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Subject[tip:x86/urgent] x86: oprofile: don't set counter width from cpuid on Core2
Commit-ID:  780eef9492b16a1543a3b2ae9f9526a735fc9856
Gitweb: http://git.kernel.org/tip/780eef9492b16a1543a3b2ae9f9526a735fc9856
Author: "Tim Blechmann" <tim@klingt.org>
AuthorDate: Thu, 19 Feb 2009 17:34:03 +0100
Commit: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 3 Mar 2009 12:04:22 +0100

x86: oprofile: don't set counter width from cpuid on Core2

Impact: fix stuck NMIs and non-working oprofile on certain CPUs

Resetting the counter width of the performance counters on Intel's
Core2 CPUs, breaks the delivery of NMIs, when running in x86_64 mode.

This should fix bug #12395:

http://bugzilla.kernel.org/show_bug.cgi?id=12395

Signed-off-by: Tim Blechmann <tim@klingt.org>
Signed-off-by: Robert Richter <robert.richter@amd.com>
LKML-Reference: <20090303100412.GC10085@erda.amd.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
arch/x86/oprofile/op_model_ppro.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
index e9f80c7..10131fb 100644
--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -78,8 +78,18 @@ static void ppro_setup_ctrs(struct op_msrs const * const msrs)
if (cpu_has_arch_perfmon) {
union cpuid10_eax eax;
eax.full = cpuid_eax(0xa);
- if (counter_width < eax.split.bit_width)
- counter_width = eax.split.bit_width;
+
+ /*
+ * For Core2 (family 6, model 15), don't reset the
+ * counter width:
+ */
+ if (!(eax.split.version_id == 0 &&
+ current_cpu_data.x86 == 6 &&
+ current_cpu_data.x86_model == 15)) {
+
+ if (counter_width < eax.split.bit_width)
+ counter_width = eax.split.bit_width;
+ }
}

/* clear all counters */

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