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source: bootcd/isolinux/syslinux-6.03/gpxe/src/arch/i386/image/bzimage.c

Last change on this file was e16e8f2, checked in by Edwin Eefting <edwin@datux.nl>, 3 years ago
bootstuff
Property mode set to `100644`
File size: 15.3 KB

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1	/*
2	* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
3	*
4	* This program is free software; you can redistribute it and/or
5	* modify it under the terms of the GNU General Public License as
6	* published by the Free Software Foundation; either version 2 of the
7	* License, or any later version.
8	*
9	* This program is distributed in the hope that it will be useful, but
10	* WITHOUT ANY WARRANTY; without even the implied warranty of
11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12	* General Public License for more details.
13	*
14	* You should have received a copy of the GNU General Public License
15	* along with this program; if not, write to the Free Software
16	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17	*/
18
19	FILE_LICENCE ( GPL2_OR_LATER );
20
21	/**
22	* @file
23	*
24	* Linux bzImage image format
25	*
26	*/
27
28	#include <stdint.h>
29	#include <stdlib.h>
30	#include <string.h>
31	#include <errno.h>
32	#include <assert.h>
33	#include <realmode.h>
34	#include <bzimage.h>
35	#include <gpxe/uaccess.h>
36	#include <gpxe/image.h>
37	#include <gpxe/segment.h>
38	#include <gpxe/init.h>
39	#include <gpxe/cpio.h>
40	#include <gpxe/features.h>
41
42	FEATURE ( FEATURE_IMAGE, "bzImage", DHCP_EB_FEATURE_BZIMAGE, 1 );
43
44	struct image_type bzimage_image_type __image_type ( PROBE_NORMAL );
45
46	/**
47	* bzImage context
48	*/
49	struct bzimage_context {
50	/** Boot protocol version */
51	unsigned int version;
52	/** Real-mode kernel portion load segment address */
53	unsigned int rm_kernel_seg;
54	/** Real-mode kernel portion load address */
55	userptr_t rm_kernel;
56	/** Real-mode kernel portion file size */
57	size_t rm_filesz;
58	/** Real-mode heap top (offset from rm_kernel) */
59	size_t rm_heap;
60	/** Command line (offset from rm_kernel) */
61	size_t rm_cmdline;
62	/** Command line maximum length */
63	size_t cmdline_size;
64	/** Real-mode kernel portion total memory size */
65	size_t rm_memsz;
66	/** Non-real-mode kernel portion load address */
67	userptr_t pm_kernel;
68	/** Non-real-mode kernel portion file and memory size */
69	size_t pm_sz;
70	/** Video mode */
71	unsigned int vid_mode;
72	/** Memory limit */
73	uint64_t mem_limit;
74	/** Initrd address */
75	physaddr_t ramdisk_image;
76	/** Initrd size */
77	physaddr_t ramdisk_size;
78
79	/** Command line magic block */
80	struct bzimage_cmdline cmdline_magic;
81	/** bzImage header */
82	struct bzimage_header bzhdr;
83	};
84
85	/**
86	* Parse bzImage header
87	*
88	* @v image bzImage file
89	* @v bzimg bzImage context
90	* @v src bzImage to parse
91	* @ret rc Return status code
92	*/
93	static int bzimage_parse_header ( struct image *image,
94	struct bzimage_context *bzimg,
95	userptr_t src ) {
96	unsigned int syssize;
97	int is_bzimage;
98
99	/* Sanity check */
100	if ( image->len < ( BZI_HDR_OFFSET + sizeof ( bzimg->bzhdr ) ) ) {
101	DBGC ( image, "bzImage %p too short for kernel header\n",
102	image );
103	return -ENOEXEC;
104	}
105
106	/* Read in header structures */
107	memset ( bzimg, 0, sizeof ( *bzimg ) );
108	copy_from_user ( &bzimg->cmdline_magic, src, BZI_CMDLINE_OFFSET,
109	sizeof ( bzimg->cmdline_magic ) );
110	copy_from_user ( &bzimg->bzhdr, src, BZI_HDR_OFFSET,
111	sizeof ( bzimg->bzhdr ) );
112
113	/* Calculate size of real-mode portion */
114	bzimg->rm_filesz =
115	( ( bzimg->bzhdr.setup_sects ? bzimg->bzhdr.setup_sects : 4 ) + 1 ) << 9;
116	if ( bzimg->rm_filesz > image->len ) {
117	DBGC ( image, "bzImage %p too short for %zd byte of setup\n",
118	image, bzimg->rm_filesz );
119	return -ENOEXEC;
120	}
121	bzimg->rm_memsz = BZI_ASSUMED_RM_SIZE;
122
123	/* Calculate size of protected-mode portion */
124	bzimg->pm_sz = ( image->len - bzimg->rm_filesz );
125	syssize = ( ( bzimg->pm_sz + 15 ) / 16 );
126
127	/* Check for signatures and determine version */
128	if ( bzimg->bzhdr.boot_flag != BZI_BOOT_FLAG ) {
129	DBGC ( image, "bzImage %p missing 55AA signature\n", image );
130	return -ENOEXEC;
131	}
132	if ( bzimg->bzhdr.header == BZI_SIGNATURE ) {
133	/* 2.00+ */
134	bzimg->version = bzimg->bzhdr.version;
135	} else {
136	/* Pre-2.00. Check that the syssize field is correct,
137	* as a guard against accepting arbitrary binary data,
138	* since the 55AA check is pretty lax. Note that the
139	* syssize field is unreliable for protocols between
140	* 2.00 and 2.03 inclusive, so we should not always
141	* check this field.
