Linux-libre 4.2-gnu

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index f95603842..7437b41f6 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -12,7 +12,6 @@
 #include <linux/percpu.h>
 #include <linux/timex.h>
 #include <linux/static_key.h>
-#include <linux/mm.h>
 
 #include <asm/hpet.h>
 #include <asm/timer.h>
@@ -196,10 +195,6 @@ static void cyc2ns_init(int cpu)
 
 	c2n->head = c2n->data;
 	c2n->tail = c2n->data;
-
-        // Don't let TuxOnIce make data RO - a secondary CPU will cause a triple fault
-        // if it loads microcode, which then does a printk, which may end up invoking cycles_2_ns
-        SetPageTOI_Untracked(virt_to_page(c2n));
 }
 
 static inline unsigned long long cycles_2_ns(unsigned long long cyc)
@@ -603,10 +598,19 @@ static unsigned long quick_pit_calibrate(void)
 			if (!pit_expect_msb(0xff-i, &delta, &d2))
 				break;
 
+			delta -= tsc;
+
+			/*
+			 * Extrapolate the error and fail fast if the error will
+			 * never be below 500 ppm.
+			 */
+			if (i == 1 &&
+			    d1 + d2 >= (delta * MAX_QUICK_PIT_ITERATIONS) >> 11)
+				return 0;
+
 			/*
 			 * Iterate until the error is less than 500 ppm
 			 */
-			delta -= tsc;
 			if (d1+d2 >= delta >> 11)
 				continue;