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1.1 root 1: /*
2: * Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
3: *
4: * Mach Operating System
5: * Copyright (c) 1992, 1991 Carnegie Mellon University
6: * All Rights Reserved.
7: *
8: * Permission to use, copy, modify and distribute this software and its
9: * documentation is hereby granted, provided that both the copyright
10: * notice and this permission notice appear in all copies of the
11: * software, derivative works or modified versions, and any portions
12: * thereof, and that both notices appear in supporting documentation.
13: *
14: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
15: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
16: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17: *
18: * Carnegie Mellon requests users of this software to return to
19: *
20: * Software Distribution Coordinator or [email protected]
21: * School of Computer Science
22: * Carnegie Mellon University
23: * Pittsburgh PA 15213-3890
24: *
25: * any improvements or extensions that they make and grant Carnegie Mellon
26: * the rights to redistribute these changes.
27: */
28:
29: /*
30: * HISTORY
1.1.1.2 ! root 31: * asm.S,v
! 32: Revision 1.2 1993/07/11 12:02:19 andrew
! 33: Fixes from bde, including support for loading @ any MB boundary (e.g. a
! 34: kernel linked for 0xfe100000 will load at the 1MB mark) and read-ahead
! 35: buffering to speed booting from floppies. Also works with aha174x
! 36: controllers in enhanced mode.
! 37:
! 38: *
! 39: * 93/06/28 bde
! 40: * Switch IDT for debugger.
! 41: *
! 42: * Change all addr16's to addr32's and all data16's to data32's.
! 43: *
! 44: * 93/06/26 bde
! 45: * Avoid "pushw $xreal". Gas botches it even for 32-bit mode.
1.1 root 46: *
1.1.1.2 ! root 47: Revision 1.1 1993/03/21 18:08:21 cgd
! 48: after 0.2.2 "stable" patches applied
! 49:
1.1 root 50: * Revision 2.2 92/04/04 11:34:13 rpd
51: * Fix Intel Copyright as per B. Davies authorization.
52: * [92/04/03 rvb]
53: * From 2.5 boot: pruned inb(), outb(), and pzero().
54: * [92/03/30 rvb]
55: *
56: * Revision 2.2 91/04/02 14:35:10 mbj
57: * Added _sp() => where is the stack at. [kupfer]
58: * Add Intel copyright
59: * [90/02/09 rvb]
60: *
61: */
62:
63: /*
64: Copyright 1988, 1989, 1990, 1991, 1992
65: by Intel Corporation, Santa Clara, California.
66:
67: All Rights Reserved
68:
69: Permission to use, copy, modify, and distribute this software and
70: its documentation for any purpose and without fee is hereby
71: granted, provided that the above copyright notice appears in all
72: copies and that both the copyright notice and this permission notice
73: appear in supporting documentation, and that the name of Intel
74: not be used in advertising or publicity pertaining to distribution
75: of the software without specific, written prior permission.
76:
77: INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
78: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
79: IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
80: CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
81: LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
82: NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
83: WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
84: */
85:
86: .file "asm.s"
87:
88: #include "asm.h"
89:
90:
91: CR0_PE_ON = 0x1
92: CR0_PE_OFF = 0xfffffffe
93:
94: .globl _ouraddr
95: .text
96:
97: /*
98: #
99: # real_to_prot()
100: # transfer from real mode to protected mode.
101: */
102:
103: ENTRY(real_to_prot)
104: # guarantee that interrupt is disabled when in prot mode
105: cli
106:
107: # load the gdtr
1.1.1.2 ! root 108: addr32
1.1 root 109: data32
110: lgdt EXT(Gdtr)
111:
112: # set the PE bit of CR0
113: mov %cr0, %eax
114:
115: data32
116: or $CR0_PE_ON, %eax
117: mov %eax, %cr0
118:
119: # make intrasegment jump to flush the processor pipeline and
120: # reload CS register
121: data32
122: ljmp $0x18, $xprot
123:
124: xprot:
125: # we are in USE32 mode now
1.1.1.2 ! root 126: # set up the protected mode segment registers : DS, SS, ES
1.1 root 127: mov $0x20, %eax
128: movw %ax, %ds
129: movw %ax, %ss
130: movw %ax, %es
131:
1.1.1.2 ! root 132: # load idtr so we can debug
! 133: lidt EXT(Idtr_prot)
! 134:
1.1 root 135: ret
136:
137: /*
138: #
139: # prot_to_real()
140: # transfer from protected mode to real mode
141: #
142: */
143:
144: ENTRY(prot_to_real)
145:
146: # set up a dummy stack frame for the second seg change.
147: movl _ouraddr, %eax
148: sarl $4, %eax
149: pushw %ax
1.1.1.2 ! root 150: movw $xreal, %ax # gas botches pushw $xreal - extra bytes 0, 0
! 151: pushw %ax # decode to add %al, (%eax) (%al usually 0)
1.1 root 152:
153: # Change to use16 mode.
154: ljmp $0x28, $x16
155:
156: x16:
157: # clear the PE bit of CR0
158: mov %cr0, %eax
159: data32
160: and $CR0_PE_OFF, %eax
161: mov %eax, %cr0
162:
163: # make intersegment jmp to flush the processor pipeline
164: # using the fake stack frame set up earlier
165: # and reload CS register
166: lret
167:
168: xreal:
169: # we are in real mode now
170: # set up the real mode segment registers : DS, SS, ES
171: movw %cs, %ax
172: movw %ax, %ds
173: movw %ax, %ss
174: movw %ax, %es
175:
1.1.1.2 ! root 176: # load idtr so we can debug
! 177: addr32
! 178: data32
! 179: lidt EXT(Idtr_real)
! 180:
1.1 root 181: data32
182: ret
183:
184: /*
185: #
186: # startprog(phyaddr)
187: # start the program on protected mode where phyaddr is the entry point
188: #
189: */
190:
191: ENTRY(startprog)
192: push %ebp
193: mov %esp, %ebp
194:
195: # get things we need into registers
196: movl 0x8(%ebp), %ecx # entry offset
197: movl 0x0c(%ebp), %eax # &argv
198:
199: # make a new stack at 0:0xa0000 (big segs)
200: mov $0x10, %ebx
201: movw %bx, %ss
1.1.1.2 ! root 202: movl $0xa0000, %ebx
! 203: movl %ebx, %esp
1.1 root 204:
205: # push some number of args onto the stack
206: pushl $0 # nominally a cyl offset in the boot.
207: pushl 0x8(%eax) # argv[2] = bootdev
208: pushl 0x4(%eax) # argv[1] = howto
209: pushl $0 # dummy 'return' address
210:
211: # push on our entry address
212: mov $0x08, %ebx # segment
213: pushl %ebx
214: pushl %ecx
215:
216: # convert over the other data segs
217: mov $0x10, %ebx
218: movw %bx, %ds
219: movw %bx, %es
220:
221: # convert the PC (and code seg)
222: lret
223: /*
224: #
225: # pbzero( dst, cnt)
226: # where src is a virtual address and dst is a physical address
227: */
228:
229: ENTRY(pbzero)
230: push %ebp
231: mov %esp, %ebp
232: push %es
233: push %esi
234: push %edi
235: push %ecx
236:
237: cld
238:
239: # set %es to point at the flat segment
240: mov $0x10, %eax
241: movw %ax, %es
242:
243: mov 0x8(%ebp), %edi # destination
244: mov 0xc(%ebp), %ecx # count
1.1.1.2 ! root 245: mov $0x0, %eax # value
1.1 root 246:
247: rep
248: stosb
249:
250: pop %ecx
251: pop %edi
252: pop %esi
253: pop %es
254: pop %ebp
255:
256: ret
257: /*
258: #
259: # pcpy(src, dst, cnt)
260: # where src is a virtual address and dst is a physical address
261: #
262: */
263:
264: ENTRY(pcpy)
265: push %ebp
266: mov %esp, %ebp
267: push %es
268: push %esi
269: push %edi
270: push %ecx
271:
272: cld
273:
274: # set %es to point at the flat segment
275: mov $0x10, %eax
276: movw %ax, %es
277:
278: mov 0x8(%ebp), %esi # source
279: mov 0xc(%ebp), %edi # destination
280: mov 0x10(%ebp), %ecx # count
281:
282: rep
283: movsb
284:
285: pop %ecx
286: pop %edi
287: pop %esi
288: pop %es
289: pop %ebp
290:
291: ret
292:
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