[PATCH v3 1/2] x86/asm: add _ASM_RIP() macro for x86-64 (%rip) suffix
From: H. Peter Anvin (Intel)
Date: Fri Sep 10 2021 - 15:59:54 EST
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@xxxxxxxxx>
---
arch/x86/include/asm/asm.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 3ad3da9a7d97..c5a19ccda0fe 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -6,11 +6,13 @@
# define __ASM_FORM(x, ...) x,## __VA_ARGS__
# define __ASM_FORM_RAW(x, ...) x,## __VA_ARGS__
# define __ASM_FORM_COMMA(x, ...) x,## __VA_ARGS__,
+# define __ASM_REGPFX %
#else
#include <linux/stringify.h>
# define __ASM_FORM(x, ...) " " __stringify(x,##__VA_ARGS__) " "
# define __ASM_FORM_RAW(x, ...) __stringify(x,##__VA_ARGS__)
# define __ASM_FORM_COMMA(x, ...) " " __stringify(x,##__VA_ARGS__) ","
+# define __ASM_REGPFX %%
#endif
#define _ASM_BYTES(x, ...) __ASM_FORM(.byte x,##__VA_ARGS__ ;)
@@ -49,6 +51,9 @@
#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 */
--
2.31.1