[PATCH 1/4] arm64: use generic strnlen_user and strncpy_from_user functions
Will Deacon
will.deacon at arm.com
Tue Dec 17 07:20:04 EST 2013
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 at arm.com>
---
arch/arm64/Kconfig | 2 ++
arch/arm64/include/asm/uaccess.h | 25 +++------------
arch/arm64/include/asm/word-at-a-time.h | 54 +++++++++++++++++++++++++++++++++
arch/arm64/kernel/arm64ksyms.c | 5 +--
arch/arm64/lib/Makefile | 8 ++---
arch/arm64/lib/strncpy_from_user.S | 50 ------------------------------
arch/arm64/lib/strnlen_user.S | 47 ----------------------------
7 files changed, 64 insertions(+), 127 deletions(-)
create mode 100644 arch/arm64/include/asm/word-at-a-time.h
delete mode 100644 arch/arm64/lib/strncpy_from_user.S
delete mode 100644 arch/arm64/lib/strnlen_user.S
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d4dd22ee4b7..295bf2de7128 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -17,6 +17,8 @@ config ARM64
select GENERIC_IRQ_SHOW
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
+ select GENERIC_STRNCPY_FROM_USER
+ select GENERIC_STRNLEN_USER
select GENERIC_TIME_VSYSCALL
select HARDIRQS_SW_RESEND
select HAVE_ARCH_TRACEHOOK
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 7ecc2b23882e..6c0f684aca81 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -100,6 +100,7 @@ static inline void set_fs(mm_segment_t fs)
})
#define access_ok(type, addr, size) __range_ok(addr, size)
+#define user_addr_max get_fs
/*
* The "__xxx" versions of the user access functions do not verify the address
@@ -240,9 +241,6 @@ extern unsigned long __must_check __copy_to_user(void __user *to, const void *fr
extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
-extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
-extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
-
static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (access_ok(VERIFY_READ, from, n))
@@ -276,24 +274,9 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
return n;
}
-static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
-{
- long res = -EFAULT;
- if (access_ok(VERIFY_READ, src, 1))
- res = __strncpy_from_user(dst, src, count);
- return res;
-}
-
-#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
+extern long strncpy_from_user(char *dest, const char __user *src, long count);
-static inline long __must_check strnlen_user(const char __user *s, long n)
-{
- unsigned long res = 0;
-
- if (__addr_ok(s))
- res = __strnlen_user(s, n);
-
- return res;
-}
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *str, long n);
#endif /* __ASM_UACCESS_H */
diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h
new file mode 100644
index 000000000000..27a167d044d9
--- /dev/null
+++ b/arch/arm64/include/asm/word-at-a-time.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2013 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/>.
+ */
+#ifndef __ASM_WORD_AT_A_TIME_H
+#define __ASM_WORD_AT_A_TIME_H
+
+#ifndef __AARCH64EB__
+
+#include <linux/kernel.h>
+
+struct word_at_a_time {
+ const unsigned long one_bits, high_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
+
+static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
+ const struct word_at_a_time *c)
+{
+ unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
+ *bits = mask;
+ return mask;
+}
+
+#define prep_zero_mask(a, bits, c) (bits)
+
+static inline unsigned long create_zero_mask(unsigned long bits)
+{
+ bits = (bits - 1) & ~bits;
+ return bits >> 7;
+}
+
+static inline unsigned long find_zero(unsigned long mask)
+{
+ return fls64(mask) >> 3;
+}
+
+#else /* __AARCH64EB__ */
+#include <asm-generic/word-at-a-time.h>
+#endif
+
+#endif /* __ASM_WORD_AT_A_TIME_H */
diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
index e7ee770c0697..338b568cd8ae 100644
--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -29,13 +29,10 @@
#include <asm/checksum.h>
- /* user mem (segment) */
-EXPORT_SYMBOL(__strnlen_user);
-EXPORT_SYMBOL(__strncpy_from_user);
-
EXPORT_SYMBOL(copy_page);
EXPORT_SYMBOL(clear_page);
+ /* user mem (segment) */
EXPORT_SYMBOL(__copy_from_user);
EXPORT_SYMBOL(__copy_to_user);
EXPORT_SYMBOL(__clear_user);
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
--
1.8.2.2
More information about the linux-arm-kernel
mailing list