Patch "x86/mm: Clean up register saving in the __enc_copy() assembly code" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

x86/mm: Clean up register saving in the __enc_copy() assembly code

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-mm-clean-up-register-saving-in-the-__enc_copy-assembly-code.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Tom Lendacky <[email protected]>
Date: Wed, 10 Jan 2018 13:25:56 -0600
Subject: x86/mm: Clean up register saving in the __enc_copy() assembly code

From: Tom Lendacky <[email protected]>

commit 1303880179e67c59e801429b7e5d0f6b21137d99 upstream.

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.

---
 arch/x86/mm/mem_encrypt_boot.S |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

@@ -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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-mm-clean-up-register-saving-in-the-__enc_copy-assembly-code.patch queue-4.14/x86-mm-use-a-struct-to-reduce-parameters-for-sme-pgd-mapping.patch queue-4.14/x86-mm-centralize-pmd-flags-in-sme_encrypt_kernel.patch queue-4.14/x86-retpoline-fill-rsb-on-context-switch-for-affected-cpus.patch queue-4.14/x86-mm-prepare-sme_encrypt_kernel-for-page-aligned-encryption.patch queue-4.14/x86-retpoline-add-lfence-to-the-retpoline-rsb-filling-rsb-macros.patch