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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 1303880179e67c59e801429b7e5d0f6b21137d99 Mon Sep 17 00:00:00 2001
From: Tom Lendacky <thomas.lendacky@amd.com>
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 <thomas.lendacky@amd.com>

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.

Tested-by: Gabriel Craciunescu <nix.or.die@gmail.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Borislav 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: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/arch/x86/mm/mem_encrypt_boot.S
+++ b/arch/x86/mm/mem_encrypt_boot.S
@@ -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 thomas.lendacky@amd.com 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