From 637b86e75f4c255a4446bc0b67ce9d914b9d2d42 Mon Sep 17 00:00:00 2001 From: Venkatesh Pallipadi Date: Fri, 10 Jul 2009 09:57:39 -0700 Subject: [PATCH] x86, pat: Add lookup_memtype to get the current memtype of a paddr Add a new routine lookup_memtype() to get the current memtype based on the PAT reserves and frees. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha Signed-off-by: H. Peter Anvin --- arch/x86/mm/pat.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 1a9d0f07593f..71aa6f7246c6 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -573,6 +573,51 @@ int free_memtype(u64 start, u64 end) } +/** + * 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 -- 2.45.2