[PATCH 10/33] x86, pkeys: new page fault error code bit: PF_PK

From: Dave Hansen
Date: Fri Feb 12 2016 - 16:10:04 EST



From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

Note: "PK" is how the Intel SDM refers to this bit, so we also
use that nomenclature.

This only defines the bit, it does not plumb it anywhere to be
handled.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---

b/arch/x86/mm/fault.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff -puN arch/x86/mm/fault.c~pkeys-05-pfec arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~pkeys-05-pfec 2016-02-12 10:44:18.080331119 -0800
+++ b/arch/x86/mm/fault.c 2016-02-12 10:44:18.084331302 -0800
@@ -33,6 +33,7 @@
* bit 2 == 0: kernel-mode access 1: user-mode access
* bit 3 == 1: use of reserved bit detected
* bit 4 == 1: fault was an instruction fetch
+ * bit 5 == 1: protection keys block access
*/
enum x86_pf_error_code {

@@ -41,6 +42,7 @@ enum x86_pf_error_code {
PF_USER = 1 << 2,
PF_RSVD = 1 << 3,
PF_INSTR = 1 << 4,
+ PF_PK = 1 << 5,
};

/*
@@ -916,6 +918,12 @@ static int spurious_fault_check(unsigned

if ((error_code & PF_INSTR) && !pte_exec(*pte))
return 0;
+ /*
+ * Note: We do not do lazy flushing on protection key
+ * changes, so no spurious fault will ever set PF_PK.
+ */
+ if ((error_code & PF_PK))
+ return 1;

return 1;
}
_