1 /*-
2 * Copyright (c) 2021 Roger Pau Monné <royger@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 /*
28 * This multiboot2 implementation only implements a subset of the full
29 * multiboot2 specification in order to be able to boot Xen and a
30 * FreeBSD Dom0. Trying to use it to boot other multiboot2 compliant
31 * kernels will most surely fail.
32 *
33 * The full multiboot specification can be found here:
34 * https://www.gnu.org/software/grub/manual/multiboot2/multiboot.html
35 */
36
37 #include <sys/param.h>
38 #include <sys/exec.h>
39 #include <sys/linker.h>
40 #include <sys/module.h>
41 #include <sys/stdint.h>
42 #define _MACHINE_ELF_WANT_32BIT
43 #include <machine/elf.h>
44 #include <machine/metadata.h>
45 #include <string.h>
46 #include <stand.h>
47
48 #include <efi.h>
49 #include <efilib.h>
50
51 #include "bootstrap.h"
52 #include "multiboot2.h"
53 #include "loader_efi.h"
54 #include "modinfo.h"
55
56 extern int elf32_loadfile_raw(char *filename, uint64_t dest,
57 struct preloaded_file **result, int multiboot);
58 extern int elf64_load_modmetadata(struct preloaded_file *fp, uint64_t dest);
59 extern int elf64_obj_loadfile(char *filename, uint64_t dest,
60 struct preloaded_file **result);
61
62 extern void multiboot2_exec(void *entry, uint64_t multiboot_info,
63 uint64_t stack);
64
65 /*
66 * Multiboot2 header information to pass between the loading and the exec
67 * functions.
68 */
69 struct mb2hdr {
70 uint32_t efi64_entry;
71 };
72
73 static int
loadfile(char * filename,uint64_t dest,struct preloaded_file ** result)74 loadfile(char *filename, uint64_t dest, struct preloaded_file **result)
75 {
76 unsigned int i;
77 int error, fd;
78 void *header_search = NULL;
79 void *multiboot = NULL;
80 ssize_t search_size;
81 struct multiboot_header *header;
82 struct mb2hdr hdr;
83 bool keep_bs = false;
84
85 /*
86 * Read MULTIBOOT_SEARCH size in order to search for the
87 * multiboot magic header.
88 */
89 if (filename == NULL)
90 return (EFTYPE);
91 if ((fd = open(filename, O_RDONLY)) == -1)
92 return (errno);
93 header_search = malloc(MULTIBOOT_SEARCH);
94 if (header_search == NULL) {
95 error = ENOMEM;
96 goto out;
97 }
98 search_size = read(fd, header_search, MULTIBOOT_SEARCH);
99
100 for (i = 0; i < search_size; i += MULTIBOOT_HEADER_ALIGN) {
101 header = header_search + i;
102 if (header->magic == MULTIBOOT2_HEADER_MAGIC)
103 break;
104 }
105
106 if (i >= search_size) {
107 error = EFTYPE;
108 goto out;
109 }
110
111 /* Valid multiboot header has been found, validate checksum */
112 if (header->magic + header->architecture + header->header_length +
113 header->checksum != 0) {
114 printf("Multiboot checksum failed, magic: %#x "
115 "architecture: %#x header_length %#x checksum: %#x\n",
116 header->magic, header->architecture, header->header_length,
117 header->checksum);
118 error = EFTYPE;
119 goto out;
120 }
121
