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x86/boot/compressed: Move efi32_entry out of head_64.S

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Move the efi32_entry() routine out of head_64.S and into efi-mixed.S,
which reduces clutter in the complicated startup routines. It also
permits linkage of some symbols used by code to be made local.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-6-ardb@kernel.org
This commit is contained in:
Ard Biesheuvel 2022-11-22 17:10:05 +01:00 committed by Borislav Petkov
parent 91592b5c0c
commit 73a6dec80e
2 changed files with 47 additions and 55 deletions
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57
arch/x86/boot/compressed/efi_mixed.S
View File

@ -105,7 +105,7 @@ SYM_FUNC_START(__efi64_thunk)
/*
* Switch to IDT and GDT with 32-bit segments. This is the firmware GDT
* and IDT that was installed when the kernel started executing. The
* pointers were saved at the EFI stub entry point in head_64.S.
* pointers were saved by the efi32_entry() routine below.
*
* Pass the saved DS selector to the 32-bit code, and use far return to
* restore the saved CS selector.
@ -217,22 +217,59 @@ SYM_FUNC_START_LOCAL(efi_enter32)
lret
SYM_FUNC_END(efi_enter32)
/*
* This is the common EFI stub entry point for mixed mode.
*
* Arguments: %ecx image handle
* %edx EFI system table pointer
* %esi struct bootparams pointer (or NULL when not using
* the EFI handover protocol)
*
* Since this is the point of no return for ordinary execution, no registers
* are considered live except for the function parameters. [Note that the EFI
* stub may still exit and return to the firmware using the Exit() EFI boot
* service.]
*/
SYM_FUNC_START(efi32_entry)
call 1f
1: pop %ebx
/* Save firmware GDTR and code/data selectors */
sgdtl (efi32_boot_gdt - 1b)(%ebx)
movw %cs, (efi32_boot_cs - 1b)(%ebx)
movw %ds, (efi32_boot_ds - 1b)(%ebx)
/* Store firmware IDT descriptor */
sidtl (efi32_boot_idt - 1b)(%ebx)
/* Store boot arguments */
leal (efi32_boot_args - 1b)(%ebx), %ebx
movl %ecx, 0(%ebx)
movl %edx, 4(%ebx)
movl %esi, 8(%ebx)
movb $0x0, 12(%ebx) // efi_is64
/* Disable paging */
movl %cr0, %eax
btrl $X86_CR0_PG_BIT, %eax
movl %eax, %cr0
jmp startup_32
SYM_FUNC_END(efi32_entry)
.data
.balign 8
SYM_DATA_START(efi32_boot_gdt)
SYM_DATA_START_LOCAL(efi32_boot_gdt)
.word 0
.quad 0
SYM_DATA_END(efi32_boot_gdt)
SYM_DATA_START(efi32_boot_idt)
SYM_DATA_START_LOCAL(efi32_boot_idt)
.word 0
.quad 0
SYM_DATA_END(efi32_boot_idt)
SYM_DATA_START(efi32_boot_cs)
.word 0
SYM_DATA_END(efi32_boot_cs)
SYM_DATA_START(efi32_boot_ds)
.word 0
SYM_DATA_END(efi32_boot_ds)
SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
SYM_DATA(efi_is64, .byte 1)

45
arch/x86/boot/compressed/head_64.S
View File

@ -289,48 +289,6 @@ SYM_FUNC_START(efi32_stub_entry)
popl %esi
jmp efi32_entry
SYM_FUNC_END(efi32_stub_entry)
.text
/*
* This is the common EFI stub entry point for mixed mode.
*
* Arguments: %ecx image handle
* %edx EFI system table pointer
* %esi struct bootparams pointer (or NULL when not using
* the EFI handover protocol)
*
* Since this is the point of no return for ordinary execution, no registers
* are considered live except for the function parameters. [Note that the EFI
* stub may still exit and return to the firmware using the Exit() EFI boot
* service.]
*/
SYM_FUNC_START_LOCAL(efi32_entry)
call 1f
1: pop %ebx
/* Save firmware GDTR and code/data selectors */
sgdtl (efi32_boot_gdt - 1b)(%ebx)
movw %cs, (efi32_boot_cs - 1b)(%ebx)
movw %ds, (efi32_boot_ds - 1b)(%ebx)
/* Store firmware IDT descriptor */
sidtl (efi32_boot_idt - 1b)(%ebx)
/* Store boot arguments */
leal (efi32_boot_args - 1b)(%ebx), %ebx
movl %ecx, 0(%ebx)
movl %edx, 4(%ebx)
movl %esi, 8(%ebx)
movb $0x0, 12(%ebx) // efi_is64
/* Disable paging */
movl %cr0, %eax
btrl $X86_CR0_PG_BIT, %eax
movl %eax, %cr0
jmp startup_32
SYM_FUNC_END(efi32_entry)
__HEAD
#endif
.code64
@ -763,9 +721,6 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
SYM_DATA(image_offset, .long 0)
#endif
#ifdef CONFIG_EFI_MIXED
SYM_DATA(efi32_boot_args, .long 0, 0, 0)
SYM_DATA(efi_is64, .byte 1)
#define ST32_boottime 60 // offsetof(efi_system_table_32_t, boottime)
#define BS32_handle_protocol 88 // offsetof(efi_boot_services_32_t, handle_protocol)
#define LI32_image_base 32 // offsetof(efi_loaded_image_32_t, image_base)