[PATCH 07/20] x86/mm, asm-generic: Add ioremap_wt() for creating Write-Through mappings

Borislav Petkov
2015-06-04T16:55:51Z

From: Toshi Kani <toshi.kani@hp.com>

Add ioremap_wt() for creating Write-Through mappings on x86. It
follows the same model as ioremap_wc() for multi-arch support. Define
ARCH_HAS_IOREMAP_WT in the x86 version of io.h to indicate that
ioremap_wt() is implemented on x86.

Also update the PAT documentation file to cover ioremap_wt().

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: arnd@arndb.de
Cc: Elliott@hp.com
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: stefan.bader@canonical.com
Cc: x86-ml <x86@kernel.org>
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433187393-22688-5-git-send-email-toshi.kani@hp.com
Signed-off-by: Borislav Petkov <bp@suse.de>
---
Documentation/x86/pat.txt | 4 +++-
arch/x86/include/asm/io.h | 2 ++
arch/x86/mm/ioremap.c | 21 +++++++++++++++++++++
include/asm-generic/io.h | 9 +++++++++
include/asm-generic/iomap.h | 4 ++++
5 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index 521bd8adc3b8..db0de6cfc351 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -12,7 +12,7 @@ virtual addresses.

PAT allows for different types of memory attributes. The most commonly used
ones that will be supported at this time are Write-back, Uncached,
-Write-combined and Uncached Minus.
+Write-combined, Write-through and Uncached Minus.

PAT APIs
@@ -40,6 +40,8 @@ ioremap_nocache | -- | UC- | UC- |
| | | |
ioremap_wc | -- | -- | WC |
| | | |
+ioremap_wt | -- | -- | WT |
+ | | | |
set_memory_uc | UC- | -- | -- |
set_memory_wb | | | |
| | | |
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index a2b97404922d..6c3a130de503 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -35,6 +35,7 @@
*/

#define ARCH_HAS_IOREMAP_WC
+#define ARCH_HAS_IOREMAP_WT

#include <linux/string.h>
#include <linux/compiler.h>
@@ -321,6 +322,7 @@ extern void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,
enum page_cache_mode pcm);
extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size);
+extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size);

extern bool is_early_ioremap_ptep(pte_t *ptep);

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index cc0f17c5ad9f..07cd46a8f30a 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -172,6 +172,10 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
prot = __pgprot(pgprot_val(prot) |
cachemode2protval(_PAGE_CACHE_MODE_WC));
break;
+ case _PAGE_CACHE_MODE_WT:
+ prot = __pgprot(pgprot_val(prot) |
+ cachemode2protval(_PAGE_CACHE_MODE_WT));
+ break;
case _PAGE_CACHE_MODE_WB:
break;
}
@@ -297,6 +301,23 @@ void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
}
EXPORT_SYMBOL(ioremap_wc);

+/**
+ * ioremap_wt - map memory into CPU space write through
+ * @phys_addr: bus address of the memory
+ * @size: size of the resource to map
+ *
+ * This version of ioremap ensures that the memory is marked write through.
+ * Write through stores data into memory while keeping the cache up-to-date.
+ *
+ * Must be freed with iounmap.
+ */
+void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size)
+{
+ return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT,
+ __builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_wt);
+
void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 90ccba7f9f9a..f56094cfdeff 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -785,8 +785,17 @@ static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
}
#endif

+#ifndef ioremap_wt
+#define ioremap_wt ioremap_wt
+static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
+{
+ return ioremap_nocache(offset, size);
+}
+#endif
+
#ifndef iounmap
#define iounmap iounmap
+
static inline void iounmap(void __iomem *addr)
{
}
diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
index 1b41011643a5..d8f8622fa044 100644
--- a/include/asm-generic/iomap.h
+++ b/include/asm-generic/iomap.h
@@ -66,6 +66,10 @@ extern void ioport_unmap(void __iomem *);
#define ioremap_wc ioremap_nocache
#endif

+#ifndef ARCH_HAS_IOREMAP_WT
+#define ioremap_wt ioremap_nocache
+#endif
+
#ifdef CONFIG_PCI
/* Destroy a virtual mapping cookie for a PCI BAR (memory or IO) */
struct pci_dev;
--
2.3.5