1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (c) 2015 Google, Inc
4 *
5 * EFI information obtained here:
6 * http://wiki.phoenix.com/wiki/index.php/EFI_BOOT_SERVICES
7 *
8 * Loads a payload (U-Boot) within the EFI environment. This is built as an
9 * EFI application. It can be built either in 32-bit or 64-bit mode.
10 */
11
12#include <debug_uart.h>
13#include <efi.h>
14#include <efi_api.h>
15#include <errno.h>
16#include <malloc.h>
17#include <ns16550.h>
18#include <asm/cpu.h>
19#include <asm/io.h>
20#include <linux/err.h>
21#include <linux/types.h>
22
23#ifndef CONFIG_X86
24/*
25 * Problem areas:
26 * - putc() uses the ns16550 address directly and assumed I/O access. Many
27 *	platforms will use memory access
28 * get_codeseg32() is only meaningful on x86
29 */
30#error "This file needs to be ported for use on architectures"
31#endif
32
33static bool use_uart;
34
35struct __packed desctab_info {
36	uint16_t limit;
37	uint64_t addr;
38	uint16_t pad;
39};
40
41/*
42 * EFI uses Unicode and we don't. The easiest way to get a sensible output
43 * function is to use the U-Boot debug UART. We use EFI's console output
44 * function where available, and assume the built-in UART after that. We rely
45 * on EFI to set up the UART for us and just bring in the functions here.
46 * This last bit is a bit icky, but it's only for debugging anyway. We could
47 * build in ns16550.c with some effort, but this is a payload loader after
48 * all.
49 *
50 * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c.
51 * That would require some refactoring since we already build this for U-Boot.
52 * Building an EFI shared library version would have to be a separate stem.
53 * That might push us to using the SPL framework to build this stub. However
54 * that would involve a round of EFI-specific changes in SPL. Worth
55 * considering if we start needing more U-Boot functionality. Note that we
56 * could then move get_codeseg32() to arch/x86/cpu/cpu.c.
57 */
58void _debug_uart_init(void)
59{
60}
61
62void putc(const char ch)
63{
64	struct efi_priv *priv = efi_get_priv();
65
66	if (ch == '\n')
67		putc('\r');
68
69	if (use_uart) {
70		struct ns16550 *com_port = (struct ns16550 *)0x3f8;
71
72		while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0)
73			;
74		outb(ch, (ulong)&com_port->thr);
75	} else {
76		efi_putc(priv, ch);
77	}
78}
79
80void puts(const char *str)
81{
82	while (*str)
83		putc(*str++);
84}
85
86static void _debug_uart_putc(int ch)
87{
88	putc(ch);
89}
90
91DEBUG_UART_FUNCS
92
93void *memcpy(void *dest, const void *src, size_t size)
94{
95	unsigned char *dptr = dest;
96	const unsigned char *ptr = src;
97	const unsigned char *end = src + size;
98
99	while (ptr < end)
100		*dptr++ = *ptr++;
101
102	return dest;
103}
104
105void *memset(void *inptr, int ch, size_t size)
106{
107	char *ptr = inptr;
108	char *end = ptr + size;
109
110	while (ptr < end)
111		*ptr++ = ch;
112
113	return ptr;
114}
115
116static void jump_to_uboot(ulong cs32, ulong addr, ulong info)
117{
118#ifdef CONFIG_EFI_STUB_32BIT
119	/*
120	 * U-Boot requires these parameters in registers, not on the stack.
121	 * See _x86boot_start() for this code.
122	 */
123	typedef void (*func_t)(int bist, int unused, ulong info)
124		__attribute__((regparm(3)));
125
126	((func_t)addr)(0, 0, info);
127#else
128	cpu_call32(cs32, CONFIG_TEXT_BASE, info);
129#endif
130}
131
132#ifdef CONFIG_EFI_STUB_64BIT
133static void get_gdt(struct desctab_info *info)
134{
135	asm volatile ("sgdt %0" : : "m"(*info) : "memory");
136}
137#endif
138
139static inline unsigned long read_cr3(void)
140{
141	unsigned long val;
142
143	asm volatile("mov %%cr3,%0" : "=r" (val) : : "memory");
144	return val;
145}
146
147/**
148 * get_codeseg32() - Find the code segment to use for 32-bit code
149 *
150 * U-Boot only works in 32-bit mode at present, so when booting from 64-bit
151 * EFI we must first change to 32-bit mode. To do this we need to find the
152 * correct code segment to use (an entry in the Global Descriptor Table).
