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libprefix.S

Last change on this file was e16e8f2, checked in by Edwin Eefting <edwin@datux.nl>, 3 years ago
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1	/*
2	* Copyright (C) 2006 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
20	FILE_LICENCE ( GPL2_OR_LATER )
21
22	.arch i386
23
24	/**
25	* High memory temporary load address
26	*
27	* Temporary buffer into which to copy (or decompress) our runtime
28	* image, prior to calling get_memmap() and relocate(). We don't
29	* actually leave anything here once install() has returned.
30	*
31	* We use the start of an even megabyte so that we don't have to worry
32	* about the current state of the A20 line.
33	*
34	* We use 4MB rather than 2MB because some PXE stack / PMM BIOS
35	* combinations are known to place data required by other UNDI ROMs
36	* loader around the 2MB mark.
37	*/
38	.globl HIGHMEM_LOADPOINT
39	.equ HIGHMEM_LOADPOINT, ( 4 << 20 )
40
41	/* Image compression enabled */
42	#define COMPRESS 1
43
44	#define CR0_PE 1
45
46	/*****************************************************************************
47	* Utility function: print character (with LF -> LF,CR translation)
48	*
49	* Parameters:
50	* %al : character to print
51	* %ds:di : output buffer (or %di=0 to print to console)
52	* Returns:
53	* %ds:di : next character in output buffer (if applicable)
54	*****************************************************************************
55	*/
56	.section ".prefix.lib", "awx", @progbits
57	.code16
58	.globl print_character
59	print_character:
60	/* Preserve registers */
61	pushw %ax
62	pushw %bx
63	pushw %bp
64	/* If %di is non-zero, write character to buffer and exit */
65	testw %di, %di
66	jz 1f
67	movb %al, %ds:(%di)
68	incw %di
69	jmp 3f
70	1: /* Print character */
71	movw $0x0007, %bx /* page 0, attribute 7 (normal) */
72	movb $0x0e, %ah /* write char, tty mode */
73	cmpb $0x0a, %al /* '\n'? */
74	jne 2f
75	int $0x10
76	movb $0x0d, %al
77	2: int $0x10
78	/* Restore registers and return */
79	3: popw %bp
80	popw %bx
81	popw %ax
82	ret
83	.size print_character, . - print_character
84
85	/*****************************************************************************
86	* Utility function: print a NUL-terminated string
87	*
88	* Parameters:
89	* %ds:si : string to print
90	* %ds:di : output buffer (or %di=0 to print to console)
91	* Returns:
92	* %ds:si : character after terminating NUL
93	* %ds:di : next character in output buffer (if applicable)
94	*****************************************************************************
95	*/
96	.section ".prefix.lib", "awx", @progbits
97	.code16
98	.globl print_message
99	print_message:
100	/* Preserve registers */
101	pushw %ax
102	/* Print string */
103	1: lodsb
104	testb %al, %al
105	je 2f
106	call print_character
107	jmp 1b
108	2: /* Restore registers and return */
109	popw %ax
110	ret
111	.size print_message, . - print_message
112
113	/*****************************************************************************
114	* Utility functions: print hex digit/byte/word/dword
115	*
116	* Parameters:
117	* %al (low nibble) : digit to print
118	* %al : byte to print
119	* %ax : word to print
120	* %eax : dword to print
121	* %ds:di : output buffer (or %di=0 to print to console)
122	* Returns:
