Annotation of sys/arch/i386/stand/libsa/pxe_call.S, Revision 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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