[PATCH 05/25] powerpc: helper functions to initialize AMR, IAMR and UAMOR registers

[Ram Pai]

On Wed, Oct 18, 2017 at 02:24:03PM +1100, Balbir Singh wrote:
> On Fri,  8 Sep 2017 15:44:53 -0700
> Ram Pai <linuxram at us.ibm.com> wrote:
> 
> > Introduce  helper functions that can initialize the bits in the AMR,
> > IAMR and UAMOR register; the bits that correspond to the given pkey.
> > 
> > Signed-off-by: Ram Pai <linuxram at us.ibm.com>
> > ---
> >  arch/powerpc/include/asm/pkeys.h |    1 +
> >  arch/powerpc/mm/pkeys.c          |   46 ++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 47 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> > index 133f8c4..5a83ed7 100644
> > --- a/arch/powerpc/include/asm/pkeys.h
> > +++ b/arch/powerpc/include/asm/pkeys.h
> > @@ -26,6 +26,7 @@
> >  #define arch_max_pkey()  pkeys_total
> >  #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
> >  				VM_PKEY_BIT3 | VM_PKEY_BIT4)
> > +#define AMR_BITS_PER_PKEY 2
> >  
> >  #define pkey_alloc_mask(pkey) (0x1 << pkey)
> >  
> > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
> > index ebc9e84..178aa33 100644
> > --- a/arch/powerpc/mm/pkeys.c
> > +++ b/arch/powerpc/mm/pkeys.c
> > @@ -59,3 +59,49 @@ void __init pkey_initialize(void)
> >  	for (i = 2; i < (pkeys_total - os_reserved); i++)
> >  		initial_allocation_mask &= ~(0x1<<i);
> >  }
> > +
> > +#define PKEY_REG_BITS (sizeof(u64)*8)
> > +#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY))
> > +
> > +static inline void init_amr(int pkey, u8 init_bits)
> > +{
> > +	u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
> > +	u64 old_amr = read_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));
> > +
> 
> Do we need to check for reserved keys or that is at a layer above?

These routines blindly trust the caller. The assumption is the
system calls which are the gate-keepers for the keys validate
the keys before calling any lower level functions.

> 
> > +	write_amr(old_amr | new_amr_bits);
> > +}
> > +
> > +static inline void init_iamr(int pkey, u8 init_bits)
> > +{
> > +	u64 new_iamr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
> > +	u64 old_iamr = read_iamr() & ~((u64)(0x3ul) << pkeyshift(pkey));
> > +
> > +	write_iamr(old_iamr | new_iamr_bits);
> 
> Do we need to check for reserved keys here?
> 

ditto..

> > +}
> > +
> > +static void pkey_status_change(int pkey, bool enable)
> > +{
> > +	u64 old_uamor;
> > +
> > +	/* reset the AMR and IAMR bits for this key */
> > +	init_amr(pkey, 0x0);
> > +	init_iamr(pkey, 0x0);
> > +
> > +	/* enable/disable key */
> > +	old_uamor = read_uamor();
> > +	if (enable)
> > +		old_uamor |= (0x3ul << pkeyshift(pkey));
> > +	else
> > +		old_uamor &= ~(0x3ul << pkeyshift(pkey));
> > +	write_uamor(old_uamor);
> > +}
> > +
> > +void __arch_activate_pkey(int pkey)
> > +{
> > +	pkey_status_change(pkey, true);
> > +}
> > +
> > +void __arch_deactivate_pkey(int pkey)
> > +{
> > +	pkey_status_change(pkey, false);
> > +}
> 
> 
> Balbir Singh.

-- 
Ram Pai