From: Jan Beulich <JBeulich@suse.com>
Date: Mon, 1 Jun 2015 12:02:55 +0000 (+0100)
Subject: x86/asm/entry/64: Use negative immediates for stack adjustments
X-Git-Tag: v4.2-rc1~166^2^2~8^2~22
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=2bf557ea3f49576fabe24cd5daf1a34e9ee22c3c;p=cascardo%2Flinux.git

x86/asm/entry/64: Use negative immediates for stack adjustments

Doing so allows adjustments by 128 bytes (occurring for
REMOVE_PT_GPREGS_FROM_STACK 8 uses) to be expressed with a
single byte immediate.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.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/556C660F020000780007FB60@mail.emea.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/include/asm/calling.h b/arch/x86/include/asm/calling.h
index 0d76accde45b..f4e6308c4200 100644
--- a/arch/x86/include/asm/calling.h
+++ b/arch/x86/include/asm/calling.h
@@ -89,7 +89,7 @@ For 32-bit we have the following conventions - kernel is built with
 #define SIZEOF_PTREGS	21*8
 
 	.macro ALLOC_PT_GPREGS_ON_STACK addskip=0
-	subq	$15*8+\addskip, %rsp
+	addq	$-(15*8+\addskip), %rsp
 	.endm
 
 	.macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1
@@ -201,7 +201,7 @@ For 32-bit we have the following conventions - kernel is built with
 	.endm
 
 	.macro REMOVE_PT_GPREGS_FROM_STACK addskip=0
-	addq $15*8+\addskip, %rsp
+	subq $-(15*8+\addskip), %rsp
 	.endm
 
 	.macro icebp