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Linker scripts:
memtest_shared.lds
memtest_efi.lds
boot/
header.S || The standard EFI header
setup.S
efisetup.c || Macros + private functions
|| Only for 32-bit boot entry point???
startup64.S
*.c files in app/, lib/, system/, tests/
##########################################################################
## ##
## MEMTEST LINKING PART 1 - MEMTEST_SHARED ##
## ##
##########################################################################
#
# memtest_shared.lds
#
OUTPUT_FORMAT("elf64-x86-64")
ENTRY(startup64); <--------- in startup64.S
SECTIONS {
.text : {
_start = .; <---------- First section in memtest_shared-.text
*(.text)
*(.text.*)
...
.rodata
.dynsym
.dynstr
.hash
.gnu.hash
.dynamic
.rela.text
.rela.rodata
.rela.data
.rela.got
.rela.plt
.data
.got
.bss
#
# startup64.S
#
118: .globl startup64
119: startup64:
120: cld
121: cli
# Save the boot params pointer
125: movq %rsi, boot_params_addr(%rip)
127: jmp startup
143: .globl startup
144: startup:
Use startup stack until we pick a correct one
Pick the correct stack
Initialize the pml4 and pdp tables
Set the page directory base address
Initialise the GDT and the segment registers
Load the GDT and the segment registers
Initialise the IDT
Initialise the IDT descriptor
Zero the BSS (if first boot)
Initialise the FPU
Enable SSE
Call the dynamic linker to fix up the addresses in the GOT
268: call reloc <---------------- system/reloc64.c:151
get_load_address()
get_dynamic_section_offset()
get_dynamic_info()
do_relocations
276: call main <---------------- app/main.c:499 # main entry point called from the startup code
#
# Analysis of the binary
#
* objdump -h memtest_shared
.text ... File off Algn
00200000 2**4
* objdump -g memtest_shared | grep efi_setup # check for occurences
| grep efi_handover
* readelf -h memtest_shared
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: DYN (Shared object file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x200 <-----------------That's startup64 !!!
Start of program headers: 64 (bytes into file)
Start of section headers: 2821656 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 3
Size of section headers: 64 (bytes)
Number of section headers: 26
Section header string table index: 25
* objdump -d memtest_shared
memtest_shared: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <_start>:
0: cld
1: cli
9f: ljmp *-0x6(%rsp)
00000000000001e0 <efi_boot>:
1ed: jmp 210 <efi_handover>
0000000000000200 <startup64>:
202: mov %rsi,0x23df7(%rip) # 2400 <boot_params_addr>
209: jmp 220 <startup>
0000000000000210 <efi_handover>:
214: callq 68f <efi_setup>
219: mov %rax,0x23de0(%rip) # 2400 <boot_params_addr>
0000000000000220 <startup>:
2ce: ljmp *-0x6(%rsp)
##########################################################################
## ##
## MEMTEST LINKING PART 2 - MEMTEST.EFI ##
## ##
##########################################################################
#
# memtest_efi.lds
#
OUTPUT_FORMAT("binary")
ENTRY(boot); <----- in boot/header.S:36
SECTIONS {
.header : { <----- boot/header.S
*(.header)
}
.setup : { <----- boot/setup.S
*(.setup)
}
.text : {
_text_start = .;
*(.data) <----- !!! NO .text !!!!
...
#
# header.S
#
The EFI loader loads the header at ImageBase, so we have to locate the main program
after that. This means we can't load the main program at HIGH_LOAD_ADDR. Pick a load
address well away from HIGH_LOAD_ADDR, to avoid overlap when relocating code.
. # define IMAGE_BASE 0x200000
. # define BASE_OF_CODE 0x1000 <- where do these values come from?????
.section ".header", "ax", @progbits
.code16
.globl boot
boot:
"MZ", the MS-DOS header signature
.byte 0x4d
.byte 0x5a
pe_header:
coff_header:
...
#
# setup.S
#
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