[PATCH v3 4/5] x86, mm, pat: Add pgprot_writethrough() for WT

From: Toshi Kani
Date: Wed Sep 17 2014 - 15:59:43 EST


This patch adds pgprot_writethrough() for setting WT to a given
pgprot_t.

Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
arch/x86/include/asm/pgtable_types.h | 3 +++
arch/x86/mm/pat.c | 10 ++++++++++
include/asm-generic/pgtable.h | 4 ++++
3 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index bd2f50f..cc7c65d 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -394,6 +394,9 @@ extern int nx_enabled;
#define pgprot_writecombine pgprot_writecombine
extern pgprot_t pgprot_writecombine(pgprot_t prot);

+#define pgprot_writethrough pgprot_writethrough
+extern pgprot_t pgprot_writethrough(pgprot_t prot);
+
/* Indicate that x86 has its own track and untrack pfn vma functions */
#define __HAVE_PFNMAP_TRACKING

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index a214f5a..a0264d3 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -896,6 +896,16 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
}
EXPORT_SYMBOL_GPL(pgprot_writecombine);

+pgprot_t pgprot_writethrough(pgprot_t prot)
+{
+ if (pat_enabled)
+ return __pgprot(pgprot_val(prot) |
+ cachemode2protval(_PAGE_CACHE_MODE_WT));
+ else
+ return pgprot_noncached(prot);
+}
+EXPORT_SYMBOL_GPL(pgprot_writethrough);
+
#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)

static struct memtype *memtype_get_idx(loff_t pos)
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 53b2acc..1af0ed9 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -249,6 +249,10 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
#define pgprot_writecombine pgprot_noncached
#endif

+#ifndef pgprot_writethrough
+#define pgprot_writethrough pgprot_noncached
+#endif
+
/*
* When walking page tables, get the address of the next boundary,
* or the end address of the range if that comes earlier. Although no
--
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