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 <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 26285fc17bafea2c9d4569baf22a274b70d389c7..449b797f8b7b5cd037bc3267534daeb6df309488 100644 (file)
--- 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 a8ef7fa5360e3832b5a8c5304750608dd8ac49fd..2298771b066b16fcde0de2c1f150b1c86f7ddb6f 100644 (file)
--- 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 010c90c1f5dacb8d36a2e4e967df0dc89f893afc..5071778fdd20482992f31a1a3ed24cdfb7112809 100644 (file)
--- 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);
+}