[PATCH v6 1/7] pmem: add wb_cache_pmem() to the PMEM API

Ross Zwisler
2015-12-23T19:39:32Z

The function __arch_wb_cache_pmem() was already an internal implementation
detail of the x86 PMEM API, but this functionality needs to be exported as
part of the general PMEM API to handle the fsync/msync case for DAX mmaps.

One thing worth noting is that we really do want this to be part of the
PMEM API as opposed to a stand-alone function like clflush_cache_range()
because of ordering restrictions. By having wb_cache_pmem() as part of the
PMEM API we can leave it unordered, call it multiple times to write back
large amounts of memory, and then order the multiple calls with a single
wmb_pmem().

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
arch/x86/include/asm/pmem.h | 11 ++++++-----
include/linux/pmem.h | 22 +++++++++++++++++++++-
2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index 1544fab..c57fd1e 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -67,18 +67,19 @@ static inline void arch_wmb_pmem(void)
}

/**
- * __arch_wb_cache_pmem - write back a cache range with CLWB
+ * arch_wb_cache_pmem - write back a cache range with CLWB
* @vaddr: virtual start address
* @size: number of bytes to write back
*
* Write back a cache range using the CLWB (cache line write back)
* instruction. This function requires explicit ordering with an
- * arch_wmb_pmem() call. This API is internal to the x86 PMEM implementation.
+ * arch_wmb_pmem() call.
*/
-static inline void __arch_wb_cache_pmem(void *vaddr, size_t size)
+static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
{
u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
unsigned long clflush_mask = x86_clflush_size - 1;
+ void *vaddr = (void __force *)addr;
void *vend = vaddr + size;
void *p;

@@ -115,7 +116,7 @@ static inline size_t arch_copy_from_iter_pmem(void __pmem *addr, size_t bytes,
len = copy_from_iter_nocache(vaddr, bytes, i);

if (__iter_needs_pmem_wb(i))
- __arch_wb_cache_pmem(vaddr, bytes);
+ arch_wb_cache_pmem(addr, bytes);

return len;
}
@@ -133,7 +134,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
void *vaddr = (void __force *)addr;

memset(vaddr, 0, size);
- __arch_wb_cache_pmem(vaddr, size);
+ arch_wb_cache_pmem(addr, size);
}

static inline bool __arch_has_wmb_pmem(void)
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
index acfea8c..7c3d11a 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -53,12 +53,18 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
{
BUG();
}
+
+static inline void arch_wb_cache_pmem(void __pmem *addr, size_t size)
+{
+ BUG();
+}
#endif

/*
* Architectures that define ARCH_HAS_PMEM_API must provide
* implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
- * arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem().
+ * arch_copy_from_iter_pmem(), arch_clear_pmem(), arch_wb_cache_pmem()
+ * and arch_has_wmb_pmem().
*/
static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
{
@@ -178,4 +184,18 @@ static inline void clear_pmem(void __pmem *addr, size_t size)
else
default_clear_pmem(addr, size);
}
+
+/**
+ * wb_cache_pmem - write back processor cache for PMEM memory range
+ * @addr: virtual start address
+ * @size: number of bytes to write back
+ *
+ * Write back the processor cache range starting at 'addr' for 'size' bytes.
+ * This function requires explicit ordering with a wmb_pmem() call.
+ */
+static inline void wb_cache_pmem(void __pmem *addr, size_t size)
+{
+ if (arch_has_pmem_api())
+ arch_wb_cache_pmem(addr, size);
+}
#endif /* __PMEM_H__ */
--
2.6.3