Commit f2407ef3 authored by Ram Pai's avatar Ram Pai Committed by Michael Ellerman
Browse files

powerpc: helper to validate key-access permissions of a pte 



helper function that checks if the read/write/execute is allowed
on the pte.

Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent a6590ca5

arch/powerpc/include/asm/book3s/64/pgtable.h

+2 −0
Original line number Diff line number Diff line
@@ -571,6 +571,8 @@ static inline int pte_present(pte_t pte) 
	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT));

}



extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute);



#define pte_access_permitted pte_access_permitted

static inline bool pte_access_permitted(pte_t pte, bool write)

{

arch/powerpc/include/asm/pkeys.h

+9 −0
Original line number Diff line number Diff line
@@ -71,6 +71,15 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) 
		((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)

arch/powerpc/mm/pkeys.c

+28 −0
Original line number Diff line number Diff line
@@ -358,3 +358,31 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, 
	/* Nothing to override. */

	return vma_pkey(vma);

}



static bool pkey_access_permitted(int pkey, bool write, bool execute)

{

	int pkey_shift;

	u64 amr;



	if (!pkey)

		return true;



	if (!is_pkey_enabled(pkey))

		return true;



	pkey_shift = pkeyshift(pkey);

	if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift)))

		return true;



	amr = read_amr(); /* Delay reading amr until absolutely needed */

	return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) ||

		(write &&  !(amr & (AMR_WR_BIT << pkey_shift))));

}



bool arch_pte_access_permitted(u64 pte, bool write, bool execute)

{

	if (static_branch_likely(&pkey_disabled))

		return true;



	return pkey_access_permitted(pte_to_pkey_bits(pte), write, execute);

}