142	*/
143	bzimg->version = 0x0100;
144	if ( bzimg->bzhdr.syssize != syssize ) {
145	DBGC ( image, "bzImage %p bad syssize %x (expected "
146	"%x)\n", image, bzimg->bzhdr.syssize, syssize );
147	return -ENOEXEC;
148	}
149	}
150
151	/* Determine image type */
152	is_bzimage = ( ( bzimg->version >= 0x0200 ) ?
153	( bzimg->bzhdr.loadflags & BZI_LOAD_HIGH ) : 0 );
154
155	/* Calculate load address of real-mode portion */
156	bzimg->rm_kernel_seg = ( is_bzimage ? 0x1000 : 0x9000 );
157	bzimg->rm_kernel = real_to_user ( bzimg->rm_kernel_seg, 0 );
158
159	/* Allow space for the stack and heap */
160	bzimg->rm_memsz += BZI_STACK_SIZE;
161	bzimg->rm_heap = bzimg->rm_memsz;
162
163	/* Allow space for the command line */
164	bzimg->rm_cmdline = bzimg->rm_memsz;
165	bzimg->rm_memsz += BZI_CMDLINE_SIZE;
166
167	/* Calculate load address of protected-mode portion */
168	bzimg->pm_kernel = phys_to_user ( is_bzimage ? BZI_LOAD_HIGH_ADDR
169	: BZI_LOAD_LOW_ADDR );
170
171	/* Extract video mode */
172	bzimg->vid_mode = bzimg->bzhdr.vid_mode;
173
174	/* Extract memory limit */
175	bzimg->mem_limit = ( ( bzimg->version >= 0x0203 ) ?
176	bzimg->bzhdr.initrd_addr_max : BZI_INITRD_MAX );
177
178	/* Extract command line size */
179	bzimg->cmdline_size = ( ( bzimg->version >= 0x0206 ) ?
