1 /*-
2 * Copyright (c) 2014 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 multiboot implementation only implements a subset of the full
29 * multiboot specification in order to be able to boot Xen and a
30 * FreeBSD Dom0. Trying to use it to boot other multiboot compliant
31 * kernels will most surely fail.
32 *
33 * The full multiboot specification can be found here:
34 * http://www.gnu.org/software/grub/manual/multiboot/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 "bootstrap.h"
49 #include "multiboot.h"
50 #include "libi386.h"
51 #include <btxv86.h>
52
53 #define MULTIBOOT_SUPPORTED_FLAGS \
54 (MULTIBOOT_PAGE_ALIGN|MULTIBOOT_MEMORY_INFO)
55 #define NUM_MODULES 2
56
57 extern int elf32_loadfile_raw(char *filename, uint64_t dest,
58 struct preloaded_file **result, int multiboot);
59 extern int elf64_load_modmetadata(struct preloaded_file *fp, uint64_t dest);
60 extern int elf64_obj_loadfile(char *filename, uint64_t dest,
61 struct preloaded_file **result);
62
63 static int multiboot_loadfile(char *, uint64_t, struct preloaded_file **);
64 static int multiboot_exec(struct preloaded_file *);
65
66 static int multiboot_obj_loadfile(char *, uint64_t, struct preloaded_file **);
67 static int multiboot_obj_exec(struct preloaded_file *fp);
68
69 struct file_format multiboot = { multiboot_loadfile, multiboot_exec };
70 struct file_format multiboot_obj =
71 { multiboot_obj_loadfile, multiboot_obj_exec };
72
73 extern void multiboot_tramp();
74
75 static const char mbl_name[] = "FreeBSD Loader";
76
77 static int
multiboot_loadfile(char * filename,uint64_t dest,struct preloaded_file ** result)78 multiboot_loadfile(char *filename, uint64_t dest,
79 struct preloaded_file **result)
80 {
81 uint32_t *magic;
82 int i, error;
83 caddr_t header_search;
84 ssize_t search_size;
85 int fd;
86 struct multiboot_header *header;
87 char *cmdline;
88
89 /*
90 * Read MULTIBOOT_SEARCH size in order to search for the
91 * multiboot magic header.
92 */
93 if (filename == NULL)
94 return (EFTYPE);
95 if ((fd = open(filename, O_RDONLY)) == -1)
96 return (errno);
97 header_search = malloc(MULTIBOOT_SEARCH);
98 if (header_search == NULL) {
99 close(fd);
100 return (ENOMEM);
101 }
102 search_size = read(fd, header_search, MULTIBOOT_SEARCH);
103 magic = (uint32_t *)header_search;
104
105 header = NULL;
106 for (i = 0; i < (search_size / sizeof(uint32_t)); i++) {
107 if (magic[i] == MULTIBOOT_HEADER_MAGIC) {
108 header = (struct multiboot_header *)&magic[i];
109 break;
110 }
111 }
112
113 if (header == NULL) {
114 error = EFTYPE;
115 goto out;
116 }
117
118 /* Valid multiboot header has been found, validate checksum */
119 if (header->magic + header->flags + header->checksum != 0) {
120 printf(
121 "Multiboot checksum failed, magic: 0x%x flags: 0x%x checksum: 0x%x\n",
122 header->magic, header->flags, header->checksum);
123 error = EFTYPE;
124 goto out;
125 }
126
127 if ((header->flags & ~MULTIBOOT_SUPPORTED_FLAGS) != 0) {
128 printf("Unsupported multiboot flags found: 0x%x\n",
129 header->flags);
130 error = EFTYPE;
131 goto out;
132 }
133
134 error = elf32_loadfile_raw(filename, dest, result, 1);
135 if (error != 0) {
136 printf(
137 "elf32_loadfile_raw failed: %d unable to load multiboot kernel\n",
138 error);
139 goto out;
140 }
141
142 /*
143 * f_addr is already aligned to PAGE_SIZE, make sure
144 * f_size it's also aligned so when the modules are loaded
145 * they are aligned to PAGE_SIZE.
