390fb6b471
When the BIOS returns ebx = 0, the current entry is still valid and needs to be included in the Multiboot memory map. Fixing this meant that using bx as the entry index doesn't work any more because it's 0 on the last entry (and it was SeaBIOS-specific anyway), so the whole loop had to change a bit and should be more generic as a result (ebx can be an arbitrary continuation number now, and the entry size returned by the BIOS is used instead of hard-coding 20 bytes). Signed-off-by: Kevin Wolf <mail@kevin-wolf.de> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> Message-id: 1372018066-21822-2-git-send-email-mail@kevin-wolf.de Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
193 lines
4.2 KiB
ArmAsm
193 lines
4.2 KiB
ArmAsm
/*
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* Multiboot Option ROM
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright Novell Inc, 2009
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* Authors: Alexander Graf <agraf@suse.de>
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*/
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#include "optionrom.h"
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#define BOOT_ROM_PRODUCT "multiboot loader"
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#define MULTIBOOT_MAGIC 0x2badb002
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#define GS_PROT_JUMP 0
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#define GS_GDT_DESC 6
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BOOT_ROM_START
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run_multiboot:
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cli
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cld
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mov %cs, %eax
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shl $0x4, %eax
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/* set up a long jump descriptor that is PC relative */
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/* move stack memory to %gs */
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mov %ss, %ecx
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shl $0x4, %ecx
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mov %esp, %ebx
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add %ebx, %ecx
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sub $0x20, %ecx
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sub $0x30, %esp
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shr $0x4, %ecx
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mov %cx, %gs
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/* now push the indirect jump descriptor there */
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mov (prot_jump), %ebx
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add %eax, %ebx
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movl %ebx, %gs:GS_PROT_JUMP
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mov $8, %bx
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movw %bx, %gs:GS_PROT_JUMP + 4
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/* fix the gdt descriptor to be PC relative */
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movw (gdt_desc), %bx
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movw %bx, %gs:GS_GDT_DESC
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movl (gdt_desc+2), %ebx
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add %eax, %ebx
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movl %ebx, %gs:GS_GDT_DESC + 2
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xor %eax, %eax
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mov %eax, %es
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/* Read the bootinfo struct into RAM */
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read_fw_blob(FW_CFG_INITRD)
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/* FS = bootinfo_struct */
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read_fw FW_CFG_INITRD_ADDR
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shr $4, %eax
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mov %ax, %fs
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/* Account for the EBDA in the multiboot structure's e801
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* map.
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*/
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int $0x12
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cwtl
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movl %eax, %fs:4
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/* ES = mmap_addr */
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mov %fs:48, %eax
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shr $4, %eax
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mov %ax, %es
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/* Initialize multiboot mmap structs using int 0x15(e820) */
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xor %ebx, %ebx
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/* Start storing mmap data at %es:0 */
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xor %edi, %edi
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mmap_loop:
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/* The multiboot entry size has offset -4, so leave some space */
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add $4, %di
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/* entry size (mmap struct) & max buffer size (int15) */
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movl $20, %ecx
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/* e820 */
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movl $0x0000e820, %eax
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/* 'SMAP' magic */
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movl $0x534d4150, %edx
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int $0x15
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mmap_check_entry:
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/* Error or last entry already done? */
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jb mmap_done
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mmap_store_entry:
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/* store entry size */
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/* old as(1) doesn't like this insn so emit the bytes instead:
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movl %ecx, %es:-4(%edi)
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*/
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.dc.b 0x26,0x67,0x66,0x89,0x4f,0xfc
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/* %edi += entry_size, store as mbs_mmap_length */
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add %ecx, %edi
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movw %di, %fs:0x2c
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/* Continuation value 0 means last entry */
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test %ebx, %ebx
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jnz mmap_loop
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mmap_done:
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real_to_prot:
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/* Load the GDT before going into protected mode */
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lgdt:
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data32 lgdt %gs:GS_GDT_DESC
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/* get us to protected mode now */
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movl $1, %eax
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movl %eax, %cr0
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/* the LJMP sets CS for us and gets us to 32-bit */
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ljmp:
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data32 ljmp *%gs:GS_PROT_JUMP
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prot_mode:
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.code32
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/* initialize all other segments */
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movl $0x10, %eax
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movl %eax, %ss
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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/* Read the kernel and modules into RAM */
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read_fw_blob(FW_CFG_KERNEL)
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/* Jump off to the kernel */
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read_fw FW_CFG_KERNEL_ENTRY
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mov %eax, %ecx
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/* EBX contains a pointer to the bootinfo struct */
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read_fw FW_CFG_INITRD_ADDR
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movl %eax, %ebx
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/* EAX has to contain the magic */
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movl $MULTIBOOT_MAGIC, %eax
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ljmp2:
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jmp *%ecx
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/* Variables */
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.align 4, 0
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prot_jump: .long prot_mode
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.short 8
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.align 4, 0
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gdt:
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/* 0x00 */
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.byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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/* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
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/* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
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/* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00
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/* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00
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gdt_desc:
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.short (5 * 8) - 1
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.long gdt
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BOOT_ROM_END
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