
357		return new_fdt_addr;
358
359	pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
360
361	efi_free(sys_table, initrd_size, initrd_addr);
362	efi_free(sys_table, fdt_size, fdt_addr);
363
364fail_free_image:
365	efi_free(sys_table, image_size, *image_addr);
366	efi_free(sys_table, reserve_size, reserve_addr);
367fail_free_cmdline:
368	free_screen_info(sys_table, si);
369	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
370fail:
371	return EFI_ERROR;
372}
373
374/*
375 * This is the base address at which to start allocating virtual memory ranges
376 * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
377 * any allocation we choose, and eliminate the risk of a conflict after kexec.
378 * The value chosen is the largest non-zero power of 2 suitable for this purpose
379 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
380 * be mapped efficiently.
381 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
382 * map everything below 1 GB.
383 */
384#define EFI_RT_VIRTUAL_BASE	SZ_512M
385
386static int cmp_mem_desc(const void *l, const void *r)
387{
388	const efi_memory_desc_t *left = l, *right = r;
389
390	return (left->phys_addr > right->phys_addr) ? 1 : -1;
391}
392
393/*
394 * Returns whether region @left ends exactly where region @right starts,
395 * or false if either argument is NULL.
396 */
397static bool regions_are_adjacent(efi_memory_desc_t *left,
398				 efi_memory_desc_t *right)
399{
400	u64 left_end;
401
402	if (left == NULL || right == NULL)
403		return false;
404
405	left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
406
407	return left_end == right->phys_addr;
408}
409
410/*
411 * Returns whether region @left and region @right have compatible memory type
412 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
413 */
414static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
415						      efi_memory_desc_t *right)
416{
417	static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
418					 EFI_MEMORY_WC | EFI_MEMORY_UC |
419					 EFI_MEMORY_RUNTIME;
420
421	return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
422}
423
424/*
425 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
426 *
427 * This function populates the virt_addr fields of all memory region descriptors
428 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
429 * are also copied to @runtime_map, and their total count is returned in @count.
430 */
431void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
432		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
433		     int *count)
434{
435	u64 efi_virt_base = EFI_RT_VIRTUAL_BASE;
436	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
437	int l;
438
439	/*
440	 * To work around potential issues with the Properties Table feature
441	 * introduced in UEFI 2.5, which may split PE/COFF executable images
442	 * in memory into several RuntimeServicesCode and RuntimeServicesData
443	 * regions, we need to preserve the relative offsets between adjacent
444	 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
445	 * The easiest way to find adjacent regions is to sort the memory map
446	 * before traversing it.
447	 */
448	sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);
449
450	for (l = 0; l < map_size; l += desc_size, prev = in) {
451		u64 paddr, size;
452
453		in = (void *)memory_map + l;
454		if (!(in->attribute & EFI_MEMORY_RUNTIME))
455			continue;
456
457		paddr = in->phys_addr;
458		size = in->num_pages * EFI_PAGE_SIZE;
459
460		/*
461		 * Make the mapping compatible with 64k pages: this allows
462		 * a 4k page size kernel to kexec a 64k page size kernel and
463		 * vice versa.
464		 */
465		if (!regions_are_adjacent(prev, in) ||
466		    !regions_have_compatible_memory_type_attrs(prev, in)) {
467
468			paddr = round_down(in->phys_addr, SZ_64K);
469			size += in->phys_addr - paddr;
470
471			/*
472			 * Avoid wasting memory on PTEs by choosing a virtual
473			 * base that is compatible with section mappings if this
474			 * region has the appropriate size and physical
475			 * alignment. (Sections are 2 MB on 4k granule kernels)
476			 */
477			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
478				efi_virt_base = round_up(efi_virt_base, SZ_2M);
479			else
480				efi_virt_base = round_up(efi_virt_base, SZ_64K);
481		}
482
483		in->virt_addr = efi_virt_base + in->phys_addr - paddr;
484		efi_virt_base += size;
485
486		memcpy(out, in, desc_size);
487		out = (void *)out + desc_size;
488		++*count;
489	}
490}