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Commit 87bbabbe authored by Ram Pai's avatar Ram Pai Committed by Michael Ellerman
Browse files

powerpc: implementation for arch_override_mprotect_pkey() 



arch independent code calls arch_override_mprotect_pkey()
to return a pkey that best matches the requested protection.

This patch provides the implementation.

Signed-off-by: default avatarRam Pai <linuxram@us.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 013a91b3

arch/powerpc/include/asm/mmu_context.h

+5 −0
Original line number Diff line number Diff line
@@ -198,6 +198,11 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, 
#define thread_pkey_regs_save(thread)

#define thread_pkey_regs_restore(new_thread, old_thread)

#define thread_pkey_regs_init(thread)



static inline int vma_pkey(struct vm_area_struct *vma)

{

	return 0;

}

#endif /* CONFIG_PPC_MEM_KEYS */



#endif /* __KERNEL__ */

arch/powerpc/include/asm/pkeys.h

+20 −1
Original line number Diff line number Diff line
@@ -41,6 +41,13 @@ static inline u64 pkey_to_vmflag_bits(u16 pkey) 
	return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);

}



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



#define pkey_alloc_mask(pkey) (0x1 << pkey)
@@ -137,10 +144,22 @@ static inline int execute_only_pkey(struct mm_struct *mm) 
	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,

arch/powerpc/mm/pkeys.c

+36 −0
Original line number Diff line number Diff line
@@ -322,3 +322,39 @@ int __execute_only_pkey(struct mm_struct *mm) 
		mm->context.execute_only_pkey = execute_only_pkey;

	return execute_only_pkey;

}



static inline bool vma_is_pkey_exec_only(struct vm_area_struct *vma)

{

	/* Do this check first since the vm_flags should be hot */

	if ((vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) != VM_EXEC)

		return false;



	return (vma_pkey(vma) == vma->vm_mm->context.execute_only_pkey);

}



/*

 * This should only be called for *plain* mprotect calls.

 */

int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot,

				  int pkey)

{

	/*

	 * If the currently associated pkey is execute-only, but the requested

	 * protection requires read or write, move it back to the default pkey.

	 */

	if (vma_is_pkey_exec_only(vma) && (prot & (PROT_READ | PROT_WRITE)))

		return 0;



	/*

	 * The requested protection is execute-only. Hence let's use an

	 * execute-only pkey.

	 */

	if (prot == PROT_EXEC) {

		pkey = execute_only_pkey(vma->vm_mm);

		if (pkey > 0)

			return pkey;

	}



	/* Nothing to override. */

	return vma_pkey(vma);

}