123	* %ds:di : next character in output buffer (if applicable)
124	*****************************************************************************
125	*/
126	.section ".prefix.lib", "awx", @progbits
127	.code16
128	.globl print_hex_dword
129	print_hex_dword:
130	rorl $16, %eax
131	call print_hex_word
132	rorl $16, %eax
133	/* Fall through */
134	.size print_hex_dword, . - print_hex_dword
135	.globl print_hex_word
136	print_hex_word:
137	xchgb %al, %ah
138	call print_hex_byte
139	xchgb %al, %ah
140	/* Fall through */
141	.size print_hex_word, . - print_hex_word
142	.globl print_hex_byte
143	print_hex_byte:
144	rorb $4, %al
145	call print_hex_nibble
146	rorb $4, %al
147	/* Fall through */
148	.size print_hex_byte, . - print_hex_byte
149	.globl print_hex_nibble
150	print_hex_nibble:
151	/* Preserve registers */
152	pushw %ax
153	/* Print digit (technique by Norbert Juffa <norbert.juffa@amd.com> */
154	andb $0x0f, %al
155	cmpb $10, %al
156	sbbb $0x69, %al
157	das
158	call print_character
159	/* Restore registers and return */
160	popw %ax
161	ret
162	.size print_hex_nibble, . - print_hex_nibble
163
164	/*****************************************************************************
165	* Utility function: print PCI bus:dev.fn
166	*
167	* Parameters:
168	* %ax : PCI bus:dev.fn to print
169	* %ds:di : output buffer (or %di=0 to print to console)
170	* Returns:
171	* %ds:di : next character in output buffer (if applicable)
172	*****************************************************************************
173	*/
174	.section ".prefix.lib", "awx", @progbits
175	.code16
176	.globl print_pci_busdevfn
177	print_pci_busdevfn:
178	/* Preserve registers */
179	pushw %ax
180	/* Print bus */
181	xchgb %al, %ah
182	call print_hex_byte
183	/* Print ":" */
184	movb $( ':' ), %al
185	call print_character
186	/* Print device */
187	movb %ah, %al
188	shrb $3, %al
189	call print_hex_byte
190	/* Print "." */
191	movb $( '.' ), %al
192	call print_character
193	/* Print function */
194	movb %ah, %al
195	andb $0x07, %al
196	call print_hex_nibble
197	/* Restore registers and return */
198	popw %ax
199	ret
200	.size print_pci_busdevfn, . - print_pci_busdevfn
201
202	/*****************************************************************************
203	* Utility function: clear current line
204	*
205	* Parameters:
206	* %ds:di : output buffer (or %di=0 to print to console)
207	* Returns:
208	* %ds:di : next character in output buffer (if applicable)
209	*****************************************************************************
210	*/
211	.section ".prefix.lib", "awx", @progbits
212	.code16
213	.globl print_kill_line
214	print_kill_line:
215	/* Preserve registers */
216	pushw %ax
217	pushw %cx
218	/* Print CR */
219	movb $( '\r' ), %al
220	call print_character
221	/* Print 79 spaces */
222	movb $( ' ' ), %al
223	movw $79, %cx
224	1: call print_character
225	loop 1b
226	/* Print CR */
227	movb $( '\r' ), %al
228	call print_character
229	/* Restore registers and return */
230	popw %cx
231	popw %ax
232	ret
233	.size print_kill_line, . - print_kill_line
234
235	/****************************************************************************
236	* pm_call (real-mode near call)
237	*
238	* Call routine in 16-bit protected mode for access to extended memory
239	*
240	* Parameters:
241	* %ax : address of routine to call in 16-bit protected mode
