linux-kernel - Re: [patch?] s2ram + P4 + tsc = annoyance

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: <1198779574.4425.50.camel@homer.simson.net>
Date:	Thu, 27 Dec 2007 19:19:34 +0100
From:	Mike Galbraith <efault@....de>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch?] s2ram + P4 + tsc = annoyance


Or, reset to pristine prior to testing, though that's more lines to
accomplish the same thing.  Either way, or some other way...

If check_tsc_warp() is called after initial boot, and the TSC has in the
meantime been set (BIOS, user, silicon, elves) to a value lower than the
last stored/stale value, we blame the TSC.  Reset to pristine condition
after every test.

Signed-off-by: Mike Galbraith <efault@....de>

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 9125efe..05d8f25 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -129,24 +129,24 @@ void __cpuinit check_tsc_sync_source(int cpu)
 	while (atomic_read(&stop_count) != cpus-1)
 		cpu_relax();
 
-	/*
-	 * Reset it - just in case we boot another CPU later:
-	 */
-	atomic_set(&start_count, 0);
-
 	if (nr_warps) {
 		printk("\n");
 		printk(KERN_WARNING "Measured %Ld cycles TSC warp between CPUs,"
 				    " turning off TSC clock.\n", max_warp);
 		mark_tsc_unstable("check_tsc_sync_source failed");
-		nr_warps = 0;
-		max_warp = 0;
-		last_tsc = 0;
 	} else {
 		printk(" passed.\n");
 	}
 
 	/*
+	 * Reset it - just in case we boot another CPU later:
+	 */
+	atomic_set(&start_count, 0);
+	nr_warps = 0;
+	max_warp = 0;
+	last_tsc = 0;
+
+	/*
 	 * Let the target continue with the bootup:
 	 */
 	atomic_inc(&stop_count);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/