u-boot/arch/x86/cpu/start64.S
Simon Glass 8f015d3781 x86: Improve the trampoline in 64-bit mode
At present this leaves the stack at the pre-relocation value. This is not
ideal since we want to have U-Boot running entirely from the top of
memory.

In addition, the new global_data pointer is not actually used, since
the global_data pointer itself is relocated, then the pre-relocation value
is changed, so the effective value (after relocation) does not update.

Adjust the implementation to follow the 32-bit code more closely, with a
trampoline function which is passed the new stack and global_data pointer.
This ensures that the correct values come through even when relocating.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2023-07-17 17:12:07 +08:00

47 lines
1,004 B
ArmAsm

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* 64-bit x86 Startup Code
*
* Copyright 2019 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*/
#include <config.h>
.section .text.start
.code64
.globl _start
.type _start, @function
_start:
/* Set up memory using the existing stack */
mov %rsp, %rdi
call board_init_f_alloc_reserve
mov %rax, %rsp
call board_init_f_init_reserve
xor %rdi, %rdi
call board_init_f
call board_init_f_r
/* Should not return here */
jmp .
.globl board_init_f_r_trampoline64
.type board_init_f_r_trampoline64, @function
board_init_f_r_trampoline64:
/*
* SDRAM has been initialised, U-Boot code has been copied into
* RAM, BSS has been cleared and relocation adjustments have been
* made. It is now time to jump into the in-RAM copy of U-Boot
*
* %eax = Address of top of new stack
*/
/* Stack grows down from top of SDRAM */
movq %rsi, %rsp
/* New gd is in rdi */
/* Re-enter U-Boot by calling board_init_f_r() */
call board_init_f_r