180	bzimg->bzhdr.cmdline_size : BZI_CMDLINE_SIZE );
181
182	DBGC ( image, "bzImage %p version %04x RM %#lx+%#zx PM %#lx+%#zx "
183	"cmdlen %zd\n", image, bzimg->version,
184	user_to_phys ( bzimg->rm_kernel, 0 ), bzimg->rm_filesz,
185	user_to_phys ( bzimg->pm_kernel, 0 ), bzimg->pm_sz,
186	bzimg->cmdline_size );
187
188	return 0;
189	}
190
191	/**
192	* Update bzImage header in loaded kernel
193	*
194	* @v image bzImage file
195	* @v bzimg bzImage context
196	* @v dst bzImage to update
197	*/
198	static void bzimage_update_header ( struct image *image,
199	struct bzimage_context *bzimg,
200	userptr_t dst ) {
201
202	/* Set loader type */
203	if ( bzimg->version >= 0x0200 )
204	bzimg->bzhdr.type_of_loader = BZI_LOADER_TYPE_GPXE;
205
206	/* Set heap end pointer */
207	if ( bzimg->version >= 0x0201 ) {
208	bzimg->bzhdr.heap_end_ptr = ( bzimg->rm_heap - 0x200 );
209	bzimg->bzhdr.loadflags \|= BZI_CAN_USE_HEAP;
210	}
211
212	/* Set command line */
213	if ( bzimg->version >= 0x0202 ) {
214	bzimg->bzhdr.cmd_line_ptr = user_to_phys ( bzimg->rm_kernel,
215	bzimg->rm_cmdline );
216	} else {
217	bzimg->cmdline_magic.magic = BZI_CMDLINE_MAGIC;
218	bzimg->cmdline_magic.offset = bzimg->rm_cmdline;
219	bzimg->bzhdr.setup_move_size = bzimg->rm_memsz;
220	}
221
222	/* Set video mode */
223	bzimg->bzhdr.vid_mode = bzimg->vid_mode;
224
225	/* Set initrd address */
226	if ( bzimg->version >= 0x0200 ) {
227	bzimg->bzhdr.ramdisk_image = bzimg->ramdisk_image;
228	bzimg->bzhdr.ramdisk_size = bzimg->ramdisk_size;
229	}
230
231	/* Write out header structures */
232	copy_to_user ( dst, BZI_CMDLINE_OFFSET, &bzimg->cmdline_magic,
233	sizeof ( bzimg->cmdline_magic ) );
234	copy_to_user ( dst, BZI_HDR_OFFSET, &bzimg->bzhdr,
235	sizeof ( bzimg->bzhdr ) );
236
237	DBGC ( image, "bzImage %p vidmode %d\n", image, bzimg->vid_mode );
238	}
239
240	/**
241	* Parse kernel command line for bootloader parameters
242	*
243	* @v image bzImage file
244	* @v bzimg bzImage context
245	* @v cmdline Kernel command line
246	* @ret rc Return status code
247	*/
248	static int bzimage_parse_cmdline ( struct image *image,
249	struct bzimage_context *bzimg,
250	const char *cmdline ) {
251	char *vga;
252	char *mem;
253
254	/* Look for "vga=" */
255	if ( ( vga = strstr ( cmdline, "vga=" ) ) ) {
256	vga += 4;
257	if ( strcmp ( vga, "normal" ) == 0 ) {
258	bzimg->vid_mode = BZI_VID_MODE_NORMAL;
259	} else if ( strcmp ( vga, "ext" ) == 0 ) {
260	bzimg->vid_mode = BZI_VID_MODE_EXT;
261	} else if ( strcmp ( vga, "ask" ) == 0 ) {
262	bzimg->vid_mode = BZI_VID_MODE_ASK;
263	} else {
264	bzimg->vid_mode = strtoul ( vga, &vga, 0 );
265	if ( vga && ( vga != ' ' ) ) {
266	DBGC ( image, "bzImage %p strange \"vga=\""
267	"terminator '%c'\n", image, *vga );
268	}
269	}
270	}
271
272	/* Look for "mem=" */
273	if ( ( mem = strstr ( cmdline, "mem=" ) ) ) {
274	mem += 4;
275	bzimg->mem_limit = strtoul ( mem, &mem, 0 );
276	switch ( *mem ) {
277	case 'G':
278	case 'g':
279	bzimg->mem_limit <<= 10;
280	case 'M':
281	case 'm':
282	bzimg->mem_limit <<= 10;
283	case 'K':
284	case 'k':
285	bzimg->mem_limit <<= 10;
286	break;
287	case '\0':
288	case ' ':
289	break;
290	default:
291	DBGC ( image, "bzImage %p strange \"mem=\" "
292	"terminator '%c'\n", image, *mem );
293	break;
294	}
295	bzimg->mem_limit -= 1;
296	}
297
298	return 0;
299	}
300
301	/**
302	* Set command line
303	*
304	* @v image bzImage image