146 */
147 (*result)->f_size = roundup((*result)->f_size, PAGE_SIZE);
148
149 out:
150 free(header_search);
151 close(fd);
152 return (error);
153 }
154
155 static int
multiboot_exec(struct preloaded_file * fp)156 multiboot_exec(struct preloaded_file *fp)
157 {
158 vm_offset_t modulep, kernend, entry;
159 struct file_metadata *md;
160 Elf_Ehdr *ehdr;
161 struct multiboot_info *mb_info = NULL;
162 struct multiboot_mod_list *mb_mod = NULL;
163 char *cmdline = NULL;
164 size_t len;
165 int error, mod_num;
166 struct xen_header header;
167
168 _Static_assert(sizeof(header) <= PAGE_SIZE, "header too large for page");
169
170 /*
171 * Don't pass the memory size found by the bootloader, the memory
172 * available to Dom0 will be lower than that.
173 */
174 unsetenv("smbios.memory.enabled");
175
176 /* Allocate the multiboot struct and fill the basic details. */
177 mb_info = malloc(sizeof(struct multiboot_info));
178 if (mb_info == NULL) {
179 error = ENOMEM;
180 goto error;
181 }
182 bzero(mb_info, sizeof(struct multiboot_info));
183 mb_info->flags = MULTIBOOT_INFO_MEMORY|MULTIBOOT_INFO_BOOT_LOADER_NAME;
184 mb_info->mem_lower = bios_basemem / 1024;
185 mb_info->mem_upper = bios_extmem / 1024;
186 mb_info->boot_loader_name = VTOP(mbl_name);
187
188 /* Set the Xen command line. */
189 if (fp->f_args == NULL) {
190 /* Add the Xen command line if it is set. */
191 cmdline = getenv("xen_cmdline");
192 if (cmdline != NULL) {
193 fp->f_args = strdup(cmdline);
194 if (fp->f_args == NULL) {
195 error = ENOMEM;
196 goto error;
197 }
198 }
199 }
200 if (fp->f_args != NULL) {
201 len = strlen(fp->f_name) + 1 + strlen(fp->f_args) + 1;
202 cmdline = malloc(len);
203 if (cmdline == NULL) {
204 error = ENOMEM;
205 goto error;
206 }
207 snprintf(cmdline, len, "%s %s", fp->f_name, fp->f_args);
208 mb_info->cmdline = VTOP(cmdline);
209 mb_info->flags |= MULTIBOOT_INFO_CMDLINE;
210 }
211
212 /* Find the entry point of the Xen kernel and save it for later */
213 if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL) {
214 printf("Unable to find %s entry point\n", fp->f_name);
215 error = EINVAL;
216 goto error;
217 }
218 ehdr = (Elf_Ehdr *)&(md->md_data);
219 entry = ehdr->e_entry & 0xffffff;
220
221 /*
222 * Prepare the multiboot module list, Xen assumes the first
223 * module is the Dom0 kernel, and the second one is the initramfs.
224 * This is not optimal for FreeBSD, that doesn't have a initramfs
225 * but instead loads modules dynamically and creates the metadata
226 * info on-the-fly.
227 *
228 * As expected, the first multiboot module is going to be the
229 * FreeBSD kernel loaded as a raw file. The second module is going
230 * to contain the metadata info and the loaded modules.
231 *
232 * There's a small header prefixed in the second module that contains
233 * some information required to calculate the relocated address of
234 * modulep based on the original offset of modulep from the start of
235 * the module address. Note other fields might be added to this header
236 * if required.
