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
33 static bool use_uart;
34
35 struct __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 */
_debug_uart_init(void)58 void _debug_uart_init(void)
59 {
60 }
61
putc(const char ch)62 void 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
puts(const char * str)80 void puts(const char *str)
81 {
82 while (*str)
83 putc(*str++);
84 }
85
_debug_uart_putc(int ch)86 static inline void _debug_uart_putc(int ch)
87 {
88 putc(ch);
89 }
90
91 DEBUG_UART_FUNCS
92
memcpy(void * dest,const void * src,size_t size)93 void *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
memset(void * inptr,int ch,size_t size)105 void *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
jump_to_uboot(ulong cs32,ulong addr,ulong info)116 static 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
get_gdt(struct desctab_info * info)133 static void get_gdt(struct desctab_info *info)
134 {
135 asm volatile ("sgdt %0" : : "m"(*info) : "memory");
136 }
137 #endif
138
read_cr3(void)139 static 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 */
get_codeseg32(void)156 static 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 */
setup_info_table(struct efi_priv * priv,int size)244 static 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 */
add_entry_addr(struct efi_priv * priv,enum efi_entry_t type,void * ptr1,int size1,void * ptr2,int size2)280 static 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 */
efi_main(efi_handle_t image,struct efi_system_table * sys_table)301 efi_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