linux-kernel - [patch V2 01/17] x86/vdso: Mark the TSC clocksource path likely

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: <20200207124402.328922847@linutronix.de>
Date:   Fri, 07 Feb 2020 13:38:48 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, John Stultz <john.stultz@...aro.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Andy Lutomirski <luto@...nel.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paulburton@...nel.org>,
        James Hogan <jhogan@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>, Andrei Vagin <avagin@...il.com>
Subject: [patch V2 01/17] x86/vdso: Mark the TSC clocksource path likely

Jumping out of line for the TSC clcoksource read is creating awful
code. TSC is likely to be the clocksource at least on bare metal and the PV
interfaces are sufficiently more work that the jump over the TSC read is
just in the noise.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/vdso/gettimeofday.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -243,7 +243,7 @@ static u64 vread_hvclock(void)
 
 static inline u64 __arch_get_hw_counter(s32 clock_mode)
 {
-	if (clock_mode == VCLOCK_TSC)
+	if (likely(clock_mode == VCLOCK_TSC))
 		return (u64)rdtsc_ordered();
 	/*
 	 * For any memory-mapped vclock type, we need to make sure that gcc