242	* Returns:
243	* none
244	* Corrupts:
245	* %ax
246	*
247	* The specified routine is called in 16-bit protected mode, with:
248	*
249	* %cs : 16-bit code segment with base matching real-mode %cs
250	* %ss : 16-bit data segment with base matching real-mode %ss
251	* %ds,%es,%fs,%gs : 32-bit data segment with zero base and 4GB limit
252	*
253	****************************************************************************
254	*/
255
256	#ifndef KEEP_IT_REAL
257
258	/* GDT for protected-mode calls */
259	.section ".prefix.lib", "awx", @progbits
260	.align 16
261	pm_call_vars:
262	gdt:
263	gdt_limit: .word gdt_length - 1
264	gdt_base: .long 0
265	.word 0 /* padding */
266	pm_cs: /* 16-bit protected-mode code segment */
267	.equ PM_CS, pm_cs - gdt
268	.word 0xffff, 0
269	.byte 0, 0x9b, 0x00, 0
270	pm_ss: /* 16-bit protected-mode stack segment */
271	.equ PM_SS, pm_ss - gdt
272	.word 0xffff, 0
273	.byte 0, 0x93, 0x00, 0
274	pm_ds: /* 32-bit protected-mode flat data segment */
275	.equ PM_DS, pm_ds - gdt
276	.word 0xffff, 0
277	.byte 0, 0x93, 0xcf, 0
278	gdt_end:
279	.equ gdt_length, . - gdt
280	.size gdt, . - gdt
281
282	.section ".prefix.lib", "awx", @progbits
283	.align 16
284	pm_saved_gdt:
285	.long 0, 0
286	.size pm_saved_gdt, . - pm_saved_gdt
287
288	.equ pm_call_vars_size, . - pm_call_vars
289	#define PM_CALL_VAR(x) ( -pm_call_vars_size + ( (x) - pm_call_vars ) )
290
291	.section ".prefix.lib", "awx", @progbits
292	.code16
293	pm_call:
294	/* Preserve registers, flags, and RM return point */
295	pushw %bp
296	movw %sp, %bp
297	subw $pm_call_vars_size, %sp
298	andw $0xfff0, %sp
299	pushfl
300	pushw %gs
301	pushw %fs
302	pushw %es
303	pushw %ds
304	pushw %ss
305	pushw %cs
306	pushw $99f
307
308	/* Set up local variable block, and preserve GDT */
309	pushw %cx
310	pushw %si
311	pushw %di
312	pushw %ss
313	popw %es
314	movw $pm_call_vars, %si
315	leaw PM_CALL_VAR(pm_call_vars)(%bp), %di
316	movw $pm_call_vars_size, %cx
317	cs rep movsb
318	popw %di
319	popw %si
320	popw %cx
321	sgdt PM_CALL_VAR(pm_saved_gdt)(%bp)
322
323	/* Set up GDT bases */
324	pushl %eax
325	pushl %edi
326	xorl %eax, %eax
327	movw %ss, %ax
328	shll $4, %eax
329	movzwl %bp, %edi
330	addr32 leal PM_CALL_VAR(gdt)(%eax, %edi), %eax
331	movl %eax, PM_CALL_VAR(gdt_base)(%bp)
332	movw %cs, %ax
333	movw $PM_CALL_VAR(pm_cs), %di
334	call set_seg_base
335	movw %ss, %ax
336	movw $PM_CALL_VAR(pm_ss), %di
337	call set_seg_base
338	popl %edi
339	popl %eax
340
341	/* Switch CPU to protected mode and load up segment registers */
342	pushl %eax
343	cli
344	data32 lgdt PM_CALL_VAR(gdt)(%bp)
345	movl %cr0, %eax
346	orb $CR0_PE, %al
347	movl %eax, %cr0
348	ljmp $PM_CS, $1f
349	1: movw $PM_SS, %ax
350	movw %ax, %ss
351	movw $PM_DS, %ax
352	movw %ax, %ds
353	movw %ax, %es
354	movw %ax, %fs
355	movw %ax, %gs
356	popl %eax
357
358	/* Call PM routine */
359	call *%ax
360
361	/* Set real-mode segment limits on %ds, %es, %fs and %gs */
362	movw %ss, %ax
363	movw %ax, %ds
364	movw %ax, %es
365	movw %ax, %fs
366	movw %ax, %gs
367
368	/* Return CPU to real mode */
369	movl %cr0, %eax
370	andb $0!CR0_PE, %al
371	movl %eax, %cr0
372
373	/* Restore registers and flags */
374	lret /* will ljmp to 99f */
375	99: popw %ss
376	popw %ds
377	popw %es
378	popw %fs
379	popw %gs
380	data32 lgdt PM_CALL_VAR(pm_saved_gdt)(%bp)
