[PATCH 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Thu Feb 16 13:12:46 AEDT 2017
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 at linux.vnet.ibm.com> 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
I actually found the issue with this patch. I will be sending V3 after
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