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Message-Id: <d58f339a9c0dd8352b50d2f7a216f67ec2844f20.1434152192.git.luto@kernel.org>
Date: Fri, 12 Jun 2015 16:41:41 -0700
From: Andy Lutomirski <luto@...nel.org>
To: x86@...nel.org
Cc: Borislav Petkov <bp@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
John Stultz <john.stultz@...aro.org>,
linux-kernel@...r.kernel.org, Len Brown <lenb@...nel.org>,
Huang Rui <ray.huang@....com>,
Denys Vlasenko <dvlasenk@...hat.com>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 07/17] x86/cpu/amd: Use the full 64-bit TSC to detect the 2.6.2 bug
This code is timing 100k indirect calls, so the added overhead of
counting the number of cycles elapsed as a 64-bit number should be
insignificant. Drop the optimization of using a 32-bit count.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
arch/x86/kernel/cpu/amd.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5bd3a99dc20b..c5ceec532799 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -107,7 +107,7 @@ static void init_amd_k6(struct cpuinfo_x86 *c)
const int K6_BUG_LOOP = 1000000;
int n;
void (*f_vide)(void);
- unsigned long d, d2;
+ u64 d, d2;
printk(KERN_INFO "AMD K6 stepping B detected - ");
@@ -118,10 +118,10 @@ static void init_amd_k6(struct cpuinfo_x86 *c)
n = K6_BUG_LOOP;
f_vide = vide;
- rdtscl(d);
+ d = native_read_tsc();
while (n--)
f_vide();
- rdtscl(d2);
+ d2 = native_read_tsc();
d = d2-d;
if (d > 20*K6_BUG_LOOP)
--
2.4.2
--
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