Annotation of sys/arch/amd64/stand/libsa/pxe_call.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: pxe_call.S,v 1.4 2006/01/02 00:26:29 tom Exp $ */
2: /* $NetBSD: pxe_call.S,v 1.2 2002/03/27 17:24:22 kanaoka Exp $ */
3:
4: /*
5: * Copyright 2001 Wasabi Systems, Inc.
6: * All rights reserved.
7: *
8: * Written by Jason R. Thorpe for Wasabi Systems, Inc.
9: *
10: * Redistribution and use in source and binary forms, with or without
11: * modification, are permitted provided that the following conditions
12: * are met:
13: * 1. Redistributions of source code must retain the above copyright
14: * notice, this list of conditions and the following disclaimer.
15: * 2. Redistributions in binary form must reproduce the above copyright
16: * notice, this list of conditions and the following disclaimer in the
17: * documentation and/or other materials provided with the distribution.
18: * 3. All advertising materials mentioning features or use of this software
19: * must display the following acknowledgement:
20: * This product includes software developed for the NetBSD Project by
21: * Wasabi Systems, Inc.
22: * 4. The name of Wasabi Systems, Inc. may not be used to endorse
23: * or promote products derived from this software without specific prior
24: * written permission.
25: *
26: * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28: * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29: * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
30: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36: * POSSIBILITY OF SUCH DAMAGE.
37: */
38:
39: /*
40: * Low level PXE BIOS call glue.
41: */
42:
43: #include <machine/asm.h>
44: #include <assym.h>
45:
46: #include "gidt.h"
47:
48: ENTRY(pxecall_bangpxe)
49: .code32
50: pushl %ebp
51: movl %esp, %ebp
52: pushl %ebx
53: pushl %ecx
54: pushl %edx
55:
56: /* For simplicity, just move all 32 bits. */
57: movl 8(%ebp), %ebx
58:
59: pushw _C_LABEL(pxe_command_buf_seg)
60: pushw _C_LABEL(pxe_command_buf_off)
61: pushw %bx
62:
63: call prot_to_real /* Enter real mode */
64: .code16
65:
66: sti
67: /* The encoding is: 0x9a offlo offhi seglo seghi */
68: lcall $0, $0xffff
69: .globl _C_LABEL(bangpxe_off)
70: _C_LABEL(bangpxe_off) = . - 4
71: .globl _C_LABEL(bangpxe_seg)
72: _C_LABEL(bangpxe_seg) = . - 2
73:
74: cli
75: call real_to_prot /* Leave real mode */
76: .code32
77:
78: add $6, %esp
79:
80: popl %edx
81: popl %ecx
82: popl %ebx
83: popl %ebp
84: ret
85:
86: ENTRY(pxecall_pxenv)
87: .code32
88: pushl %ebp
89: movl %esp, %ebp
90: pushl %ebx
91: pushl %ecx
92: pushl %edx
93: pushl %edi
94:
95: /*
96: * Using the PXENV+ calling convention, the (16 bit) function
97: * number is passed in %bx, with the address of the command
98: * buffer in %es:%di.
99: */
100: movl 8(%ebp), %ebx /* For simplicity, just move all 32 bits. */
101:
102: /*
103: * prot_to_real() will set %es to BOOTSEG, so we just need to set
104: * %(e)di up here. Remember to relocate it!
105: */
106: movl $_C_LABEL(pxe_command_buf), %edi
107: subl $LINKADDR, %edi
108:
109: call prot_to_real /* Enter real mode */
110: .code16
111:
112: /* The encoding is: 0x9a offlo offhi seglo seghi */
113: lcall $0, $0xffff
114: .globl _C_LABEL(pxenv_off)
115: _C_LABEL(pxenv_off) = . - 4
116: .globl _C_LABEL(pxenv_seg)
117: _C_LABEL(pxenv_seg) = . - 2
118:
119: call real_to_prot /* Leave real mode */
120: .code32
121:
122: popl %edi
123: popl %edx
124: popl %ecx
125: popl %ebx
126: popl %ebp
127: ret
128:
129: /*
130: * prot_to_real()
131: *
132: * Switch the processor back into real mode.
133: */
134: .globl prot_to_real
135: prot_to_real:
136: .code32
137: ljmp $S16TEXT, $p2r16 - LINKADDR
138: p2r16:
139: .code16
140:
141: movw $S16DATA, %ax
142: movw %ax, %ds
143: movw %ax, %es
144:
145: movl %cr0, %eax /* Disable protected mode */
146: andl $~CR0_PE, %eax
147: movl %eax, %cr0
148:
149: /* reload real cs:ip */
150: data32 ljmp $(LINKADDR >> 4), $p2r16real - LINKADDR
151: p2r16real:
152: xorw %ax, %ax /* Reset segment registers: */
153: movw %ax, %ss /* %ss: for our stack */
154:
155: movw $LINKADDR >> 4, %ax /* We're linked to LINKADDR/16:0000 */
156: movw %ax, %ds /* %ds: so we can get at Idtr_real */
157:
158: .extern Idtr_real
159: data32 addr32 lidt (Idtr_real - LINKADDR); /* Set up IDT for real mode */
160:
161: movw %cs, %ax
162: movw %ax, %ds
163: movw %ax, %es /* Set %ds = %es = %cs */
164:
165: /*
166: * We were called from 32-bit mode, so there's a 32-bit
167: * return address on the stack. No segment. This is within
168: * the flat memory model, so we need to adjust it back so
169: * that it's relative to our 16-bit %cs.
170: */
171: popl %eax
172: subl $LINKADDR, %eax
173: pushw %ax
174: ret
175:
176: /*
177: * real_to_prot()
178: *
179: * Switch the processor back into protected mode.
180: */
181: .globl real_to_prot
182: real_to_prot:
183: .code16
184:
185: movw $LINKADDR >> 4, %ax /* We're linked to LINKADDR/16:0000 */
186: movw %ax, %ds
187: data32 addr32 lgdt (Gdtr - LINKADDR) /* Reload the GDT */
188:
189: movl %cr0, %eax /* Enable protected mode */
190: orl $CR0_PE, %eax
191: movl %eax, %cr0
192:
193: data32 ljmp $S32TEXT, $r2p32 /* Reload %cs, flush pipeline */
194: r2p32:
195: .code32
196: /* Reload 32-bit %ds, %ss, %es */
197: movl $S32DATA, %eax
198: mov %ax, %ds
199: mov %ax, %ss
200: mov %ax, %es
201:
202: /* Load IDT for debugger and DOS/BIOS interface */
203: .extern Idtr
204: lidt Idtr
205:
206: xorl %eax, %eax
207: popw %ax /* 16-bit return addr on stack */
208: addl $LINKADDR, %eax
209: pushl %eax /* Now have correct 32-bit ret addr */
210: ret
211:
212: .end
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