Commit 93e489ad authored by David Woodhouse's avatar David Woodhouse Committed by Ingo Molnar
Browse files

x86/kexec: Clean up register usage in relocate_kernel() 



The memory encryption flag is passed in %r8 because that's where the
calling convention puts it. Instead of moving it to %r12 and then using
%r8 for other things, just leave it in %r8 and use other registers
instead.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20241205153343.3275139-13-dwmw2@infradead.org
parent b7155dfd

arch/x86/kernel/relocate_kernel_64.S

+6 −11
Original line number Diff line number Diff line
@@ -79,24 +79,18 @@ SYM_CODE_START_NOALIGN(relocate_kernel) 
	movq	%cr4, %r13

	movq	%r13, saved_cr4(%rip)



	/* Save SME active flag */

	movq	%r8, %r12



	/* save indirection list for jumping back */

	movq	%rdi, pa_backup_pages_map(%rip)



	/* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */

	movq	%rcx, %r11



	/* Physical address of control page */

	movq    %rsi, %r8



	/* setup a new stack at the end of the physical control page */

	lea	PAGE_SIZE(%r8), %rsp

	lea	PAGE_SIZE(%rsi), %rsp



	/* jump to identity mapped page */

	addq	$(identity_mapped - relocate_kernel), %r8

	pushq	%r8

	addq	$(identity_mapped - relocate_kernel), %rsi

	pushq	%rsi

	ANNOTATE_UNRET_SAFE

	ret

	int3
@@ -107,8 +101,9 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	/*

	 * %rdi	indirection page

	 * %rdx start address

	 * %r8 host_mem_enc_active

	 * %r9 page table page

	 * %r11 preserve_context

	 * %r12 host_mem_enc_active

	 * %r13 original CR4 when relocate_kernel() was invoked

	 */
@@ -161,7 +156,7 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	 * entries that will conflict with the now unencrypted memory

	 * used by kexec. Flush the caches before copying the kernel.

	 */

	testq	%r12, %r12

	testq	%r8, %r8

	jz .Lsme_off

	wbinvd

.Lsme_off: