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

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Message-ID: <174367967740.14745.10059693585282358485.tip-bot2@tip-bot2>
Date: Thu, 03 Apr 2025 11:27:46 -0000
From: "tip-bot2 for Uros Bizjak" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>, Ingo Molnar <mingo@...nel.org>,
 Andy Lutomirski <luto@...nel.org>, Brian Gerst <brgerst@...il.com>,
 Juergen Gross <jgross@...e.com>, Andrew Cooper <andrew.cooper3@...rix.com>,
 Rik van Riel <riel@...riel.com>, "H. Peter Anvin" <hpa@...or.com>,
 Peter Zijlstra <peterz@...radead.org>,
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/mm] x86/idle: Remove CONFIG_AS_TPAUSE

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     a72d55dc3bd6555cc1f97459b42b7f62ae480f13
Gitweb:        https://git.kernel.org/tip/a72d55dc3bd6555cc1f97459b42b7f62ae480f13
Author:        Uros Bizjak <ubizjak@...il.com>
AuthorDate:    Wed, 02 Apr 2025 20:08:08 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Thu, 03 Apr 2025 13:19:18 +02:00

x86/idle: Remove CONFIG_AS_TPAUSE

There is not much point in CONFIG_AS_TPAUSE at all when the emitted
assembly is always the same - it only obfuscates the __tpause() code
in essence.

Remove the TPAUSE insn mnemonic from __tpause() and leave only
the equivalent byte-wise definition. This can then be changed
back to insn mnemonic once binutils 2.31.1 is the minimum version
to build the kernel. (Right now it's 2.25.)

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Rik van Riel <riel@...riel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: https://lore.kernel.org/r/20250402180827.3762-4-ubizjak@gmail.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 6d20a6c..fa88585 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 0e020a6..6a2ec20 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -138,16 +138,9 @@ 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 */