arm64: use generic strnlen_user and strncpy_from_user functions

This patch implements the word-at-a-time interface for arm64 using the
same algorithm as ARM. We use the fls64 macro, which expands to a clz
instruction via a compiler builtin. Big-endian configurations make use
of the implementation from asm-generic.

With this implemented, we can replace our byte-at-a-time strnlen_user
and strncpy_from_user functions with the optimised generic versions.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

3 files changed, 3 insertions, 102 deletions

diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
index 59acc0ef0462..328ce1a99daa 100644
--- a/arch/arm64/lib/Makefile
+++ b/arch/arm64/lib/Makefile
@@ -1,6 +1,4 @@
-lib-y           := bitops.o delay.o                                     \
-                   strncpy_from_user.o strnlen_user.o clear_user.o      \
-                   copy_from_user.o copy_to_user.o copy_in_user.o       \
-                   copy_page.o clear_page.o                             \
-                   memchr.o memcpy.o memmove.o memset.o                 \
+lib-y           := bitops.o clear_user.o delay.o copy_from_user.o       \
+                   copy_to_user.o copy_in_user.o copy_page.o            \
+                   clear_page.o memchr.o memcpy.o memmove.o memset.o    \
                    strchr.o strrchr.o
diff --git a/arch/arm64/lib/strncpy_from_user.S b/arch/arm64/lib/strncpy_from_user.S
deleted file mode 100644
index 56e448a831a0..000000000000
--- a/arch/arm64/lib/strncpy_from_user.S
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Based on arch/arm/lib/strncpy_from_user.S
- *
- * Copyright (C) 1995-2000 Russell King
- * Copyright (C) 2012 ARM Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <linux/linkage.h>
-#include <asm/assembler.h>
-#include <asm/errno.h>
-
-        .text
-        .align  5
-
-/*
- * Copy a string from user space to kernel space.
- *  x0 = dst, x1 = src, x2 = byte length
- * returns the number of characters copied (strlen of copied string),
- *  -EFAULT on exception, or "len" if we fill the whole buffer
- */
-ENTRY(__strncpy_from_user)
-        mov     x4, x1
-1:      subs    x2, x2, #1
-        bmi     2f
-USER(9f, ldrb   w3, [x1], #1    )
-        strb    w3, [x0], #1
-        cbnz    w3, 1b
-        sub     x1, x1, #1      // take NUL character out of count
-2:      sub     x0, x1, x4
-        ret
-ENDPROC(__strncpy_from_user)
-
-        .section .fixup,"ax"
-        .align  0
-9:      strb    wzr, [x0]       // null terminate
-        mov     x0, #-EFAULT
-        ret
-        .previous
diff --git a/arch/arm64/lib/strnlen_user.S b/arch/arm64/lib/strnlen_user.S
deleted file mode 100644
index 7f7b176a5646..000000000000
--- a/arch/arm64/lib/strnlen_user.S
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Based on arch/arm/lib/strnlen_user.S
- *
- * Copyright (C) 1995-2000 Russell King
- * Copyright (C) 2012 ARM Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <linux/linkage.h>
-#include <asm/assembler.h>
-#include <asm/errno.h>
-
-        .text
-        .align  5
-
-/* Prototype: unsigned long __strnlen_user(const char *str, long n)
- * Purpose  : get length of a string in user memory
- * Params   : str - address of string in user memory
- * Returns  : length of string *including terminator*
- *            or zero on exception, or n if too long
- */
-ENTRY(__strnlen_user)
-        mov     x2, x0
-1:      subs    x1, x1, #1
-        b.mi    2f
-USER(9f, ldrb   w3, [x0], #1    )
-        cbnz    w3, 1b
-2:      sub     x0, x0, x2
-        ret
-ENDPROC(__strnlen_user)
-
-        .section .fixup,"ax"
-        .align  0
-9:      mov     x0, #0
-        ret
-        .previous