x86/cpu: Uninline CR4 accessors

cpu_tlbstate is exported because various TLB-related functions need
access to it, but cpu_tlbstate is sensitive information which should
only be accessed by well-contained kernel functions and not be directly
exposed to modules.

The various CR4 accessors require cpu_tlbstate as the CR4 shadow cache
is located there.

In preparation for unexporting cpu_tlbstate, create a builtin function
for manipulating CR4 and rework the various helpers to use it.

No functional change.

 [ bp: push the export of native_write_cr4() only when CONFIG_LKTDM=m to
   the last patch in the series. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200421092558.939985695@linutronix.de

1 files changed, 5 insertions, 31 deletions

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 6f66d841262d..d804030079da 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -276,37 +276,25 @@ static inline bool nmi_uaccess_okay(void)
 
 #define nmi_uaccess_okay nmi_uaccess_okay
 
+void cr4_update_irqsoff(unsigned long set, unsigned long clear);
+unsigned long cr4_read_shadow(void);
+
 /* Initialize cr4 shadow for this CPU. */
 static inline void cr4_init_shadow(void)
 {
 	this_cpu_write(cpu_tlbstate.cr4, __read_cr4());
 }
 
-static inline void __cr4_set(unsigned long cr4)
-{
-	lockdep_assert_irqs_disabled();
-	this_cpu_write(cpu_tlbstate.cr4, cr4);
-	__write_cr4(cr4);
-}
-
 /* Set in this cpu's CR4. */
 static inline void cr4_set_bits_irqsoff(unsigned long mask)
 {
-	unsigned long cr4;
-
-	cr4 = this_cpu_read(cpu_tlbstate.cr4);
-	if ((cr4 | mask) != cr4)
-		__cr4_set(cr4 | mask);
+	cr4_update_irqsoff(mask, 0);
 }
 
 /* Clear in this cpu's CR4. */
 static inline void cr4_clear_bits_irqsoff(unsigned long mask)
 {
-	unsigned long cr4;
-
-	cr4 = this_cpu_read(cpu_tlbstate.cr4);
-	if ((cr4 & ~mask) != cr4)
-		__cr4_set(cr4 & ~mask);
+	cr4_update_irqsoff(0, mask);
 }
 
 /* Set in this cpu's CR4. */
@@ -329,20 +317,6 @@ static inline void cr4_clear_bits(unsigned long mask)
 	local_irq_restore(flags);
 }
 
-static inline void cr4_toggle_bits_irqsoff(unsigned long mask)
-{
-	unsigned long cr4;
-
-	cr4 = this_cpu_read(cpu_tlbstate.cr4);
-	__cr4_set(cr4 ^ mask);
-}
-
-/* Read the CR4 shadow. */
-static inline unsigned long cr4_read_shadow(void)
-{
-	return this_cpu_read(cpu_tlbstate.cr4);
-}
-
 /*
  * Mark all other ASIDs as invalid, preserves the current.
  */