linux-kernel - [PATCH 04/13] jump_label, x86: Factor out the __jump

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Date:   Thu, 06 May 2021 21:33:56 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, jpoimboe@...hat.com, jbaron@...mai.com,
        rostedt@...dmis.org, ardb@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: [PATCH 04/13] jump_label, x86: Factor out the __jump_table generation

Both arch_static_branch() and arch_static_branch_jump() have the same
blurb to generate the __jump_table entry, share it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/include/asm/jump_label.h |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -14,15 +14,19 @@
 #include <linux/stringify.h>
 #include <linux/types.h>
 
+#define JUMP_TABLE_ENTRY				\
+	".pushsection __jump_table,  \"aw\" \n\t"	\
+	_ASM_ALIGN "\n\t"				\
+	".long 1b - . \n\t"				\
+	".long %l[l_yes] - . \n\t"			\
+	_ASM_PTR "%c0 + %c1 - .\n\t"			\
+	".popsection \n\t"
+
 static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
 		".byte " __stringify(BYTES_NOP5) "\n\t"
-		".pushsection __jump_table,  \"aw\" \n\t"
-		_ASM_ALIGN "\n\t"
-		".long 1b - ., %l[l_yes] - . \n\t"
-		_ASM_PTR "%c0 + %c1 - .\n\t"
-		".popsection \n\t"
+		JUMP_TABLE_ENTRY
 		: :  "i" (key), "i" (branch) : : l_yes);
 
 	return false;
@@ -33,13 +37,9 @@ static __always_inline bool arch_static_
 static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
 {
 	asm_volatile_goto("1:"
-		".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
-		"2:\n\t"
-		".pushsection __jump_table,  \"aw\" \n\t"
-		_ASM_ALIGN "\n\t"
-		".long 1b - ., %l[l_yes] - . \n\t"
-		_ASM_PTR "%c0 + %c1 - .\n\t"
-		".popsection \n\t"
+		".byte 0xe9 \n\t"
+		".long %l[l_yes] - (. + 4) \n\t"
+		JUMP_TABLE_ENTRY
 		: :  "i" (key), "i" (branch) : : l_yes);
 
 	return false;