Commit e2ab9eab authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov
Browse files

x86/boot/compressed: Move 32-bit entrypoint code into .text section 



Move the code that stores the arguments passed to the EFI entrypoint
into the .text section, so that it can be moved into a separate
compilation unit in a subsequent patch.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-3-ardb@kernel.org
parent cb8bda8a

arch/x86/boot/compressed/head_64.S

+34 −14
Original line number Diff line number Diff line
@@ -303,24 +303,41 @@ SYM_FUNC_START(efi32_stub_entry) 
	popl	%ecx

	popl	%edx

	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	%ebp

	subl	$ rva(1b), %ebp



	movl	%esi, rva(efi32_boot_args+8)(%ebp)

SYM_INNER_LABEL(efi32_pe_stub_entry, SYM_L_LOCAL)

	movl	%ecx, rva(efi32_boot_args)(%ebp)

	movl	%edx, rva(efi32_boot_args+4)(%ebp)

	movb	$0, rva(efi_is64)(%ebp)

1:	pop	%ebx



	/* Save firmware GDTR and code/data selectors */

	sgdtl	rva(efi32_boot_gdt)(%ebp)

	movw	%cs, rva(efi32_boot_cs)(%ebp)

	movw	%ds, rva(efi32_boot_ds)(%ebp)

	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	rva(efi32_boot_idt)(%ebp)

	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
@@ -328,7 +345,8 @@ SYM_INNER_LABEL(efi32_pe_stub_entry, SYM_L_LOCAL) 
	movl	%eax, %cr0



	jmp	startup_32

SYM_FUNC_END(efi32_stub_entry)

SYM_FUNC_END(efi32_entry)

	__HEAD

#endif



	.code64
@@ -831,7 +849,9 @@ SYM_FUNC_START(efi32_pe_entry) 
	 */

	subl	%esi, %ebx

	movl	%ebx, rva(image_offset)(%ebp)	// save image_offset

	jmp	efi32_pe_stub_entry

	xorl	%esi, %esi

	jmp	efi32_entry			// pass %ecx, %edx, %esi

						// no other registers remain live



2:	popl	%edi				// restore callee-save registers

	popl	%ebx