[PATCH 1/8] x86, pkeys: add fault handling for PF_PK page fault bit

Dave Hansen
2016-05-31T15:30:18Z

From: Dave Hansen <dave.hansen@linux.intel.com>

PF_PK means that a memory access violated the protection key
access restrictions. It is unconditionally an access_error()
because the permissions set on the VMA don't matter (the PKRU
value overrides it), and we never "resolve" PK faults (like
how a COW can "resolve write fault).

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
---

b/arch/x86/mm/fault.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff -puN arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~pkeys-105-add-pk-to-fault 2016-05-31 08:27:47.161025766 -0700
+++ b/arch/x86/mm/fault.c 2016-05-31 08:27:47.166025992 -0700
@@ -1107,6 +1107,15 @@ access_error(unsigned long error_code, s
{
/* This is only called for the current mm, so: */
bool foreign = false;
+
+ /*
+ * Read or write was blocked by protection keys. This is
+ * always an unconditional error and can never result in
+ * a follow-up action to resolve the fault, like a COW.
+ */
+ if (error_code & PF_PK)
+ return 1;
+
/*
* Make sure to check the VMA so that we do not perform
* faults just to hit a PF_PK as soon as we fill in a
_