381	popfl
382	movw %bp, %sp
383	popw %bp
384	ret
385	.size pm_call, . - pm_call
386
387	set_seg_base:
388	rolw $4, %ax
389	movw %ax, 2(%bp,%di)
390	andw $0xfff0, 2(%bp,%di)
391	movb %al, 4(%bp,%di)
392	andb $0x0f, 4(%bp,%di)
393	ret
394	.size set_seg_base, . - set_seg_base
395
396	#endif /* KEEP_IT_REAL */
397
398	/****************************************************************************
399	* copy_bytes (real-mode or 16-bit protected-mode near call)
400	*
401	* Copy bytes
402	*
403	* Parameters:
404	* %ds:esi : source address
405	* %es:edi : destination address
406	* %ecx : length
407	* Returns:
408	* %ds:esi : next source address
409	* %es:edi : next destination address
410	* Corrupts:
411	* None
412	****************************************************************************
413	*/
414	.section ".prefix.lib", "awx", @progbits
415	.code16
416	copy_bytes:
417	pushl %ecx
418	rep addr32 movsb
419	popl %ecx
420	ret
421	.size copy_bytes, . - copy_bytes
422
423	/****************************************************************************
424	* install_block (real-mode near call)
425	*
426	* Install block to specified address
427	*
428	* Parameters:
429	* %esi : source physical address (must be a multiple of 16)
430	* %edi : destination physical address (must be a multiple of 16)
431	* %ecx : length of (decompressed) data
432	* %edx : total length of block (including any uninitialised data portion)
433	* Returns:
434	* %esi : next source physical address (will be a multiple of 16)
435	* Corrupts:
436	* none
437	****************************************************************************
438	*/
439	.section ".prefix.lib", "awx", @progbits
440	.code16
441	install_block:
442
443	#ifdef KEEP_IT_REAL
444
445	/* Preserve registers */
446	pushw %ds
447	pushw %es
448	pushl %ecx
449	pushl %edi
450
451	/* Convert %esi and %edi to segment registers */
452	shrl $4, %esi
453	movw %si, %ds
454	xorw %si, %si
455	shrl $4, %edi
456	movw %di, %es
457	xorw %di, %di
458
459	#else /* KEEP_IT_REAL */
460
461	/* Call self in protected mode */
462	pushw %ax
463	movw $1f, %ax
464	call pm_call
465	popw %ax
466	ret
467	1:
468	/* Preserve registers */
469	pushl %ecx
470	pushl %edi
471
472	#endif /* KEEP_IT_REAL */
473
474
475	#if COMPRESS
476	/* Decompress source to destination */
477	call decompress16
478	#else
479	/* Copy source to destination */
480	call copy_bytes
481	#endif
482
483	/* Zero .bss portion */
484	negl %ecx
485	addl %edx, %ecx
486	pushw %ax
487	xorw %ax, %ax
488	rep addr32 stosb
489	popw %ax
490
491	/* Round up %esi to start of next source block */
492	addl $0xf, %esi
493	andl $~0xf, %esi
494
495
496	#ifdef KEEP_IT_REAL
497
498	/* Convert %ds:esi back to a physical address */
499	movzwl %ds, %cx
500	shll $4, %ecx
501	addl %ecx, %esi
502
503	/* Restore registers */
504	popl %edi
505	popl %ecx
506	popw %es
507	popw %ds
508
509	#else /* KEEP_IT_REAL */
510
511	/* Restore registers */
512	popl %edi
513	popl %ecx
514
515	#endif
516
517	ret
518	.size install_block, . - install_block
519
520	/****************************************************************************
521	* alloc_basemem (real-mode near call)
522	*
523	* Allocate space for .text16 and .data16 from top of base memory.
524	* Memory is allocated using the BIOS free base memory counter at
525	* 0x40:13.
