Subject: Re: [PATCH 02/25] powerpc: define an additional vma bit for protection keys.

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 23 Oct 2017 14:58:55 +0530

"Aneesh Kumar K.V" <[email-masked]> writes:

> Ram Pai <[email-masked]> writes:
>
>> powerpc needs an additional vma bit to support 32 keys.
>> Till the additional vma bit lands in include/linux/mm.h
>> we have to define  it  in powerpc specific header file.
>> This is  needed to get pkeys working on power.
>>
>> Signed-off-by: Ram Pai <[email-masked]>
>> ---
>>  arch/powerpc/include/asm/pkeys.h |   18 ++++++++++++++++++
>>  1 files changed, 18 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
>> index c02305a..44e01a2 100644
>> --- a/arch/powerpc/include/asm/pkeys.h
>> +++ b/arch/powerpc/include/asm/pkeys.h
>> @@ -3,6 +3,24 @@
>>
>>  extern bool pkey_inited;
>>  extern bool pkey_execute_disable_support;
>> +
>> +/*
>> + * powerpc needs an additional vma bit to support 32 keys.
>> + * Till the additional vma bit lands in include/linux/mm.h
>> + * we have to carry the hunk below. This is  needed to get
>> + * pkeys working on power. -- Ram
>> + */
>> +#ifndef VM_HIGH_ARCH_BIT_4
>> +#define VM_HIGH_ARCH_BIT_4	36
>> +#define VM_HIGH_ARCH_4	BIT(VM_HIGH_ARCH_BIT_4)
>> +#define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
>> +#define VM_PKEY_BIT0	VM_HIGH_ARCH_0
>> +#define VM_PKEY_BIT1	VM_HIGH_ARCH_1
>> +#define VM_PKEY_BIT2	VM_HIGH_ARCH_2
>> +#define VM_PKEY_BIT3	VM_HIGH_ARCH_3
>> +#define VM_PKEY_BIT4	VM_HIGH_ARCH_4
>> +#endif
>> +
>>  #define ARCH_VM_PKEY_FLAGS 0
>
> Do we want them in pkeys.h ? Even if they are arch specific for the
> existing ones we have them in include/linux/mm.h. IIUC, vmflags details
> are always in mm.h? This will be the first exception to that?

Also can we move that 

#if defined (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)
# define VM_PKEY_SHIFT	VM_HIGH_ARCH_BIT_0
# define VM_PKEY_BIT0	VM_HIGH_ARCH_0	/* A protection key is a 4-bit value */
# define VM_PKEY_BIT1	VM_HIGH_ARCH_1
# define VM_PKEY_BIT2	VM_HIGH_ARCH_2
# define VM_PKEY_BIT3	VM_HIGH_ARCH_3
#endif

to

#if defined (CONFIG_ARCH_HAS_PKEYS)
# define VM_PKEY_SHIFT	VM_HIGH_ARCH_BIT_0
# define VM_PKEY_BIT0	VM_HIGH_ARCH_0	/* A protection key is a 4-bit value */
# define VM_PKEY_BIT1	VM_HIGH_ARCH_1
# define VM_PKEY_BIT2	VM_HIGH_ARCH_2
# define VM_PKEY_BIT3	VM_HIGH_ARCH_3
#endif

And then later update the generic to handle PKEY_BIT4?

-aneesh