linux-kernel - [PATCH v3 06/12] Revert "x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs"

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Message-Id: <1545062607-8599-7-git-send-email-yamada.masahiro@socionext.com>
Date:   Tue, 18 Dec 2018 01:03:21 +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>,
        David Woodhouse <dwmw@...zon.co.uk>,
        linux-kernel@...r.kernel.org,
        Alexey Dobriyan <adobriyan@...il.com>,
        Nadav Amit <namit@...are.com>
Subject: [PATCH v3 06/12] Revert "x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs"

This reverts commit 77f48ec28e4ccff94d2e5f4260a83ac27a7f3099.

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

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

I blindly reverted here, but I will clean it up
in a different way later.

 arch/x86/include/asm/alternative-asm.h | 20 ++++++--------------
 arch/x86/include/asm/alternative.h     | 11 +++++++++--
 arch/x86/kernel/macros.S               |  1 -
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index 8e4ea39..31b627b 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -7,24 +7,16 @@
 #include <asm/asm.h>
 
 #ifdef CONFIG_SMP
-.macro LOCK_PREFIX_HERE
+	.macro LOCK_PREFIX
+672:	lock
 	.pushsection .smp_locks,"a"
 	.balign 4
-	.long 671f - .		# offset
+	.long 672b - .
 	.popsection
-671:
-.endm
-
-.macro LOCK_PREFIX insn:vararg
-	LOCK_PREFIX_HERE
-	lock \insn
-.endm
+	.endm
 #else
-.macro LOCK_PREFIX_HERE
-.endm
-
-.macro LOCK_PREFIX insn:vararg
-.endm
+	.macro LOCK_PREFIX
+	.endm
 #endif
 
 /*
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index d7faa16..4cd6a3b 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -31,8 +31,15 @@
  */
 
 #ifdef CONFIG_SMP
-#define LOCK_PREFIX_HERE "LOCK_PREFIX_HERE\n\t"
-#define LOCK_PREFIX "LOCK_PREFIX "
+#define LOCK_PREFIX_HERE \
+		".pushsection .smp_locks,\"a\"\n"	\
+		".balign 4\n"				\
+		".long 671f - .\n" /* offset */		\
+		".popsection\n"				\
+		"671:"
+
+#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "
+
 #else /* ! CONFIG_SMP */
 #define LOCK_PREFIX_HERE ""
 #define LOCK_PREFIX ""
diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S
index 852487a..f1fe1d5 100644
--- a/arch/x86/kernel/macros.S
+++ b/arch/x86/kernel/macros.S
@@ -8,4 +8,3 @@
 
 #include <linux/compiler.h>
 #include <asm/refcount.h>
-#include <asm/alternative-asm.h>
-- 
2.7.4