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pxeprefix.S

Last change on this file was e16e8f2, checked in by Edwin Eefting <edwin@datux.nl>, 3 years ago
bootstuff
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1	FILE_LICENCE ( GPL2_OR_LATER )
2
3	#define PXENV_UNDI_SHUTDOWN 0x0005
4	#define PXENV_UNDI_GET_NIC_TYPE 0x0012
5	#define PXENV_UNDI_GET_IFACE_INFO 0x0013
6	#define PXENV_STOP_UNDI 0x0015
7	#define PXENV_UNLOAD_STACK 0x0070
8
9	#define PXE_HACK_EB54 0x0001
10
11	.text
12	.arch i386
13	.org 0
14	.code16
15
16	#include <undi.h>
17
18	#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
19	#define EB_MAGIC_1 ( 'E' + ( 't' << 8 ) + ( 'h' << 16 ) + ( 'e' << 24 ) )
20	#define EB_MAGIC_2 ( 'r' + ( 'b' << 8 ) + ( 'o' << 16 ) + ( 'o' << 24 ) )
21
22	/*****************************************************************************
23	* Entry point: set operating context, print welcome message
24	*****************************************************************************
25	*/
26	.section ".prefix", "ax", @progbits
27	jmp $0x7c0, $1f
28	1:
29	/* Preserve registers for possible return to PXE */
30	pushfl
31	pushal
32	pushw %gs
33	pushw %fs
34	pushw %es
35	pushw %ds
36
37	/* Store magic word on PXE stack and remember PXE %ss:esp */
38	pushl $STACK_MAGIC
39	movw %ss, %cs:pxe_ss
40	movl %esp, %cs:pxe_esp
41
42	/* Set up segments */
43	movw %cs, %ax
44	movw %ax, %ds
45	movw $0x40, %ax /* BIOS data segment access */
46	movw %ax, %fs
47	/* Set up stack just below 0x7c00 */
48	xorw %ax, %ax
49	movw %ax, %ss
50	movl $0x7c00, %esp
51	/* Clear direction flag, for the sake of sanity */
52	cld
53	/* Print welcome message */
54	movw $10f, %si
55	xorw %di, %di
56	call print_message
57	.section ".prefix.data", "aw", @progbits
58	10: .asciz "PXE->EB:"
59	.previous
60
61	/*****************************************************************************
62	* Find us a usable !PXE or PXENV+ entry point
63	*****************************************************************************
64	*/
65	detect_pxe:
66	/* Plan A: !PXE pointer from the stack */
67	lgsl pxe_esp, %ebp /* %gs:%bp -> original stack */
68	lesw %gs:52(%bp), %bx
69	call is_valid_ppxe
70	je have_ppxe
71
72	/* Plan B: PXENV+ pointer from initial ES:BX */
73	movw %gs:32(%bp),%bx
74	movw %gs:8(%bp),%es
75	call is_valid_pxenv
76	je have_pxenv
77
78	/* Plan C: PXENV+ structure via INT 1Ah */
79	movw $0x5650, %ax
80	int $0x1a
81	jc 1f
82	cmpw $0x564e, %ax
83	jne 1f
84	call is_valid_pxenv
85	je have_pxenv
86	1:
87	/* Plan D: scan base memory for !PXE */
88	call memory_scan_ppxe
89	je have_ppxe
90
91	/* Plan E: scan base memory for PXENV+ */
92	call memory_scan_pxenv
93	jne stack_not_found
94
95	have_pxenv:
96	movw %bx, pxenv_offset
97	movw %es, pxenv_segment
98
99	cmpw $0x201, %es:6(%bx) /* API version >= 2.01 */
100	jb 1f
101	cmpb $0x2c, %es:8(%bx) /* ... and structure long enough */
102	jb 2f
103
104	lesw %es:0x28(%bx), %bx /* Find !PXE from PXENV+ */
105	call is_valid_ppxe
106	je have_ppxe
107	2:
108	call memory_scan_ppxe /* We are supposed to have !PXE... */
109	je have_ppxe
110	1:
111	lesw pxenv_segoff, %bx /* Nope, we're stuck with PXENV+ */
112
113	/* Record entry point and UNDI segments */
114	pushl %es:0x0a(%bx) /* Entry point */
115	pushw %es:0x24(%bx) /* UNDI code segment */
116	pushw %es:0x26(%bx) /* UNDI code size */
117	pushw %es:0x20(%bx) /* UNDI data segment */
118	pushw %es:0x22(%bx) /* UNDI data size */
119
120	/* Print "PXENV+ at <address>" */
121	movw $10f, %si
122	jmp check_have_stack
123	.section ".prefix.data", "aw", @progbits
124	10: .asciz " PXENV+ at "