153 *
154 * Return: code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found
155 */
156static int get_codeseg32(void)
157{
158	int cs32 = 0;
159
160#ifdef CONFIG_EFI_STUB_64BIT
161	struct desctab_info gdt;
162	uint64_t *ptr;
163	int i;
164
165	get_gdt(&gdt);
166	for (ptr = (uint64_t *)(unsigned long)gdt.addr, i = 0; i < gdt.limit;
167	     i += 8, ptr++) {
168		uint64_t desc = *ptr;
169		uint64_t base, limit;
170
171		/*
172		 * Check that the target U-Boot jump address is within the
173		 * selector and that the selector is of the right type.
174		 */
175		base = ((desc >> GDT_BASE_LOW_SHIFT) & GDT_BASE_LOW_MASK) |
176			((desc >> GDT_BASE_HIGH_SHIFT) & GDT_BASE_HIGH_MASK)
177				<< 16;
178		limit = ((desc >> GDT_LIMIT_LOW_SHIFT) & GDT_LIMIT_LOW_MASK) |
179			((desc >> GDT_LIMIT_HIGH_SHIFT) & GDT_LIMIT_HIGH_MASK)
180				<< 16;
181		base <<= 12;	/* 4KB granularity */
182		limit <<= 12;
183		if ((desc & GDT_PRESENT) && (desc & GDT_NOTSYS) &&
184		    !(desc & GDT_LONG) && (desc & GDT_4KB) &&
185		    (desc & GDT_32BIT) && (desc & GDT_CODE) &&
186		    CONFIG_TEXT_BASE > base &&
187		    CONFIG_TEXT_BASE + CONFIG_SYS_MONITOR_LEN < limit
188		) {
189			cs32 = i;
190			break;
191		}
192	}
193
194#ifdef DEBUG
195	puts("\ngdt: ");
196	printhex8(gdt.limit);
197	puts(", addr: ");
198	printhex8(gdt.addr >> 32);
199	printhex8(gdt.addr);
200	for (i = 0; i < gdt.limit; i += 8) {
201		uint32_t *ptr = (uint32_t *)((unsigned long)gdt.addr + i);
202
203		puts("\n");
204		printhex2(i);
205		puts(": ");
206		printhex8(ptr[1]);
207		puts("  ");
208		printhex8(ptr[0]);
209	}
210	puts("\n ");
211	puts("32-bit code segment: ");
212	printhex2(cs32);
213	puts("\n ");
214
215	puts("page_table: ");
216	printhex8(read_cr3());
217	puts("\n ");
218#endif
219	if (!cs32) {
220		puts("Can't find 32-bit code segment\n");
221		return -ENOENT;
222	}
223#endif
224
225	return cs32;
226}
227
228/**
229 * setup_info_table() - sets up a table containing information from EFI
230 *
231 * We must call exit_boot_services() before jumping out of the stub into U-Boot
232 * proper, so that U-Boot has full control of peripherals, memory, etc.
233 *
234 * Once we do this, we cannot call any boot-services functions so we must find
235 * out everything we need to before doing that.
236 *
237 * Set up a struct efi_info_hdr table which can hold various records (e.g.
238 * struct efi_entry_memmap) with information obtained from EFI.
