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
 21/*
 22 * This is the base address at which to start allocating virtual memory ranges
 23 * for UEFI Runtime Services. 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#define EFI_RT_VIRTUAL_BASE	SZ_512M
 33#define EFI_RT_VIRTUAL_SIZE	SZ_512M
 34
 35#ifdef CONFIG_ARM64
 36# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64
 37#else
 38# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
 39#endif
 40
 41static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
 42
 43efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
 44			     void *__image, void **__fh)
 45{
 46	efi_file_io_interface_t *io;
 47	efi_loaded_image_t *image = __image;
 48	efi_file_handle_t *fh;
 49	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
 50	efi_status_t status;
 51	void *handle = (void *)(unsigned long)image->device_handle;
 52
 53	status = sys_table_arg->boottime->handle_protocol(handle,
 54				 &fs_proto, (void **)&io);
 55	if (status != EFI_SUCCESS) {
 56		efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
 57		return status;
 58	}
 59
 60	status = io->open_volume(io, &fh);
 61	if (status != EFI_SUCCESS)
 62		efi_printk(sys_table_arg, "Failed to open volume\n");
 63
 64	*__fh = fh;
 65	return status;
 66}
 67
 68void efi_char16_printk(efi_system_table_t *sys_table_arg,
 69			      efi_char16_t *str)
 70{
 71	struct efi_simple_text_output_protocol *out;
 72
 73	out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
 74	out->output_string(out, str);
 75}
 76
 77static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
 78{
 79	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
 80	efi_status_t status;
 81	unsigned long size;
 82	void **gop_handle = NULL;
 83	struct screen_info *si = NULL;
 84
 85	size = 0;
 86	status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 87				&gop_proto, NULL, &size, gop_handle);
 88	if (status == EFI_BUFFER_TOO_SMALL) {
 89		si = alloc_screen_info(sys_table_arg);
 90		if (!si)
 91			return NULL;
 92		efi_setup_gop(sys_table_arg, si, &gop_proto, size);
 93	}
 94	return si;
 95}
 96
 97/*
 98 * This function handles the architcture specific differences between arm and
 99 * arm64 regarding where the kernel image must be loaded and any memory that
100 * must be reserved. On failure it is required to free all
101 * all allocations it has made.
102 */
103efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
104				 unsigned long *image_addr,
105				 unsigned long *image_size,
106				 unsigned long *reserve_addr,
107				 unsigned long *reserve_size,
108				 unsigned long dram_base,
109				 efi_loaded_image_t *image);
110/*
111 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
112 * that is described in the PE/COFF header.  Most of the code is the same
113 * for both archictectures, with the arch-specific code provided in the
114 * handle_kernel_image() function.
115 */
116unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
117			       unsigned long *image_addr)
118{
119	efi_loaded_image_t *image;
120	efi_status_t status;
121	unsigned long image_size = 0;
122	unsigned long dram_base;
123	/* addr/point and size pairs for memory management*/
124	unsigned long initrd_addr;
125	u64 initrd_size = 0;
126	unsigned long fdt_addr = 0;  /* Original DTB */
127	unsigned long fdt_size = 0;
128	char *cmdline_ptr = NULL;
129	int cmdline_size = 0;
130	unsigned long new_fdt_addr;
131	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
132	unsigned long reserve_addr = 0;
133	unsigned long reserve_size = 0;
134	enum efi_secureboot_mode secure_boot;
135	struct screen_info *si;
136
137	/* Check if we were booted by the EFI firmware */
138	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
139		goto fail;
140
141	status = check_platform_features(sys_table);
142	if (status != EFI_SUCCESS)
143		goto fail;
144
145	/*
146	 * Get a handle to the loaded image protocol.  This is used to get
147	 * information about the running image, such as size and the command
148	 * line.
