x86/mm/pkeys: Add functions to fetch PKRU
This adds the raw instruction to access PKRU as well as some
accessor functions that correctly handle when the CPU does not
support the instruction. We don't use it here, but we will use
read_pkru() in the next patch.
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/20160212210215.15238D34@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 0687c47..e997dcc 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -99,6 +99,14 @@
return pte_flags(pte) & _PAGE_DIRTY;
}
+
+static inline u32 read_pkru(void)
+{
+ if (boot_cpu_has(X86_FEATURE_OSPKE))
+ return __read_pkru();
+ return 0;
+}
+
static inline int pte_young(pte_t pte)
{
return pte_flags(pte) & _PAGE_ACCESSED;