Ram Pai <linux...@us.ibm.com> writes:
> 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 <linux...@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));
> +
> + 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);
> +}
> +
> +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);
> +}
That one is confusing, we discussed this outside the list, but want to
bring the list to further discussion. So now the core kernel request
for a key via mm_pkey_alloc(). Why not do the below there
static inline int mm_pkey_alloc(struct mm_struct *mm)
{
/*
* Note: this is the one and only place we make sure
* that the pkey is valid as far as the hardware is
* concerned. The rest of the kernel trusts that
* only good, valid pkeys come out of here.
*/
u32 all_pkeys_mask = (u32)(~(0x0));
int ret;
if (!pkey_inited)
return -1;
/*
* Are we out of pkeys? We must handle this specially
* because ffz() behavior is undefined if there are no
* zeros.
*/
if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
return -1;
ret = ffz((u32)mm_pkey_allocation_map(mm));
mm_set_pkey_allocated(mm, ret);
return ret;
}
your mm_pkey_allocation_map() should have the keys specified in AMOR and
UAMOR marked as allocatied. It is in use by hypervisor and OS respectively.
There is no need of __arch_activate_key() etc. and by default if the OS
has not requested for a key for its internal use UAMOR should be
0xFFFFFFFF and that AMOR value you derive from the device tree based of
what keys hypervisor has reserved.
-aneesh
