4.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
commit 03da3ff1cfcd7774c8780d2547ba0d995f7dc03d upstream.
In 2007, commit 07190a08eef36 ("Mark TSC on GeodeLX reliable")
bypassed verification of the TSC on Geode LX. However, this code
(now in the check_system_tsc_reliable() function in
arch/x86/kernel/tsc.c) was only present if CONFIG_MGEODE_LX was
set.
OpenWRT has recently started building its generic Geode target
for Geode GX, not LX, to include support for additional
platforms. This broke the timekeeping on LX-based devices,
because the TSC wasn't marked as reliable:
https://dev.openwrt.org/ticket/20531
By adding a runtime check on is_geode_lx(), we can also include
the fix if CONFIG_MGEODEGX1 or CONFIG_X86_GENERIC are set, thus
fixing the problem.
Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Cc: Andres Salomon <dilinger@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Marcelo Tosatti <marcelo@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1442409003.131189.87.camel@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/tsc.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -21,6 +21,7 @@
#include <asm/hypervisor.h>
#include <asm/nmi.h>
#include <asm/x86_init.h>
+#include <asm/geode.h>
unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */
EXPORT_SYMBOL(cpu_khz);
@@ -1004,15 +1005,17 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable);
static void __init check_system_tsc_reliable(void)
{
-#ifdef CONFIG_MGEODE_LX
- /* RTSC counts during suspend */
+#if defined(CONFIG_MGEODEGX1) || defined(CONFIG_MGEODE_LX) || defined(CONFIG_X86_GENERIC)
+ if (is_geode_lx()) {
+ /* RTSC counts during suspend */
#define RTSC_SUSP 0x100
- unsigned long res_low, res_high;
+ unsigned long res_low, res_high;
- rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
- /* Geode_LX - the OLPC CPU has a very reliable TSC */
- if (res_low & RTSC_SUSP)
- tsc_clocksource_reliable = 1;
+ rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
+ /* Geode_LX - the OLPC CPU has a very reliable TSC */
+ if (res_low & RTSC_SUSP)
+ tsc_clocksource_reliable = 1;
+ }
#endif
if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
tsc_clocksource_reliable = 1;
--
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