Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip:
  x86: prevent PGE flush from interruption/preemption
  x86: use explicit copy in vdso_gettimeofday()
  namespacecheck: automated fixes
  x86/xen: fix arbitrary_virt_to_machine()
  x86: don't read maxlvt before checking if APIC is mapped
  x86: disable TSC for sched_clock() when calibration failed
  x86: distangle user disabled TSC from unstable
  x86: fix setup of cyc2ns in tsc_64.c

1 files changed, 12 insertions, 1 deletions

diff --git a/include/asm-x86/tlbflush.h b/include/asm-x86/tlbflush.h
index 0c0674d94255..35c76ceb9f40 100644
--- a/include/asm-x86/tlbflush.h
+++ b/include/asm-x86/tlbflush.h
@@ -22,12 +22,23 @@ static inline void __native_flush_tlb(void)
 
 static inline void __native_flush_tlb_global(void)
 {
-        unsigned long cr4 = read_cr4();
+        unsigned long flags;
+        unsigned long cr4;
 
+        /*
+         * Read-modify-write to CR4 - protect it from preemption and
+         * from interrupts. (Use the raw variant because this code can
+         * be called from deep inside debugging code.)
+         */
+        raw_local_irq_save(flags);
+
+        cr4 = read_cr4();
         /* clear PGE */
         write_cr4(cr4 & ~X86_CR4_PGE);
         /* write old PGE again and flush TLBs */
         write_cr4(cr4);
+
+        raw_local_irq_restore(flags);
 }
 
 static inline void __native_flush_tlb_single(unsigned long addr)