149	 */
150	status = sys_table->boottime->handle_protocol(handle,
151					&loaded_image_proto, (void *)&image);
152	if (status != EFI_SUCCESS) {
153		pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
154		goto fail;
155	}
156
157	dram_base = get_dram_base(sys_table);
158	if (dram_base == EFI_ERROR) {
159		pr_efi_err(sys_table, "Failed to find DRAM base\n");
160		goto fail;
161	}
162
163	/*
164	 * Get the command line from EFI, using the LOADED_IMAGE
165	 * protocol. We are going to copy the command line into the
166	 * device tree, so this can be allocated anywhere.
167	 */
168	cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
169	if (!cmdline_ptr) {
170		pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
171		goto fail;
172	}
173
174	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
175	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
176	    cmdline_size == 0)
177		efi_parse_options(CONFIG_CMDLINE);
178
179	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
180		efi_parse_options(cmdline_ptr);
181
182	pr_efi(sys_table, "Booting Linux Kernel...\n");
183
184	si = setup_graphics(sys_table);
185
186	status = handle_kernel_image(sys_table, image_addr, &image_size,
187				     &reserve_addr,
188				     &reserve_size,
189				     dram_base, image);
190	if (status != EFI_SUCCESS) {
191		pr_efi_err(sys_table, "Failed to relocate kernel\n");
192		goto fail_free_cmdline;
193	}
194
195	/* Ask the firmware to clear memory on unclean shutdown */
196	efi_enable_reset_attack_mitigation(sys_table);
197
198	secure_boot = efi_get_secureboot(sys_table);
199
200	/*
201	 * Unauthenticated device tree data is a security hazard, so ignore
202	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
203	 * boot is enabled if we can't determine its state.
204	 */
205	if (secure_boot != efi_secureboot_mode_disabled &&
206	    strstr(cmdline_ptr, "dtb=")) {
207		pr_efi(sys_table, "Ignoring DTB from command line.\n");
208	} else {
209		status = handle_cmdline_files(sys_table, image, cmdline_ptr,
210					      "dtb=",
211					      ~0UL, &fdt_addr, &fdt_size);
212
213		if (status != EFI_SUCCESS) {
214			pr_efi_err(sys_table, "Failed to load device tree!\n");
215			goto fail_free_image;
216		}
217	}
218
219	if (fdt_addr) {
220		pr_efi(sys_table, "Using DTB from command line\n");
221	} else {
222		/* Look for a device tree configuration table entry. */
223		fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
224		if (fdt_addr)
225			pr_efi(sys_table, "Using DTB from configuration table\n");
226	}
227
228	if (!fdt_addr)
229		pr_efi(sys_table, "Generating empty DTB\n");
230
231	status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
232				      efi_get_max_initrd_addr(dram_base,
233							      *image_addr),
234				      (unsigned long *)&initrd_addr,
235				      (unsigned long *)&initrd_size);
236	if (status != EFI_SUCCESS)
237		pr_efi_err(sys_table, "Failed initrd from command line!\n");
238
239	efi_random_get_seed(sys_table);
240
241	/* hibernation expects the runtime regions to stay in the same place */
242	if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) {
243		/*
244		 * Randomize the base of the UEFI runtime services region.
245		 * Preserve the 2 MB alignment of the region by taking a
246		 * shift of 21 bit positions into account when scaling
247		 * the headroom value using a 32-bit random value.
248		 */
249		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
250					    EFI_RT_VIRTUAL_BASE -
251					    EFI_RT_VIRTUAL_SIZE;
252		u32 rnd;
253
254		status = efi_get_random_bytes(sys_table, sizeof(rnd),
255					      (u8 *)&rnd);
256		if (status == EFI_SUCCESS) {
257			virtmap_base = EFI_RT_VIRTUAL_BASE +
258				       (((headroom >> 21) * rnd) >> (32 - 21));
259		}
260	}
261
262	new_fdt_addr = fdt_addr;
263	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
264				&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
265				initrd_addr, initrd_size, cmdline_ptr,
266				fdt_addr, fdt_size);
267
268	/*
269	 * If all went well, we need to return the FDT address to the
270	 * calling function so it can be passed to kernel as part of
271	 * the kernel boot protocol.
