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Date: Thu, 07 Jul 2016 05:47:20 -0700
From: Dave Hansen <dave@...1.net>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, linux-api@...r.kernel.org,
linux-arch@...r.kernel.org, linux-mm@...ck.org,
torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
Dave Hansen <dave@...1.net>, dave.hansen@...ux.intel.com,
arnd@...db.de, mgorman@...hsingularity.net, hughd@...gle.com,
viro@...iv.linux.org.uk
Subject: [PATCH 1/9] x86, pkeys: add fault handling for PF_PK page fault bit
From: Dave Hansen <dave.hansen@...ux.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@...ux.intel.com>
Cc: linux-api@...r.kernel.org
Cc: linux-arch@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: x86@...nel.org
Cc: torvalds@...ux-foundation.org
Cc: akpm@...ux-foundation.org
Cc: Arnd Bergmann <arnd@...db.de>
Cc: mgorman@...hsingularity.net
Cc: hughd@...gle.com
Cc: viro@...iv.linux.org.uk
---
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 2016-07-07 05:46:59.554745699 -0700
+++ b/arch/x86/mm/fault.c 2016-07-07 05:46:59.558745881 -0700
@@ -1112,6 +1112,15 @@ 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
_
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