122 if (header->architecture != MULTIBOOT2_ARCHITECTURE_I386) {
123 printf("Unsupported architecture: %#x\n",
124 header->architecture);
125 error = EFTYPE;
126 goto out;
127 }
128
129 multiboot = malloc(header->header_length - sizeof(*header));
130 error = lseek(fd, i + sizeof(*header), SEEK_SET);
131 if (error != i + sizeof(*header)) {
132 printf("Unable to set file pointer to header location: %d\n",
133 error);
134 goto out;
135 }
136 search_size = read(fd, multiboot,
137 header->header_length - sizeof(*header));
138
139 bzero(&hdr, sizeof(hdr));
140 for (i = 0; i < search_size; ) {
141 struct multiboot_header_tag *tag;
142 struct multiboot_header_tag_entry_address *entry;
143 struct multiboot_header_tag_information_request *req;
144 unsigned int j;
145
146 tag = multiboot + i;
147
148 switch(tag->type) {
149 case MULTIBOOT_HEADER_TAG_INFORMATION_REQUEST:
150 req = (void *)tag;
151 for (j = 0;
152 j < (tag->size - sizeof(*tag)) / sizeof(uint32_t);
153 j++) {
154 switch (req->requests[j]) {
155 case MULTIBOOT_TAG_TYPE_MMAP:
156 case MULTIBOOT_TAG_TYPE_BASIC_MEMINFO:
157 /* Only applicable to BIOS. */
158 break;
159
160 case MULTIBOOT_TAG_TYPE_EFI_BS:
161 case MULTIBOOT_TAG_TYPE_EFI64:
162 case MULTIBOOT_TAG_TYPE_EFI64_IH:
163 /* Tags unconditionally added. */
164 break;
165
166 default:
167 if (req->flags &
168 MULTIBOOT_HEADER_TAG_OPTIONAL)
169 break;
170
171 printf(
172 "Unknown non-optional information request %u\n",
173 req->requests[j]);
174 error = EINVAL;
175 goto out;
176 }
177 }
178 break;
179
180 case MULTIBOOT_HEADER_TAG_EFI_BS:
181 /* Never shut down BS. */
182 keep_bs = true;
183 break;
184
185 case MULTIBOOT_HEADER_TAG_MODULE_ALIGN:
186 /* We will align modules by default already. */
187 case MULTIBOOT_HEADER_TAG_END:
188 break;
189
190 case MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS_EFI64:
191 entry = (void *)tag;
192 hdr.efi64_entry = entry->entry_addr;
193 break;
194
195 default:
196 if (tag->flags & MULTIBOOT_HEADER_TAG_OPTIONAL)
197 break;
198 printf("Unknown header tag %#x not optional\n",
199 tag->type);
200 error = EINVAL;
201 goto out;
202 }
203
204 i += roundup2(tag->size, MULTIBOOT_TAG_ALIGN);
205 if (tag->type == MULTIBOOT_HEADER_TAG_END)
206 break;
207 }
208
209 if (hdr.efi64_entry == 0) {
210 printf("No EFI64 entry address provided\n");
211 error = EINVAL;
212 goto out;
213 }
214 if (!keep_bs) {
215 printf("Unable to boot MB2 with BS exited\n");
216 error = EINVAL;
217 goto out;
218 }
219
220 error = elf32_loadfile_raw(filename, dest, result, 1);
221 if (error != 0) {
222 printf(
223 "elf32_loadfile_raw failed: %d unable to load multiboot kernel\n",
224 error);
225 goto out;
226 }
227
228 file_addmetadata(*result, MODINFOMD_NOCOPY | MODINFOMD_MB2HDR,
229 sizeof(hdr), &hdr);
230
231 /*
232 * f_addr is already aligned to PAGE_SIZE, make sure
233 * f_size it's also aligned so when the modules are loaded
234 * they are aligned to PAGE_SIZE.
