diff options
Diffstat (limited to 'arch/powerpc/mm/book3s64/pkeys.c')
| -rw-r--r-- | arch/powerpc/mm/book3s64/pkeys.c | 300 |
1 files changed, 171 insertions, 129 deletions
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c index d174106bab67..69a6b87f2bb4 100644 --- a/arch/powerpc/mm/book3s64/pkeys.c +++ b/arch/powerpc/mm/book3s64/pkeys.c @@ -10,58 +10,103 @@ #include <asm/mmu.h> #include <asm/setup.h> #include <linux/pkeys.h> -#include <linux/of_device.h> +#include <linux/of_fdt.h> -DEFINE_STATIC_KEY_TRUE(pkey_disabled); -int pkeys_total; /* Total pkeys as per device tree */ -u32 initial_allocation_mask; /* Bits set for the initially allocated keys */ -u32 reserved_allocation_mask; /* Bits set for reserved keys */ -static bool pkey_execute_disable_supported; -static bool pkeys_devtree_defined; /* property exported by device tree */ -static u64 pkey_amr_mask; /* Bits in AMR not to be touched */ -static u64 pkey_iamr_mask; /* Bits in AMR not to be touched */ -static u64 pkey_uamor_mask; /* Bits in UMOR not to be touched */ +int num_pkey; /* Max number of pkeys supported */ +/* + * Keys marked in the reservation list cannot be allocated by userspace + */ +u32 reserved_allocation_mask __ro_after_init; + +/* Bits set for the initially allocated keys */ +static u32 initial_allocation_mask __ro_after_init; + +/* + * Even if we allocate keys with sys_pkey_alloc(), we need to make sure + * other thread still find the access denied using the same keys. + */ +static u64 default_amr = ~0x0UL; +static u64 default_iamr = 0x5555555555555555UL; +u64 default_uamor __ro_after_init; +/* + * Key used to implement PROT_EXEC mmap. Denies READ/WRITE + * We pick key 2 because 0 is special key and 1 is reserved as per ISA. + */ static int execute_only_key = 2; +static bool pkey_execute_disable_supported; + #define AMR_BITS_PER_PKEY 2 #define AMR_RD_BIT 0x1UL #define AMR_WR_BIT 0x2UL #define IAMR_EX_BIT 0x1UL -#define PKEY_REG_BITS (sizeof(u64)*8) +#define PKEY_REG_BITS (sizeof(u64) * 8) #define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY)) -static void scan_pkey_feature(void) +static int __init dt_scan_storage_keys(unsigned long node, + const char *uname, int depth, + void *data) { - u32 vals[2]; - struct device_node *cpu; + const char *type = of_get_flat_dt_prop(node, "device_type", NULL); + const __be32 *prop; + int *pkeys_total = (int *) data; - cpu = of_find_node_by_type(NULL, "cpu"); - if (!cpu) - return; + /* We are scanning "cpu" nodes only */ + if (type == NULL || strcmp(type, "cpu") != 0) + return 0; - if (of_property_read_u32_array(cpu, - "ibm,processor-storage-keys", vals, 2)) - return; + prop = of_get_flat_dt_prop(node, "ibm,processor-storage-keys", NULL); + if (!prop) + return 0; + *pkeys_total = be32_to_cpu(prop[0]); + return 1; +} + +static int scan_pkey_feature(void) +{ + int ret; + int pkeys_total = 0; /* - * Since any pkey can be used for data or execute, we will just treat - * all keys as equal and track them as one entity. + * Pkey is not supported with Radix translation. */ - pkeys_total = vals[0]; - pkeys_devtree_defined = true; -} + if (early_radix_enabled()) + return 0; -static inline bool pkey_mmu_enabled(void) -{ - if (firmware_has_feature(FW_FEATURE_LPAR)) - return pkeys_total; - else - return cpu_has_feature(CPU_FTR_PKEY); + /* + * Only P7 and above supports SPRN_AMR update with MSR[PR] = 1 + */ + if (!early_cpu_has_feature(CPU_FTR_ARCH_206)) + return 0; + + ret = of_scan_flat_dt(dt_scan_storage_keys, &pkeys_total); + if (ret == 0) { + /* + * Let's assume 32 pkeys on P8/P9 bare metal, if its not defined by device + * tree. We make this exception since some version of skiboot forgot to + * expose this property on power8/9. + */ + if (!firmware_has_feature(FW_FEATURE_LPAR)) { + unsigned long pvr = mfspr(SPRN_PVR); + + if (PVR_VER(pvr) == PVR_POWER8 || PVR_VER(pvr) == PVR_POWER8E || + PVR_VER(pvr) == PVR_POWER8NVL || PVR_VER(pvr) == PVR_POWER9) + pkeys_total = 32; + } + } + + /* + * Adjust the upper limit, based on the number of bits supported by + * arch-neutral code. + */ + pkeys_total = min_t(int, pkeys_total, + ((ARCH_VM_PKEY_FLAGS >> VM_PKEY_SHIFT) + 1)); + return pkeys_total; } -static int pkey_initialize(void) +void __init pkey_early_init_devtree(void) { - int os_reserved, i; + int pkeys_total, i; /* * We define PKEY_DISABLE_EXECUTE in addition to the arch-neutral @@ -80,31 +125,14 @@ static int pkey_initialize(void) != (sizeof(u64) * BITS_PER_BYTE)); /* scan the device tree for pkey feature */ - scan_pkey_feature(); - - /* - * Let's assume 32 pkeys on P8 bare metal, if its not defined by device - * tree. We make this exception since skiboot forgot to expose this - * property on power8. - */ - if (!pkeys_devtree_defined && !firmware_has_feature(FW_FEATURE_LPAR) && - cpu_has_feature(CPU_FTRS_POWER8)) - pkeys_total = 32; - - /* - * Adjust the upper limit, based on the number of bits supported by - * arch-neutral code. - */ - pkeys_total = min_t(int, pkeys_total, - ((ARCH_VM_PKEY_FLAGS >> VM_PKEY_SHIFT)+1)); + pkeys_total = scan_pkey_feature(); + if (!pkeys_total) + goto out; - if (!pkey_mmu_enabled() || radix_enabled() || !pkeys_total) - static_branch_enable(&pkey_disabled); - else - static_branch_disable(&pkey_disabled); + /* Allow all keys to be modified by default */ + default_uamor = ~0x0UL; - if (static_branch_likely(&pkey_disabled)) - return 0; + cur_cpu_spec->mmu_features |= MMU_FTR_PKEY; /* * The device tree cannot be relied to indicate support for @@ -118,53 +146,86 @@ static int pkey_initialize(void) #ifdef CONFIG_PPC_4K_PAGES /* * The OS can manage only 8 pkeys due to its inability to represent them - * in the Linux 4K PTE. + * in the Linux 4K PTE. Mark all other keys reserved. */ - os_reserved = pkeys_total - 8; + num_pkey = min(8, pkeys_total); #else - os_reserved = 0; + num_pkey = pkeys_total; #endif - /* Bits are in LE format. */ - reserved_allocation_mask = (0x1 << 1) | (0x1 << execute_only_key); - - /* register mask is in BE format */ - pkey_amr_mask = ~0x0ul; - pkey_amr_mask &= ~(0x3ul << pkeyshift(0)); - - 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++) { - reserved_allocation_mask |= (0x1 << i); - pkey_uamor_mask &= ~(0x3ul << pkeyshift(i)); - } - initial_allocation_mask = reserved_allocation_mask | (0x1 << 0); - - if (unlikely((pkeys_total - os_reserved) <= execute_only_key)) { + if (unlikely(num_pkey <= execute_only_key) || !pkey_execute_disable_supported) { /* * 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; + } else { + /* + * Mark the execute_only_pkey as not available for + * user allocation via pkey_alloc. + */ + reserved_allocation_mask |= (0x1 << execute_only_key); + + /* + * Deny READ/WRITE for execute_only_key. + * Allow execute in IAMR. + */ + default_amr |= (0x3ul << pkeyshift(execute_only_key)); + default_iamr &= ~(0x1ul << pkeyshift(execute_only_key)); + + /* + * Clear the uamor bits for this key. + */ + default_uamor &= ~(0x3ul << pkeyshift(execute_only_key)); } - return 0; -} + /* + * Allow access for only key 0. And prevent any other modification. + */ + default_amr &= ~(0x3ul << pkeyshift(0)); + default_iamr &= ~(0x1ul << pkeyshift(0)); + default_uamor &= ~(0x3ul << pkeyshift(0)); + /* + * key 0 is special in that we want to consider it an allocated + * key which is preallocated. We don't allow changing AMR bits + * w.r.t key 0. But one can pkey_free(key0) + */ + initial_allocation_mask |= (0x1 << 0); -arch_initcall(pkey_initialize); + /* + * key 1 is recommended not to be used. PowerISA(3.0) page 1015, + * programming note. + */ + reserved_allocation_mask |= (0x1 << 1); + default_uamor &= ~(0x3ul << pkeyshift(1)); + + /* + * Prevent the usage of OS reserved keys. Update UAMOR + * for those keys. Also mark the rest of the bits in the + * 32 bit mask as reserved. + */ + for (i = num_pkey; i < 32 ; i++) { + reserved_allocation_mask |= (0x1 << i); + default_uamor &= ~(0x3ul << pkeyshift(i)); + } + /* + * Prevent the allocation of reserved keys too. + */ + initial_allocation_mask |= reserved_allocation_mask; + + pr_info("Enabling pkeys with max key count %d\n", num_pkey); +out: + /* + * Setup uamor on boot cpu + */ + mtspr(SPRN_UAMOR, default_uamor); + + return; +} void pkey_mm_init(struct mm_struct *mm) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return; mm_pkey_allocation_map(mm) = initial_allocation_mask; mm->context.execute_only_pkey = execute_only_key; @@ -196,30 +257,6 @@ static inline void write_iamr(u64 value) mtspr(SPRN_IAMR, value); } -static inline u64 read_uamor(void) -{ - return mfspr(SPRN_UAMOR); -} - -static inline void write_uamor(u64 value) -{ - mtspr(SPRN_UAMOR, value); -} - -static bool is_pkey_enabled(int pkey) -{ - u64 uamor = read_uamor(); - u64 pkey_bits = 0x3ul << pkeyshift(pkey); - u64 uamor_pkey_bits = (uamor & pkey_bits); - - /* - * Both the bits in UAMOR corresponding to the key should be set or - * reset. - */ - WARN_ON(uamor_pkey_bits && (uamor_pkey_bits != pkey_bits)); - return !!(uamor_pkey_bits); -} - static inline void init_amr(int pkey, u8 init_bits) { u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey)); @@ -245,8 +282,18 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, { u64 new_amr_bits = 0x0ul; u64 new_iamr_bits = 0x0ul; + u64 pkey_bits, uamor_pkey_bits; + + /* + * Check whether the key is disabled by UAMOR. + */ + pkey_bits = 0x3ul << pkeyshift(pkey); + uamor_pkey_bits = (default_uamor & pkey_bits); - if (!is_pkey_enabled(pkey)) + /* + * Both the bits in UAMOR corresponding to the key should be set + */ + if (uamor_pkey_bits != pkey_bits) return -EINVAL; if (init_val & PKEY_DISABLE_EXECUTE) { @@ -268,7 +315,7 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, void thread_pkey_regs_save(struct thread_struct *thread) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return; /* @@ -276,38 +323,33 @@ void thread_pkey_regs_save(struct thread_struct *thread) */ thread->amr = read_amr(); thread->iamr = read_iamr(); - thread->uamor = read_uamor(); } void thread_pkey_regs_restore(struct thread_struct *new_thread, struct thread_struct *old_thread) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return; if (old_thread->amr != new_thread->amr) write_amr(new_thread->amr); if (old_thread->iamr != new_thread->iamr) write_iamr(new_thread->iamr); - if (old_thread->uamor != new_thread->uamor) - write_uamor(new_thread->uamor); } void thread_pkey_regs_init(struct thread_struct *thread) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return; - thread->amr = pkey_amr_mask; - thread->iamr = pkey_iamr_mask; - thread->uamor = pkey_uamor_mask; + thread->amr = default_amr; + thread->iamr = default_iamr; - write_uamor(pkey_uamor_mask); - write_amr(pkey_amr_mask); - write_iamr(pkey_iamr_mask); + write_amr(default_amr); + write_iamr(default_iamr); } -int __execute_only_pkey(struct mm_struct *mm) +int execute_only_pkey(struct mm_struct *mm) { return mm->context.execute_only_pkey; } @@ -366,7 +408,7 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute) bool arch_pte_access_permitted(u64 pte, bool write, bool execute) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return true; return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute); @@ -383,7 +425,7 @@ bool arch_pte_access_permitted(u64 pte, bool write, bool execute) bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, bool execute, bool foreign) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return true; /* * Do not enforce our key-permissions on a foreign vma. @@ -396,7 +438,7 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm) { - if (static_branch_likely(&pkey_disabled)) + if (!mmu_has_feature(MMU_FTR_PKEY)) return; /* Duplicate the oldmm pkey state in mm: */ |