diff options
Diffstat (limited to 'src/arch/x86/init/entry.S')
| -rw-r--r-- | src/arch/x86/init/entry.S | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/arch/x86/init/entry.S b/src/arch/x86/init/entry.S new file mode 100644 index 0000000000..af29296403 --- /dev/null +++ b/src/arch/x86/init/entry.S @@ -0,0 +1,149 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 1999 Ronald G. Minnich + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include <arch/rom_segs.h> + .code16 + .globl _stage0 +_stage0: + cli + + /* Save the BIST result. */ + movl %eax, %ebp; + + /* thanks to kmliu@sis.com.tw for this TLB fix */ + /* IMMEDIATELY invalidate the translation lookaside buffer (TLB) before + * executing any further code. Even though paging is disabled we + * could still get false address translations due to the TLB if we + * didn't invalidate it. + */ + xorl %eax, %eax + movl %eax, %cr3 /* Invalidate TLB. */ + + /* Switch to protected mode. */ + + /* NOTE: With GNU assembler version 2.15.94.0.2.2 (i386-redhat-linux) + * using BFD version 2.15.94.0.2.2 20041220 this works fine without all + * the ld hackery and other things. So leave it as is with this comment. + */ + + data32 lgdt %cs:gdtptr + + movl %cr0, %eax + andl $0x7FFAFFD1, %eax /* PG, AM, WP, NE, TS, EM, MP = 0 */ + orl $0x60000001, %eax /* CD, NW, PE = 1 */ + movl %eax, %cr0 + + /* Restore BIST result. */ + movl %ebp, %eax + + // port80_post(0x23) + /* Now we are in protected mode. Jump to a 32 bit code segment. */ + data32 ljmp $ROM_CODE_SEG, $protected_stage0 + + /* I am leaving this weird jump in here in the event that future gas + * bugs force it to be used. + */ + /* .byte 0x66 */ + .code32 + /* ljmp $ROM_CODE_SEG, $protected_stage0 */ + + /* .code16 */ + .align 4 + .globl gdt16 +gdt16 = . - _stage0 +gdt16x: + .word gdt16xend - gdt16x -1 /* Compute the table limit. */ + .long gdt16x + .word 0 + + /* selgdt 0x08, flat code segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xcf, 0x00 + + /* selgdt 0x10, flat data segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x93, 0xcf, 0x00 +gdt16xend: + + /* From now on we are 32 bit. */ + .code32 + + /* We have two gdts where we could have one. That is ok. + * + * Let's not worry about this -- optimizing gdt is pointless since + * we're only in it for a little bit. + * + * Btw. note the trick below: The GDT points to ITSELF, and the first + * good descriptor is at offset 8. So you word-align the table, and + * then because you chose 8, you get a nice 64-bit aligned GDT entry, + * which is good as this is the size of the entry. + * Just in case you ever wonder why people do this. + */ + .align 4 + .globl gdtptr + .globl gdt_limit +gdt_limit = gdt_end - gdt - 1 /* Compute the table limit. */ + +gdt: +gdtptr: + .word gdt_end - gdt -1 /* Compute the table limit. */ + .long gdt /* We know the offset. */ + .word 0 + + /* selgdt 0x08, flat code segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xcf, 0x00 + + /* selgdt 0x10, flat data segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x93, 0xcf, 0x00 + +gdt_end: + +/* Reset vector. */ + +/* + * RVECTOR: Size of reset vector, default is 0x10. + * RESRVED: Size of vpd code, default is 0xf0. + * BOOTBLK: Size of bootblock code, default is 0x1f00 (8k-256b). + */ + +SEGMENT_SIZE = 0x10000 +RVECTOR = 0x00010 + +/* Due to YET ANOTHER BUG in GNU bintools, you can NOT have a code16 here. + * I think we should leave it this way forever, as the bugs come and + * go -- and come again. + * + * .code16 + * .section ".rom.text" + */ +.section ".reset", "ax" + .globl _resetjump +_resetjump: + /* GNU bintools bugs again. This jumps to stage0 - 2. Sigh. */ + /* jmp _stage0 */ + .byte 0xe9 + .int _stage0 - ( . + 2 ) + + /* Note: The above jump is hand coded to work around bugs in binutils. + * 5 bytes are used for a 3 byte instruction. This works because x86 + * is little endian and allows us to use supported 32 bit relocations + * instead of the weird 16 bit relocations that binutils does not + * handle consistenly between versions because they are used so rarely. + */ |