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From: Matthew Wilcox <willy@infradead.org>
To: linux-kernel@vger.kernel.org
Cc: minchan@kernel.org, Matthew Wilcox <mawilcox@microsoft.com>,
	akpm@linuxfoundation.org, mpe@ellerman.id.au
Subject: [PATCH v4 1/8] Add multibyte memset functions
Date: Thu, 20 Jul 2017 11:45:32 -0700
Message-ID: <20170720184539.31609-2-willy@infradead.org> (raw)
In-Reply-To: <20170720184539.31609-1-willy@infradead.org>

From: Matthew Wilcox <mawilcox@microsoft.com>

memset16(), memset32() and memset64() are like memset(), but allow the
caller to fill the destination with a value larger than a single byte.
memset_l() and memset_p() allow the caller to use unsigned long and
pointer values respectively.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 include/linux/string.h | 30 +++++++++++++++++++++++
 lib/string.c           | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index a467e617eeb0..c8bdafffd2f0 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -99,6 +99,36 @@ extern __kernel_size_t strcspn(const char *,const char *);
 #ifndef __HAVE_ARCH_MEMSET
 extern void * memset(void *,int,__kernel_size_t);
 #endif
+
+#ifndef __HAVE_ARCH_MEMSET16
+extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
+#endif
+
+static inline void *memset_l(unsigned long *p, unsigned long v,
+		__kernel_size_t n)
+{
+	if (BITS_PER_LONG == 32)
+		return memset32((uint32_t *)p, v, n);
+	else
+		return memset64((uint64_t *)p, v, n);
+}
+
+static inline void *memset_p(void **p, void *v, __kernel_size_t n)
+{
+	if (BITS_PER_LONG == 32)
+		return memset32((uint32_t *)p, (uintptr_t)v, n);
+	else
+		return memset64((uint64_t *)p, (uintptr_t)v, n);
+}
+
 #ifndef __HAVE_ARCH_MEMCPY
 extern void * memcpy(void *,const void *,__kernel_size_t);
 #endif
diff --git a/lib/string.c b/lib/string.c
index ebbb99c775bd..198148bb61fd 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -723,6 +723,72 @@ void memzero_explicit(void *s, size_t count)
 }
 EXPORT_SYMBOL(memzero_explicit);
 
+#ifndef __HAVE_ARCH_MEMSET16
+/**
+ * memset16() - Fill a memory area with a uint16_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint16_t instead
+ * of a byte.  Remember that @count is the number of uint16_ts to
+ * store, not the number of bytes.
+ */
+void *memset16(uint16_t *s, uint16_t v, size_t count)
+{
+	uint16_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset16);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+/**
+ * memset32() - Fill a memory area with a uint32_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint32_t instead
+ * of a byte.  Remember that @count is the number of uint32_ts to
+ * store, not the number of bytes.
+ */
+void *memset32(uint32_t *s, uint32_t v, size_t count)
+{
+	uint32_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset32);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+/**
+ * memset64() - Fill a memory area with a uint64_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint64_t instead
+ * of a byte.  Remember that @count is the number of uint64_ts to
+ * store, not the number of bytes.
+ */
+void *memset64(uint64_t *s, uint64_t v, size_t count)
+{
+	uint64_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset64);
+#endif
+
 #ifndef __HAVE_ARCH_MEMCPY
 /**
  * memcpy - Copy one area of memory to another
-- 
2.13.2

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-20 18:45 [PATCH v4 0/8] Multibyte memset variations Matthew Wilcox
2017-07-20 18:45 ` Matthew Wilcox [this message]
2017-07-20 18:45 ` [PATCH v4 2/8] Add testcases for memset16/32/64 Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 3/8] x86: Implement memset16, memset32 & memset64 Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 4/8] ARM: Implement " Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 5/8] alpha: Add support for memset16 Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 6/8] zram: Convert to using memset_l Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 7/8] sym53c8xx_2: Convert to use memset32 Matthew Wilcox
2017-07-20 18:45 ` [PATCH v4 8/8] vga: Optimise console scrolling Matthew Wilcox
2017-07-25  5:27 ` [PATCH v4 0/8] Multibyte memset variations Michael Ellerman
2017-07-25 13:08   ` Matthew Wilcox

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