linux-kernel - [PATCH -tip 4/4] x86/idle: Remove CONFIG_AS

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Message-ID: <20250402180827.3762-4-ubizjak@gmail.com>
Date: Wed,  2 Apr 2025 20:08:08 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH -tip 4/4] x86/idle: Remove CONFIG_AS_TPAUSE

There is no point to have CONFIG_AS_TPAUSE when the emitted assembly
is always the same. Remove TPAUSE insn mnemonic and leave only the
equivalent byte-wise definition. This will be changed back to
insn mnemonic once binutils 2.31.1 is the minimum version to
build the kernel.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
---
 arch/x86/Kconfig.assembler   |  4 ----
 arch/x86/include/asm/mwait.h | 11 ++---------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
index 6d20a6ce0507..fa8858546d5e 100644
--- a/arch/x86/Kconfig.assembler
+++ b/arch/x86/Kconfig.assembler
@@ -15,10 +15,6 @@ config AS_SHA256_NI
 	def_bool $(as-instr,sha256msg1 %xmm0$(comma)%xmm1)
 	help
 	  Supported by binutils >= 2.24 and LLVM integrated assembler
-config AS_TPAUSE
-	def_bool $(as-instr,tpause %ecx)
-	help
-	  Supported by binutils >= 2.31.1 and LLVM integrated assembler >= V7
 
 config AS_GFNI
 	def_bool $(as-instr,vgf2p8mulb %xmm0$(comma)%xmm1$(comma)%xmm2)
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index 65228861b894..5141d2acc0ef 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -133,16 +133,9 @@ static __always_inline void mwait_idle_with_hints(unsigned long eax, unsigned lo
  */
 static inline void __tpause(u32 ecx, u32 edx, u32 eax)
 {
-	/* "tpause %ecx, %edx, %eax" */
-	#ifdef CONFIG_AS_TPAUSE
-	asm volatile("tpause %%ecx"
-		     :
-		     : "c"(ecx), "d"(edx), "a"(eax));
-	#else
+	/* "tpause %ecx" */
 	asm volatile(".byte 0x66, 0x0f, 0xae, 0xf1"
-		     :
-		     : "c"(ecx), "d"(edx), "a"(eax));
-	#endif
+		     :: "c" (ecx), "d" (edx), "a" (eax));
 }
 
 #endif /* _ASM_X86_MWAIT_H */
-- 
2.42.0