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Commit 6cf514fc authored by Hugh Dickins's avatar Hugh Dickins Committed by Ingo Molnar
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x86: PAT: make pat_x_mtrr_type() more readable 



Clean up over-complications in pat_x_mtrr_type().
And if reserve_memtype() ignores stray req_type bits when
pat_enabled, it's better to mask them off when not also.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent faeca31d

arch/x86/mm/pat.c

+12 −35
Original line number Diff line number Diff line
@@ -159,47 +159,31 @@ static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */ 
 * The intersection is based on "Effective Memory Type" tables in IA-32

 * SDM vol 3a

 */

static int pat_x_mtrr_type(u64 start, u64 end, unsigned long prot,

				unsigned long *ret_prot)

static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)

{

	unsigned long pat_type;

	u8 mtrr_type;



	pat_type = prot & _PAGE_CACHE_MASK;

	prot &= (~_PAGE_CACHE_MASK);



	/*

	 * We return the PAT request directly for types where PAT takes

	 * precedence with respect to MTRR and for UC_MINUS.

	 * Consistency checks with other PAT requests is done later

	 * while going through memtype list.

	 */

	if (pat_type == _PAGE_CACHE_WC) {

		*ret_prot = prot | _PAGE_CACHE_WC;

		return 0;

	} else if (pat_type == _PAGE_CACHE_UC_MINUS) {

		*ret_prot = prot | _PAGE_CACHE_UC_MINUS;

		return 0;

	} else if (pat_type == _PAGE_CACHE_UC) {

		*ret_prot = prot | _PAGE_CACHE_UC;

		return 0;

	}

	if (req_type == _PAGE_CACHE_WC ||

	    req_type == _PAGE_CACHE_UC_MINUS ||

	    req_type == _PAGE_CACHE_UC)

		return req_type;



	/*

	 * Look for MTRR hint to get the effective type in case where PAT

	 * request is for WB.

	 */

	mtrr_type = mtrr_type_lookup(start, end);



	if (mtrr_type == MTRR_TYPE_UNCACHABLE) {

		*ret_prot = prot | _PAGE_CACHE_UC;

	} else if (mtrr_type == MTRR_TYPE_WRCOMB) {

		*ret_prot = prot | _PAGE_CACHE_WC;

	} else {

		*ret_prot = prot | _PAGE_CACHE_WB;

	}



	return 0;

	if (mtrr_type == MTRR_TYPE_UNCACHABLE)

		return _PAGE_CACHE_UC;

	if (mtrr_type == MTRR_TYPE_WRCOMB)

		return _PAGE_CACHE_WC;

	return _PAGE_CACHE_WB;

}



/*
@@ -232,7 +216,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type, 
			if (req_type == -1) {

				*ret_type = _PAGE_CACHE_WB;

			} else {

				*ret_type = req_type;

				*ret_type = req_type & _PAGE_CACHE_MASK;

			}

		}

		return 0;
@@ -264,14 +248,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type, 
		}

	} else {

		req_type &= _PAGE_CACHE_MASK;

		err = pat_x_mtrr_type(start, end, req_type, &actual_type);

	}



	if (err) {

		if (ret_type)

			*ret_type = actual_type;



		return -EINVAL;

		actual_type = pat_x_mtrr_type(start, end, req_type);

	}



	new_entry  = kmalloc(sizeof(struct memtype), GFP_KERNEL);