Re: [PATCH V2 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write

[Michael Ellerman]

"Aneesh Kumar K.V"  writes:

> Michael Ellerman  writes:
>
>> "Aneesh Kumar K.V"  writes:
>>> diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h 
>>> b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>>> index 0735d5a8049f..8720a406bbbe 100644
>>> --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>>> +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>>> @@ -16,6 +16,9 @@
>>>  #include 
>>>  #include 
>>>  
>>> +#ifndef __ASSEMBLY__
>>> +#include 
>>> +#endif
>>
>> I assume that's for the VM_BUG_ON() you add below. But if so wouldn't
>> the #include be better placed in book3s/64/pgtable.h also?
>
> mmu-hash.h has got a hack that is explained below
>
> #ifndef __ASSEMBLY__
> #include 
> #endif
> /*
>  * This is necessary to get the definition of PGTABLE_RANGE which we
>  * need for various slices related matters. Note that this isn't the
>  * complete pgtable.h but only a portion of it.
>  */
> #include 
>
> This is the only place where we do that book3s/64/pgtable.h include this
> way. Everybody should include asm/pgable.h which picks the righ version
> based on different config option.

I don't understand how that is related.

If you're adding a VM_BUG_ON() in book3s/64/pgtable.h, why isn't the
include of mmdebug.h in that file also?

cheers

Re: [PATCH V2 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write

[Aneesh Kumar K.V]

Michael Ellerman  writes:

> "Aneesh Kumar K.V"  writes:
>> diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h 
>> b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> index 0735d5a8049f..8720a406bbbe 100644
>> --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> @@ -16,6 +16,9 @@
>>  #include 
>>  #include 
>>  
>> +#ifndef __ASSEMBLY__
>> +#include 
>> +#endif
>
> I assume that's for the VM_BUG_ON() you add below. But if so wouldn't
> the #include be better placed in book3s/64/pgtable.h also?

mmu-hash.h has got a hack that is explained below

#ifndef __ASSEMBLY__
#include 
#endif
/*
 * This is necessary to get the definition of PGTABLE_RANGE which we
 * need for various slices related matters. Note that this isn't the
 * complete pgtable.h but only a portion of it.
 */
#include 

This is the only place where we do that book3s/64/pgtable.h include this
way. Everybody should include asm/pgable.h which picks the righ version
based on different config option.

#
>
>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
>> b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> index fef738229a68..c684ef6cbd10 100644
>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> @@ -512,6 +512,32 @@ static inline pte_t pte_mkhuge(pte_t pte)
>>  return pte;
>>  }
>>  
>> +#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);
>> +}
>> +
>
>
> cheers

-aneesh

Re: [PATCH V2 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write

[Michael Ellerman]

"Aneesh Kumar K.V"  writes:
> diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h 
> b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> index 0735d5a8049f..8720a406bbbe 100644
> --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> @@ -16,6 +16,9 @@
>  #include 
>  #include 
>  
> +#ifndef __ASSEMBLY__
> +#include 
> +#endif

I assume that's for the VM_BUG_ON() you add below. But if so wouldn't
the #include be better placed in book3s/64/pgtable.h also?

> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
> b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index fef738229a68..c684ef6cbd10 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -512,6 +512,32 @@ static inline pte_t pte_mkhuge(pte_t pte)
>   return pte;
>  }
>  
> +#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);
> +}
> +


cheers

[PATCH V2 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write

[Aneesh Kumar K.V]

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.

Acked-By: Michael Neuling 
Signed-off-by: Aneesh Kumar K.V 
---
 arch/powerpc/include/asm/book3s/64/mmu-hash.h |  3 +++
 arch/powerpc/include/asm/book3s/64/pgtable.h  | 32 +--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h 
b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 0735d5a8049f..8720a406bbbe 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -16,6 +16,9 @@
 #include 
 #include 
 
+#ifndef __ASSEMBLY__
+#include 
+#endif
 /*
  * This is necessary to get the definition of PGTABLE_RANGE which we
  * need for various slices related matters. Note that this isn't the
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
b/arch/powerpc/include/asm/book3s/64/pgtable.h
index fef738229a68..c684ef6cbd10 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -441,8 +441,8 @@ static inline pte_t pte_clear_soft_dirty(pte_t pte)
  */
 static inline int pte_protnone(pte_t pte)
 {
-   return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED)) ==
-   cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED);
+   return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX)) ==
+   cpu_to_be64(_PAGE_PRESENT);
 }
 #endif /* CONFIG_NUMA_BALANCING */
 
@@ -512,6 +512,32 @@ static inline pte_t pte_mkhuge(pte_t pte)
return pte;
 }
 
+#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_modify(pte_t pte, pgprot_t newprot)
 {
/* FIXME!! check whether this need to be a conditional */
@@ -873,6 +899,7 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
 #define pmd_mkclean(pmd)   pte_pmd(pte_mkclean(pmd_pte(pmd)))
 #define pmd_mkyoung(pmd)   pte_pmd(pte_mkyoung(pmd_pte(pmd)))
 #define pmd_mkwrite(pmd)   pte_pmd(pte_mkwrite(pmd_pte(pmd)))
+#define pmd_mk_savedwrite(pmd) pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))
 
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 #define pmd_soft_dirty(pmd)pte_soft_dirty(pmd_pte(pmd))
@@ -889,6 +916,7 @@ static inline int pmd_protnone(pmd_t pmd)
 
 #define __HAVE_ARCH_PMD_WRITE
 #define pmd_write(pmd) pte_write(pmd_pte(pmd))
+#define pmd_savedwrite(pmd)pte_savedwrite(pmd_pte(pmd))
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
-- 
2.7.4