237 *
238 * Native layout:
239 * fp->f_addr + fp->f_size
240 * +---------+----------------+------------+
241 * | | | |
242 * | Kernel | Modules | Metadata |
243 * | | | |
244 * +---------+----------------+------------+
245 * fp->f_addr modulep kernend
246 *
247 * Xen dom0 layout:
248 * fp->f_addr fp->f_addr + fp->f_size
249 * +---------+------------+----------------+------------+
250 * | | | | |
251 * | Kernel | xen_header | Modules | Metadata |
252 * | | | | |
253 * +---------+------------+----------------+------------+
254 * modulep kernend
255 * \________/\__________________________________________/
256 * module 0 module 1
257 */
258
259 fp = file_findfile(NULL, "elf kernel");
260 if (fp == NULL) {
261 printf("No FreeBSD kernel provided, aborting\n");
262 error = EINVAL;
263 goto error;
264 }
265
266 mb_mod = malloc(sizeof(struct multiboot_mod_list) * NUM_MODULES);
267 if (mb_mod == NULL) {
268 error = ENOMEM;
269 goto error;
270 }
271
272 bzero(mb_mod, sizeof(struct multiboot_mod_list) * NUM_MODULES);
273
274 error = bi_load64(fp->f_args, &modulep, &kernend, 0);
275 if (error != 0) {
276 printf("bi_load64 failed: %d\n", error);
277 goto error;
278 }
279
280 mb_mod[0].mod_start = fp->f_addr;
281 mb_mod[0].mod_end = fp->f_addr + fp->f_size - PAGE_SIZE;
282
283 mb_mod[1].mod_start = mb_mod[0].mod_end;
284 mb_mod[1].mod_end = kernend;
285 /* Indicate the kernel metadata is prefixed with a xen_header. */
286 cmdline = strdup("header");
287 if (cmdline == NULL) {
288 printf("Out of memory, aborting\n");
289 error = ENOMEM;
290 goto error;
291 }
292 mb_mod[1].cmdline = VTOP(cmdline);
293
294 mb_info->mods_count = NUM_MODULES;
295 mb_info->mods_addr = VTOP(mb_mod);
296 mb_info->flags |= MULTIBOOT_INFO_MODS;
297
298 header.flags = XENHEADER_HAS_MODULEP_OFFSET;
299 header.modulep_offset = modulep - mb_mod[1].mod_start;
300 archsw.arch_copyin(&header, mb_mod[1].mod_start, sizeof(header));
301
302 dev_cleanup();
303 __exec((void *)VTOP(multiboot_tramp), (void *)entry,
304 (void *)VTOP(mb_info));
305
306 panic("exec returned");
307
308 error:
309 if (mb_mod)
310 free(mb_mod);
311 if (mb_info)
312 free(mb_info);
313 if (cmdline)
314 free(cmdline);
315 return (error);
316 }
317
318 static int
multiboot_obj_loadfile(char * filename,uint64_t dest,struct preloaded_file ** result)319 multiboot_obj_loadfile(char *filename, uint64_t dest,
320 struct preloaded_file **result)
321 {
322 struct preloaded_file *mfp, *kfp, *rfp;
323 struct kernel_module *kmp;
324 int error, mod_num;
325
326 /* See if there's a multiboot kernel loaded */
327 mfp = file_findfile(NULL, "elf multiboot kernel");
328 if (mfp == NULL)
329 return (EFTYPE);
330
331 /*
332 * We have a multiboot kernel loaded, see if there's a FreeBSD
333 * kernel loaded also.
334 */
335 kfp = file_findfile(NULL, "elf kernel");
336 if (kfp == NULL) {
337 /*
338 * No kernel loaded, this must be it. The kernel has to
339 * be loaded as a raw file, it will be processed by
340 * Xen and correctly loaded as an ELF file.
341 */
342 rfp = file_loadraw(filename, "elf kernel", 0);
343 if (rfp == NULL) {
344 printf(
345 "Unable to load %s as a multiboot payload kernel\n",
346 filename);
347 return (EINVAL);
348 }
349
350 /* Load kernel metadata... */
351 setenv("kernelname", filename, 1);
352 error = elf64_load_modmetadata(rfp, rfp->f_addr + rfp->f_size);
353 if (error) {
354 printf("Unable to load kernel %s metadata error: %d\n",
355 rfp->f_name, error);
356 return (EINVAL);
357 }
358
359
360 /*
361 * Reserve one page at the end of the kernel to place some
362 * metadata in order to cope for Xen relocating the modules and
363 * the metadata information.
364 */
365 rfp->f_size = roundup(rfp->f_size, PAGE_SIZE);
366 rfp->f_size += PAGE_SIZE;
367 *result = rfp;
368 } else {
369 /* The rest should be loaded as regular modules */
370 error = elf64_obj_loadfile(filename, dest, result);
371 if (error != 0) {
372 printf("Unable to load %s as an object file, error: %d",
373 filename, error);
374 return (error);
375 }
376 }
377
378 return (0);
379 }
380
381 static int
multiboot_obj_exec(struct preloaded_file * fp)382 multiboot_obj_exec(struct preloaded_file *fp)
383 {
384
385 return (EFTYPE);
386 }
387