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Diffstat (limited to 'arch/powerpc/include/asm/pkeys.h')
| -rw-r--r-- | arch/powerpc/include/asm/pkeys.h | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h new file mode 100644 index 000000000..20ebf153c --- /dev/null +++ b/arch/powerpc/include/asm/pkeys.h @@ -0,0 +1,209 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * PowerPC Memory Protection Keys management + * + * Copyright 2017, Ram Pai, IBM Corporation. + */ + +#ifndef _ASM_POWERPC_KEYS_H +#define _ASM_POWERPC_KEYS_H + +#include <linux/jump_label.h> +#include <asm/firmware.h> + +DECLARE_STATIC_KEY_TRUE(pkey_disabled); +extern int pkeys_total; /* total pkeys as per device tree */ +extern u32 initial_allocation_mask; /* bits set for the initially allocated keys */ +extern u32 reserved_allocation_mask; /* bits set for reserved keys */ + +#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \ + VM_PKEY_BIT3 | VM_PKEY_BIT4) + +/* Override any generic PKEY permission defines */ +#define PKEY_DISABLE_EXECUTE 0x4 +#define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS | \ + PKEY_DISABLE_WRITE | \ + PKEY_DISABLE_EXECUTE) + +static inline u64 pkey_to_vmflag_bits(u16 pkey) +{ + return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS); +} + +static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags) +{ + if (static_branch_likely(&pkey_disabled)) + return 0x0UL; + + return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) | + ((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) | + ((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) | + ((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) | + ((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL)); +} + +static inline int vma_pkey(struct vm_area_struct *vma) +{ + if (static_branch_likely(&pkey_disabled)) + return 0; + return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; +} + +#define arch_max_pkey() pkeys_total + +static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) +{ + return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) | + ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) | + ((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) + +#define __mm_pkey_allocated(mm, pkey) { \ + mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \ +} + +#define __mm_pkey_free(mm, pkey) { \ + mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey); \ +} + +#define __mm_pkey_is_allocated(mm, pkey) \ + (mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey)) + +#define __mm_pkey_is_reserved(pkey) (reserved_allocation_mask & \ + pkey_alloc_mask(pkey)) + +static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) +{ + if (pkey < 0 || pkey >= arch_max_pkey()) + return false; + + /* Reserved keys are never allocated. */ + if (__mm_pkey_is_reserved(pkey)) + return false; + + return __mm_pkey_is_allocated(mm, pkey); +} + +/* + * Returns a positive, 5-bit key on success, or -1 on failure. + * Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and + * mm_pkey_free(). + */ +static inline int mm_pkey_alloc(struct mm_struct *mm) +{ + /* + * Note: this is the one and only place we make sure that the pkey is + * valid as far as the hardware is concerned. The rest of the kernel + * trusts that only good, valid pkeys come out of here. + */ + u32 all_pkeys_mask = (u32)(~(0x0)); + int ret; + + if (static_branch_likely(&pkey_disabled)) + return -1; + + /* + * Are we out of pkeys? We must handle this specially because ffz() + * behavior is undefined if there are no zeros. + */ + if (mm_pkey_allocation_map(mm) == all_pkeys_mask) + return -1; + + ret = ffz((u32)mm_pkey_allocation_map(mm)); + __mm_pkey_allocated(mm, ret); + + return ret; +} + +static inline int mm_pkey_free(struct mm_struct *mm, int pkey) +{ + if (static_branch_likely(&pkey_disabled)) + return -1; + + if (!mm_pkey_is_allocated(mm, pkey)) + return -EINVAL; + + __mm_pkey_free(mm, pkey); + + return 0; +} + +/* + * Try to dedicate one of the protection keys to be used as an + * execute-only protection key. + */ +extern int __execute_only_pkey(struct mm_struct *mm); +static inline int execute_only_pkey(struct mm_struct *mm) +{ + if (static_branch_likely(&pkey_disabled)) + return -1; + + return __execute_only_pkey(mm); +} + +extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, + int prot, int pkey); +static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, + int prot, int pkey) +{ + if (static_branch_likely(&pkey_disabled)) + return 0; + + /* + * Is this an mprotect_pkey() call? If so, never override the value that + * came from the user. + */ + if (pkey != -1) + return pkey; + + return __arch_override_mprotect_pkey(vma, prot, pkey); +} + +extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, + unsigned long init_val); +static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, + unsigned long init_val) +{ + if (static_branch_likely(&pkey_disabled)) + return -EINVAL; + + /* + * userspace should not change pkey-0 permissions. + * pkey-0 is associated with every page in the kernel. + * If userspace denies any permission on pkey-0, the + * kernel cannot operate. + */ + if (pkey == 0) + return init_val ? -EINVAL : 0; + + return __arch_set_user_pkey_access(tsk, pkey, init_val); +} + +static inline bool arch_pkeys_enabled(void) +{ + return !static_branch_likely(&pkey_disabled); +} + +extern void pkey_mm_init(struct mm_struct *mm); +extern bool arch_supports_pkeys(int cap); +extern unsigned int arch_usable_pkeys(void); +extern void thread_pkey_regs_save(struct thread_struct *thread); +extern void thread_pkey_regs_restore(struct thread_struct *new_thread, + struct thread_struct *old_thread); +extern void thread_pkey_regs_init(struct thread_struct *thread); +#endif /*_ASM_POWERPC_KEYS_H */ |