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Subject[PATCH 2/2] ARC: provide optimal __get_user_fn()
Date
From: Vineet Gupta <vgupta@synopsys.com>

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/uaccess.h | 51 ++++++++++++++++++++++++++++++++++++++++
1 files changed, 51 insertions(+), 0 deletions(-)

diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
index 503c98d..d9cbae4 100644
--- a/arch/arc/include/asm/uaccess.h
+++ b/arch/arc/include/asm/uaccess.h
@@ -35,6 +35,57 @@
#define __access_ok(addr, sz) (unlikely(__kernel_ok) || \
likely(__user_ok((addr), (sz))))

+/*********** Single byte/s-word/word copies ******************/
+
+#define __get_user_fn(sz, u, k) \
+({ \
+ long __ret = 0; /* success by default */ \
+ switch (sz) { \
+ case 1: __arc_get_user_one(*(k), u, "ldb", __ret); break; \
+ case 2: __arc_get_user_one(*(k), u, "ldw", __ret); break; \
+ case 4: __arc_get_user_one(*(k), u, "ld", __ret); break; \
+ case 8: __arc_get_user_one_64(*(k), u, __ret); break; \
+ } \
+ __ret; \
+})
+
+#define __arc_get_user_one(dst, src, op, ret) \
+ __asm__ __volatile__( \
+ "1: "op" %1,[%2]\n" \
+ "2: ;nop\n" \
+ " .section .fixup, \"ax\"\n" \
+ " .align 4\n" \
+ "3: mov %0, %3\n" \
+ " j 2b\n" \
+ " .previous\n" \
+ " .section __ex_table, \"a\"\n" \
+ " .align 4\n" \
+ " .word 1b,3b\n" \
+ " .previous\n" \
+ \
+ : "+r" (ret), "=r" (dst) \
+ : "r" (src), "i" (-EFAULT))
+
+#define __arc_get_user_one_64(dst, src, ret) \
+ __asm__ __volatile__( \
+ "1: ld %1,[%2]\n" \
+ "4: ld %R1,[%2, 4]\n" \
+ "2: ;nop\n" \
+ " .section .fixup, \"ax\"\n" \
+ " .align 4\n" \
+ "3: mov %0, %3\n" \
+ " j 2b\n" \
+ " .previous\n" \
+ " .section __ex_table, \"a\"\n" \
+ " .align 4\n" \
+ " .word 1b,3b\n" \
+ " .word 4b,3b\n" \
+ " .previous\n" \
+ \
+ : "+r" (ret), "=r" (dst) \
+ : "r" (src), "i" (-EFAULT))
+
+
static inline unsigned long
__arc_copy_from_user(void *to, const void __user *from, unsigned long n)
{
--
1.7.4.1


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