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Date: Wed, 1 Oct 2014 17:54:41 +0300
From: Or Gerlitz <ogerlitz@...lanox.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org, Amir Vadai <amirv@...lanox.com>,
Jack Morgenstein <jackm@....mellanox.co.il>,
Moshe Lazer <moshel@...lanox.com>,
Tal Alon <talal@...lanox.com>,
Yevgeny Petrilin <yevgenyp@...lanox.com>,
Or Gerlitz <ogerlitz@...lanox.com>
Subject: [PATCH net-next 1/2] pgtable: Add API to query if write combining is available
From: Moshe Lazer <moshel@...lanox.com>
Currently the kernel write-combining interface provides a best effort
mechanism in which the caller simply invokes pgprot_writecombine().
If write combining is available, the region is mapped for it, otherwise
the region is (silently) mapped as non-cached.
In some cases, however, the calling driver must know if write combining
is available, so a silent best effort mechanism is not sufficient.
Add writecombine_available(), which returns 1 if the system
supports write combining and 0 if it doesn't.
Signed-off-by: Moshe Lazer <moshel@...lanox.com>
Signed-off-by: Jack Morgenstein <jackm@....mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
---
arch/arm/include/asm/pgtable.h | 6 ++++++
arch/arm64/include/asm/pgtable.h | 5 +++++
arch/ia64/include/asm/pgtable.h | 6 ++++++
arch/powerpc/include/asm/pgtable.h | 6 ++++++
arch/x86/include/asm/pgtable_types.h | 2 ++
arch/x86/mm/pat.c | 9 +++++++++
include/asm-generic/pgtable.h | 8 ++++++++
7 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 01baef0..87224dc 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -119,6 +119,12 @@ extern pgprot_t pgprot_s2_device;
#define pgprot_writecombine(prot) \
__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE)
+#define writecombine_available writecombine_available
+static inline int writecombine_available(void)
+{
+ return 1;
+}
+
#define pgprot_stronglyordered(prot) \
__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index ffe1ba0..f284cb6 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -296,6 +296,11 @@ static inline int has_transparent_hugepage(void)
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRnE) | PTE_PXN | PTE_UXN)
#define pgprot_writecombine(prot) \
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
+#define writecombine_available writecombine_available
+static inline int writecombine_available(void)
+{
+ return 1;
+}
#define __HAVE_PHYS_MEM_ACCESS_PROT
struct file;
extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 7935115..66bfd00 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -356,6 +356,12 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
#define pgprot_noncached(prot) __pgprot((pgprot_val(prot) & ~_PAGE_MA_MASK) | _PAGE_MA_UC)
#define pgprot_writecombine(prot) __pgprot((pgprot_val(prot) & ~_PAGE_MA_MASK) | _PAGE_MA_WC)
+#define writecombine_available writecombine_available
+static inline int writecombine_available(void)
+{
+ return 1;
+}
+
struct file;
extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot);
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index d98c1ec..a52e035 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -267,6 +267,12 @@ extern int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long addre
#define pgprot_writecombine pgprot_noncached_wc
+#define writecombine_available writecombine_available
+static inline int writecombine_available(void)
+{
+ return 1;
+}
+
struct file;
extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot);
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index f216963..5f8d2b4 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -337,6 +337,8 @@ extern int nx_enabled;
#define pgprot_writecombine pgprot_writecombine
extern pgprot_t pgprot_writecombine(pgprot_t prot);
+#define writecombine_available writecombine_available
+int writecombine_available(void);
/* 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 6574388..c144ab3 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -797,6 +797,15 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
}
EXPORT_SYMBOL_GPL(pgprot_writecombine);
+int writecombine_available(void)
+{
+ if (pat_enabled)
+ return 1;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(writecombine_available);
+
#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..f503e5b 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -249,6 +249,14 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
#define pgprot_writecombine pgprot_noncached
#endif
+#ifndef writecombine_available
+#define writecombine_available writecombine_available
+static inline int writecombine_available(void)
+{
+ return 0;
+}
+#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
--
1.7.1
--
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