Commit 73a6dec8 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov
Browse files

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



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: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-6-ardb@kernel.org
parent 91592b5c

arch/x86/boot/compressed/efi_mixed.S

+47 −10
Original line number Diff line number Diff line
@@ -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)

arch/x86/boot/compressed/head_64.S

+0 −45
Original line number Diff line number Diff line
@@ -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)