[tip:x86/mm] x86/mm/pat: Add pgprot_writethrough()

[tip-bot for Toshi Kani]

Commit-ID:  d1b4bfbfac32da43bfc8425be1c4303548e20527
Gitweb:     http://git.kernel.org/tip/d1b4bfbfac32da43bfc8425be1c4303548e20527
Author:     Toshi Kani <toshi.kani@xxxxxx>
AuthorDate: Thu, 4 Jun 2015 18:55:18 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 7 Jun 2015 15:28:58 +0200

x86/mm/pat: Add pgprot_writethrough()

Add pgprot_writethrough() for setting page protection flags to
Write-Through mode.

Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Elliott@xxxxxx
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: arnd@xxxxxxxx
Cc: hch@xxxxxx
Cc: hmh@xxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: linux-mm <linux-mm@xxxxxxxxx>
Cc: linux-nvdimm@xxxxxxxxxxxx
Cc: stefan.bader@xxxxxxxxxxxxx
Cc: yigal@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1433436928-31903-11-git-send-email-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/pgtable_types.h | 3 +++
 arch/x86/mm/pat.c                    | 7 +++++++
 include/asm-generic/pgtable.h        | 4 ++++
 3 files changed, 14 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 78f0c8c..13f310b 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -367,6 +367,9 @@ 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 6311193..076187c 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -1000,6 +1000,13 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
 }
 EXPORT_SYMBOL_GPL(pgprot_writecombine);
 
+pgprot_t pgprot_writethrough(pgprot_t prot)
+{
+	return __pgprot(pgprot_val(prot) |
+				cachemode2protval(_PAGE_CACHE_MODE_WT));
+}
+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 39f1d6a..bd910ce 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -262,6 +262,10 @@ 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
+
 #ifndef pgprot_device
 #define pgprot_device pgprot_noncached
 #endif
--
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