On Thursday 16 February 2017 03:16 AM, Andrew Morton wrote:
On Thu, 9 Feb 2017 08:30:59 +0530 "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:
With this our protnone becomes a present pte with READ/WRITE/EXEC bit cleared.
By default we also set _PAGE_PRIVILEGED on such pte. This is now used to help
us identify a protnone pte that as saved write bit. For such pte, we will clear
the _PAGE_PRIVILEGED bit. The pte still remain non-accessible from both user
and kernel.
I don't see how these patches differ from the ones which are presently
in -mm.
It helps to have a [0/n] email for a patch series and to put a version
number in there as well.
+#define pte_mk_savedwrite pte_mk_savedwrite
+static inline pte_t pte_mk_savedwrite(pte_t pte)
+{
+ /*
+ * Used by Autonuma subsystem to preserve the write bit
+ * while marking the pte PROT_NONE. Only allow this
+ * on PROT_NONE pte
+ */
+ VM_BUG_ON((pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX | _PAGE_PRIVILEGED)) !=
+ cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED));
+ return __pte(pte_val(pte) & ~_PAGE_PRIVILEGED);
+}
+
+#define pte_savedwrite pte_savedwrite
+static inline bool pte_savedwrite(pte_t pte)
+{
+ /*
+ * Saved write ptes are prot none ptes that doesn't have
+ * privileged bit sit. We mark prot none as one which has
+ * present and pviliged bit set and RWX cleared. To mark
+ * protnone which used to have _PAGE_WRITE set we clear
+ * the privileged bit.
+ */
+ return !(pte_raw(pte) & cpu_to_be64(_PAGE_RWX | _PAGE_PRIVILEGED));
+}
+
static inline pte_t pte_mkdevmap(pte_t pte)
{
return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
arch/powerpc/include/asm/book3s/64/pgtable.h doesn't have
pte_mkdevmap(). What tree are you patching here?
I did post a V2 of this for which you replied
https://lkml.kernel.org/r/20170214162008.bd592c747fc5e167c10ce7b8@xxxxxxxxxxxxxxxxxxxx
I actually found the issue with this patch. I will be sending V3 after
more testing.
-aneesh
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