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Commit 13038801 authored by Tom Lendacky's avatar Tom Lendacky Committed by Ingo Molnar
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x86/mm: Clean up register saving in the __enc_copy() assembly code 



Clean up the use of PUSH and POP and when registers are saved in the
__enc_copy() assembly function in order to improve the readability of the code.

Move parameter register saving into general purpose registers earlier
in the code and move all the pushes to the beginning of the function
with corresponding pops at the end.

We do this to prepare fixes.

Tested-by: default avatarGabriel Craciunescu <nix.or.die@gmail.com>
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180110192556.6026.74187.stgit@tlendack-t1.amdoffice.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 327867fa

arch/x86/mm/mem_encrypt_boot.S

+10 −10
Original line number Diff line number Diff line
@@ -103,20 +103,19 @@ ENTRY(__enc_copy) 
	orq	$X86_CR4_PGE, %rdx

	mov	%rdx, %cr4



	push	%r15



	movq	%rcx, %r9		/* Save kernel length */

	movq	%rdi, %r10		/* Save encrypted kernel address */

	movq	%rsi, %r11		/* Save decrypted kernel address */



	/* Set the PAT register PA5 entry to write-protect */

	push	%rcx

	movl	$MSR_IA32_CR_PAT, %ecx

	rdmsr

	push	%rdx			/* Save original PAT value */

	mov	%rdx, %r15		/* Save original PAT value */

	andl	$0xffff00ff, %edx	/* Clear PA5 */

	orl	$0x00000500, %edx	/* Set PA5 to WP */

	wrmsr

	pop	%rdx			/* RDX contains original PAT value */

	pop	%rcx



	movq	%rcx, %r9		/* Save kernel length */

	movq	%rdi, %r10		/* Save encrypted kernel address */

	movq	%rsi, %r11		/* Save decrypted kernel address */



	wbinvd				/* Invalidate any cache entries */
@@ -138,12 +137,13 @@ ENTRY(__enc_copy) 
	jnz	1b			/* Kernel length not zero? */



	/* Restore PAT register */

	push	%rdx			/* Save original PAT value */

	movl	$MSR_IA32_CR_PAT, %ecx

	rdmsr

	pop	%rdx			/* Restore original PAT value */

	mov	%r15, %rdx		/* Restore original PAT value */

	wrmsr



	pop	%r15



	ret

.L__enc_copy_end:

ENDPROC(__enc_copy)