284 lines
6.2 KiB
ArmAsm
Executable file
284 lines
6.2 KiB
ArmAsm
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* linux/boot/head.S
|
|
*
|
|
* Copyright (C) 1991, 1992, 1993 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* head.S contains the 32-bit startup code.
|
|
*
|
|
* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
|
|
* the page directory will exist. The startup code will be overwritten by
|
|
* the page directory. [According to comments etc elsewhere on a compressed
|
|
* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
|
|
*
|
|
* Page 0 is deliberately kept safe, since System Management Mode code in
|
|
* laptops may need to access the BIOS data stored there. This is also
|
|
* useful for future device drivers that either access the BIOS via VM86
|
|
* mode.
|
|
*/
|
|
|
|
/*
|
|
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
|
|
*/
|
|
.text
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
#include <asm/page_types.h>
|
|
#include <asm/boot.h>
|
|
#include <asm/asm-offsets.h>
|
|
#include <asm/bootparam.h>
|
|
|
|
/*
|
|
* The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X
|
|
* relocation to get the symbol address in PIC. When the compressed x86
|
|
* kernel isn't built as PIC, the linker optimizes R_386_GOT32X
|
|
* relocations to their fixed symbol addresses. However, when the
|
|
* compressed x86 kernel is loaded at a different address, it leads
|
|
* to the following load failure:
|
|
*
|
|
* Failed to allocate space for phdrs
|
|
*
|
|
* during the decompression stage.
|
|
*
|
|
* If the compressed x86 kernel is relocatable at run-time, it should be
|
|
* compiled with -fPIE, instead of -fPIC, if possible and should be built as
|
|
* Position Independent Executable (PIE) so that linker won't optimize
|
|
* R_386_GOT32X relocation to its fixed symbol address. Older
|
|
* linkers generate R_386_32 relocations against locally defined symbols,
|
|
* _bss, _ebss, _got, _egot and _end, in PIE. It isn't wrong, just less
|
|
* optimal than R_386_RELATIVE. But the x86 kernel fails to properly handle
|
|
* R_386_32 relocations when relocating the kernel. To generate
|
|
* R_386_RELATIVE relocations, we mark _bss, _ebss, _got, _egot and _end as
|
|
* hidden:
|
|
*/
|
|
.hidden _bss
|
|
.hidden _ebss
|
|
.hidden _got
|
|
.hidden _egot
|
|
.hidden _end
|
|
|
|
__HEAD
|
|
ENTRY(startup_32)
|
|
cld
|
|
/*
|
|
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
|
|
* us to not reload segments
|
|
*/
|
|
testb $KEEP_SEGMENTS, BP_loadflags(%esi)
|
|
jnz 1f
|
|
|
|
cli
|
|
movl $__BOOT_DS, %eax
|
|
movl %eax, %ds
|
|
movl %eax, %es
|
|
movl %eax, %fs
|
|
movl %eax, %gs
|
|
movl %eax, %ss
|
|
1:
|
|
|
|
/*
|
|
* Calculate the delta between where we were compiled to run
|
|
* at and where we were actually loaded at. This can only be done
|
|
* with a short local call on x86. Nothing else will tell us what
|
|
* address we are running at. The reserved chunk of the real-mode
|
|
* data at 0x1e4 (defined as a scratch field) are used as the stack
|
|
* for this calculation. Only 4 bytes are needed.
|
|
*/
|
|
leal (BP_scratch+4)(%esi), %esp
|
|
call 1f
|
|
1: popl %ebp
|
|
subl $1b, %ebp
|
|
|
|
/*
|
|
* %ebp contains the address we are loaded at by the boot loader and %ebx
|
|
* contains the address where we should move the kernel image temporarily
|
|
* for safe in-place decompression.
|
|
*/
|
|
|
|
#ifdef CONFIG_RELOCATABLE
|
|
movl %ebp, %ebx
|
|
movl BP_kernel_alignment(%esi), %eax
|
|
decl %eax
|
|
addl %eax, %ebx
|
|
notl %eax
|
|
andl %eax, %ebx
|
|
cmpl $LOAD_PHYSICAL_ADDR, %ebx
|
|
jae 1f
|
|
#endif
|
|
movl $LOAD_PHYSICAL_ADDR, %ebx
|
|
1:
|
|
|
|
/* Target address to relocate to for decompression */
|
|
movl BP_init_size(%esi), %eax
|
|
subl $_end, %eax
|
|
addl %eax, %ebx
|
|
|
|
/* Set up the stack */
|
|
leal boot_stack_end(%ebx), %esp
|
|
|
|
/* Zero EFLAGS */
|
|
pushl $0
|
|
popfl
|
|
|
|
/*
|
|
* Copy the compressed kernel to the end of our buffer
|
|
* where decompression in place becomes safe.
