diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3c51c66..6e71dcf 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -15,12 +15,14 @@
 #include <linux/context_tracking.h>	/* exception_enter(), ...	*/
 #include <linux/uaccess.h>		/* faulthandler_disabled()	*/
 
+#include <asm/cpufeature.h>		/* boot_cpu_has, ...		*/
 #include <asm/traps.h>			/* dotraplinkage, ...		*/
 #include <asm/pgalloc.h>		/* pgd_*(), ...			*/
 #include <asm/kmemcheck.h>		/* kmemcheck_*(), ...		*/
 #include <asm/fixmap.h>			/* VSYSCALL_ADDR		*/
 #include <asm/vsyscall.h>		/* emulate_vsyscall		*/
 #include <asm/vm86.h>			/* struct vm86			*/
+#include <asm/mmu_context.h>		/* vma_pkey()			*/
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/exceptions.h>
@@ -169,6 +171,56 @@
 	return prefetch;
 }
 
+/*
+ * A protection key fault means that the PKRU value did not allow
+ * access to some PTE.  Userspace can figure out what PKRU was
+ * from the XSAVE state, and this function fills out a field in
+ * siginfo so userspace can discover which protection key was set
+ * on the PTE.
+ *
+ * If we get here, we know that the hardware signaled a PF_PK
+ * fault and that there was a VMA once we got in the fault
+ * handler.  It does *not* guarantee that the VMA we find here
+ * was the one that we faulted on.
+ *
+ * 1. T1   : mprotect_key(foo, PAGE_SIZE, pkey=4);
+ * 2. T1   : set PKRU to deny access to pkey=4, touches page
+ * 3. T1   : faults...
+ * 4.    T2: mprotect_key(foo, PAGE_SIZE, pkey=5);
+ * 5. T1   : enters fault handler, takes mmap_sem, etc...
+ * 6. T1   : reaches here, sees vma_pkey(vma)=5, when we really
+ *	     faulted on a pte with its pkey=4.
+ */
+static void fill_sig_info_pkey(int si_code, siginfo_t *info,
+		struct vm_area_struct *vma)
+{
+	/* This is effectively an #ifdef */
+	if (!boot_cpu_has(X86_FEATURE_OSPKE))
+		return;
+
+	/* Fault not from Protection Keys: nothing to do */
+	if (si_code != SEGV_PKUERR)
+		return;
+	/*
+	 * force_sig_info_fault() is called from a number of
+	 * contexts, some of which have a VMA and some of which
+	 * do not.  The PF_PK handing happens after we have a
+	 * valid VMA, so we should never reach this without a
+	 * valid VMA.
+	 */
+	if (!vma) {
+		WARN_ONCE(1, "PKU fault with no VMA passed in");
+		info->si_pkey = 0;
+		return;
+	}
+	/*
+	 * si_pkey should be thought of as a strong hint, but not
+	 * absolutely guranteed to be 100% accurate because of
+	 * the race explained above.
+	 */
+	info->si_pkey = vma_pkey(vma);
+}
+
 static void
 force_sig_info_fault(int si_signo, int si_code, unsigned long address,
 		     struct task_struct *tsk, struct vm_area_struct *vma,
@@ -187,6 +239,8 @@
 		lsb = PAGE_SHIFT;
 	info.si_addr_lsb = lsb;
 
+	fill_sig_info_pkey(si_code, &info, vma);
+
 	force_sig_info(si_signo, &info, tsk);
 }
 
@@ -847,7 +901,15 @@
 bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
 		      unsigned long address, struct vm_area_struct *vma)
 {
-	__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
+	/*
+	 * This OSPKE check is not strictly necessary at runtime.
+	 * But, doing it this way allows compiler optimizations
+	 * if pkeys are compiled out.
+	 */
+	if (boot_cpu_has(X86_FEATURE_OSPKE) && (error_code & PF_PK))
+		__bad_area(regs, error_code, address, vma, SEGV_PKUERR);
+	else
+		__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
 }
 
 static void