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 <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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 @@
* 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 @@
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 @@
}
} 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);