[PATCH v2 1/7] x86/asm: Add _ASM_RIP() macro for x86-64 (%rip) suffix

[Nikolay Borisov <nik.borisov@suse.com>]

From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

[ Upstream commit 0576d1ed1e153bf34b54097e0561ede382ba88b0 ]

Add a macro _ASM_RIP() to add a (%rip) suffix on 64 bits only. This is
useful for immediate memory references where one doesn't want gcc
to possibly use a register indirection as it may in the case of an "m"
constraint.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210910195910.2542662-3-hpa@zytor.com
Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
---
 arch/x86/include/asm/asm.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index cd339b88d5d4..9116ef22bc53 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -6,12 +6,13 @@
 # define __ASM_FORM(x)	x
 # define __ASM_FORM_RAW(x)     x
 # define __ASM_FORM_COMMA(x) x,
+# define __ASM_REGPFX			%
 #else
 #include <linux/stringify.h>
-
 # define __ASM_FORM(x)	" " __stringify(x) " "
 # define __ASM_FORM_RAW(x)     __stringify(x)
 # define __ASM_FORM_COMMA(x) " " __stringify(x) ","
+# define __ASM_REGPFX			%%
 #endif
 
 #ifndef __x86_64__
@@ -48,6 +49,9 @@
 #define _ASM_SI		__ASM_REG(si)
 #define _ASM_DI		__ASM_REG(di)
 
+/* Adds a (%rip) suffix on 64 bits only; for immediate memory references */
+#define _ASM_RIP(x)	__ASM_SEL_RAW(x, x (__ASM_REGPFX rip))
+
 #ifndef __x86_64__
 /* 32 bit */
 
-- 
2.34.1