Merge commit 'v2.6.26' into sched/devel

[pandora-kernel.git] / arch / x86 / kernel / tsc_32.c

diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c
index e479072..65b7063 100644 (file)
--- a/arch/x86/kernel/tsc_32.c
+++ b/arch/x86/kernel/tsc_32.c
@@ -14,7 +14,10 @@
 
 #include "mach_timer.h"
 
-static int tsc_enabled;
+/* native_sched_clock() is called before tsc_init(), so
+   we must start with the TSC soft disabled to prevent
+   erroneous rdtsc usage on !cpu_has_tsc processors */
+static int tsc_disabled = -1;
 
 /*
  * On some systems the TSC frequency does not
@@ -28,8 +31,8 @@ EXPORT_SYMBOL_GPL(tsc_khz);
 static int __init tsc_setup(char *str)
 {
        printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
-                               "cannot disable TSC completely.\n");
-       mark_tsc_unstable("user disabled TSC");
+              "cannot disable TSC completely.\n");
+       tsc_disabled = 1;
        return 1;
 }
 #else
@@ -120,7 +123,7 @@ unsigned long long native_sched_clock(void)
         *   very important for it to be as fast as the platform
         *   can achive it. )
         */
-       if (unlikely(!tsc_enabled && !tsc_unstable))
+       if (unlikely(tsc_disabled))
                /* No locking but a rare wrong value is not a big deal: */
                return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
 
@@ -322,7 +325,6 @@ void mark_tsc_unstable(char *reason)
 {
        if (!tsc_unstable) {
                tsc_unstable = 1;
-               tsc_enabled = 0;
                printk("Marking TSC unstable due to: %s.\n", reason);
                /* Can be called before registration */
                if (clocksource_tsc.mult)
@@ -336,7 +338,7 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable);
 static int __init dmi_mark_tsc_unstable(const struct dmi_system_id *d)
 {
        printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
-                      d->ident);
+              d->ident);
        tsc_unstable = 1;
        return 0;
 }
@@ -403,7 +405,7 @@ void __init tsc_init(void)
 {
        int cpu;
 
-       if (!cpu_has_tsc)
+       if (!cpu_has_tsc || tsc_disabled > 0)
                return;
 
        cpu_khz = calculate_cpu_khz();
@@ -414,6 +416,9 @@ void __init tsc_init(void)
                return;
        }
 
+       /* now allow native_sched_clock() to use rdtsc */
+       tsc_disabled = 0;
+
        printk("Detected %lu.%03lu MHz processor.\n",
                                (unsigned long)cpu_khz / 1000,
                                (unsigned long)cpu_khz % 1000);
@@ -441,8 +446,6 @@ void __init tsc_init(void)
        if (check_tsc_unstable()) {
                clocksource_tsc.rating = 0;
                clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
-       } else
-               tsc_enabled = 1;
-
+       }
        clocksource_register(&clocksource_tsc);
 }