235 */
236 (*result)->f_size = roundup((*result)->f_size, PAGE_SIZE);
237
238 out:
239 if (header_search != NULL)
240 free(header_search);
241 if (multiboot != NULL)
242 free(multiboot);
243 close(fd);
244 return (error);
245 }
246
add_string(void * buf,unsigned int type,const char * str)247 static unsigned int add_string(void *buf, unsigned int type, const char *str)
248 {
249 struct multiboot_tag *tag;
250
251 tag = buf;
252 tag->type = type;
253 tag->size = sizeof(*tag) + strlen(str) + 1;
254 strcpy(buf + sizeof(*tag), str);
255 return (roundup2(tag->size, MULTIBOOT_TAG_ALIGN));
256 }
257
add_efi(void * buf)258 static unsigned int add_efi(void *buf)
259 {
260 struct multiboot_tag *bs;
261 struct multiboot_tag_efi64 *efi64;
262 struct multiboot_tag_efi64_ih *ih;
263 unsigned int len;
264
265 len = 0;
266 bs = buf;
267 bs->type = MULTIBOOT_TAG_TYPE_EFI_BS;
268 bs->size = sizeof(*bs);
269 len += roundup2(bs->size, MULTIBOOT_TAG_ALIGN);
270
271 efi64 = buf + len;
272 efi64->type = MULTIBOOT_TAG_TYPE_EFI64;
273 efi64->size = sizeof(*efi64);
274 efi64->pointer = (uintptr_t)ST;
275 len += roundup2(efi64->size, MULTIBOOT_TAG_ALIGN);
276
277 ih = buf + len;
278 ih->type = MULTIBOOT_TAG_TYPE_EFI64_IH;
279 ih->size = sizeof(*ih);
280 ih->pointer = (uintptr_t)IH;
281
282 return (len + roundup2(ih->size, MULTIBOOT_TAG_ALIGN));
283 }
284
add_module(void * buf,vm_offset_t start,vm_offset_t end,const char * cmdline)285 static unsigned int add_module(void *buf, vm_offset_t start, vm_offset_t end,
286 const char *cmdline)
287 {
288 struct multiboot_tag_module *mod;
289
290 mod = buf;
291 mod->type = MULTIBOOT_TAG_TYPE_MODULE;
292 mod->size = sizeof(*mod);
293 mod->mod_start = start;
294 mod->mod_end = end;
295 if (cmdline != NULL)
296 {
297 strcpy(buf + sizeof(*mod), cmdline);
298 mod->size += strlen(cmdline) + 1;
299 }
300
301 return (roundup2(mod->size, MULTIBOOT_TAG_ALIGN));
302 }
303
add_end(void * buf)304 static unsigned int add_end(void *buf)
305 {
306 struct multiboot_tag *tag;
307
308 tag = buf;
309 tag->type = MULTIBOOT_TAG_TYPE_END;
310 tag->size = sizeof(*tag);
311
312 return (roundup2(tag->size, MULTIBOOT_TAG_ALIGN));
313 }
314
315 static int
exec(struct preloaded_file * fp)316 exec(struct preloaded_file *fp)
317 {
318 EFI_PHYSICAL_ADDRESS addr = 0;
319 EFI_PHYSICAL_ADDRESS stack = 0;
320 EFI_STATUS status;
321 void *multiboot_space;
322 vm_offset_t modulep, kernend, kern_base,
323 payload_base;
324 char *cmdline = NULL;
325 size_t len;
326 int error;
327 uint32_t *total_size;
328 struct file_metadata *md;
329 struct xen_header header;
330 struct mb2hdr *hdr;
331
332
333 _Static_assert(sizeof(header) <= PAGE_SIZE, "header too big");
334
335 if ((md = file_findmetadata(fp,
336 MODINFOMD_NOCOPY | MODINFOMD_MB2HDR)) == NULL) {
337 printf("Missing Multiboot2 EFI64 entry point\n");
338 return(EFTYPE);
339 }
340 hdr = (void *)&md->md_data;
341
342 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
343 EFI_SIZE_TO_PAGES(PAGE_SIZE), &addr);
344 if (EFI_ERROR(status)) {
345 printf("Failed to allocate pages for multiboot2 header: %lu\n",
346 EFI_ERROR_CODE(status));
347 error = ENOMEM;
348 goto error;
349 }
350 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
351 EFI_SIZE_TO_PAGES(128 * 1024), &stack);
352 if (EFI_ERROR(status)) {
353 printf("Failed to allocate pages for Xen stack: %lu\n",
354 EFI_ERROR_CODE(status));
355 error = ENOMEM;
356 goto error;
357 }
358
359 /*
360 * Scratch space to build the multiboot2 header. Reserve the start of
361 * the space to place the header with the size, which we don't know
362 * yet.