305	* @v bzimg bzImage context
306	* @v cmdline Kernel command line
307	* @ret rc Return status code
308	*/
309	static int bzimage_set_cmdline ( struct image *image,
310	struct bzimage_context *bzimg,
311	const char *cmdline ) {
312	size_t cmdline_len;
313
314	/* Copy command line down to real-mode portion */
315	cmdline_len = ( strlen ( cmdline ) + 1 );
316	if ( cmdline_len > bzimg->cmdline_size )
317	cmdline_len = bzimg->cmdline_size;
318	copy_to_user ( bzimg->rm_kernel, bzimg->rm_cmdline,
319	cmdline, cmdline_len );
320	DBGC ( image, "bzImage %p command line \"%s\"\n", image, cmdline );
321
322	return 0;
323	}
324
325	/**
326	* Load initrd
327	*
328	* @v image bzImage image
329	* @v initrd initrd image
330	* @v address Address at which to load, or UNULL
331	* @ret len Length of loaded image, rounded up to 4 bytes
332	*/
333	static size_t bzimage_load_initrd ( struct image *image,
334	struct image *initrd,
335	userptr_t address ) {
336	char *filename = initrd->cmdline;
337	struct cpio_header cpio;
338	size_t offset = 0;
339
340	/* Do not include kernel image itself as an initrd */
341	if ( initrd == image )
342	return 0;
343
344	/* Create cpio header before non-prebuilt images */
345	if ( filename && filename[0] ) {
346	size_t name_len = ( strlen ( filename ) + 1 );
347
348	DBGC ( image, "bzImage %p inserting initrd %p as %s\n",
349	image, initrd, filename );
350	memset ( &cpio, '0', sizeof ( cpio ) );
351	memcpy ( cpio.c_magic, CPIO_MAGIC, sizeof ( cpio.c_magic ) );
352	cpio_set_field ( cpio.c_mode, 0100644 );
353	cpio_set_field ( cpio.c_nlink, 1 );
354	cpio_set_field ( cpio.c_filesize, initrd->len );
355	cpio_set_field ( cpio.c_namesize, name_len );
356	if ( address ) {
357	copy_to_user ( address, offset, &cpio,
358	sizeof ( cpio ) );
359	}
360	offset += sizeof ( cpio );
361	if ( address ) {
362	copy_to_user ( address, offset, filename,
363	name_len );
364	}
365	offset += name_len;
366	offset = ( ( offset + 0x03 ) & ~0x03 );
367	}
368
369	/* Copy in initrd image body */
370	if ( address )
371	memcpy_user ( address, offset, initrd->data, 0, initrd->len );
372	offset += initrd->len;
373	if ( address ) {
374	DBGC ( image, "bzImage %p has initrd %p at [%lx,%lx)\n",
375	image, initrd, user_to_phys ( address, 0 ),
376	user_to_phys ( address, offset ) );
377	}
378
379	/* Round up to 4-byte boundary */
380	offset = ( ( offset + 0x03 ) & ~0x03 );
381	return offset;
382	}
383
384	/**
385	* Load initrds, if any
386	*
387	* @v image bzImage image
388	* @v bzimg bzImage context
389	* @ret rc Return status code
390	*/
391	static int bzimage_load_initrds ( struct image *image,
392	struct bzimage_context *bzimg ) {
393	struct image *initrd;
394	size_t total_len = 0;
395	physaddr_t address;
396	int rc;
397
398	/* Add up length of all initrd images */
399	for_each_image ( initrd )
400	total_len += bzimage_load_initrd ( image, initrd, UNULL );
401
402	/* Give up if no initrd images found */
403	if ( ! total_len )
404	return 0;
405
406	/* Find a suitable start address. Try 1MB boundaries,
407	* starting from the downloaded kernel image itself and
408	* working downwards until we hit an available region.
409	*/
410	for ( address = ( user_to_phys ( image->data, 0 ) & ~0xfffff ) ; ;
411	address -= 0x100000 ) {
412	/* Check that we're not going to overwrite the
413	* kernel itself. This check isn't totally
414	* accurate, but errs on the side of caution.
