lkml.org 
[lkml]   [2018]   [Jan]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.14 44/89] x86/mm: Clean up register saving in the __enc_copy() assembly code
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

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)

\
 
 \ /
  Last update: 2018-01-22 10:10    [W:0.272 / U:0.908 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site