125	.previous
126
127	have_ppxe:
128	movw %bx, ppxe_offset
129	movw %es, ppxe_segment
130
131	pushl %es:0x10(%bx) /* Entry point */
132	pushw %es:0x30(%bx) /* UNDI code segment */
133	pushw %es:0x36(%bx) /* UNDI code size */
134	pushw %es:0x28(%bx) /* UNDI data segment */
135	pushw %es:0x2e(%bx) /* UNDI data size */
136
137	/* Print "!PXE at <address>" */
138	movw $10f, %si
139	jmp check_have_stack
140	.section ".prefix.data", "aw", @progbits
141	10: .asciz " !PXE at "
142	.previous
143
144	is_valid_ppxe:
145	cmpl $0x45585021, %es:(%bx)
146	jne 1f
147	movzbw %es:4(%bx), %cx
148	cmpw $0x58, %cx
149	jae is_valid_checksum
150	1:
151	ret
152
153	is_valid_pxenv:
154	cmpl $0x4e455850, %es:(%bx)
155	jne 1b
156	cmpw $0x2b56, %es:4(%bx)
157	jne 1b
158	movzbw %es:8(%bx), %cx
159	cmpw $0x28, %cx
160	jb 1b
161
162	is_valid_checksum:
163	pushw %ax
164	movw %bx, %si
165	xorw %ax, %ax
166	2:
167	es lodsb
168	addb %al, %ah
169	loopw 2b
170	popw %ax
171	ret
172
173	memory_scan_ppxe:
174	movw $is_valid_ppxe, %dx
175	jmp memory_scan_common
176
177	memory_scan_pxenv:
178	movw $is_valid_pxenv, %dx
179
180	memory_scan_common:
181	movw %fs:(0x13), %ax
182	shlw $6, %ax
183	decw %ax
184	1: incw %ax
185	cmpw $( 0xa000 - 1 ), %ax
186	ja 2f
187	movw %ax, %es
188	xorw %bx, %bx
189	call *%dx
190	jne 1b
191	2: ret
192
193	/*****************************************************************************
194	* Sanity check: we must have an entry point
195	*****************************************************************************
196	*/
197	check_have_stack:
198	/* Save common values pushed onto the stack */
199	popl undi_data_segoff
200	popl undi_code_segoff
201	popl entry_segoff
202
203	/* Print have !PXE/PXENV+ message; structure pointer in %es:%bx */
204	call print_message
205	call print_segoff
206	movb $( ',' ), %al
207	call print_character
208
209	/* Check for entry point */
210	movl entry_segoff, %eax
211	testl %eax, %eax
212	jnz 99f
213	/* No entry point: print message and skip everything else */
214	stack_not_found:
215	movw $10f, %si
216	call print_message
217	jmp finished
218	.section ".prefix.data", "aw", @progbits
219	10: .asciz " No PXE stack found!\n"
220	.previous
221	99:
222
223	/*****************************************************************************
224	* Calculate base memory usage by UNDI
225	*****************************************************************************
226	*/
227	find_undi_basemem_usage:
228	movw undi_code_segment, %ax
229	movw undi_code_size, %bx
230	movw undi_data_segment, %cx
231	movw undi_data_size, %dx
232	cmpw %ax, %cx
233	ja 1f
234	xchgw %ax, %cx
235	xchgw %bx, %dx
236	1: /* %ax:%bx now describes the lower region, %cx:%dx the higher */
237	shrw $6, %ax /* Round down to nearest kB */
238	movw %ax, undi_fbms_start
239	addw $0x0f, %dx /* Round up to next segment */
240	shrw $4, %dx
241	addw %dx, %cx
242	addw $((1024 / 16) - 1), %cx /* Round up to next kB */
243	shrw $6, %cx
244	movw %cx, undi_fbms_end
245
246	/*****************************************************************************
247	* Print information about detected PXE stack
248	*****************************************************************************
249	*/
250	print_structure_information:
251	/* Print entry point */
252	movw $10f, %si
253	call print_message
254	les entry_segoff, %bx
255	call print_segoff
256	.section ".prefix.data", "aw", @progbits
257	10: .asciz " entry point at "
258	.previous
259	/* Print UNDI code segment */
260	movw $10f, %si
261	call print_message
262	les undi_code_segoff, %bx
263	call print_segoff
