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 <common.h>
13 #include <debug_uart.h>
14 #include <efi.h>
15 #include <efi_api.h>
16 #include <errno.h>
17 #include <malloc.h>
18 #include <ns16550.h>
19 #include <asm/cpu.h>
20 #include <asm/io.h>
21 #include <linux/err.h>
22 #include <linux/types.h>
23
24 #ifndef CONFIG_X86
25 /*
26 * Problem areas:
27 * - putc() uses the ns16550 address directly and assumed I/O access. Many
28 * platforms will use memory access
29 * get_codeseg32() is only meaningful on x86
30 */
31 #error "This file needs to be ported for use on architectures"
32 #endif
33
34 static struct efi_priv *global_priv;
35 static bool use_uart;
36
37 struct __packed desctab_info {
38 uint16_t limit;
39 uint64_t addr;
40 uint16_t pad;
41 };
42
43 /*
44 * EFI uses Unicode and we don't. The easiest way to get a sensible output
45 * function is to use the U-Boot debug UART. We use EFI's console output
46 * function where available, and assume the built-in UART after that. We rely
47 * on EFI to set up the UART for us and just bring in the functions here.
48 * This last bit is a bit icky, but it's only for debugging anyway. We could
49 * build in ns16550.c with some effort, but this is a payload loader after
50 * all.
51 *
52 * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c.
53 * That would require some refactoring since we already build this for U-Boot.
54 * Building an EFI shared library version would have to be a separate stem.
55 * That might push us to using the SPL framework to build this stub. However
56 * that would involve a round of EFI-specific changes in SPL. Worth
57 * considering if we start needing more U-Boot functionality. Note that we
58 * could then move get_codeseg32() to arch/x86/cpu/cpu.c.
59 */
_debug_uart_init(void)60 void _debug_uart_init(void)
61 {
62 }
63
putc(const char ch)64 void putc(const char ch)
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(global_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 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_SYS_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_SYS_TEXT_BASE > base &&
187 CONFIG_SYS_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
setup_info_table(struct efi_priv * priv,int size)228 static int setup_info_table(struct efi_priv *priv, int size)
229 {
230 struct efi_info_hdr *info;
231 efi_status_t ret;
232
233 /* Get some memory for our info table */
234 priv->info_size = size;
235 info = efi_malloc(priv, priv->info_size, &ret);
236 if (ret) {
237 printhex2(ret);
238 puts(" No memory for info table: ");
239 return ret;
240 }
241
242 memset(info, '\0', sizeof(*info));
243 info->version = EFI_TABLE_VERSION;
244 info->hdr_size = sizeof(*info);
245 priv->info = info;
246 priv->next_hdr = (char *)info + info->hdr_size;
247
248 return 0;
249 }
250
add_entry_addr(struct efi_priv * priv,enum efi_entry_t type,void * ptr1,int size1,void * ptr2,int size2)251 static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type,
252 void *ptr1, int size1, void *ptr2, int size2)
253 {
254 struct efi_entry_hdr *hdr = priv->next_hdr;
255
256 hdr->type = type;
257 hdr->size = size1 + size2;
258 hdr->addr = 0;
259 hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16);
260 priv->next_hdr += hdr->link;
261 memcpy(hdr + 1, ptr1, size1);
262 memcpy((void *)(hdr + 1) + size1, ptr2, size2);
263 priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info;
264 }
265
266 /**
267 * efi_main() - Start an EFI image
268 *
269 * This function is called by our EFI start-up code. It handles running
270 * U-Boot. If it returns, EFI will continue.
271 */
efi_main(efi_handle_t image,struct efi_system_table * sys_table)272 efi_status_t EFIAPI efi_main(efi_handle_t image,
273 struct efi_system_table *sys_table)
274 {
275 struct efi_priv local_priv, *priv = &local_priv;
276 struct efi_boot_services *boot = sys_table->boottime;
277 struct efi_mem_desc *desc;
278 struct efi_entry_memmap map;
279 struct efi_gop *gop;
280 struct efi_entry_gopmode mode;
281 struct efi_entry_systable table;
282 efi_guid_t efi_gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
283 efi_uintn_t key, desc_size, size;
284 efi_status_t ret;
285 u32 version;
286 int cs32;
287
288 ret = efi_init(priv, "Payload", image, sys_table);
289 if (ret) {
290 printhex2(ret);
291 puts(" efi_init() failed\n");
292 return ret;
293 }
294 global_priv = priv;
295
296 cs32 = get_codeseg32();
297 if (cs32 < 0)
298 return EFI_UNSUPPORTED;
299
300 /* Get the memory map so we can switch off EFI */
301 size = 0;
302 ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version);
303 if (ret != EFI_BUFFER_TOO_SMALL) {
304 printhex2(EFI_BITS_PER_LONG);
305 putc(' ');
306 printhex2(ret);
307 puts(" No memory map\n");
308 return ret;
309 }
310 size += 1024; /* Since doing a malloc() may change the memory map! */
311 desc = efi_malloc(priv, size, &ret);
312 if (!desc) {
313 printhex2(ret);
314 puts(" No memory for memory descriptor\n");
315 return ret;
316 }
317 ret = setup_info_table(priv, size + 128);
318 if (ret)
319 return ret;
320
321 ret = boot->locate_protocol(&efi_gop_guid, NULL, (void **)&gop);
322 if (ret) {
323 puts(" GOP unavailable\n");
324 } else {
325 mode.fb_base = gop->mode->fb_base;
326 mode.fb_size = gop->mode->fb_size;
327 mode.info_size = gop->mode->info_size;
328 add_entry_addr(priv, EFIET_GOP_MODE, &mode, sizeof(mode),
329 gop->mode->info,
330 sizeof(struct efi_gop_mode_info));
331 }
332
333 ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version);
334 if (ret) {
335 printhex2(ret);
336 puts(" Can't get memory map\n");
337 return ret;
338 }
339
340 table.sys_table = (ulong)sys_table;
341 add_entry_addr(priv, EFIET_SYS_TABLE, &table, sizeof(table), NULL, 0);
342
343 ret = boot->exit_boot_services(image, key);
344 if (ret) {
345 /*
346 * Unfortunately it happens that we cannot exit boot services
347 * the first time. But the second time it work. I don't know
348 * why but this seems to be a repeatable problem. To get
349 * around it, just try again.
350 */
351 printhex2(ret);
352 puts(" Can't exit boot services\n");
353 size = sizeof(desc);
354 ret = boot->get_memory_map(&size, desc, &key, &desc_size,
355 &version);
356 if (ret) {
357 printhex2(ret);
358 puts(" Can't get memory map\n");
359 return ret;
360 }
361 ret = boot->exit_boot_services(image, key);
362 if (ret) {
363 printhex2(ret);
364 puts(" Can't exit boot services 2\n");
365 return ret;
366 }
367 }
368
369 /* The EFI UART won't work now, switch to a debug one */
370 use_uart = true;
371
372 map.version = version;
373 map.desc_size = desc_size;
374 add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size);
375 add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0);
376
377 memcpy((void *)CONFIG_SYS_TEXT_BASE, _binary_u_boot_bin_start,
378 (ulong)_binary_u_boot_bin_end -
379 (ulong)_binary_u_boot_bin_start);
380
381 #ifdef DEBUG
382 puts("EFI table at ");
383 printhex8((ulong)priv->info);
384 puts(" size ");
385 printhex8(priv->info->total_size);
386 #endif
387 putc('\n');
388 jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info);
389
390 return EFI_LOAD_ERROR;
391 }
392