239 *
240 * @priv: Pointer to our private information which contains the list
241 * @size: Size of the table to allocate
242 * Return: 0 if OK, non-zero on error
243 */
244static int setup_info_table(struct efi_priv *priv, int size)
245{
246	struct efi_info_hdr *info;
247	efi_status_t ret;
248
249	/* Get some memory for our info table */
250	priv->info_size = size;
251	info = efi_malloc(priv, priv->info_size, &ret);
252	if (ret) {
253		printhex2(ret);
254		puts(" No memory for info table: ");
255		return ret;
256	}
257
258	memset(info, '\0', sizeof(*info));
259	info->version = EFI_TABLE_VERSION;
260	info->hdr_size = sizeof(*info);
261	priv->info = info;
262	priv->next_hdr = (char *)info + info->hdr_size;
263
264	return 0;
265}
266
267/**
268 * add_entry_addr() - Add a new entry to the efi_info list
269 *
270 * This adds an entry, consisting of a tag and two lots of data. This avoids the
271 * caller having to coalesce the data first
272 *
273 * @priv: Pointer to our private information which contains the list
274 * @type: Type of the entry to add
275 * @ptr1: Pointer to first data block to add
276 * @size1: Size of first data block in bytes (can be 0)
277 * @ptr2: Pointer to second data block to add
278 * @size2: Size of second data block in bytes (can be 0)
279 */
280static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type,
281			   void *ptr1, int size1, void *ptr2, int size2)
282{
283	struct efi_entry_hdr *hdr = priv->next_hdr;
284
285	hdr->type = type;
286	hdr->size = size1 + size2;
287	hdr->addr = 0;
288	hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16);
289	priv->next_hdr += hdr->link;
290	memcpy(hdr + 1, ptr1, size1);
291	memcpy((void *)(hdr + 1) + size1, ptr2, size2);
292	priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info;
293}
294
295/**
296 * efi_main() - Start an EFI image
297 *
298 * This function is called by our EFI start-up code. It handles running
299 * U-Boot. If it returns, EFI will continue.
300 */
301efi_status_t EFIAPI efi_main(efi_handle_t image,
302			     struct efi_system_table *sys_table)
303{
304	struct efi_priv local_priv, *priv = &local_priv;
305	struct efi_boot_services *boot = sys_table->boottime;
306	struct efi_entry_memmap map;
307	struct efi_gop *gop;
308	struct efi_entry_gopmode mode;
309	struct efi_entry_systable table;
310	efi_guid_t efi_gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
311	efi_status_t ret;
312	int cs32;
313
314	ret = efi_init(priv, "Payload", image, sys_table);
315	if (ret) {
316		printhex2(ret);
317		puts(" efi_init() failed\n");
318		return ret;
319	}
320	efi_set_priv(priv);
321
322	cs32 = get_codeseg32();
323	if (cs32 < 0)
324		return EFI_UNSUPPORTED;
325
326	ret = efi_store_memory_map(priv);
327	if (ret)
328		return ret;
329
330	ret = setup_info_table(priv, priv->memmap_size + 128);
331	if (ret)
332		return ret;
333
334	ret = boot->locate_protocol(&efi_gop_guid, NULL, (void **)&gop);
335	if (ret) {
336		puts(" GOP unavailable\n");
337	} else {
338		mode.fb_base = gop->mode->fb_base;
339		mode.fb_size = gop->mode->fb_size;
340		mode.info_size = gop->mode->info_size;
341		add_entry_addr(priv, EFIET_GOP_MODE, &mode, sizeof(mode),
342			       gop->mode->info,
343			       sizeof(struct efi_gop_mode_info));
344	}
345
346	table.sys_table = (ulong)sys_table;
347	add_entry_addr(priv, EFIET_SYS_TABLE, &table, sizeof(table), NULL, 0);
348
349	ret = efi_call_exit_boot_services();
350	if (ret)
351		return ret;
352
353	/* The EFI UART won't work now, switch to a debug one */
354	use_uart = true;
355
356	map.version = priv->memmap_version;
357	map.desc_size = priv->memmap_desc_size;
358	add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map),
359		       priv->memmap_desc, priv->memmap_size);
360	add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0);
361
362	memcpy((void *)CONFIG_TEXT_BASE, _binary_u_boot_bin_start,
363	       (ulong)_binary_u_boot_bin_end -
364	       (ulong)_binary_u_boot_bin_start);
365
366#ifdef DEBUG
367	puts("EFI table at ");
368	printhex8((ulong)priv->info);
369	puts(" size ");
370	printhex8(priv->info->total_size);
371#endif
372	putc('\n');
373	jump_to_uboot(cs32, CONFIG_TEXT_BASE, (ulong)priv->info);
374
375	return EFI_LOAD_ERROR;
376}
377