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Commit ca91e6c0 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc/mm: Move around testing of _PAGE_PRESENT in hash code 



Instead of adding _PAGE_PRESENT to the access permission mask
in each low level routine independently, we add it once from
hash_page().

We also move the preliminary access check (the racy one before
the PTE is locked) up so it applies to the huge page case. This
duplicates code in __hash_page_huge() which we'll remove in a
subsequent patch to fix a race in there.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent b1623e7e

arch/powerpc/mm/hash_low_64.S

+0 −9
Original line number Original line Diff line number Diff line
@@ -68,9 +68,6 @@ _GLOBAL(__hash_page_4K) 
	std	r8,STK_PARM(r8)(r1)

	std	r8,STK_PARM(r8)(r1)

	std	r9,STK_PARM(r9)(r1)

	std	r9,STK_PARM(r9)(r1)

	

	

	/* Add _PAGE_PRESENT to access */

	ori	r4,r4,_PAGE_PRESENT



	/* Save non-volatile registers.

	/* Save non-volatile registers.

	 * r31 will hold "old PTE"

	 * r31 will hold "old PTE"

	 * r30 is "new PTE"

	 * r30 is "new PTE"
@@ -347,9 +344,6 @@ _GLOBAL(__hash_page_4K) 
	std	r8,STK_PARM(r8)(r1)

	std	r8,STK_PARM(r8)(r1)

	std	r9,STK_PARM(r9)(r1)

	std	r9,STK_PARM(r9)(r1)





	/* Add _PAGE_PRESENT to access */

	ori	r4,r4,_PAGE_PRESENT



	/* Save non-volatile registers.

	/* Save non-volatile registers.

	 * r31 will hold "old PTE"

	 * r31 will hold "old PTE"

	 * r30 is "new PTE"

	 * r30 is "new PTE"
@@ -687,9 +681,6 @@ _GLOBAL(__hash_page_64K) 
	std	r8,STK_PARM(r8)(r1)

	std	r8,STK_PARM(r8)(r1)

	std	r9,STK_PARM(r9)(r1)

	std	r9,STK_PARM(r9)(r1)





	/* Add _PAGE_PRESENT to access */

	ori	r4,r4,_PAGE_PRESENT



	/* Save non-volatile registers.

	/* Save non-volatile registers.

	 * r31 will hold "old PTE"

	 * r31 will hold "old PTE"

	 * r30 is "new PTE"

	 * r30 is "new PTE"

arch/powerpc/mm/hash_utils_64.c

+11 −8
Original line number Original line Diff line number Diff line
@@ -955,6 +955,17 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) 
		return 1;

		return 1;

	}

	}





	/* Add _PAGE_PRESENT to the required access perm */

	access |= _PAGE_PRESENT;



	/* Pre-check access permissions (will be re-checked atomically

	 * in __hash_page_XX but this pre-check is a fast path

	 */

	if (access & ~pte_val(*ptep)) {

		DBG_LOW(" no access !\n");

		return 1;

	}



#ifdef CONFIG_HUGETLB_PAGE

#ifdef CONFIG_HUGETLB_PAGE

	if (hugeshift)

	if (hugeshift)

		return __hash_page_huge(ea, access, vsid, ptep, trap, local,

		return __hash_page_huge(ea, access, vsid, ptep, trap, local,
@@ -967,14 +978,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) 
	DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),

	DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),

		pte_val(*(ptep + PTRS_PER_PTE)));

		pte_val(*(ptep + PTRS_PER_PTE)));

#endif

#endif

	/* Pre-check access permissions (will be re-checked atomically

	 * in __hash_page_XX but this pre-check is a fast path

	 */

	if (access & ~pte_val(*ptep)) {

		DBG_LOW(" no access !\n");

		return 1;

	}



	/* Do actual hashing */

	/* Do actual hashing */

#ifdef CONFIG_PPC_64K_PAGES

#ifdef CONFIG_PPC_64K_PAGES

	/* If _PAGE_4K_PFN is set, make sure this is a 4k segment */

	/* If _PAGE_4K_PFN is set, make sure this is a 4k segment */