Diff of /trunk/mkinitrd-magellan/isolinux/com32.inc

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	revision 1132 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 1133 by niro, Thu Aug 19 09:50:43 2010 UTC
#	Line 1	Line 1
	;; $Id: com32.inc,v 1.1 2007-09-01 22:44:04 niro Exp $
1	;; -----------------------------------------------------------------------	;; -----------------------------------------------------------------------
2	;;	;;
3	;;   Copyright 1994-2003 H. Peter Anvin - All Rights Reserved	;;   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
4	;;	;;
5	;;   This program is free software; you can redistribute it and/or modify	;;   This program is free software; you can redistribute it and/or modify
6	;;   it under the terms of the GNU General Public License as published by	;;   it under the terms of the GNU General Public License as published by
#	Line 27	Line 26
26	; "mov ax,0x4cff; int 0x21" in 16-bit mode.  This will abort the	; "mov ax,0x4cff; int 0x21" in 16-bit mode.  This will abort the
27	; program with an error if run in 16-bit mode.	; program with an error if run in 16-bit mode.
28	;	;
29	pm_idt: equ 0x100000
30	pm_entry: equ 0x101000	; We need to make this a proper section rather
31		; than using absolute numbers, in order to work
32		; around a bug in GNU ld 2.17, which is still in
33		; use as of this writing in the form of Debian
34		; 4.0 (etch).
35		bits 32
36		section .com32 exec write nobits align=16
37		pm_idt equ 0x100000 ; Needs to be absolute...
38		resb 4096
39		pm_entry: ; Needs to not be...
40
41	bits 16	bits 16
42	section .data	section .data
43	align 2, db 0	alignz 2
44	com32_pmidt:	com32_pmidt:
45	dw 8*256 ; Limit	dw 8*256 ; Limit
46	dd pm_idt ; Address	dd pm_idt ; Address
#	Line 44  com32_rmidt:	Line 52  com32_rmidt:
52	section .text	section .text
53	is_com32_image:	is_com32_image:
54	push si ; Save file handle	push si ; Save file handle
55	push dx ; File length held in DX:AX	push eax ; Save file length
	push ax
56
57	call make_plain_cmdline	call make_plain_cmdline
58	; Copy the command line into the low cmdline buffer	; Copy the command line into the low cmdline buffer
#	Line 58  is_com32_image:	Line 65  is_com32_image:
65	sub cx,si	sub cx,si
66	fs rep movsb	fs rep movsb
67
68	call highmemsize ; We need the high memory size...	mov si,KernelCName
69		mov di,Com32Name
70		call strcpy
71
72	call comboot_setup_api ; Set up the COMBOOT-style API	call comboot_setup_api ; Set up the COMBOOT-style API
73
74	mov edi,pm_entry ; Load address	mov edi,pm_entry ; Load address
75	pop eax ; File length	pop eax ; File length
76	pop si ; File handle	pop si ; File handle
77	xor dx,dx ; No padding	xor dx,dx ; No padding
78		mov bx,abort_check ; Don't print dots, but allow abort
79	call load_high	call load_high
	call crlf
80
81	com32_start:	com32_start:
82	mov ebx,com32_call_start ; Where to go in PM	mov ebx,com32_call_start ; Where to go in PM
#	Line 75  com32_enter_pm:	Line 85  com32_enter_pm:
85	cli	cli
86	mov ax,cs	mov ax,cs
87	mov ds,ax	mov ds,ax
88	mov [SavedSSSP],sp	mov [RealModeSSSP],sp
89	mov [SavedSSSP+2],ss	mov [RealModeSSSP+2],ss
90	cld	cld
91	call a20_test	call a20_test
92	jnz .a20ok	jnz .a20ok
93	call enable_a20	call enable_a20
94
95	.a20ok:	.a20ok:
96		mov byte [bcopy_gdt.TSS+5],89h ; Mark TSS unbusy
97
98	lgdt [bcopy_gdt] ; We can use the same GDT just fine	lgdt [bcopy_gdt] ; We can use the same GDT just fine
99	lidt [com32_pmidt] ; Set up the IDT	lidt [com32_pmidt] ; Set up the IDT
100	mov eax,cr0	mov eax,cr0
101	or al,1	or al,1
102	mov cr0,eax ; Enter protected mode	mov cr0,eax ; Enter protected mode
103	jmp 20h:.in_pm	jmp PM_CS32:.in_pm
104
105	bits 32	bits 32
106	.in_pm:	.in_pm:
107	xor eax,eax ; Available for future use...	xor eax,eax ; Available for future use...
