linux-kernel - [RFC][PATCH 2/3] x86/entry: Provide ASM_INSTR

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Date:   Thu, 07 May 2020 18:10:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de
Cc:     jpoimboe@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org,
        luto@...nel.org, peterz@...radead.org
Subject: [RFC][PATCH 2/3] x86/entry: Provide ASM_INSTR_{BEGIN,END}

To reduce clutter.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/include/asm/irq_stack.h |   10 ++--------
 arch/x86/include/asm/kvm_host.h  |   10 ++--------
 include/linux/compiler.h         |   14 ++++++++++++++
 3 files changed, 18 insertions(+), 16 deletions(-)

--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -24,15 +24,9 @@ do {									\
 	asm volatile(							\
 		"movq	%%rsp, (%[ts])				\n"	\
 		"movq	%[ts], %%rsp				\n"	\
-		"1:						\n"	\
-		"	.pushsection .discard.instr_begin	\n"	\
-		"	.long 1b - .				\n"	\
-		"	.popsection				\n"	\
+		ASM_INSTR_BEGIN						\
 		_asm "                                          \n"	\
-		"2:						\n"	\
-		"	.pushsection .discard.instr_end		\n"	\
-		"	.long 2b - .				\n"	\
-		"	.popsection				\n"	\
+		ASM_INSTR_END						\
 		"popq	%%rsp					\n"	\
 		:							\
 		: [ts] "r" (tos), ##__VA_ARGS__				\
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1601,15 +1601,9 @@ asmlinkage void kvm_spurious_fault(void)
 	insn "\n\t"							\
 	"jmp	668f \n\t"						\
 	"667: \n\t"							\
-	"1: \n\t"							\
-	".pushsection .discard.instr_begin \n\t"			\
-	".long 1b - . \n\t"						\
-	".popsection \n\t"						\
+	ASM_INSTR_BEGIN							\
 	"call	kvm_spurious_fault \n\t"				\
-	"1: \n\t"							\
-	".pushsection .discard.instr_end \n\t"				\
-	".long 1b - . \n\t"						\
-	".popsection \n\t"						\
+	ASM_INSTR_END							\
 	"668: \n\t"							\
 	_ASM_EXTABLE(666b, 667b)
 
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -135,12 +135,26 @@ void ftrace_likely_update(struct ftrace_
 		     ".popsection\n\t" : : "i" (__COUNTER__));		\
 })
 
+#define ASM_INSTR_BEGIN							\
+	"999:\n\t"							\
+	".pushsection .discard.instr_begin\n\t"				\
+	".long 999b - .\n\t"						\
+	".popsection\n\t"
+
+#define ASM_INSTR_END							\
+	"999:\n\t"							\
+	".pushsection .discard.instr_end\n\t"				\
+	".long 999b - .\n\t"						\
+	".popsection\n\t"
+
 #else
 #define annotate_reachable()
 #define annotate_unreachable()
 #define __annotate_jump_table
 #define instr_begin()		do { } while(0)
 #define instr_end()		do { } while(0)
+#define ASM_INSTR_BEGIN
+#define ASM_INSTR_END
 #endif
 
 #ifndef ASM_UNREACHABLE