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Revise headers and entry points in EFI stub

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This commit is contained in:
Ruihan Li
2025-03-07 23:30:17 +08:00
committed by Tate, Hongliang Tian
parent fbb8ea6ad1
commit 81bfa6ed6e
11 changed files with 144 additions and 172 deletions
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5
ostd/libs/linux-bzimage/setup/src/main.rs
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@ -27,15 +27,14 @@ use linux_boot_params::BootParams;
mod console;
mod loader;
// Unfortunately, the entrypoint is not defined here in the main.rs file.
// See the exported functions in the x86 module for details.
// The entry points are defined in `x86/*/setup.S`.
mod x86;
fn get_payload(boot_params: &BootParams) -> &'static [u8] {
let hdr = &boot_params.hdr;
// The payload_offset field is not recorded in the relocation table, so we need to
// calculate the loaded offset manually.
let loaded_offset = x86::get_image_loaded_offset();
let loaded_offset = x86::image_load_offset();
let payload_offset = (loaded_offset + hdr.payload_offset as isize) as usize;
let payload_length = hdr.payload_length as usize;
// SAFETY: the payload_offset and payload_length is valid if we assume that the

22
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/efi.rs
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@ -13,24 +13,8 @@ use super::{decoder::decode_payload, relocation::apply_rela_relocations};
const PAGE_SIZE: u64 = 4096;
// Suppress warnings since using todo!.
#[expect(unreachable_code)]
#[expect(unused_variables)]
#[expect(clippy::diverging_sub_expression)]
#[export_name = "efi_stub_entry"]
extern "sysv64" fn efi_stub_entry(handle: Handle, system_table: *const SystemTable) -> ! {
// SAFETY: handle and system_table are valid pointers. It is only called once.
unsafe { system_init(handle, system_table) };
uefi::helpers::init().unwrap();
let boot_params = todo!("Use EFI boot services to fill boot params");
efi_phase_boot(boot_params);
}
#[export_name = "efi_handover_entry"]
extern "sysv64" fn efi_handover_entry(
#[export_name = "main_efi_handover64"]
extern "sysv64" fn main_efi_handover64(
handle: Handle,
system_table: *const SystemTable,
boot_params_ptr: *mut BootParams,
@ -74,7 +58,7 @@ fn efi_phase_boot(boot_params: &mut BootParams) -> ! {
uefi::println!("[EFI stub] Relocations applied.");
uefi::println!(
"[EFI stub] Stub loaded at {:#x?}",
crate::x86::get_image_loaded_offset()
crate::x86::image_load_offset()
);
// Fill the boot params with the RSDP address if it is not provided.

61
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/header.S
View File

@ -1,61 +0,0 @@
/* SPDX-License-Identifier: MPL-2.0 */
// The compatibility file for the Linux x86 Boot Protocol.
// See https://www.kernel.org/doc/html/v5.6/x86/boot.html for
// more information on the Linux x86 Boot Protocol.
// Some of the fields filled with a 0xab* values should be filled
// by the torjan builder.
// Asterinas will use only a few of these fields, and some of them
// are filled by the loader and will be read by Asterinas.
.section ".header", "a"
CODE32_START = 0x100000
SETUP_SECTS = 7 # so that the legacy setup could occupy a page
SETUP_SECTS_SIZE = 0x200 * (SETUP_SECTS + 1)
.code16
.org 0x01f1
hdr_start:
setup_sects: .byte SETUP_SECTS
root_flags: .word 1
syssize: .long 0
ram_size: .word 0
vid_mode: .word 0xfffd
root_dev: .word 0
boot_flag: .word 0xAA55
jump: .byte 0xeb
jump_addr: .byte hdr_end-jump_addr
magic: .ascii "HdrS"
.word 0x020f
realmode_swtch: .word 0, 0
start_sys_seg: .word 0
.word 0
type_of_loader: .byte 0
loadflags: .byte (1 << 0)
setup_move_size: .word 0
code32_start: .long CODE32_START
ramdisk_image: .long 0
ramdisk_size: .long 0
bootsect_kludge: .long 0
heap_end_ptr: .word 65535
ext_loader_ver: .byte 0
ext_loader_type: .byte 0
cmd_line_ptr: .long 0
initrd_addr_max: .long 0x7fffffff
kernel_alignment: .long 0x1000000
relocatable_kernel: .byte 0
min_alignment: .byte 0x10
xloadflags: .word 0b01111 # all handover protocols except kexec
cmdline_size: .long 4096-1
hardware_subarch: .long 0
hardware_subarch_data: .quad 0
payload_offset: .long 0xabababab # at 0x248/4, to be filled by the builder
payload_length: .long 0xabababab # at 0x24c/4, to be filled by the builder
setup_data: .quad 0
pref_address: .quad CODE32_START - SETUP_SECTS_SIZE
init_size: .long 0xabababab # at 0x260/4, to be filled by the builder
# The handover_offset should be efi_handover_setup_entry - CODE32_START - 0x200
# But we use ABI workaround to avoid the relocation of efi_handover_setup_entry
handover_offset: .long 0x10
kernel_info_offset: .long 0
hdr_end:

2
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/linker.ld
View File

@ -1,4 +1,4 @@
ENTRY(efi_handover_setup_entry)
ENTRY(entry_efi_pe64)
OUTPUT_ARCH(i386:x86-64)
OUTPUT_FORMAT(elf64-x86-64)

2
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/mod.rs
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@ -6,8 +6,6 @@ mod relocation;
use core::arch::{asm, global_asm};
global_asm!(include_str!("header.S"));
global_asm!(include_str!("setup.S"));
pub const ASTER_ENTRY_POINT: u32 = 0x8001200;

4
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/relocation.rs
View File

@ -1,6 +1,6 @@
// SPDX-License-Identifier: MPL-2.0
use crate::x86::get_image_loaded_offset;
use crate::x86::image_load_offset;
/// Apply the relocations in the `.rela.*` sections.
///
@ -18,7 +18,7 @@ use crate::x86::get_image_loaded_offset;
/// Failure to do relocations will cause `dyn Trait` objects to break.
pub unsafe fn apply_rela_relocations() {
use core::arch::asm;
let image_loaded_offset = get_image_loaded_offset();
let image_loaded_offset = image_load_offset();
let mut start: usize;
let end: usize;

95
ostd/libs/linux-bzimage/setup/src/x86/amd64_efi/setup.S
View File

@ -1,43 +1,74 @@
/* SPDX-License-Identifier: MPL-2.0 */
// The load address of the setup section is CODE32_START (0x100000).
// See the linker script.
.section ".setup", "ax"
.code32
.global entry_legacy32
entry_legacy32:
// This is the 32-bit Linux legacy entry point.
// Not supported. However, there doesn't seem to be a way to disable this
// entry point in the header, so provide a dummy implementation here.
hlt
jmp entry_legacy32
.global entry_efi_handover32
entry_efi_handover32:
// This is the 32-bit EFI handover entry point.
// Not supported. This entry point is not enabled in the header, so it
// should not be reachable. We declare the entry point anyway, because
// its offset is needed in the header. We provide a dummy implementation
// just in case.
jmp entry_legacy32
// The 64-bit Linux legacy entry point must be 0x200 bytes after the 32-bit
// one. This is required by the x86 Linux boot protocol.
.skip 0x200 - (. - entry_legacy32)
.code64
// start_of_setup32 should be loaded at CODE32_START, which is our base.
.global start_of_setup32
start_of_setup32:
entry_legacy64:
// This is the 64-bit Linux legacy entry point.
// `efi_handover_setup_entry64` should be at efi_handover_setup_entry32 + 0x200, but
// we could provide the 32 bit dummy entry point as the 64 bit entry point - 0x200
// since we do not provide 32-bit entry point in the x86_64 specific implementation.
.org 0x210
.global efi_handover_setup_entry
efi_handover_setup_entry:
// The 3 parameters of is stored in rdi, rsi and rdx (sysv64).
// Do not use them.
// Not supported. We need to enable this entry point in the header,
// otherwise the boot loader will think the kernel does not support
// 64-bit.
jmp halt
// Setup the stack.
lea rsp, [rip + setup_stack_top]
lea rax, [rip + halt]
push rax # the return address
mov rbp, rsp
add rbp, -4
push rbp
mov rbp, rsp
// The 64-bit EFI handover entry point must be 0x200 bytes after the 32-bit
// one. This is required by the x86 Linux boot protocol.
.skip 0x200 - (. - entry_efi_handover32)
.extern efi_handover_entry
lea rax, [rip + efi_handover_entry]
call rax
entry_efi_handover64:
// This is the 64-bit EFI handover entry point.
//
// Arguments:
// RDI: void *handle
// RSI: efi_system_table_t *table
// RDX: struct boot_params *bp
// We can reuse the stack provided by the UEFI firmware until a short time
// after exiting the UEFI boot services. So we don't build our own stack.
//
// But the stack must be 16-byte aligned! So we drop the return address.
add rsp, 8
// Call the Rust main routine.
call main_efi_handover64
// The main routine should not return. If it does, there is nothing we can
// do but stop the machine.
jmp halt
.global entry_efi_pe64
entry_efi_pe64:
// This is the 64-bit EFI PE/COFF entry point.
// Not supported yet. Just stop the machine.
jmp halt
// Unreachable here.
halt:
hlt
jmp halt
// A small stack for the setup code.
.section .data
.align 0x1000 / 8
.global setup_stack
setup_stack:
.skip 0x1000
.global setup_stack_top
setup_stack_top:

