1/* SPDX-License-Identifier: GPL-2.0+ */
  2/*
  3 * PowerPC Memory Protection Keys management
  4 *
  5 * Copyright 2017, Ram Pai, IBM Corporation.
  6 */
  7
  8#ifndef _ASM_POWERPC_KEYS_H
  9#define _ASM_POWERPC_KEYS_H
 10
 11#include <linux/jump_label.h>
 12#include <asm/firmware.h>
 13
 14extern int num_pkey;
 15extern u32 reserved_allocation_mask; /* bits set for reserved keys */
 16
 17#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
 18			    VM_PKEY_BIT3 | VM_PKEY_BIT4)
 19
 20/* Override any generic PKEY permission defines */
 21#define PKEY_DISABLE_EXECUTE   0x4
 22#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS | \
 23				PKEY_DISABLE_WRITE  | \
 24				PKEY_DISABLE_EXECUTE)
 25
 26#ifdef CONFIG_PPC_BOOK3S_64
 27#include <asm/book3s/64/pkeys.h>
 28#else
 29#error "Not supported"
 30#endif
 31
 32
 33static inline u64 pkey_to_vmflag_bits(u16 pkey)
 34{
 35	return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
 36}
 37
 38static inline int vma_pkey(struct vm_area_struct *vma)
 39{
 40	if (!mmu_has_feature(MMU_FTR_PKEY))
 41		return 0;
 42	return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
 43}
 44
 45static inline int arch_max_pkey(void)
 46{
 47	return num_pkey;
 48}
 49
 50#define pkey_alloc_mask(pkey) (0x1 << pkey)
 51
 52#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
 53
 54#define __mm_pkey_allocated(mm, pkey) {	\
 55	mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
 56}
 57
 58#define __mm_pkey_free(mm, pkey) {	\
 59	mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey);	\
 60}
 61
 62#define __mm_pkey_is_allocated(mm, pkey)	\
 63	(mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
 64
 65#define __mm_pkey_is_reserved(pkey) (reserved_allocation_mask & \
 66				       pkey_alloc_mask(pkey))
 67
 68static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 69{
 70	if (pkey < 0 || pkey >= arch_max_pkey())
 71		return false;
 72
 73	/* Reserved keys are never allocated. */
 74	if (__mm_pkey_is_reserved(pkey))
 75		return false;
 76
 77	return __mm_pkey_is_allocated(mm, pkey);
 78}
 79
 80/*
 81 * Returns a positive, 5-bit key on success, or -1 on failure.
 82 * Relies on the mmap_lock to protect against concurrency in mm_pkey_alloc() and
 83 * mm_pkey_free().
 84 */
 85static inline int mm_pkey_alloc(struct mm_struct *mm)
 86{
 87	/*
 88	 * Note: this is the one and only place we make sure that the pkey is
 89	 * valid as far as the hardware is concerned. The rest of the kernel
 90	 * trusts that only good, valid pkeys come out of here.
 91	 */
 92	u32 all_pkeys_mask = (u32)(~(0x0));
 93	int ret;
 94
 95	if (!mmu_has_feature(MMU_FTR_PKEY))
 96		return -1;
 97	/*
 98	 * Are we out of pkeys? We must handle this specially because ffz()
 99	 * behavior is undefined if there are no zeros.
100	 */
101	if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
102		return -1;
103
104	ret = ffz((u32)mm_pkey_allocation_map(mm));
105	__mm_pkey_allocated(mm, ret);
106
107	return ret;
108}
109
110static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
111{
112	if (!mmu_has_feature(MMU_FTR_PKEY))
113		return -1;
114
115	if (!mm_pkey_is_allocated(mm, pkey))
116		return -EINVAL;
117
118	__mm_pkey_free(mm, pkey);
119
120	return 0;
121}
122
123/*
124 * Try to dedicate one of the protection keys to be used as an
125 * execute-only protection key.
126 */
127extern int execute_only_pkey(struct mm_struct *mm);
128extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
129					 int prot, int pkey);
130static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
131					      int prot, int pkey)
132{
133	if (!mmu_has_feature(MMU_FTR_PKEY))
134		return 0;
135
136	/*
137	 * Is this an mprotect_pkey() call? If so, never override the value that
138	 * came from the user.
139	 */
140	if (pkey != -1)
141		return pkey;
142
143	return __arch_override_mprotect_pkey(vma, prot, pkey);
144}
145
146extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
147				       unsigned long init_val);
148static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
149					    unsigned long init_val)
150{
151	if (!mmu_has_feature(MMU_FTR_PKEY))
152		return -EINVAL;
153
154	/*
155	 * userspace should not change pkey-0 permissions.
156	 * pkey-0 is associated with every page in the kernel.
157	 * If userspace denies any permission on pkey-0, the
158	 * kernel cannot operate.
159	 */
160	if (pkey == 0)
161		return init_val ? -EINVAL : 0;
162
163	return __arch_set_user_pkey_access(tsk, pkey, init_val);
164}
165
166static inline bool arch_pkeys_enabled(void)
167{
168	return mmu_has_feature(MMU_FTR_PKEY);
169}
170
171extern void pkey_mm_init(struct mm_struct *mm);
172#endif /*_ASM_POWERPC_KEYS_H */