From f2407ef3ba225665ee24965f69bc84435fb590cf Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 18 Jan 2018 17:50:37 -0800 Subject: [PATCH] powerpc: helper to validate key-access permissions of a pte helper function that checks if the read/write/execute is allowed on the pte. Signed-off-by: Ram Pai Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/book3s/64/pgtable.h | 2 ++ arch/powerpc/include/asm/pkeys.h | 9 +++++++++ arch/powerpc/mm/pkeys.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 39 insertions(+) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 26285fc17baf..449b797f8b7b 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -571,6 +571,8 @@ static inline int pte_present(pte_t pte) return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT)); } +extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute); + #define pte_access_permitted pte_access_permitted static inline bool pte_access_permitted(pte_t pte, bool write) { diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index a8ef7fa5360e..2298771b066b 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -71,6 +71,15 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) ((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL)); } +static inline u16 pte_to_pkey_bits(u64 pteflags) +{ + return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL)); +} + #define pkey_alloc_mask(pkey) (0x1 << pkey) #define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map) diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 010c90c1f5da..5071778fdd20 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -358,3 +358,31 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, /* Nothing to override. */ return vma_pkey(vma); } + +static bool pkey_access_permitted(int pkey, bool write, bool execute) +{ + int pkey_shift; + u64 amr; + + if (!pkey) + return true; + + if (!is_pkey_enabled(pkey)) + return true; + + pkey_shift = pkeyshift(pkey); + if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift))) + return true; + + amr = read_amr(); /* Delay reading amr until 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 (static_branch_likely(&pkey_disabled)) + return true; + + return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute); +} -- 2.11.0