29
ostd/libs/linux-bzimage/setup/src/x86/legacy_i386/header.S → ostd/libs/linux-bzimage/setup/src/x86/header.S
View File

@ -10,9 +10,13 @@
// are filled by the loader and will be read by Asterinas.
.section ".header", "a"
CODE32_START = 0x100000
SETUP_SECTS = 7 # so that the legacy setup could occupy a page
.code16
# Real-mode setup sectors. We don't use them. Their size is set to one page.
SETUP_SECTS = 7
SETUP_SECTS_SIZE = 0x200 * (SETUP_SECTS + 1)
.org 0x01f1
hdr_start:
setup_sects: .byte SETUP_SECTS
@ -30,7 +34,7 @@ realmode_swtch: .word 0, 0
start_sys_seg: .word 0
.word 0
type_of_loader: .byte 0
loadflags: .byte (1 << 0)
loadflags: .byte (1 << 0) # LOADED_HIGH
setup_move_size: .word 0
code32_start: .long CODE32_START
ramdisk_image: .long 0
@ -44,15 +48,32 @@ initrd_addr_max: .long 0x7fffffff
kernel_alignment: .long 0x1000000
relocatable_kernel: .byte 0
min_alignment: .byte 0x10
.if {CFG_TARGET_ARCH_X86_64}
# Note that we don't actually support the legacy 64-bit entry point
# (XLF_KERNEL_64). But we have to specify it, otherwise the boot loader
# will think this kernel does not have 64-bit support.
xloadflags: .word 0b01011 # Bit 0: XLF_KERNEL_64
# Bit 1: XLF_CAN_BE_LOADED_ABOVE_4G
# Bit 3: XLF_EFI_HANDOVER_64
.else
xloadflags: .word 0
.endif
cmdline_size: .long 4096 - 1
hardware_subarch: .long 0
hardware_subarch_data: .quad 0
payload_offset: .long 0xabababab # at 0x248/4, to be filled by the builder
payload_length: .long 0xabababab # at 0x24c/4, to be filled by the builder
setup_data: .quad 0
pref_address: .quad CODE32_START - 0x200 * (SETUP_SECTS + 1);
pref_address: .quad CODE32_START
init_size: .long 0xabababab # at 0x260/4, to be filled by the builder
.if {CFG_TARGET_ARCH_X86_64}
handover_offset: .long (entry_efi_handover32 - entry_legacy32)
.else
handover_offset: .long 0
.endif
kernel_info_offset: .long 0
hdr_end:

10
ostd/libs/linux-bzimage/setup/src/x86/legacy_i386/mod.rs
View File

@ -4,23 +4,21 @@ use core::arch::{asm, global_asm};
use linux_boot_params::BootParams;
global_asm!(include_str!("header.S"));
global_asm!(include_str!("setup.S"));
use crate::console::{print_hex, print_str};
pub const ASTER_ENTRY_POINT: u32 = 0x8001000;
#[export_name = "_bzimage_entry_32"]
extern "cdecl" fn bzimage_entry(boot_params_ptr: u32) -> ! {
#[export_name = "main_legacy32"]
extern "cdecl" fn main_legacy32(boot_params_ptr: u32) -> ! {
// SAFETY: this init function is only called once.
unsafe { crate::console::init() };
// println!("[setup] bzImage loaded at {:#x}", x86::relocation::get_image_loaded_offset());
// println!("[setup] bzImage loaded at {:#x}", x86::relocation::image_load_offset());
unsafe {
print_str("[setup] bzImage loaded offset: ");
print_hex(crate::x86::get_image_loaded_offset() as u64);
print_hex(crate::x86::image_load_offset() as u64);
print_str("\n");
}

38
ostd/libs/linux-bzimage/setup/src/x86/legacy_i386/setup.S
View File

@ -1,25 +1,31 @@
/* SPDX-License-Identifier: MPL-2.0 */
// 32-bit setup code starts here, and will be loaded at CODE32_START.
// The load address of the setup section is CODE32_START (0x100000).
// See the linker script.
.section ".setup", "ax"
.code32
.global start_of_setup32
start_of_setup32:
mov eax, offset __stack_top
mov esp, eax
mov eax, offset halt
push eax # the return address
mov ebp, esp
add ebp, -4
push ebp
mov ebp, esp
.global entry_legacy32
entry_legacy32:
// This is the 32-bit Linux legacy entry point.
//
// Arguments:
// RSI: struct boot_params *bp
// The rust entrypoint of the bzImage
.extern _bzimage_entry_32
push esi # the boot_params pointer
call _bzimage_entry_32
// Set up the stack.
mov esp, offset __stack_top
// Call the Rust main routine.
push esi
call main_legacy32
// The main routine should not return. If it does, there is nothing we can
// do but stop the machine.
jmp halt
// All other types of entry points are not enabled in the header.
// So we don't care about them.
// Unreachable here.
halt:
hlt
jmp halt

44
ostd/libs/linux-bzimage/setup/src/x86/mod.rs
View File

@ -1,38 +1,34 @@
// SPDX-License-Identifier: MPL-2.0
use core::arch::global_asm;
cfg_if::cfg_if! {
if #[cfg(target_arch = "x86_64")] {
mod amd64_efi;
const CFG_TARGET_ARCH_X86_64: usize = 1;
} else if #[cfg(target_arch = "x86")] {
mod legacy_i386;
const CFG_TARGET_ARCH_X86_64: usize = 0;
} else {
compile_error!("Unsupported target_arch");
compile_error!("unsupported target architecture");
}
}
// This is enforced in the linker script of the setup.
const START_OF_SETUP32_VA: usize = 0x100000;
global_asm!(
include_str!("header.S"),
CFG_TARGET_ARCH_X86_64 = const CFG_TARGET_ARCH_X86_64,
);
/// The setup is a position-independent executable. We can get the loaded base
/// address from the symbol.
#[inline]
pub fn get_image_loaded_offset() -> isize {
let address_of_start: usize;
#[cfg(target_arch = "x86_64")]
unsafe {
core::arch::asm!(
"lea {}, [rip + start_of_setup32]",
out(reg) address_of_start,
options(pure, nomem, nostack)
);
/// Returns the difference between the real load address and the one in the linker script.
pub fn image_load_offset() -> isize {
/// The load address of the `entry_legacy32` symbol specified in the linker script.
const CODE32_START: isize = 0x100000;
extern "C" {
fn entry_legacy32();
}
#[cfg(target_arch = "x86")]
unsafe {
core::arch::asm!(
"lea {}, [start_of_setup32]",
out(reg) address_of_start,
options(pure, nomem, nostack)
);
}
address_of_start as isize - START_OF_SETUP32_VA as isize
(entry_legacy32 as usize as isize) - CODE32_START
}