272	 */
273	if (status == EFI_SUCCESS)
274		return new_fdt_addr;
275
276	pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
277
278	efi_free(sys_table, initrd_size, initrd_addr);
279	efi_free(sys_table, fdt_size, fdt_addr);
280
281fail_free_image:
282	efi_free(sys_table, image_size, *image_addr);
283	efi_free(sys_table, reserve_size, reserve_addr);
284fail_free_cmdline:
285	free_screen_info(sys_table, si);
286	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
287fail:
288	return EFI_ERROR;
289}
290
291static int cmp_mem_desc(const void *l, const void *r)
292{
293	const efi_memory_desc_t *left = l, *right = r;
294
295	return (left->phys_addr > right->phys_addr) ? 1 : -1;
296}
297
298/*
299 * Returns whether region @left ends exactly where region @right starts,
300 * or false if either argument is NULL.
301 */
302static bool regions_are_adjacent(efi_memory_desc_t *left,
303				 efi_memory_desc_t *right)
304{
305	u64 left_end;
306
307	if (left == NULL || right == NULL)
308		return false;
309
310	left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
311
312	return left_end == right->phys_addr;
313}
314
315/*
316 * Returns whether region @left and region @right have compatible memory type
317 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
318 */
319static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
320						      efi_memory_desc_t *right)
321{
322	static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
323					 EFI_MEMORY_WC | EFI_MEMORY_UC |
324					 EFI_MEMORY_RUNTIME;
325
326	return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
327}
328
329/*
330 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
331 *
332 * This function populates the virt_addr fields of all memory region descriptors
333 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
334 * are also copied to @runtime_map, and their total count is returned in @count.
335 */
336void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
337		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
338		     int *count)
339{
340	u64 efi_virt_base = virtmap_base;
341	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
342	int l;
343
344	/*
345	 * To work around potential issues with the Properties Table feature
346	 * introduced in UEFI 2.5, which may split PE/COFF executable images
347	 * in memory into several RuntimeServicesCode and RuntimeServicesData
348	 * regions, we need to preserve the relative offsets between adjacent
349	 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
350	 * The easiest way to find adjacent regions is to sort the memory map
351	 * before traversing it.
352	 */
353	if (IS_ENABLED(CONFIG_ARM64))
354		sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc,
355		     NULL);
356
357	for (l = 0; l < map_size; l += desc_size, prev = in) {
358		u64 paddr, size;
359
360		in = (void *)memory_map + l;
361		if (!(in->attribute & EFI_MEMORY_RUNTIME))
362			continue;
363
364		paddr = in->phys_addr;
365		size = in->num_pages * EFI_PAGE_SIZE;
366
367		/*
368		 * Make the mapping compatible with 64k pages: this allows
369		 * a 4k page size kernel to kexec a 64k page size kernel and
370		 * vice versa.
371		 */
372		if ((IS_ENABLED(CONFIG_ARM64) &&
373		     !regions_are_adjacent(prev, in)) ||
374		    !regions_have_compatible_memory_type_attrs(prev, in)) {
375
376			paddr = round_down(in->phys_addr, SZ_64K);
377			size += in->phys_addr - paddr;
378
379			/*
380			 * Avoid wasting memory on PTEs by choosing a virtual
381			 * base that is compatible with section mappings if this
382			 * region has the appropriate size and physical
383			 * alignment. (Sections are 2 MB on 4k granule kernels)
384			 */
385			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
386				efi_virt_base = round_up(efi_virt_base, SZ_2M);
387			else
388				efi_virt_base = round_up(efi_virt_base, SZ_64K);
389		}
390
391		in->virt_addr = efi_virt_base + in->phys_addr - paddr;
392		efi_virt_base += size;
393
394		memcpy(out, in, desc_size);
395		out = (void *)out + desc_size;
396		++*count;
397	}
398}