From 1303880179e67c59e801429b7e5d0f6b21137d99 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 10 Jan 2018 13:25:56 -0600 Subject: [PATCH] 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: Gabriel Craciunescu Signed-off-by: Tom Lendacky Reviewed-by: Borislav Petkov Cc: Borislav Petkov Cc: Brijesh Singh Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180110192556.6026.74187.stgit@tlendack-t1.amdoffice.net Signed-off-by: Ingo Molnar --- arch/x86/mm/mem_encrypt_boot.S | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S index 730e6d541df1..de3688461145 100644 --- a/arch/x86/mm/mem_encrypt_boot.S +++ b/arch/x86/mm/mem_encrypt_boot.S @@ -103,21 +103,20 @@ ENTRY(__enc_copy) orq $X86_CR4_PGE, %rdx mov %rdx, %cr4 - /* Set the PAT register PA5 entry to write-protect */ - push %rcx - movl $MSR_IA32_CR_PAT, %ecx - rdmsr - push %rdx /* 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 + 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 */ + movl $MSR_IA32_CR_PAT, %ecx + rdmsr + mov %rdx, %r15 /* Save original PAT value */ + andl $0xffff00ff, %edx /* Clear PA5 */ + orl $0x00000500, %edx /* Set PA5 to WP */ + wrmsr + wbinvd /* Invalidate any cache entries */ /* Copy/encrypt 2MB at a time */ @@ -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)