264	.section ".prefix.data", "aw", @progbits
265	10: .asciz "\n UNDI code segment "
266	.previous
267	/* Print UNDI data segment */
268	movw $10f, %si
269	call print_message
270	les undi_data_segoff, %bx
271	call print_segoff
272	.section ".prefix.data", "aw", @progbits
273	10: .asciz ", data segment "
274	.previous
275	/* Print UNDI memory usage */
276	movw $10f, %si
277	call print_message
278	movw undi_fbms_start, %ax
279	call print_word
280	movb $( '-' ), %al
281	call print_character
282	movw undi_fbms_end, %ax
283	call print_word
284	movw $20f, %si
285	call print_message
286	.section ".prefix.data", "aw", @progbits
287	10: .asciz " ("
288	20: .asciz "kB)\n"
289	.previous
290
291	/*****************************************************************************
292	* Determine physical device
293	*****************************************************************************
294	*/
295	get_physical_device:
296	/* Issue PXENV_UNDI_GET_NIC_TYPE */
297	movw $PXENV_UNDI_GET_NIC_TYPE, %bx
298	call pxe_call
299	jnc 1f
300	call print_pxe_error
301	jmp no_physical_device
302	1: /* Determine physical device type */
303	movb ( pxe_parameter_structure + 0x02 ), %al
304	cmpb $2, %al
305	je pci_physical_device
306	jmp no_physical_device
307
308	pci_physical_device:
309	/* Record PCI bus:dev.fn and vendor/device IDs */
310	movl ( pxe_parameter_structure + 0x03 ), %eax
311	movl %eax, pci_vendor
312	movw ( pxe_parameter_structure + 0x0b ), %ax
313	movw %ax, pci_busdevfn
314	movw $10f, %si
315	call print_message
316	call print_pci_busdevfn
317	jmp 99f
318	.section ".prefix.data", "aw", @progbits
319	10: .asciz " UNDI device is PCI "
320	.previous
321
322	no_physical_device:
323	/* No device found, or device type not understood */
324	movw $10f, %si
325	call print_message
326	.section ".prefix.data", "aw", @progbits
327	10: .asciz " Unable to determine UNDI physical device"
328	.previous
329
330	99:
331
332	/*****************************************************************************
333	* Determine interface type
334	*****************************************************************************
335	*/
336	get_iface_type:
337	/* Issue PXENV_UNDI_GET_IFACE_INFO */
338	movw $PXENV_UNDI_GET_IFACE_INFO, %bx
339	call pxe_call
340	jnc 1f
341	call print_pxe_error
342	jmp 99f
343	1: /* Print interface type */
344	movw $10f, %si
345	call print_message
346	leaw ( pxe_parameter_structure + 0x02 ), %si
347	call print_message
348	.section ".prefix.data", "aw", @progbits
349	10: .asciz ", type "
350	.previous
351	/* Check for "Etherboot" interface type */
352	cmpl $EB_MAGIC_1, ( pxe_parameter_structure + 0x02 )
353	jne 99f
354	cmpl $EB_MAGIC_2, ( pxe_parameter_structure + 0x06 )
355	jne 99f
356	movw $10f, %si
357	call print_message
358	.section ".prefix.data", "aw", @progbits
359	10: .asciz " (workaround enabled)"
360	.previous
361	/* Flag Etherboot workarounds as required */
362	orw $PXE_HACK_EB54, pxe_hacks
363
364	99: movb $0x0a, %al
365	call print_character
366
367	/*****************************************************************************
368	* Leave NIC in a safe state
369	*****************************************************************************
370	*/
371	#ifndef PXELOADER_KEEP_PXE
372	shutdown_nic:
373	/* Issue PXENV_UNDI_SHUTDOWN */
374	movw $PXENV_UNDI_SHUTDOWN, %bx
375	call pxe_call
376	jnc 1f
377	call print_pxe_error
378	1:
379	unload_base_code:
380	/* Etherboot treats PXENV_UNLOAD_STACK as PXENV_STOP_UNDI, so
381	* we must not issue this call if the underlying stack is
382	* Etherboot and we were not intending to issue a PXENV_STOP_UNDI.
