From 6cf514fce18589ea1e0521c5f2d7c2bb280fefc7 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 16 Jun 2008 18:42:43 +0100 Subject: [PATCH] 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: Hugh Dickins Signed-off-by: Ingo Molnar --- arch/x86/mm/pat.c | 47 ++++++++++++----------------------------------- 1 file changed, 12 insertions(+), 35 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 7c21572..ac3a2b1 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -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); -- 2.7.4