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x86, pat: Add lookup_memtype to get the current memtype of a paddr

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Add a new routine lookup_memtype() to get the current memtype based on
the PAT reserves and frees.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Venkatesh Pallipadi 2009-07-10 09:57:39 -07:00 committed by H. Peter Anvin
parent f584174096
commit 637b86e75f
1 changed files with 45 additions and 0 deletions
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45
arch/x86/mm/pat.c
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@ -573,6 +573,51 @@ unlock_ret:
}
/**
* lookup_memtype - Looksup the memory type for a physical address
* @paddr: physical address of which memory type needs to be looked up
*
* Only to be called when PAT is enabled
*
* Returns _PAGE_CACHE_WB, _PAGE_CACHE_WC, _PAGE_CACHE_UC_MINUS or
* _PAGE_CACHE_UC
*/
static unsigned long lookup_memtype(u64 paddr)
{
int rettype = _PAGE_CACHE_WB;
struct memtype *entry;
if (is_ISA_range(paddr, paddr + PAGE_SIZE - 1))
return rettype;
if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) {
struct page *page;
spin_lock(&memtype_lock);
page = pfn_to_page(paddr >> PAGE_SHIFT);
rettype = get_page_memtype(page);
spin_unlock(&memtype_lock);
/*
* -1 from get_page_memtype() implies RAM page is in its
* default state and not reserved, and hence of type WB
*/
if (rettype == -1)
rettype = _PAGE_CACHE_WB;
return rettype;
}
spin_lock(&memtype_lock);
entry = memtype_rb_search(&memtype_rbroot, paddr);
if (entry != NULL)
rettype = entry->type;
else
rettype = _PAGE_CACHE_UC_MINUS;
spin_unlock(&memtype_lock);
return rettype;
}
/**
* io_reserve_memtype - Request a memory type mapping for a region of memory
* @start: start (physical address) of the region