383	*/
384	#ifdef PXELOADER_KEEP_UNDI
385	testw $PXE_HACK_EB54, pxe_hacks
386	jnz 99f
387	#endif /* PXELOADER_KEEP_UNDI */
388	/* Issue PXENV_UNLOAD_STACK */
389	movw $PXENV_UNLOAD_STACK, %bx
390	call pxe_call
391	jnc 1f
392	call print_pxe_error
393	jmp 99f
394	1: /* Free base memory used by PXE base code */
395	movw undi_fbms_start, %ax
396	movw %fs:(0x13), %bx
397	call free_basemem
398	99:
399	andw $~( UNDI_FL_INITIALIZED \| UNDI_FL_KEEP_ALL ), flags
400	#endif /* PXELOADER_KEEP_PXE */
401
402	/*****************************************************************************
403	* Unload UNDI driver
404	*****************************************************************************
405	*/
406	#ifndef PXELOADER_KEEP_UNDI
407	unload_undi:
408	/* Issue PXENV_STOP_UNDI */
409	movw $PXENV_STOP_UNDI, %bx
410	call pxe_call
411	jnc 1f
412	call print_pxe_error
413	jmp 99f
414	1: /* Free base memory used by UNDI */
415	movw undi_fbms_end, %ax
416	movw undi_fbms_start, %bx
417	call free_basemem
418	/* Clear UNDI_FL_STARTED */
419	andw $~UNDI_FL_STARTED, flags
420	99:
421	#endif /* PXELOADER_KEEP_UNDI */
422
423	/*****************************************************************************
424	* Print remaining free base memory
425	*****************************************************************************
426	*/
427	print_free_basemem:
428	movw $10f, %si
429	call print_message
430	movw %fs:(0x13), %ax
431	call print_word
432	movw $20f, %si
433	call print_message
434	.section ".prefix.data", "aw", @progbits
435	10: .asciz " "
436	20: .asciz "kB free base memory after PXE unload\n"
437	.previous
438
439	/*****************************************************************************
440	* Exit point
441	*****************************************************************************
442	*/
443	finished:
444	jmp run_gpxe
445
446	/*****************************************************************************
447	* Subroutine: print segment:offset address
448	*
449	* Parameters:
450	* %es:%bx : segment:offset address to print
451	* %ds:di : output buffer (or %di=0 to print to console)
452	* Returns:
453	* %ds:di : next character in output buffer (if applicable)
454	*****************************************************************************
455	*/
456	print_segoff:
457	/* Preserve registers */
458	pushw %ax
459	/* Print "<segment>:offset" */
460	movw %es, %ax
461	call print_hex_word
462	movb $( ':' ), %al
463	call print_character
464	movw %bx, %ax
465	call print_hex_word
466	/* Restore registers and return */
467	popw %ax
468	ret
469
470	/*****************************************************************************
471	* Subroutine: print decimal word
472	*
473	* Parameters:
474	* %ax : word to print
475	* %ds:di : output buffer (or %di=0 to print to console)
476	* Returns:
477	* %ds:di : next character in output buffer (if applicable)
478	*****************************************************************************
479	*/
480	print_word:
481	/* Preserve registers */
482	pushw %ax
483	pushw %bx
484	pushw %cx
485	pushw %dx
486	/* Build up digit sequence on stack */
487	movw $10, %bx
488	xorw %cx, %cx
489	1: xorw %dx, %dx
490	divw %bx, %ax
491	pushw %dx
492	incw %cx
493	testw %ax, %ax
494	jnz 1b
495	/* Print digit sequence */
