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

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / include / asm / tlbflush.h

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index f68f9c836cca09bcd7fc7c5795e219dcaa3f216b..4a08dd2ab32ade77dcbfff6a8e8b77f5d5e43764 100644 (file)
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -348,15 +348,17 @@ static inline void invalidate_user_asid(u16 asid)
  */
 static inline void __native_flush_tlb(void)
 {
-       invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid));
        /*
-        * If current->mm == NULL then we borrow a mm which may change
-        * during a task switch and therefore we must not be preempted
-        * while we write CR3 back:
+        * Preemption or interrupts must be disabled to protect the access
+        * to the per CPU variable and to prevent being preempted between
+        * read_cr3() and write_cr3().
         */
-       preempt_disable();
+       WARN_ON_ONCE(preemptible());
+
+       invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid));
+
+       /* If current->mm == NULL then the read_cr3() "borrows" an mm */
        native_write_cr3(__native_read_cr3());
-       preempt_enable();
 }
 
 /*