363 */
364 multiboot_space = (void *)(uintptr_t)(addr + sizeof(uint32_t) * 2);
365
366 /*
367 * Don't pass the memory size found by the bootloader, the memory
368 * available to Dom0 will be lower than that.
369 */
370 unsetenv("smbios.memory.enabled");
371
372 /* Set the Xen command line. */
373 if (fp->f_args == NULL) {
374 /* Add the Xen command line if it is set. */
375 cmdline = getenv("xen_cmdline");
376 if (cmdline != NULL) {
377 fp->f_args = strdup(cmdline);
378 if (fp->f_args == NULL) {
379 error = ENOMEM;
380 goto error;
381 }
382 }
383 }
384 if (fp->f_args != NULL) {
385 len = strlen(fp->f_name) + 1 + strlen(fp->f_args) + 1;
386 cmdline = malloc(len);
387 if (cmdline == NULL) {
388 error = ENOMEM;
389 goto error;
390 }
391 snprintf(cmdline, len, "%s %s", fp->f_name, fp->f_args);
392 multiboot_space += add_string(multiboot_space,
393 MULTIBOOT_TAG_TYPE_CMDLINE, cmdline);
394 free(cmdline);
395 }
396
397 multiboot_space += add_string(multiboot_space,
398 MULTIBOOT_TAG_TYPE_BOOT_LOADER_NAME, "FreeBSD Loader");
399 multiboot_space += add_efi(multiboot_space);
400
401 /*
402 * Prepare the multiboot module list, Xen assumes the first
403 * module is the Dom0 kernel, and the second one is the initramfs.
404 * This is not optimal for FreeBSD, that doesn't have a initramfs
405 * but instead loads modules dynamically and creates the metadata
406 * info on-the-fly.
407 *
408 * As expected, the first multiboot module is going to be the
409 * FreeBSD kernel loaded as a raw file. The second module is going
410 * to contain the metadata info and the loaded modules.
411 *
412 * There's a small header prefixed in the second module that contains
413 * some information required to calculate the relocated address of
414 * modulep based on the original offset of modulep from the start of
415 * the module address. Note other fields might be added to this header
416 * if required.
417 *
418 * Native layout:
419 * fp->f_addr + fp->f_size
420 * +---------+----------------+------------+
421 * | | | |
422 * | Kernel | Modules | Metadata |
423 * | | | |
424 * +---------+----------------+------------+
425 * fp->f_addr modulep kernend
426 *
427 * Xen dom0 layout:
428 * fp->f_addr fp->f_addr + fp->f_size
429 * +---------+------------+----------------+------------+
430 * | | | | |
431 * | Kernel | xen_header | Modules | Metadata |
432 * | | | | |
433 * +---------+------------+----------------+------------+
434 * modulep kernend
435 * \________/\__________________________________________/
436 * module 0 module 1
437 */
438
439 fp = file_findfile(NULL, md_kerntype);
440 if (fp == NULL) {
441 printf("No FreeBSD kernel provided, aborting\n");
442 error = EINVAL;
443 goto error;
444 }
445
446 error = bi_load(fp->f_args, &modulep, &kernend, false);
447 if (error != 0)
448 goto error;
449
450 /*
451 * Note that the Xen kernel requires to be started with BootServices
452 * enabled, and hence we cannot use efi_copy_finish to relocate the
453 * loaded data from the staging area to the expected loaded addresses.
454 * This is fine because the Xen kernel is relocatable, so it can boot
455 * fine straight from the staging area. We use efi_translate to get the
456 * staging addresses where the kernels and metadata are currently
457 * loaded.
