diff options
| -rw-r--r-- | arch/powerpc/mm/pkeys.c | 63 |
1 files changed, 18 insertions, 45 deletions
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 04f65974e97b..0e7810ccd1ae 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -18,6 +18,7 @@ u32 initial_allocation_mask; /* Bits set for reserved keys */ u64 pkey_amr_mask; /* Bits in AMR not to be touched */ u64 pkey_iamr_mask; /* Bits in AMR not to be touched */ u64 pkey_uamor_mask; /* Bits in UMOR not to be touched */ +int execute_only_key = 2; #define AMR_BITS_PER_PKEY 2 #define AMR_RD_BIT 0x1UL @@ -120,7 +121,8 @@ int pkey_initialize(void) #else os_reserved = 0; #endif - initial_allocation_mask = (0x1 << 0) | (0x1 << 1); + initial_allocation_mask = (0x1 << 0) | (0x1 << 1) | + (0x1 << execute_only_key); /* register mask is in BE format */ pkey_amr_mask = ~0x0ul; @@ -128,9 +130,11 @@ int pkey_initialize(void) pkey_iamr_mask = ~0x0ul; pkey_iamr_mask &= ~(0x3ul << pkeyshift(0)); + pkey_iamr_mask &= ~(0x3ul << pkeyshift(execute_only_key)); pkey_uamor_mask = ~0x0ul; pkey_uamor_mask &= ~(0x3ul << pkeyshift(0)); + pkey_uamor_mask &= ~(0x3ul << pkeyshift(execute_only_key)); /* mark the rest of the keys as reserved and hence unavailable */ for (i = (pkeys_total - os_reserved); i < pkeys_total; i++) { @@ -138,6 +142,17 @@ int pkey_initialize(void) pkey_uamor_mask &= ~(0x3ul << pkeyshift(i)); } + if (unlikely((pkeys_total - os_reserved) <= execute_only_key)) { + /* + * Insufficient number of keys to support + * execute only key. Mark it unavailable. + * Any AMR, UAMOR, IAMR bit set for + * this key is irrelevant since this key + * can never be allocated. + */ + execute_only_key = -1; + } + return 0; } @@ -148,8 +163,7 @@ void pkey_mm_init(struct mm_struct *mm) if (static_branch_likely(&pkey_disabled)) return; mm_pkey_allocation_map(mm) = initial_allocation_mask; - /* -1 means unallocated or invalid */ - mm->context.execute_only_pkey = -1; + mm->context.execute_only_pkey = execute_only_key; } static inline u64 read_amr(void) @@ -301,48 +315,7 @@ static inline bool pkey_allows_readwrite(int pkey) int __execute_only_pkey(struct mm_struct *mm) { - bool need_to_set_mm_pkey = false; - int execute_only_pkey = mm->context.execute_only_pkey; - int ret; - - /* Do we need to assign a pkey for mm's execute-only maps? */ - if (execute_only_pkey == -1) { - /* Go allocate one to use, which might fail */ - execute_only_pkey = mm_pkey_alloc(mm); - if (execute_only_pkey < 0) - return -1; - need_to_set_mm_pkey = true; - } - - /* - * We do not want to go through the relatively costly dance to set AMR - * if we do not need to. Check it first and assume that if the - * execute-only pkey is readwrite-disabled than we do not have to set it - * ourselves. - */ - if (!need_to_set_mm_pkey && !pkey_allows_readwrite(execute_only_pkey)) - return execute_only_pkey; - - /* - * Set up AMR so that it denies access for everything other than - * execution. - */ - ret = __arch_set_user_pkey_access(current, execute_only_pkey, - PKEY_DISABLE_ACCESS | - PKEY_DISABLE_WRITE); - /* - * If the AMR-set operation failed somehow, just return 0 and - * effectively disable execute-only support. - */ - if (ret) { - mm_pkey_free(mm, execute_only_pkey); - return -1; - } - - /* We got one, store it and use it from here on out */ - if (need_to_set_mm_pkey) - mm->context.execute_only_pkey = execute_only_pkey; - return execute_only_pkey; + return mm->context.execute_only_pkey; } static inline bool vma_is_pkey_exec_only(struct vm_area_struct *vma) |