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Commit bd0d63f8 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Michael Ellerman
Browse files

powerpc/mm: Move page fault VMA access checks to a helper 



Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d2e0d2c5

arch/powerpc/mm/fault.c

+33 −24
Original line number Diff line number Diff line
@@ -222,6 +222,37 @@ static bool bad_kernel_fault(bool is_exec, unsigned long error_code, 
	return is_exec || (address >= TASK_SIZE);

}



static bool access_error(bool is_write, bool is_exec,

			 struct vm_area_struct *vma)

{

	/*

	 * Allow execution from readable areas if the MMU does not

	 * provide separate controls over reading and executing.

	 *

	 * Note: That code used to not be enabled for 4xx/BookE.

	 * It is now as I/D cache coherency for these is done at

	 * set_pte_at() time and I see no reason why the test

	 * below wouldn't be valid on those processors. This -may-

	 * break programs compiled with a really old ABI though.

	 */

	if (is_exec) {

		return !(vma->vm_flags & VM_EXEC) &&

			(cpu_has_feature(CPU_FTR_NOEXECUTE) ||

			 !(vma->vm_flags & (VM_READ | VM_WRITE)));

	}



	if (is_write) {

		if (unlikely(!(vma->vm_flags & VM_WRITE)))

			return true;

		return false;

	}



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

		return true;



	return false;

}



#ifdef CONFIG_PPC_SMLPAR

static inline void cmo_account_page_fault(void)

{
@@ -461,30 +492,8 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 
		return bad_area(regs, address);



good_area:

	if (is_exec) {

		/*

		 * Allow execution from readable areas if the MMU does not

		 * provide separate controls over reading and executing.

		 *

		 * Note: That code used to not be enabled for 4xx/BookE.

		 * It is now as I/D cache coherency for these is done at

		 * set_pte_at() time and I see no reason why the test

		 * below wouldn't be valid on those processors. This -may-

		 * break programs compiled with a really old ABI though.

		 */

		if (unlikely(!(vma->vm_flags & VM_EXEC) &&

			     (cpu_has_feature(CPU_FTR_NOEXECUTE) ||

			      !(vma->vm_flags & (VM_READ | VM_WRITE)))))

			return bad_area(regs, address);

	/* a write */

	} else if (is_write) {

		if (unlikely(!(vma->vm_flags & VM_WRITE)))

	if (unlikely(access_error(is_write, is_exec, vma)))

		return bad_area(regs, address);

	/* a read */

	} else {

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

			return bad_area(regs, address);

	}



	/*

	 * If for any reason at all we couldn't handle the fault,