On 31/07/2017 02:12, Ram Pai wrote:
> helper function that checks if the read/write/execute is allowed
> on the pte.
>
> Signed-off-by: Ram Pai <linux...@us.ibm.com>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 4 +++
> arch/powerpc/include/asm/pkeys.h | 12 +++++++++++
> arch/powerpc/mm/pkeys.c | 28
> ++++++++++++++++++++++++++
> 3 files changed, 44 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h
> b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 060a1b2..2bec0f6 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -477,6 +477,10 @@ static inline void write_uamor(u64 value)
> mtspr(SPRN_UAMOR, value);
> }
>
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute);
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
> #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
> static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> unsigned long addr, pte_t *ptep)
> diff --git a/arch/powerpc/include/asm/pkeys.h
> b/arch/powerpc/include/asm/pkeys.h
> index 4b7e3f4..ba7bff6 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -85,6 +85,18 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
> ((pteflags & H_PAGE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
> }
>
> +static inline u16 pte_to_pkey_bits(u64 pteflags)
> +{
> + if (!pkey_inited)
> + return 0x0UL;
Is it really needed to make such a check in this low level function ?
The only caller is already checking for pkey_inited before making the call.
> +
> + return (((pteflags & H_PAGE_PKEY_BIT0) ? 0x10 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT1) ? 0x8 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT2) ? 0x4 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT3) ? 0x2 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT4) ? 0x1 : 0x0UL));
> +}
> +
> #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
> diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
> index edcbf48..8d756ef 100644
> --- a/arch/powerpc/mm/pkeys.c
> +++ b/arch/powerpc/mm/pkeys.c
> @@ -201,3 +201,31 @@ int __arch_override_mprotect_pkey(struct vm_area_struct
> *vma, int prot,
> */
> return vma_pkey(vma);
> }
> +
> +static bool pkey_access_permitted(int pkey, bool write, bool execute)
> +{
> + int pkey_shift;
> + u64 amr;
> +
> + if (!pkey)
> + return true;
> +
> + pkey_shift = pkeyshift(pkey);
> + if (!(read_uamor() & (0x3UL << pkey_shift)))
> + return true;
> +
> + if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift)))
> + return true;
> +
> + amr = read_amr(); /* delay reading amr uptil absolutely needed*/
> + return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) ||
> + (write && !(amr & (AMR_WR_BIT << pkey_shift))));
> +}
> +
> +bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
> +{
> + if (!pkey_inited)
> + return true;
> + return pkey_access_permitted(pte_to_pkey_bits(pte),
> + write, execute);
> +}
>
