linux-kernel - [PATCH v3 01/12] Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"

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Date:   Tue, 18 Dec 2018 01:03:16 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     Richard Biener <rguenther@...e.de>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Juergen Gross <jgross@...e.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kernel@...r.kernel.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Nadav Amit <namit@...are.com>
Subject: [PATCH v3 01/12] Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"

This partially reverts commit 5bdcd510c2ac9efaf55c4cbd8d46421d8e2320cd.

The in-kernel workarounds will be replaced with GCC's new
"asm inline" syntax.

Only the asm_volatile_goto parts were reverted.

The other cleanups (removal of unneeded #error, replacement of
STATIC_JUMP_IF_TRUE/FALSE with STATIC_JUMP_IF_NOP/JMP) are kept.

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
---

 arch/x86/include/asm/jump_label.h | 22 +++++++++++++++++-----
 arch/x86/kernel/macros.S          |  1 -
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index a5fb34f..cf88ebf 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -20,9 +20,15 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
 {
-	asm_volatile_goto("STATIC_BRANCH_NOP l_yes=\"%l[l_yes]\" key=\"%c0\" "
-			  "branch=\"%c1\""
-			: :  "i" (key), "i" (branch) : : l_yes);
+	asm_volatile_goto("1:"
+		".byte " __stringify(STATIC_KEY_INIT_NOP) "\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"
+		: :  "i" (key), "i" (branch) : : l_yes);
+
 	return false;
 l_yes:
 	return true;
@@ -30,8 +36,14 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 
 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
 {
-	asm_volatile_goto("STATIC_BRANCH_JMP l_yes=\"%l[l_yes]\" key=\"%c0\" "
-			  "branch=\"%c1\""
+	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"
 		: :  "i" (key), "i" (branch) : : l_yes);
 
 	return false;
diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S
index 161c950..bf8b9c9 100644
--- a/arch/x86/kernel/macros.S
+++ b/arch/x86/kernel/macros.S
@@ -13,4 +13,3 @@
 #include <asm/paravirt.h>
 #include <asm/asm.h>
 #include <asm/cpufeature.h>
-#include <asm/jump_label.h>
-- 
2.7.4