0316e1a69f
Add the code necessary to create the linux trampoline blob. Don't enforce this for the in-coreboot build or use objcopy to produce linux_trampoline.o as it is a bit trickier to get all the details right than I had hoped: - you have to know the elf architecture of the host machine - you might have to have more tools (xxd, perl, etc) installed Change-Id: I9b7877c58d90f9fb21d16e0061a31e19fffa2470 Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org> Reviewed-on: https://review.coreboot.org/12505 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com>
134 lines
2.9 KiB
ArmAsm
134 lines
2.9 KiB
ArmAsm
/*
|
|
* linux_trampoline
|
|
*
|
|
* Copyright (C) 2013 Patrick Georgi <patrick@georgi-clan.de>
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
/* NOTE: THIS CODE MUST REMAIN POSITION INDEPENDENT
|
|
* IT SHOULDN'T USE THE STACK
|
|
* AND IN GENERAL EXPECT NOTHING BUT RAM TO WORK
|
|
*/
|
|
.code32
|
|
.data
|
|
|
|
#include "linux_trampoline.h"
|
|
#define HEADER_SIG 0x4f49424c // LBIO little endian
|
|
#define CB_TAG_FORWARD 0x11
|
|
#define CB_TAG_MEMORY 0x1
|
|
#define CB_TAG_FRAMEBUFFER 0x12
|
|
|
|
#define E820_NR_OFFSET 0x1e8
|
|
#define LINUX_ENTRY_OFFSET 0x214
|
|
#define E820_OFFSET 0x2d0
|
|
|
|
.trampoline_start:
|
|
|
|
cld
|
|
xor %edx, %edx
|
|
mov $0, %ecx
|
|
|
|
.headerSearch:
|
|
mov $0x10000, %ebx
|
|
add %ecx, %ebx
|
|
mov (%ecx), %eax
|
|
cmp $HEADER_SIG, %eax
|
|
je .headerSearchDone // found the header
|
|
add $16, %ecx
|
|
cmp %ecx, %ebx
|
|
jne .headerSearch
|
|
|
|
.headerSearchDone:
|
|
cmp %ecx, %ebx // reached the end == not found anything?
|
|
je 2f // give up
|
|
|
|
// we assume the checksum is okay, no test
|
|
mov 4(%ecx), %ebx
|
|
add %ecx, %ebx // ebx = cb_header + header_bytes
|
|
mov 20(%ecx), %ecx // ecx = table_entries
|
|
|
|
.tableScan:
|
|
cmp $CB_TAG_FORWARD, (%ebx)
|
|
jne .testMemory
|
|
|
|
/* forward tag: assume 32bit pointer */
|
|
mov 8(%ebx), %ecx
|
|
jmp .headerSearch
|
|
|
|
.testMemory:
|
|
cmp $CB_TAG_MEMORY, (%ebx)
|
|
jne .testFramebuffer
|
|
|
|
/* memory tag: copy e820 map and entry count. also determine alt_mem_k */
|
|
mov 4(%ebx), %eax
|
|
sub $8, %eax
|
|
shr $2, %eax /* eax = number of dwords of e820 data */
|
|
cmp $(32 * 5), %eax /* linux wants at most 32 entries of 5 dwords */
|
|
jng 1f
|
|
mov $(32 * 5), %eax /* only copy 32 entries */
|
|
1:
|
|
mov %eax, %esi
|
|
mov $5, %edi
|
|
div %edi
|
|
mov %eax, (LINUX_PARAM_LOC + E820_NR_OFFSET)
|
|
mov %esi, %eax
|
|
xchg %eax, %ecx
|
|
lea 8(%ebx), %esi /* e820 data source */
|
|
mov $(LINUX_PARAM_LOC + E820_OFFSET), %edi
|
|
rep movsl
|
|
xchg %eax, %ecx
|
|
jmp .endScan
|
|
|
|
.testFramebuffer:
|
|
cmp $CB_TAG_FRAMEBUFFER, (%ebx)
|
|
jne .endScan
|
|
/* TODO: handle framebuffer tag */
|
|
|
|
.endScan:
|
|
add 4(%ebx), %ebx
|
|
dec %ecx
|
|
jnz .tableScan
|
|
|
|
/* Setup basic code and data segment selectors for Linux
|
|
**
|
|
** Flat code segment descriptor:
|
|
** selector: 0x10
|
|
** base : 0x00000000
|
|
** limit : 0xFFFFFFFF
|
|
** type : code, execute, read
|
|
**
|
|
** Flat data segment descriptor:
|
|
** selector: 0x18
|
|
** base : 0x00000000
|
|
** limit : 0xFFFFFFFF
|
|
** type : data, read/write
|
|
**
|
|
** Use TRAMPOLINE_ENTRY_LOC as a scratchpad.
|
|
*/
|
|
mov $TRAMPOLINE_ENTRY_LOC, %eax
|
|
sgdt (%eax)
|
|
mov 2(%eax), %ebx
|
|
movl $0x0000ffff, 16(%ebx)
|
|
movl $0x00cf9b00, 20(%ebx)
|
|
movl $0x0000ffff, 24(%ebx)
|
|
movl $0x00cf9300, 28(%ebx)
|
|
|
|
/* finally: jump to kernel */
|
|
mov $LINUX_PARAM_LOC, %esi
|
|
jmp *(LINUX_PARAM_LOC + LINUX_ENTRY_OFFSET)
|
|
|
|
|
|
2:
|
|
hlt
|
|
jmp 2b
|
|
|
|
.trampoline_end:
|