496	1: popw %ax
497	call print_hex_nibble
498	loop 1b
499	/* Restore registers and return */
500	popw %dx
501	popw %cx
502	popw %bx
503	popw %ax
504	ret
505
506	/*****************************************************************************
507	* Subroutine: zero 1kB block of base memory
508	*
509	* Parameters:
510	* %bx : block to zero (in kB)
511	* Returns:
512	* Nothing
513	*****************************************************************************
514	*/
515	zero_kb:
516	/* Preserve registers */
517	pushw %ax
518	pushw %cx
519	pushw %di
520	pushw %es
521	/* Zero block */
522	movw %bx, %ax
523	shlw $6, %ax
524	movw %ax, %es
525	movw $0x400, %cx
526	xorw %di, %di
527	xorw %ax, %ax
528	rep stosb
529	/* Restore registers and return */
530	popw %es
531	popw %di
532	popw %cx
533	popw %ax
534	ret
535
536	/*****************************************************************************
537	* Subroutine: free and zero base memory
538	*
539	* Parameters:
540	* %ax : Desired new free base memory counter (in kB)
541	* %bx : Expected current free base memory counter (in kB)
542	* %fs : BIOS data segment (0x40)
543	* Returns:
544	* None
545	*
546	* The base memory from %bx kB to %ax kB is unconditionally zeroed.
547	* It will be freed if and only if the expected current free base
548	* memory counter (%bx) matches the actual current free base memory
549	* counter in 0x40:0x13; if this does not match then the memory will
550	* be leaked.
551	*****************************************************************************
552	*/
553	free_basemem:
554	/* Zero base memory */
555	pushw %bx
556	1: cmpw %bx, %ax
557	je 2f
558	call zero_kb
559	incw %bx
560	jmp 1b
561	2: popw %bx
562	/* Free base memory */
563	cmpw %fs:(0x13), %bx /* Update FBMS only if "old" value */
564	jne 1f /* is correct */
565	1: movw %ax, %fs:(0x13)
566	ret
567
568	/*****************************************************************************
569	* Subroutine: make a PXE API call. Works with either !PXE or PXENV+ API.
570	*
571	* Parameters:
572	* %bx : PXE API call number
573	* %ds:pxe_parameter_structure : Parameters for PXE API call
574	* Returns:
575	* %ax : PXE status code (not exit code)
576	* CF set if %ax is non-zero
577	*****************************************************************************
578	*/
579	pxe_call:
580	/* Preserve registers */
581	pushw %di
582	pushw %es
583	/* Set up registers for PXENV+ API. %bx already set up */
584	pushw %ds
585	popw %es
586	movw $pxe_parameter_structure, %di
587	/* Set up stack for !PXE API */
588	pushw %es
589	pushw %di
590	pushw %bx
591	/* Make the API call */
592	lcall *entry_segoff
593	/* Reset the stack */
594	addw $6, %sp
595	movw pxe_parameter_structure, %ax
596	clc
597	testw %ax, %ax
598	jz 1f
599	stc
600	1: /* Clear direction flag, for the sake of sanity */
601	cld
602	/* Restore registers and return */
603	popw %es
604	popw %di
605	ret
606
607	/*****************************************************************************
608	* Subroutine: print PXE API call error message
609	*
610	* Parameters:
611	* %ax : PXE status code
612	* %bx : PXE API call number
613	* Returns:
614	* Nothing
615	*****************************************************************************
616	*/
617	print_pxe_error:
618	pushw %si
