linux/arch/x86/platform/efi/efi_thunk_64.S
Matt Fleming 4f9dbcfc40 x86/efi: Add mixed runtime services support
Setup the runtime services based on whether we're booting in EFI native
mode or not. For non-native mode we need to thunk from 64-bit into
32-bit mode before invoking the EFI runtime services.

Using the runtime services after SetVirtualAddressMap() is slightly more
complicated because we need to ensure that all the addresses we pass to
the firmware are below the 4GB boundary so that they can be addressed
with 32-bit pointers, see efi_setup_page_tables().

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
2014-03-04 21:43:14 +00:00

66 lines
1.3 KiB
ArmAsm

/*
* Copyright (C) 2014 Intel Corporation; author Matt Fleming
*/
#include <linux/linkage.h>
#include <asm/page_types.h>
.text
.code64
ENTRY(efi64_thunk)
push %rbp
push %rbx
/*
* Switch to 1:1 mapped 32-bit stack pointer.
*/
movq %rsp, efi_saved_sp(%rip)
movq efi_scratch+25(%rip), %rsp
/*
* Calculate the physical address of the kernel text.
*/
movq $__START_KERNEL_map, %rax
subq phys_base(%rip), %rax
/*
* Push some physical addresses onto the stack. This is easier
* to do now in a code64 section while the assembler can address
* 64-bit values. Note that all the addresses on the stack are
* 32-bit.
*/
subq $16, %rsp
leaq efi_exit32(%rip), %rbx
subq %rax, %rbx
movl %ebx, 8(%rsp)
leaq efi_gdt64(%rip), %rbx
subq %rax, %rbx
movl %ebx, 2(%ebx)
movl %ebx, 4(%rsp)
leaq efi_gdt32(%rip), %rbx
subq %rax, %rbx
movl %ebx, 2(%ebx)
movl %ebx, (%rsp)
leaq __efi64_thunk(%rip), %rbx
subq %rax, %rbx
call *%rbx
movq efi_saved_sp(%rip), %rsp
pop %rbx
pop %rbp
retq
ENDPROC(efi64_thunk)
.data
efi_gdt32:
.word efi_gdt32_end - efi_gdt32
.long 0 /* Filled out above */
.word 0
.quad 0x0000000000000000 /* NULL descriptor */
.quad 0x00cf9a000000ffff /* __KERNEL_CS */
.quad 0x00cf93000000ffff /* __KERNEL_DS */
efi_gdt32_end:
efi_saved_sp: .quad 0