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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2023 Arm Ltd.
*
* Based on arch/x86/include/asm/pkeys.h
*/
#ifndef _ASM_ARM64_PKEYS_H
#define _ASM_ARM64_PKEYS_H
#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2)
#define arch_max_pkey() 8
int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val);
static inline bool arch_pkeys_enabled(void)
{
return system_supports_poe();
}
static inline int vma_pkey(struct vm_area_struct *vma)
{
return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
}
static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
int prot, int pkey)
{
if (pkey != -1)
return pkey;
return vma_pkey(vma);
}
static inline int execute_only_pkey(struct mm_struct *mm)
{
// Execute-only mappings are handled by EPAN/FEAT_PAN3.
return -1;
}
#define mm_pkey_allocation_map(mm) (mm)->context.pkey_allocation_map
#define mm_set_pkey_allocated(mm, pkey) do { \
mm_pkey_allocation_map(mm) |= (1U << pkey); \
} while (0)
#define mm_set_pkey_free(mm, pkey) do { \
mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
} while (0)
static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
{
/*
* "Allocated" pkeys are those that have been returned
* from pkey_alloc() or pkey 0 which is allocated
* implicitly when the mm is created.
*/
if (pkey < 0 || pkey >= arch_max_pkey())
return false;
return mm_pkey_allocation_map(mm) & (1U << pkey);
}
/*
* Returns a positive, 3-bit key on success, or -1 on failure.
*/
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.
*/
u8 all_pkeys_mask = GENMASK(arch_max_pkey() - 1, 0);
int ret;
if (!arch_pkeys_enabled())
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(mm_pkey_allocation_map(mm));
mm_set_pkey_allocated(mm, ret);
return ret;
}
static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
{
if (!mm_pkey_is_allocated(mm, pkey))
return -EINVAL;
mm_set_pkey_free(mm, pkey);
return 0;
}
#endif /* _ASM_ARM64_PKEYS_H */
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