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PAPR defines 'ibm,processor-storage-keys' property. It exports two values. The first value holds the number of data-access keys and the second holds the number of instruction-access keys. Due to a bug in the firmware, instruction-access keys is always reported as zero. However any key can be configured to disable data-access and/or disable execution-access. The inavailablity of the second value is not a big handicap, though it could have been used to determine if the platform supported disable-execution-access. Non-PAPR platforms do not define this property in the device tree yet. Fortunately power8 is the only released Non-PAPR platform that is supported. Here, we hardcode the number of supported pkey to 32, by consulting the PowerISA3.0 This patch calculates the number of keys supported by the platform. Also it determines the platform support for read/write/execution access support for pkeys. Signed-off-by: Ram Pai <linuxram@us.ibm.com> [mpe: Use a PVR check instead of CPU_FTR for execute. Restrict to Power7/8/9 for now until older CPUs are tested.] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
219 lines
6.1 KiB
C
219 lines
6.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* PowerPC Memory Protection Keys management
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*
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* Copyright 2017, Ram Pai, IBM Corporation.
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*/
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#ifndef _ASM_POWERPC_KEYS_H
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#define _ASM_POWERPC_KEYS_H
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#include <linux/jump_label.h>
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#include <asm/firmware.h>
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DECLARE_STATIC_KEY_TRUE(pkey_disabled);
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extern int pkeys_total; /* total pkeys as per device tree */
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extern u32 initial_allocation_mask; /* bits set for reserved keys */
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/*
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* Define these here temporarily so we're not dependent on patching linux/mm.h.
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* Once it's updated we can drop these.
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*/
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#ifndef VM_PKEY_BIT0
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# define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
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# define VM_PKEY_BIT0 VM_HIGH_ARCH_0
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# define VM_PKEY_BIT1 VM_HIGH_ARCH_1
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# define VM_PKEY_BIT2 VM_HIGH_ARCH_2
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# define VM_PKEY_BIT3 VM_HIGH_ARCH_3
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# define VM_PKEY_BIT4 VM_HIGH_ARCH_4
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#endif
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#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
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VM_PKEY_BIT3 | VM_PKEY_BIT4)
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/* Override any generic PKEY permission defines */
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#define PKEY_DISABLE_EXECUTE 0x4
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#define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS | \
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PKEY_DISABLE_WRITE | \
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PKEY_DISABLE_EXECUTE)
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static inline u64 pkey_to_vmflag_bits(u16 pkey)
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{
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return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
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}
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static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
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{
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if (static_branch_likely(&pkey_disabled))
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return 0x0UL;
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return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT4 : 0x0UL) |
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((vm_flags & VM_PKEY_BIT1) ? H_PTE_PKEY_BIT3 : 0x0UL) |
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((vm_flags & VM_PKEY_BIT2) ? H_PTE_PKEY_BIT2 : 0x0UL) |
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((vm_flags & VM_PKEY_BIT3) ? H_PTE_PKEY_BIT1 : 0x0UL) |
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((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT0 : 0x0UL));
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}
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static inline int vma_pkey(struct vm_area_struct *vma)
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{
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if (static_branch_likely(&pkey_disabled))
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return 0;
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return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT;
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}
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#define arch_max_pkey() pkeys_total
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static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
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{
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return (((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
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}
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static inline u16 pte_to_pkey_bits(u64 pteflags)
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{
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return (((pteflags & H_PTE_PKEY_BIT0) ? 0x10 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT1) ? 0x8 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT2) ? 0x4 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT3) ? 0x2 : 0x0UL) |
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((pteflags & H_PTE_PKEY_BIT4) ? 0x1 : 0x0UL));
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}
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#define pkey_alloc_mask(pkey) (0x1 << pkey)
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#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
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#define __mm_pkey_allocated(mm, pkey) { \
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mm_pkey_allocation_map(mm) |= pkey_alloc_mask(pkey); \
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}
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#define __mm_pkey_free(mm, pkey) { \
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mm_pkey_allocation_map(mm) &= ~pkey_alloc_mask(pkey); \
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}
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#define __mm_pkey_is_allocated(mm, pkey) \
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(mm_pkey_allocation_map(mm) & pkey_alloc_mask(pkey))
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#define __mm_pkey_is_reserved(pkey) (initial_allocation_mask & \
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pkey_alloc_mask(pkey))
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static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
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{
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/* A reserved key is never considered as 'explicitly allocated' */
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return ((pkey < arch_max_pkey()) &&
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!__mm_pkey_is_reserved(pkey) &&
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__mm_pkey_is_allocated(mm, pkey));
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}
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extern void __arch_activate_pkey(int pkey);
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extern void __arch_deactivate_pkey(int pkey);
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/*
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* Returns a positive, 5-bit key on success, or -1 on failure.
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* Relies on the mmap_sem to protect against concurrency in mm_pkey_alloc() and
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* mm_pkey_free().
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*/
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static inline int mm_pkey_alloc(struct mm_struct *mm)
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{
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/*
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* Note: this is the one and only place we make sure that the pkey is
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* valid as far as the hardware is concerned. The rest of the kernel
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* trusts that only good, valid pkeys come out of here.
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*/
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u32 all_pkeys_mask = (u32)(~(0x0));
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int ret;
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if (static_branch_likely(&pkey_disabled))
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return -1;
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/*
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* Are we out of pkeys? We must handle this specially because ffz()
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* behavior is undefined if there are no zeros.
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*/
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if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
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return -1;
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ret = ffz((u32)mm_pkey_allocation_map(mm));
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__mm_pkey_allocated(mm, ret);
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/*
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* Enable the key in the hardware
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*/
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if (ret > 0)
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__arch_activate_pkey(ret);
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return ret;
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}
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static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
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{
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if (static_branch_likely(&pkey_disabled))
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return -1;
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if (!mm_pkey_is_allocated(mm, pkey))
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return -EINVAL;
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/*
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* Disable the key in the hardware
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*/
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__arch_deactivate_pkey(pkey);
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__mm_pkey_free(mm, pkey);
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return 0;
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}
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/*
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* Try to dedicate one of the protection keys to be used as an
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* execute-only protection key.
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*/
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extern int __execute_only_pkey(struct mm_struct *mm);
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static inline int execute_only_pkey(struct mm_struct *mm)
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{
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if (static_branch_likely(&pkey_disabled))
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return -1;
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return __execute_only_pkey(mm);
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}
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extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
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int prot, int pkey);
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static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
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int prot, int pkey)
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{
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if (static_branch_likely(&pkey_disabled))
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return 0;
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/*
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* Is this an mprotect_pkey() call? If so, never override the value that
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* came from the user.
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*/
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if (pkey != -1)
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return pkey;
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return __arch_override_mprotect_pkey(vma, prot, pkey);
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}
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extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val);
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static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val)
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{
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if (static_branch_likely(&pkey_disabled))
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return -EINVAL;
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return __arch_set_user_pkey_access(tsk, pkey, init_val);
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}
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static inline bool arch_pkeys_enabled(void)
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{
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return !static_branch_likely(&pkey_disabled);
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}
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extern void pkey_mm_init(struct mm_struct *mm);
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extern bool arch_supports_pkeys(int cap);
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extern unsigned int arch_usable_pkeys(void);
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extern void thread_pkey_regs_save(struct thread_struct *thread);
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extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
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struct thread_struct *old_thread);
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extern void thread_pkey_regs_init(struct thread_struct *thread);
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#endif /*_ASM_POWERPC_KEYS_H */
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