108	mov fs,eax	mov fs,eax
109	mov gs,eax	mov gs,eax
110		lldt ax
111
112	mov al,28h ; Set up data segments	mov al,PM_DS32 ; Set up data segments
113	mov es,eax	mov es,eax
114	mov ds,eax	mov ds,eax
115	mov ss,eax	mov ss,eax
116
117		mov al,PM_TSS ; Be nice to Intel's VT by
118		ltr ax ; giving it a valid TR
119
120	mov esp,[PMESP] ; Load protmode %esp if available	mov esp,[PMESP] ; Load protmode %esp if available
121	jmp ebx ; Go to where we need to go	jmp ebx ; Go to where we need to go
122
#	Line 110  com32_enter_pm:	Line 126  com32_enter_pm:
126	;	;
127	com32_call_start:	com32_call_start:
128	;	;
129	; Point the stack to the end of high memory	; Point the stack to the end of (permitted) high memory
130	;	;
131	mov esp,[word HighMemSize]	mov esp,[word HighMemRsvd]
132		xor sp,sp ; Align to a 64K boundary
133
134	;	;
135	; Set up the protmode IDT and the interrupt jump buffers	; Set up the protmode IDT and the interrupt jump buffers
#	Line 159  com32_call_start:	Line 176  com32_call_start:
176
177	; Now everything is set up for interrupts...	; Now everything is set up for interrupts...
178
179		push dword Com32Name ; Module filename
180		push dword [HighMemSize] ; Memory managed by Syslinux
181		push dword com32_cfarcall ; Cfarcall entry point
182	push dword com32_farcall ; Farcall entry point	push dword com32_farcall ; Farcall entry point
183	push dword (1 << 16) ; 64K bounce buffer	push dword (1 << 16) ; 64K bounce buffer
184	push dword (comboot_seg << 4) ; Bounce buffer address	push dword (xfer_buf_seg << 4) ; Bounce buffer address
185	push dword com32_intcall ; Intcall entry point	push dword com32_intcall ; Intcall entry point
186	push dword command_line ; Command line pointer	push dword command_line ; Command line pointer
187	push dword 5 ; Argument count	push dword 8 ; Argument count
188	sti ; Interrupts OK now	sti ; Interrupts OK now
189	call pm_entry ; Run the program...	call pm_entry ; Run the program...
190	; ... on return, fall through to com32_exit ...	; ... on return, fall through to com32_exit ...
#	Line 177  com32_enter_rm:	Line 197  com32_enter_rm:
197	cld	cld
198	mov [PMESP],esp ; Save exit %esp	mov [PMESP],esp ; Save exit %esp
199	xor esp,esp ; Make sure the high bits are zero	xor esp,esp ; Make sure the high bits are zero
200	jmp 08h:.in_pm16 ; Return to 16-bit mode first	jmp PM_CS16:.in_pm16 ; Return to 16-bit mode first
201
202	bits 16	bits 16
203	.in_pm16:	.in_pm16:
204	mov ax,18h ; Real-mode-like segment	mov ax,PM_DS16 ; Real-mode-like segment
205	mov es,ax	mov es,ax
206	mov ds,ax	mov ds,ax
207	mov ss,ax	mov ss,ax
#	Line 200  com32_enter_rm:	Line 220  com32_enter_rm:
220	mov es,ax	mov es,ax
221	mov fs,ax	mov fs,ax
222	mov gs,ax	mov gs,ax
223	lss sp,[SavedSSSP] ; Restore stack	lss sp,[RealModeSSSP] ; Restore stack
224	jmp bx ; Go to whereever we need to go...	jmp bx ; Go to whereever we need to go...
