On Wed, Oct 18, 2017 at 03:27:33PM +1100, Balbir Singh wrote:
> On Fri, 8 Sep 2017 15:45:00 -0700
> Ram Pai <linux...@us.ibm.com> wrote:
>
> > arch-independent code expects the arch to map
> > a pkey into the vma's protection bit setting.
> > The patch provides that ability.
> >
> > Signed-off-by: Ram Pai <linux...@us.ibm.com>
> > ---
> > arch/powerpc/include/asm/mman.h | 8 +++++++-
> > arch/powerpc/include/asm/pkeys.h | 18 ++++++++++++++++++
> > 2 files changed, 25 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/mman.h
> > b/arch/powerpc/include/asm/mman.h
> > index 30922f6..067eec2 100644
> > --- a/arch/powerpc/include/asm/mman.h
> > +++ b/arch/powerpc/include/asm/mman.h
> > @@ -13,6 +13,7 @@
> >
> > #include <asm/cputable.h>
> > #include <linux/mm.h>
> > +#include <linux/pkeys.h>
> > #include <asm/cpu_has_feature.h>
> >
> > /*
> > @@ -22,7 +23,12 @@
> > static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
> > unsigned long pkey)
> > {
> > - return (prot & PROT_SAO) ? VM_SAO : 0;
> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> > + return (((prot & PROT_SAO) ? VM_SAO : 0) |
> > + pkey_to_vmflag_bits(pkey));
> > +#else
> > + return ((prot & PROT_SAO) ? VM_SAO : 0);
> > +#endif
> > }
> > #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot,
> > pkey)
> >
> > diff --git a/arch/powerpc/include/asm/pkeys.h
> > b/arch/powerpc/include/asm/pkeys.h
> > index 0cf115f..f13e913 100644
> > --- a/arch/powerpc/include/asm/pkeys.h
> > +++ b/arch/powerpc/include/asm/pkeys.h
> > @@ -23,6 +23,24 @@
> > #define VM_PKEY_BIT4 VM_HIGH_ARCH_4
> > #endif
> >
> > +/* override any generic PKEY Permission defines */
> > +#define PKEY_DISABLE_EXECUTE 0x4
> > +#define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS |\
> > + PKEY_DISABLE_WRITE |\
> > + PKEY_DISABLE_EXECUTE)
> > +
> > +static inline u64 pkey_to_vmflag_bits(u16 pkey)
> > +{
> > + if (!pkey_inited)
> > + return 0x0UL;
> > +
> > + return (((pkey & 0x1UL) ? VM_PKEY_BIT0 : 0x0UL) |
> > + ((pkey & 0x2UL) ? VM_PKEY_BIT1 : 0x0UL) |
> > + ((pkey & 0x4UL) ? VM_PKEY_BIT2 : 0x0UL) |
> > + ((pkey & 0x8UL) ? VM_PKEY_BIT3 : 0x0UL) |
> > + ((pkey & 0x10UL) ? VM_PKEY_BIT4 : 0x0UL));
> > +}
>
> Assuming that there is a linear order between VM_PKEY_BIT4 to
> VM_PKEY_BIT0, the conditional checks can be removed
>
> (pkey & 0x1fUL) << VM_PKEY_BIT0?
yes. currently the are linear. But I am afraid it will break without
notice someday when someone decides to change the values of VM_PKEY_BITx to
be non-contiguous. I can put a BUILD_ASSERTION I suppose. But thought
this will be safe.
RP
>
>
> Balbir Singh
--
Ram Pai
