linux-kernel - [PATCH] x86/vmware: Do not trace vmware_sched

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Message-ID: <20181109152207.4d3e7d70@gandalf.local.home>
Date:   Fri, 9 Nov 2018 15:22:07 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Alok Kataria <akataria@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        virtualization@...ts.linux-foundation.org,
        GwanYeong Kim <gy741.kim@...il.com>
Subject: [PATCH] x86/vmware: Do not trace vmware_sched_clock()

From: Steven Rostedt (VMware) <rostedt@...dmis.org>

When running function tracing on a Linux guest running on VMware
Workstation, the guest would crash. This is due to tracing of the
sched_clock internal call of the VMware vmware_sched_clock(), which
causes an infinite recursion within the tracing code (clock calls must
not be traced).

Make vmware_sched_clock() not traced by ftrace.

Cc: stable@...r.kernel.org
Fixes: 80e9a4f21fd7c ("x86/vmware: Add paravirt sched clock")
Reported-by: GwanYeong Kim <gy741.kim@...il.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index d9ab49bed8af..0eda91f8eeac 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -77,7 +77,7 @@ static __init int setup_vmw_sched_clock(char *s)
 }
 early_param("no-vmw-sched-clock", setup_vmw_sched_clock);
 
-static unsigned long long vmware_sched_clock(void)
+static unsigned long long notrace vmware_sched_clock(void)
 {
 	unsigned long long ns;