526	*
527	* Parameters:
528	* none
529	* Returns:
530	* %ax : .text16 segment address
531	* %bx : .data16 segment address
532	* Corrupts:
533	* none
534	****************************************************************************
535	*/
536	.section ".prefix.lib", "awx", @progbits
537	.code16
538	.globl alloc_basemem
539	alloc_basemem:
540	/* Preserve registers */
541	pushw %fs
542
543	/* FBMS => %ax as segment address */
544	pushw $0x40
545	popw %fs
546	movw %fs:0x13, %ax
547	shlw $6, %ax
548
549	/* Calculate .data16 segment address */
550	subw $_data16_memsz_pgh, %ax
551	pushw %ax
552
553	/* Calculate .text16 segment address */
554	subw $_text16_memsz_pgh, %ax
555	pushw %ax
556
557	/* Update FBMS */
558	shrw $6, %ax
559	movw %ax, %fs:0x13
560
561	/* Retrieve .text16 and .data16 segment addresses */
562	popw %ax
563	popw %bx
564
565	/* Restore registers and return */
566	popw %fs
567	ret
568	.size alloc_basemem, . - alloc_basemem
569
570	/****************************************************************************
571	* free_basemem (real-mode near call)
572	*
573	* Free space allocated with alloc_basemem.
574	*
575	* Parameters:
576	* %ax : .text16 segment address
577	* %bx : .data16 segment address
578	* Returns:
579	* %ax : 0 if successfully freed
580	* Corrupts:
581	* none
582	****************************************************************************
583	*/
584	.section ".text16", "ax", @progbits
585	.code16
586	.globl free_basemem
587	free_basemem:
588	/* Preserve registers */
589	pushw %fs
590
591	/* Check FBMS counter */
592	pushw %ax
593	shrw $6, %ax
594	pushw $0x40
595	popw %fs
596	cmpw %ax, %fs:0x13
597	popw %ax
598	jne 1f
599
600	/* Check hooked interrupt count */
601	cmpw $0, %cs:hooked_bios_interrupts
602	jne 1f
603
604	/* OK to free memory */
605	addw $_text16_memsz_pgh, %ax
606	addw $_data16_memsz_pgh, %ax
607	shrw $6, %ax
608	movw %ax, %fs:0x13
609	xorw %ax, %ax
610
611	1: /* Restore registers and return */
612	popw %fs
613	ret
614	.size free_basemem, . - free_basemem
615
616	.section ".text16.data", "aw", @progbits
617	.globl hooked_bios_interrupts
618	hooked_bios_interrupts:
619	.word 0
620	.size hooked_bios_interrupts, . - hooked_bios_interrupts
621
622	/****************************************************************************
623	* install (real-mode near call)
624	*
625	* Install all text and data segments.
626	*
627	* Parameters:
628	* none
629	* Returns:
630	* %ax : .text16 segment address
631	* %bx : .data16 segment address
632	* Corrupts:
633	* none
634	****************************************************************************
635	*/
636	.section ".prefix.lib", "awx", @progbits
637	.code16
638	.globl install
639	install:
640	/* Preserve registers */
641	pushl %esi
642	pushl %edi
643	/* Allocate space for .text16 and .data16 */
644	call alloc_basemem
645	/* Image source = %cs:0000 */
646	xorl %esi, %esi
647	/* Image destination = HIGHMEM_LOADPOINT */
648	movl $HIGHMEM_LOADPOINT, %edi
649	/* Install text and data segments */
650	call install_prealloc
651	/* Restore registers and return */
652	popl %edi
653	popl %esi
654	ret
655	.size install, . - install
656
657	/****************************************************************************
658	* install_prealloc (real-mode near call)
659	*
660	* Install all text and data segments.
