Commit c6355995 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov
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x86/boot/compressed: Move startup32_load_idt() into .text section 



Convert startup32_load_idt() into an ordinary function and move it into
the .text section. This involves turning the rva() immediates into ones
derived from a local label, and preserving/restoring the %ebp and %ebx
as per the calling convention.

Also move the #ifdef to the only existing call site. This makes it clear
that the function call does nothing if support for memory encryption is
not compiled in.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-12-ardb@kernel.org
parent d73a257f

arch/x86/boot/compressed/head_64.S

+20 −11
Original line number Diff line number Diff line
@@ -118,7 +118,9 @@ SYM_FUNC_START(startup_32) 
1:



	/* Setup Exception handling for SEV-ES */

#ifdef CONFIG_AMD_MEM_ENCRYPT

	call	startup32_load_idt

#endif



	/* Make sure cpu supports long mode. */

	call	verify_cpu
@@ -716,10 +718,8 @@ SYM_DATA_START(boot32_idt) 
	.quad 0

	.endr

SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)

#endif



#ifdef CONFIG_AMD_MEM_ENCRYPT

	__HEAD

	.text

	.code32

/*

 * Write an IDT entry into boot32_idt
@@ -752,24 +752,32 @@ SYM_FUNC_START_LOCAL(startup32_set_idt_entry) 


	RET

SYM_FUNC_END(startup32_set_idt_entry)

#endif



SYM_FUNC_START(startup32_load_idt)

#ifdef CONFIG_AMD_MEM_ENCRYPT

	leal    rva(boot32_idt)(%ebp), %ecx

	push	%ebp

	push	%ebx



	call	1f

1:	pop	%ebp



	leal    (boot32_idt - 1b)(%ebp), %ebx



	/* #VC handler */

	leal    rva(startup32_vc_handler)(%ebp), %eax

	leal    (startup32_vc_handler - 1b)(%ebp), %eax

	movl    $X86_TRAP_VC, %edx

	movl	%ebx, %ecx

	call    startup32_set_idt_entry



	/* Load IDT */

	leal	rva(boot32_idt)(%ebp), %eax

	movl	%eax, rva(boot32_idt_desc+2)(%ebp)

	lidt    rva(boot32_idt_desc)(%ebp)

#endif

	leal	(boot32_idt_desc - 1b)(%ebp), %ecx

	movl	%ebx, 2(%ecx)

	lidt    (%ecx)



	pop	%ebx

	pop	%ebp

	RET

SYM_FUNC_END(startup32_load_idt)

#endif



/*

 * Check for the correct C-bit position when the startup_32 boot-path is used.
@@ -788,6 +796,7 @@ SYM_FUNC_END(startup32_load_idt) 
 * succeed. An incorrect C-bit position will map all memory unencrypted, so that

 * the compare will use the encrypted random data and fail.

 */

	__HEAD

SYM_FUNC_START(startup32_check_sev_cbit)

#ifdef CONFIG_AMD_MEM_ENCRYPT

	pushl	%eax