458 */
459 kern_base = (uintptr_t)efi_translate(fp->f_addr);
460 payload_base = kern_base + fp->f_size - PAGE_SIZE;
461 multiboot_space += add_module(multiboot_space, kern_base, payload_base,
462 NULL);
463 multiboot_space += add_module(multiboot_space, payload_base,
464 (uintptr_t)efi_translate(kernend), "header");
465
466 header.flags = XENHEADER_HAS_MODULEP_OFFSET;
467 header.modulep_offset = modulep - (fp->f_addr + fp->f_size - PAGE_SIZE);
468 archsw.arch_copyin(&header, fp->f_addr + fp->f_size - PAGE_SIZE,
469 sizeof(header));
470
471 multiboot_space += add_end(multiboot_space);
472 total_size = (uint32_t *)(uintptr_t)(addr);
473 *total_size = (uintptr_t)multiboot_space - addr;
474
475 if (*total_size > PAGE_SIZE)
476 panic("Multiboot header exceeds fixed size");
477
478 efi_time_fini();
479 dev_cleanup();
480 multiboot2_exec(efi_translate(hdr->efi64_entry), addr,
481 stack + 128 * 1024);
482
483 panic("exec returned");
484
485 error:
486 if (addr)
487 BS->FreePages(addr, EFI_SIZE_TO_PAGES(PAGE_SIZE));
488 if (stack)
489 BS->FreePages(stack, EFI_SIZE_TO_PAGES(128 * 1024));
490 return (error);
491 }
492
493 static int
obj_loadfile(char * filename,uint64_t dest,struct preloaded_file ** result)494 obj_loadfile(char *filename, uint64_t dest, struct preloaded_file **result)
495 {
496 struct preloaded_file *mfp, *kfp, *rfp;
497 int error;
498
499 /* See if there's a multiboot kernel loaded */
500 mfp = file_findfile(NULL, md_kerntype_mb);
501 if (mfp == NULL)
502 return (EFTYPE);
503
504 /*
505 * We have a multiboot kernel loaded, see if there's a FreeBSD
506 * kernel loaded also.
507 */
508 kfp = file_findfile(NULL, md_kerntype);
509 if (kfp == NULL) {
510 /*
511 * No kernel loaded, this must be it. The kernel has to
512 * be loaded as a raw file, it will be processed by
513 * Xen and correctly loaded as an ELF file.
514 */
515 rfp = file_loadraw(filename, md_kerntype, 0);
516 if (rfp == NULL) {
517 printf(
518 "Unable to load %s as a multiboot payload kernel\n",
519 filename);
520 return (EINVAL);
521 }
522
523 /* Load kernel metadata... */
524 setenv("kernelname", filename, 1);
525 error = elf64_load_modmetadata(rfp, rfp->f_addr + rfp->f_size);
526 if (error) {
527 printf("Unable to load kernel %s metadata error: %d\n",
528 rfp->f_name, error);
529 return (EINVAL);
530 }
531
532
533 /*
534 * Reserve one page at the end of the kernel to place some
535 * metadata in order to cope for Xen relocating the modules and
536 * the metadata information.
537 */
538 rfp->f_size = roundup(rfp->f_size, PAGE_SIZE);
539 rfp->f_size += PAGE_SIZE;
540 *result = rfp;
541 } else {
542 /* The rest should be loaded as regular modules */
543 error = elf64_obj_loadfile(filename, dest, result);
544 if (error != 0) {
545 printf("Unable to load %s as an object file, error: %d",
546 filename, error);
547 return (error);
548 }
549 }
550
551 return (0);
552 }
553
554 static int
obj_exec(struct preloaded_file * fp)555 obj_exec(struct preloaded_file *fp)
556 {
557
558 return (EFTYPE);
559 }
560
561 struct file_format multiboot2 = { loadfile, exec };
562 struct file_format multiboot2_obj = { obj_loadfile, obj_exec };
563