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/*
* PVH Option ROM
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*
* Copyright Novell Inc, 2009
* Authors: Alexander Graf <agraf@suse.de>
*
* Copyright (c) 2019 Red Hat Inc.
* Authors: Stefano Garzarella <sgarzare@redhat.com>
*/
#include "optionrom.h"
#define BOOT_ROM_PRODUCT "PVH loader"
#define GS_PROT_JUMP 0
#define GS_GDT_DESC 6
#ifdef OPTION_ROM_START
#undef OPTION_ROM_START
#endif
#ifdef OPTION_ROM_END
#undef OPTION_ROM_END
#endif
/*
* Redefine OPTION_ROM_START and OPTION_ROM_END, because this rom is produced
* linking multiple objects.
* signrom.py will add padding.
*/
#define OPTION_ROM_START \
.code16; \
.text; \
.global _start; \
_start:; \
.short 0xaa55; \
.byte 3; /* desired size in 512 units */
#define OPTION_ROM_END \
_end:
BOOT_ROM_START
run_pvhboot:
cli
cld
mov %cs, %eax
shl $0x4, %eax
/* set up a long jump descriptor that is PC relative */
/* move stack memory to %gs */
mov %ss, %ecx
shl $0x4, %ecx
mov %esp, %ebx
add %ebx, %ecx
sub $0x20, %ecx
sub $0x30, %esp
shr $0x4, %ecx
mov %cx, %gs
/* now push the indirect jump descriptor there */
mov (prot_jump), %ebx
add %eax, %ebx
movl %ebx, %gs:GS_PROT_JUMP
mov $8, %bx
movw %bx, %gs:GS_PROT_JUMP + 4
/* fix the gdt descriptor to be PC relative */
movw (gdt_desc), %bx
movw %bx, %gs:GS_GDT_DESC
movl (gdt_desc+2), %ebx
add %eax, %ebx
movl %ebx, %gs:GS_GDT_DESC + 2
/* initialize HVM memmap table using int 0x15(e820) */
/* ES = pvh_e820 struct */
mov $pvh_e820, %eax
shr $4, %eax
mov %ax, %es
/* start storing memmap table at %es:8 (pvh_e820.table) */
mov $8,%edi
xor %ebx, %ebx
jmp memmap_loop
memmap_loop_check:
/* pvh_e820 can contains up to 128 entries */
cmp $128, %ebx
je memmap_done
memmap_loop:
/* entry size (hvm_memmap_table_entry) & max buffer size (int15) */
movl $24, %ecx
/* e820 */
movl $0x0000e820, %eax
/* 'SMAP' magic */
movl $0x534d4150, %edx
/* store counter value at %es:0 (pvh_e820.entries) */
movl %ebx, %es:0
int $0x15
/* error or last entry already done? */
jb memmap_err
/* %edi += entry size (hvm_memmap_table_entry) */
add $24, %edi
/* continuation value 0 means last entry */
test %ebx, %ebx
jnz memmap_loop_check
/* increase pvh_e820.entries to save the last entry */
movl %es:0, %ebx
inc %ebx
memmap_done:
movl %ebx, %es:0
memmap_err:
/* load the GDT before going into protected mode */
lgdt:
data32 lgdt %gs:GS_GDT_DESC
/* get us to protected mode now */
movl $1, %eax
movl %eax, %cr0
/* the LJMP sets CS for us and gets us to 32-bit */
ljmp:
data32 ljmp *%gs:GS_PROT_JUMP
prot_mode:
.code32
/* initialize all other segments */
movl $0x10, %eax
movl %eax, %ss
movl %eax, %ds
movl %eax, %es
movl %eax, %fs
movl %eax, %gs
jmp pvh_load_kernel
/* Variables */
.align 4, 0
prot_jump: .long prot_mode
.short 8
.align 4, 0
gdt:
/* 0x00 */
.byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
/*
* 0x08: code segment
* (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k)
*/
.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
/*
* 0x10: data segment
* (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k)
*/
.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
/*
* 0x18: code segment
* (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b)
*/
.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00
/*
* 0x20: data segment
* (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b)
*/
.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00
gdt_desc:
.short (5 * 8) - 1
.long gdt
BOOT_ROM_END
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