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From: "H. Peter Anvin (Intel)" <hpa@zytor.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	x86@kernel.org, "H. Peter Anvin (Intel)" <hpa@zytor.com>
Subject: [PATCH v2 1/2] x86/asm: add _ASM_RIP() macro for x86-64 (%rip) suffix
Date: Thu,  9 Sep 2021 15:08:17 -0700	[thread overview]
Message-ID: <20210909220818.417312-2-hpa@zytor.com> (raw)
In-Reply-To: <20210909220818.417312-1-hpa@zytor.com>

Add a macro _ASM_RIP() to add a (%rip) suffix on 64 bits only. This is
useful for immediate memory references using e.g. an "i" constraint
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>
---
 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


  reply	other threads:[~2021-09-09 22:08 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-08 17:17 [PATCH] x86/asm: pessimize the pre-initialization case in static_cpu_has() H. Peter Anvin (Intel)
2021-09-09 17:01 ` Borislav Petkov
2021-09-09 21:28   ` H. Peter Anvin
2021-09-09 21:53     ` Borislav Petkov
2021-09-09 22:17     ` H. Peter Anvin
2021-09-10  9:14       ` Borislav Petkov
2021-09-10 19:25         ` H. Peter Anvin
2021-09-09 22:08 ` [PATCH v2 0/2] x86/asm: avoid register pressure from static_cpu_has() H. Peter Anvin (Intel)
2021-09-09 22:08   ` H. Peter Anvin (Intel) [this message]
2021-09-09 22:08   ` [PATCH v2 2/2] x86/asm: pessimize the pre-initialization case in static_cpu_has() H. Peter Anvin (Intel)
2021-09-10  9:16   ` [PATCH v2 0/2] x86/asm: avoid register pressure from static_cpu_has() Borislav Petkov
2021-09-10 13:24     ` Borislav Petkov
2021-09-10 19:59 ` [PATCH v3 0/2] x86/asm: avoid register pressure from the init case in static_cpu_has() H. Peter Anvin (Intel)
2021-09-10 19:59   ` [PATCH] drm/bochs: add Bochs PCI ID for Simics model H. Peter Anvin (Intel)
2021-09-10 19:59   ` [PATCH v3 1/2] x86/asm: add _ASM_RIP() macro for x86-64 (%rip) suffix H. Peter Anvin (Intel)
2021-09-13 19:39     ` [tip: x86/cpu] x86/asm: Add " tip-bot2 for H. Peter Anvin (Intel)
2021-09-10 19:59   ` [PATCH v3 2/2] x86/asm: avoid adding register pressure for the init case in static_cpu_has() H. Peter Anvin (Intel)
2021-09-13 19:39     ` [tip: x86/cpu] x86/asm: Avoid " tip-bot2 for H. Peter Anvin

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