619	movw $10f, %si
620	call print_message
621	xchgw %ax, %bx
622	call print_hex_word
623	movw $20f, %si
624	call print_message
625	xchgw %ax, %bx
626	call print_hex_word
627	movw $30f, %si
628	call print_message
629	popw %si
630	ret
631	.section ".prefix.data", "aw", @progbits
632	10: .asciz " UNDI API call "
633	20: .asciz " failed: status code "
634	30: .asciz "\n"
635	.previous
636
637	/*****************************************************************************
638	* PXE data structures
639	*****************************************************************************
640	*/
641	.section ".prefix.data"
642
643	pxe_esp: .long 0
644	pxe_ss: .word 0
645
646	pxe_parameter_structure: .fill 64
647
648	undi_code_segoff:
649	undi_code_size: .word 0
650	undi_code_segment: .word 0
651
652	undi_data_segoff:
653	undi_data_size: .word 0
654	undi_data_segment: .word 0
655
656	pxe_hacks: .word 0
657
658	/* The following fields are part of a struct undi_device */
659
660	undi_device:
661
662	pxenv_segoff:
663	pxenv_offset: .word 0
664	pxenv_segment: .word 0
665
666	ppxe_segoff:
667	ppxe_offset: .word 0
668	ppxe_segment: .word 0
669
670	entry_segoff:
671	entry_offset: .word 0
672	entry_segment: .word 0
673
674	undi_fbms_start: .word 0
675	undi_fbms_end: .word 0
676
677	pci_busdevfn: .word UNDI_NO_PCI_BUSDEVFN
678	isapnp_csn: .word UNDI_NO_ISAPNP_CSN
679	isapnp_read_port: .word UNDI_NO_ISAPNP_READ_PORT
680
681	pci_vendor: .word 0
682	pci_device: .word 0
683	flags:
684	.word ( UNDI_FL_INITIALIZED \| UNDI_FL_STARTED \| UNDI_FL_KEEP_ALL )
685
686	.equ undi_device_size, ( . - undi_device )
687
688	/*****************************************************************************
689	* Run gPXE main code
690	*****************************************************************************
691	*/
692	.section ".prefix"
693	run_gpxe:
694	/* Install gPXE */
695	call install
696
697	/* Set up real-mode stack */
698	movw %bx, %ss
699	movw $_estack16, %sp
700
701	#ifdef PXELOADER_KEEP_UNDI
702	/* Copy our undi_device structure to the preloaded_undi variable */
703	movw %bx, %es
704	movw $preloaded_undi, %di
705	movw $undi_device, %si
706	movw $undi_device_size, %cx
707	rep movsb
708	#endif
709
710	/* Retrieve PXE %ss:esp */
711	movw pxe_ss, %di
712	movl pxe_esp, %ebp
713
714	/* Jump to .text16 segment with %ds pointing to .data16 */
715	movw %bx, %ds
716	pushw %ax
717	pushw $1f
718	lret
719	.section ".text16", "ax", @progbits
720	1:
721	/* Update the exit hook */
722	movw %cs,pxe_exit_hook+2
723	push %ax
724	mov $2f,%ax
725	mov %ax,pxe_exit_hook
726	pop %ax
727
728	/* Run main program */
729	pushl $main
730	pushw %cs
731	call prot_call
732	popl %ecx /* discard */
733
734	/* Uninstall gPXE */
735	call uninstall
736
737	/* Restore PXE stack */
738	movw %di, %ss
739	movl %ebp, %esp
740
741	/* Jump to hook if applicable */
742	ljmpw *pxe_exit_hook
743
744	2: /* Check PXE stack magic */
745	popl %eax
746	cmpl $STACK_MAGIC, %eax
747	jne 1f
748
749	/* PXE stack OK: return to caller */
750	popw %ds
751	popw %es
752	popw %fs
753	popw %gs
754	popal
755	popfl
756	xorw %ax, %ax /* Return success */
757	lret
758
759	1: /* PXE stack corrupt or removed: use INT 18 */
760	int $0x18
761	.previous

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