225
226	com32_done:	com32_done:
	call disable_a20
227	sti	sti
228	jmp enter_command	jmp enter_command
229
#	Line 227  com32_int_rm:	Line 246  com32_int_rm:
246	jmp com32_enter_pm ; Go back to PM	jmp com32_enter_pm ; Go back to PM
247
248	;	;
249	; 16-bit system call handling code	; 16-bit intcall/farcall handling code
250	;	;
251	com32_sys_rm:	com32_sys_rm:
252	pop gs	pop gs
#	Line 248  com32_sys_rm:	Line 267  com32_sys_rm:
267	push es	push es
268	push fs	push fs
269	push gs	push gs
270	mov ebx,com32_sys_resume	mov ebx,com32_syscall.resume
271		jmp com32_enter_pm
272
273		;
274		; 16-bit cfarcall handing code
275		;
276		com32_cfar_rm:
277		retf
278		.return:
279		mov sp,[cs:Com32SysSP]
280		mov [cs:RealModeEAX],eax
281		mov ebx,com32_cfarcall.resume
282	jmp com32_enter_pm	jmp com32_enter_pm
283
284	;	;
#	Line 303  com32_intcall:	Line 333  com32_intcall:
333	com32_syscall:	com32_syscall:
334	cld	cld
335
336	movzx edi,word [word SavedSSSP]	movzx edi,word [word RealModeSSSP]
337	movzx ebx,word [word SavedSSSP+2]	movzx ebx,word [word RealModeSSSP+2]
338	sub edi,54 ; Allocate 54 bytes	sub edi,54 ; Allocate 54 bytes
339	mov [word SavedSSSP],di	mov [word RealModeSSSP],di
340	shl ebx,4	shl ebx,4
341	add edi,ebx ; Create linear address	add edi,ebx ; Create linear address
342
#	Line 330  com32_syscall:	Line 360  com32_syscall:
360	; On return, the 44-byte return structure is on the	; On return, the 44-byte return structure is on the
361	; real-mode stack, plus the 10 additional bytes used	; real-mode stack, plus the 10 additional bytes used
362	; by the target address (see above.)	; by the target address (see above.)
363	com32_sys_resume:	.resume:
364	movzx esi,word [word SavedSSSP]	movzx esi,word [word RealModeSSSP]
365	movzx eax,word [word SavedSSSP+2]	movzx eax,word [word RealModeSSSP+2]
366	mov edi,[esp+12*4] ; Dest regs	mov edi,[esp+12*4] ; Dest regs
367	shl eax,4	shl eax,4
368	add esi,eax ; Create linear address	add esi,eax ; Create linear address
#	Line 343  com32_sys_resume:	Line 373  com32_sys_resume:
373	mov cl,11 ; 44 bytes	mov cl,11 ; 44 bytes
374	rep movsd ; Copy register block	rep movsd ; Copy register block
375
376	add dword [word SavedSSSP],54 ; Remove from stack	add dword [word RealModeSSSP],54 ; Remove from stack
377
378	popad	popad
379	popfd	popfd
380	ret ; Return to 32-bit program	ret ; Return to 32-bit program
381
382		;
383		; Cfarcall invocation.  We copy the stack frame to the real-mode stack,
384		; followed by the return CS:IP and the CS:IP of the target function.
385		;
386		com32_cfarcall:
387		pushfd
388		pushad
389
390		cld
391		mov ecx,[esp+12*4] ; Size of stack frame
392
393		movzx edi,word [word RealModeSSSP]
394		movzx ebx,word [word RealModeSSSP+2]
395		mov [word Com32SysSP],di
396		sub edi,ecx ; Allocate space for stack frame
397		and edi,~3 ; Round
398		sub edi,4*2 ; Return pointer, return value
399		mov [word RealModeSSSP],di
400		shl ebx,4
401		add edi,ebx ; Create linear address
402
403		mov eax,[esp+10*4] ; CS:IP
404		stosd ; Save to stack frame
405		mov eax,com32_cfar_rm.return ; Return seg:off
406		stosd
407		mov esi,[esp+11*4] ; Stack frame
408		mov eax,ecx ; Copy the stack frame
409		shr ecx,2
410		rep movsd
411		mov ecx,eax
412		and ecx,3
413		rep movsb
414
415		mov bx,com32_cfar_rm
416		jmp com32_enter_rm
417
418		.resume:
419		popad
420		mov eax,[word RealModeEAX]
421		popfd
422		ret
423
424	bits 16	bits 16
425
426	section .bss	section .bss1
427	alignb 4	alignb 4
428		RealModeSSSP resd 1 ; Real-mode SS:SP
429		RealModeEAX resd 1 ; Real mode EAX
430	PMESP resd 1 ; Protected-mode ESP	PMESP resd 1 ; Protected-mode ESP
431	Com32SysSP resw 1 ; SP saved during COM32 syscall	Com32SysSP resw 1 ; SP saved during COM32 syscall
432
433		section .uibss
434		%if IS_SYSLINUX
435		Com32Name resb FILENAME_MAX+2
436		%else
437		Com32Name resb FILENAME_MAX
438		%endif
439
440	section .text	section .text

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