linux-kernel - [PATCH 20/20] x86/msr: Use alternative_2_io() in rdtsc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <acc41322fdb01204f365b6b7342bed403a99773a.1741988314.git.jpoimboe@kernel.org>
Date: Fri, 14 Mar 2025 14:41:33 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Uros Bizjak <ubizjak@...il.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 20/20] x86/msr: Use alternative_2_io() in rdtsc_ordered()

Use the standard alternative_2_io() interface.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/include/asm/msr.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 001853541f1e..996e3b5857c6 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -214,12 +214,13 @@ static __always_inline unsigned long long rdtsc_ordered(void)
 	 * Thus, use the preferred barrier on the respective CPU, aiming for
 	 * RDTSCP as the default.
 	 */
-	asm volatile(ALTERNATIVE_2("rdtsc",
-				   "lfence; rdtsc", X86_FEATURE_LFENCE_RDTSC,
-				   "rdtscp", X86_FEATURE_RDTSCP)
-			: EAX_EDX_RET(val, low, high)
-			/* RDTSCP clobbers ECX with MSR_TSC_AUX. */
-			:: "ecx");
+	alternative_2_io("rdtsc",
+			 "lfence; rdtsc", X86_FEATURE_LFENCE_RDTSC,
+			 "rdtscp", X86_FEATURE_RDTSCP,
+			 ARG(EAX_EDX_RET(val, low, high)),
+			 ARG(),
+			 /* RDTSCP clobbers ECX with MSR_TSC_AUX. */
+			 ARG("ecx"));
 
 	return EAX_EDX_VAL(val, low, high);
 }
-- 
2.48.1