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 <[email protected]> Signed-off-by: Robert Richter <[email protected]> LKML-Reference: <[email protected]> Cc: <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
huntrar · Mar 3, 2009 · 780eef9 · 780eef9
1 parent 0fc59d3
commit 780eef9
Showing 1 changed file with 12 additions and 2 deletions.
diff --git 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 */