x86/mm/pkeys: Add PTE bits for storing protection key

Previous documentation has referred to these 4 bits as "ignored".
That means that software could have made use of them.  But, as
far as I know, the kernel never used them.

They are still ignored when protection keys is not enabled, so
they could theoretically still get used for software purposes.

We also implement "empty" versions so that code that references
to them can be optimized away by the compiler when the config
option is not enabled.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210205.81E33ED6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 4432ab7..cae10ba 100644 (file)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -20,13 +20,18 @@
 #define _PAGE_BIT_SOFTW2       10      /* " */
 #define _PAGE_BIT_SOFTW3       11      /* " */
 #define _PAGE_BIT_PAT_LARGE    12      /* On 2MB or 1GB pages */
+#define _PAGE_BIT_SOFTW4       58      /* available for programmer */
+#define _PAGE_BIT_PKEY_BIT0    59      /* Protection Keys, bit 1/4 */
+#define _PAGE_BIT_PKEY_BIT1    60      /* Protection Keys, bit 2/4 */
+#define _PAGE_BIT_PKEY_BIT2    61      /* Protection Keys, bit 3/4 */
+#define _PAGE_BIT_PKEY_BIT3    62      /* Protection Keys, bit 4/4 */
+#define _PAGE_BIT_NX           63      /* No execute: only valid after cpuid check */
+
 #define _PAGE_BIT_SPECIAL      _PAGE_BIT_SOFTW1
 #define _PAGE_BIT_CPA_TEST     _PAGE_BIT_SOFTW1
 #define _PAGE_BIT_HIDDEN       _PAGE_BIT_SOFTW3 /* hidden by kmemcheck */
 #define _PAGE_BIT_SOFT_DIRTY   _PAGE_BIT_SOFTW3 /* software dirty tracking */
-#define _PAGE_BIT_SOFTW4       58      /* available for programmer */
-#define _PAGE_BIT_DEVMAP               _PAGE_BIT_SOFTW4
-#define _PAGE_BIT_NX           63      /* No execute: only valid after cpuid check */
+#define _PAGE_BIT_DEVMAP       _PAGE_BIT_SOFTW4
 
 /* If _PAGE_BIT_PRESENT is clear, we use these: */
 /* - if the user mapped it with PROT_NONE; pte_present gives true */
@@ -47,6 +52,17 @@
 #define _PAGE_PAT_LARGE (_AT(pteval_t, 1) << _PAGE_BIT_PAT_LARGE)
 #define _PAGE_SPECIAL  (_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL)
 #define _PAGE_CPA_TEST (_AT(pteval_t, 1) << _PAGE_BIT_CPA_TEST)
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+#define _PAGE_PKEY_BIT0        (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT0)
+#define _PAGE_PKEY_BIT1        (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT1)
+#define _PAGE_PKEY_BIT2        (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT2)
+#define _PAGE_PKEY_BIT3        (_AT(pteval_t, 1) << _PAGE_BIT_PKEY_BIT3)
+#else
+#define _PAGE_PKEY_BIT0        (_AT(pteval_t, 0))
+#define _PAGE_PKEY_BIT1        (_AT(pteval_t, 0))
+#define _PAGE_PKEY_BIT2        (_AT(pteval_t, 0))
+#define _PAGE_PKEY_BIT3        (_AT(pteval_t, 0))
+#endif
 #define __HAVE_ARCH_PTE_SPECIAL
 
 #ifdef CONFIG_KMEMCHECK