[PATCH][2.6.9-rc1-mm1] Prescott fix for perfctr

[Mikael Pettersson]

Andrew,

This eliminates a potential oops in perfctr's x86 initialisation
code when running on a P4 Model 3 Prescott processor. The P4M3
removed two control registers. I knew that and handled it in the
control setup validation code, but I forgot to also modify the
initialisation code to avoid clearing them.

Perfctr hasn't been hit by this problem on the P4M3 Noconas,
but people are reporting that oprofile and the NMI watchdog
oops due to this on P4M3 Prescotts.

Signed-off-by: Mikael Pettersson <mikpe@xxxxxxxxx>

diff -ruN linux-2.6.9-rc1-mm1/drivers/perfctr/x86.c linux-2.6.9-rc1-mm1.perfctr-p4m3-fix/drivers/perfctr/x86.c
--- linux-2.6.9-rc1-mm1/drivers/perfctr/x86.c	2004-08-26 14:33:03.000000000 +0200
+++ linux-2.6.9-rc1-mm1.perfctr-p4m3-fix/drivers/perfctr/x86.c	2004-08-26 15:26:28.000000000 +0200
@@ -865,7 +865,10 @@
 	/* clear PEBS_ENABLE and PEBS_MATRIX_VERT; they handle both PEBS
 	   and ReplayTagging, and should exist even if PEBS is disabled */
 	clear_msr_range(0x3F1, 2);
-	clear_msr_range(0x3A0, 31);
+	clear_msr_range(0x3A0, 26);
+	if (p4_IQ_ESCR_ok)
+		clear_msr_range(0x3BA, 2);
+	clear_msr_range(0x3BC, 3);
 	clear_msr_range(0x3C0, 6);
 	clear_msr_range(0x3C8, 6);
 	clear_msr_range(0x3E0, 2);
-
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