|
|
*/
|
|
pushl %esi
|
|
leal (_bss-4)(%ebp), %esi
|
|
leal (_bss-4)(%ebx), %edi
|
|
movl $(_bss - startup_32), %ecx
|
|
shrl $2, %ecx
|
|
std
|
|
rep movsl
|
|
cld
|
|
popl %esi
|
|
|
|
/*
|
|
* Jump to the relocated address.
|
|
*/
|
|
leal relocated(%ebx), %eax
|
|
jmp *%eax
|
|
ENDPROC(startup_32)
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
/*
|
|
* We don't need the return address, so set up the stack so efi_main() can find
|
|
* its arguments.
|
|
*/
|
|
ENTRY(efi_pe_entry)
|
|
add $0x4, %esp
|
|
|
|
call 1f
|
|
1: popl %esi
|
|
subl $1b, %esi
|
|
|
|
popl %ecx
|
|
movl %ecx, efi32_config(%esi) /* Handle */
|
|
popl %ecx
|
|
movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */
|
|
|
|
/* Relocate efi_config->call() */
|
|
leal efi32_config(%esi), %eax
|
|
add %esi, 40(%eax)
|
|
pushl %eax
|
|
|
|
call make_boot_params
|
|
cmpl $0, %eax
|
|
je fail
|
|
movl %esi, BP_code32_start(%eax)
|
|
popl %ecx
|
|
pushl %eax
|
|
pushl %ecx
|
|
jmp 2f /* Skip efi_config initialization */
|
|
ENDPROC(efi_pe_entry)
|
|
|
|
ENTRY(efi32_stub_entry)
|
|
add $0x4, %esp
|
|
popl %ecx
|
|
popl %edx
|
|
|
|
call 1f
|
|
1: popl %esi
|
|
subl $1b, %esi
|
|
|
|
movl %ecx, efi32_config(%esi) /* Handle */
|
|
movl %edx, efi32_config+8(%esi) /* EFI System table pointer */
|
|
|
|
/* Relocate efi_config->call() */
|
|
leal efi32_config(%esi), %eax
|
|
add %esi, 40(%eax)
|
|
pushl %eax
|
|
2:
|
|
call efi_main
|
|
cmpl $0, %eax
|
|
movl %eax, %esi
|
|
jne 2f
|
|
fail:
|
|
/* EFI init failed, so hang. */
|
|
hlt
|
|
jmp fail
|
|
2:
|
|
movl BP_code32_start(%esi), %eax
|
|
leal startup_32(%eax), %eax
|
|
jmp *%eax
|
|
ENDPROC(efi32_stub_entry)
|
|
#endif
|
|
|
|
.text
|
|
relocated:
|
|
|
|
/*
|
|
* Clear BSS (stack is currently empty)
|
|
*/
|
|
xorl %eax, %eax
|
|
leal _bss(%ebx), %edi
|
|
leal _ebss(%ebx), %ecx
|
|
subl %edi, %ecx
|
|
shrl $2, %ecx
|
|
rep stosl
|
|
|
|
/*
|
|
* Adjust our own GOT
|
|
*/
|
|
leal _got(%ebx), %edx
|
|
leal _egot(%ebx), %ecx
|
|
1:
|
|
cmpl %ecx, %edx
|
|
jae 2f
|
|
addl %ebx, (%edx)
|
|
addl $4, %edx
|
|
jmp 1b
|
|
2:
|
|
|
|
/*
|
|
* Do the extraction, and jump to the new kernel..
|
|
*/
|
|
/* push arguments for extract_kernel: */
|
|
pushl $z_output_len /* decompressed length, end of relocs */
|
|
|
|
movl BP_init_size(%esi), %eax
|
|
subl $_end, %eax
|
|
movl %ebx, %ebp
|
|
subl %eax, %ebp
|
|
pushl %ebp /* output address */
|
|
|
|
pushl $z_input_len /* input_len */
|
|
leal input_data(%ebx), %eax
|
|
pushl %eax /* input_data */
|
|
leal boot_heap(%ebx), %eax
|
|
pushl %eax /* heap area */
|
|
pushl %esi /* real mode pointer */
|
|
call extract_kernel /* returns kernel location in %eax */
|
|
addl $24, %esp
|
|
|
|
/*
|
|
* Jump to the extracted kernel.
|
|
*/
|
|
xorl %ebx, %ebx
|
|
jmp *%eax
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
.data
|
|
efi32_config:
|
|
.fill 5,8,0
|
|
.long efi_call_phys
|
|
.long 0
|
|
.byte 0
|
|
#endif
|
|
|
|
/*
|
|
* Stack and heap for uncompression
|
|
*/
|
|
.bss
|
|
.balign 4
|
|
boot_heap:
|
|
.fill BOOT_HEAP_SIZE, 1, 0
|
|
boot_stack:
|
|
.fill BOOT_STACK_SIZE, 1, 0
|
|
boot_stack_end:
|