661	*
662	* Parameters:
663	* %ax : .text16 segment address
664	* %bx : .data16 segment address
665	* %esi : Image source physical address (or zero for %cs:0000)
666	* %edi : Decompression temporary area physical address
667	* Corrupts:
668	* none
669	****************************************************************************
670	*/
671	.section ".prefix.lib", "awx", @progbits
672	.code16
673	.globl install_prealloc
674	install_prealloc:
675	/* Save registers */
676	pushal
677	pushw %ds
678	pushw %es
679
680	/* Sanity: clear the direction flag asap */
681	cld
682
683	/* Calculate physical address of payload (i.e. first source) */
684	testl %esi, %esi
685	jnz 1f
686	movw %cs, %si
687	shll $4, %esi
688	1: addl $_payload_lma, %esi
689
690	/* Install .text16 and .data16 */
691	pushl %edi
692	movzwl %ax, %edi
693	shll $4, %edi
694	movl $_text16_memsz, %ecx
695	movl %ecx, %edx
696	call install_block /* .text16 */
697	movzwl %bx, %edi
698	shll $4, %edi
699	movl $_data16_filesz, %ecx
700	movl $_data16_memsz, %edx
701	call install_block /* .data16 */
702	popl %edi
703
704	/* Set up %ds for access to .data16 */
705	movw %bx, %ds
706
707	#ifdef KEEP_IT_REAL
708	/* Initialise libkir */
709	movw %ax, (init_libkir_vector+2)
710	lcall *init_libkir_vector
711	#else
712	/* Install .text and .data to temporary area in high memory,
713	* prior to reading the E820 memory map and relocating
714	* properly.
715	*/
716	movl $_textdata_filesz, %ecx
717	movl $_textdata_memsz, %edx
718	call install_block
719
720	/* Initialise librm at current location */
721	movw %ax, (init_librm_vector+2)
722	lcall *init_librm_vector
723
724	/* Call relocate() to determine target address for relocation.
725	* relocate() will return with %esi, %edi and %ecx set up
726	* ready for the copy to the new location.
727	*/
728	movw %ax, (prot_call_vector+2)
729	pushl $relocate
730	lcall *prot_call_vector
731	popl %edx /* discard */
732
733	/* Copy code to new location */
734	pushl %edi
735	pushw %ax
736	movw $copy_bytes, %ax
737	call pm_call
738	popw %ax
739	popl %edi
740
741	/* Initialise librm at new location */
742	lcall *init_librm_vector
743
744	#endif
745	/* Restore registers */
746	popw %es
747	popw %ds
748	popal
749	ret
750	.size install_prealloc, . - install_prealloc
751
752	/* Vectors for far calls to .text16 functions */
753	.section ".data16", "aw", @progbits
754	#ifdef KEEP_IT_REAL
755	init_libkir_vector:
756	.word init_libkir
757	.word 0
758	.size init_libkir_vector, . - init_libkir_vector
759	#else
760	init_librm_vector:
761	.word init_librm
762	.word 0
763	.size init_librm_vector, . - init_librm_vector
764	prot_call_vector:
765	.word prot_call
766	.word 0
767	.size prot_call_vector, . - prot_call_vector
768	#endif
769
770	/****************************************************************************
771	* uninstall (real-mode near call)
772	*
773	* Uninstall all text and data segments.
774	*
775	* Parameters:
776	* %ax : .text16 segment address
777	* %bx : .data16 segment address
778	* Returns:
779	* none
780	* Corrupts:
781	* none
782	****************************************************************************
783	*/
784	.section ".text16", "ax", @progbits
785	.code16
786	.globl uninstall
787	uninstall:
788	call free_basemem
789	ret
790	.size uninstall, . - uninstall
791
792
793
794	/* File split information for the compressor */
795	#if COMPRESS
796	.section ".zinfo", "a", @progbits
797	.ascii "COPY"
798	.long _prefix_lma
799	.long _prefix_filesz
800	.long _max_align
801	.ascii "PACK"
802	.long _text16_lma
803	.long _text16_filesz
804	.long _max_align
805	.ascii "PACK"
806	.long _data16_lma
807	.long _data16_filesz
808	.long _max_align
809	.ascii "PACK"
810	.long _textdata_lma
811	.long _textdata_filesz
812	.long _max_align
813	#else /* COMPRESS */
814	.section ".zinfo", "a", @progbits
815	.ascii "COPY"
816	.long _prefix_lma
817	.long _filesz
818	.long _max_align
819	#endif /* COMPRESS */

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