415	*/
416	if ( address <= ( BZI_LOAD_HIGH_ADDR + image->len ) ) {
417	DBGC ( image, "bzImage %p could not find a location "
418	"for initrd\n", image );
419	return -ENOBUFS;
420	}
421	/* Check that we are within the kernel's range */
422	if ( ( address + total_len - 1 ) > bzimg->mem_limit )
423	continue;
424	/* Prepare and verify segment */
425	if ( ( rc = prep_segment ( phys_to_user ( address ), 0,
426	total_len ) ) != 0 )
427	continue;
428	/* Use this address */
429	break;
430	}
431
432	/* Record initrd location */
433	bzimg->ramdisk_image = address;
434	bzimg->ramdisk_size = total_len;
435
436	/* Construct initrd */
437	DBGC ( image, "bzImage %p constructing initrd at [%lx,%lx)\n",
438	image, address, ( address + total_len ) );
439	for_each_image ( initrd ) {
440	address += bzimage_load_initrd ( image, initrd,
441	phys_to_user ( address ) );
442	}
443
444	return 0;
445	}
446
447	/**
448	* Execute bzImage image
449	*
450	* @v image bzImage image
451	* @ret rc Return status code
452	*/
453	static int bzimage_exec ( struct image *image ) {
454	struct bzimage_context bzimg;
455	const char *cmdline = ( image->cmdline ? image->cmdline : "" );
456	int rc;
457
458	/* Read and parse header from loaded kernel */
459	if ( ( rc = bzimage_parse_header ( image, &bzimg,
460	image->priv.user ) ) != 0 )
461	return rc;
462	assert ( bzimg.rm_kernel == image->priv.user );
463
464	/* Parse command line for bootloader parameters */
465	if ( ( rc = bzimage_parse_cmdline ( image, &bzimg, cmdline ) ) != 0)
466	return rc;
467
468	/* Store command line */
469	if ( ( rc = bzimage_set_cmdline ( image, &bzimg, cmdline ) ) != 0 )
470	return rc;
471
472	/* Load any initrds */
473	if ( ( rc = bzimage_load_initrds ( image, &bzimg ) ) != 0 )
474	return rc;
475
476	/* Update kernel header */
477	bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );
478
479	/* Prepare for exiting */
480	shutdown ( SHUTDOWN_BOOT );
481
482	DBGC ( image, "bzImage %p jumping to RM kernel at %04x:0000 "
483	"(stack %04x:%04zx)\n", image, ( bzimg.rm_kernel_seg + 0x20 ),
484	bzimg.rm_kernel_seg, bzimg.rm_heap );
485
486	/* Jump to the kernel */
487	__asm__ __volatile__ ( REAL_CODE ( "movw %w0, %%ds\n\t"
488	"movw %w0, %%es\n\t"
489	"movw %w0, %%fs\n\t"
490	"movw %w0, %%gs\n\t"
491	"movw %w0, %%ss\n\t"
492	"movw %w1, %%sp\n\t"
493	"pushw %w2\n\t"
494	"pushw $0\n\t"
495	"lret\n\t" )
496	: : "r" ( bzimg.rm_kernel_seg ),
497	"r" ( bzimg.rm_heap ),
498	"r" ( bzimg.rm_kernel_seg + 0x20 ) );
499
500	/* There is no way for the image to return, since we provide
501	* no return address.
502	*/
503	assert ( 0 );
504
505	return -ECANCELED; /* -EIMPOSSIBLE */
506	}
507
508	/**
509	* Load bzImage image into memory
510	*
511	* @v image bzImage file
512	* @ret rc Return status code
513	*/
514	int bzimage_load ( struct image *image ) {
515	struct bzimage_context bzimg;
516	int rc;
517
518	/* Read and parse header from image */
519	if ( ( rc = bzimage_parse_header ( image, &bzimg,
520	image->data ) ) != 0 )
521	return rc;
522
523	/* This is a bzImage image, valid or otherwise */
524	if ( ! image->type )
525	image->type = &bzimage_image_type;
526
527	/* Prepare segments */
528	if ( ( rc = prep_segment ( bzimg.rm_kernel, bzimg.rm_filesz,
529	bzimg.rm_memsz ) ) != 0 ) {
530	DBGC ( image, "bzImage %p could not prepare RM segment: %s\n",
531	image, strerror ( rc ) );
532	return rc;
533	}
534	if ( ( rc = prep_segment ( bzimg.pm_kernel, bzimg.pm_sz,
535	bzimg.pm_sz ) ) != 0 ) {
536	DBGC ( image, "bzImage %p could not prepare PM segment: %s\n",
537	image, strerror ( rc ) );
538	return rc;
539	}
540
541	/* Load segments */
542	memcpy_user ( bzimg.rm_kernel, 0, image->data,
543	0, bzimg.rm_filesz );
544	memcpy_user ( bzimg.pm_kernel, 0, image->data,
545	bzimg.rm_filesz, bzimg.pm_sz );
546
547	/* Update and write out header */
548	bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );
549
550	/* Record real-mode segment in image private data field */
551	image->priv.user = bzimg.rm_kernel;
552
553	return 0;
554	}
555
556	/** Linux bzImage image type */
557	struct image_type bzimage_image_type __image_type ( PROBE_NORMAL ) = {
558	.name = "bzImage",
559	.load = bzimage_load,
560	.exec = bzimage_exec,
561	};

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