@@ -34,4 +34,7 @@ extern void *memchr(const void *, int, __kernel_size_t);
#define __HAVE_ARCH_MEMSET
extern void *memset(void *, int, __kernel_size_t);
+#define __HAVE_ARCH_MEMCMP
+extern int memcmp(const void *, const void *, size_t);
+
#endif
@@ -51,6 +51,7 @@ EXPORT_SYMBOL(memset);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memchr);
+EXPORT_SYMBOL(memcmp);
/* atomic bitops */
EXPORT_SYMBOL(set_bit);
@@ -2,5 +2,5 @@ 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 \
+ memchr.o memcpy.o memmove.o memset.o memcmp.o \
strchr.o strrchr.o
new file mode 100644
@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2013 ARM Ltd.
+ * Copyright (C) 2013 Linaro.
+ *
+ * This code is based on glibc cortex strings work originally authored by Linaro
+ * and re-licensed under GPLv2 for the Linux kernel. The original code can
+ * be found @
+ *
+ * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
+ * files/head:/src/aarch64/
+ *
+ * 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>
+
+/*
+* compare memory areas(when two memory areas' offset are different,
+* alignment handled by the hardware)
+*
+* Parameters:
+* x0 - const memory area 1 pointer
+* x1 - const memory area 2 pointer
+* x2 - the maximal compare byte length
+* Returns:
+* x0 - a compare result, maybe less than, equal to, or greater than ZERO
+*/
+
+/* Parameters and result. */
+#define src1 x0
+#define src2 x1
+#define limit x2
+#define result x0
+
+/* Internal variables. */
+#define data1 x3
+#define data1w w3
+#define data2 x4
+#define data2w w4
+#define has_nul x5
+#define diff x6
+#define endloop x7
+#define tmp1 x8
+#define tmp2 x9
+#define tmp3 x10
+#define pos x11
+#define limit_wd x12
+#define mask x13
+
+ENTRY(memcmp)
+ cbz limit, .Lret0
+ eor tmp1, src1, src2
+ tst tmp1, #7
+ b.ne .Lmisaligned8
+ ands tmp1, src1, #7
+ b.ne .Lmutual_align
+ sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
+ lsr limit_wd, limit_wd, #3 /* Convert to Dwords. */
+.Lloop_aligned:
+ ldr data1, [src1], #8
+ ldr data2, [src2], #8
+.Lstart_realigned:
+ subs limit_wd, limit_wd, #1
+ eor diff, data1, data2 /* Non-zero if differences found. */
+ csinv endloop, diff, xzr, cs /* Last Dword or differences. */
+ cbz endloop, .Lloop_aligned
+
+ /* Not reached the limit, must have found a diff. */
+ tbz limit_wd, #63, .Lnot_limit
+
+ /* Limit % 8 == 0 => all bytes significant. */
+ ands limit, limit, #7
+ b.eq .Lnot_limit
+
+ lsl limit, limit, #3 /* Bits -> bytes. */
+ mov mask, #~0
+#ifdef __ARM64EB__
+ lsr mask, mask, limit
+#else
+ lsl mask, mask, limit
+#endif
+ bic data1, data1, mask
+ bic data2, data2, mask
+
+ orr diff, diff, mask
+ b .Lnot_limit
+
+.Lmutual_align:
+ /*
+ * Sources are mutually aligned, but are not currently at an
+ * alignment boundary. Round down the addresses and then mask off
+ * the bytes that precede the start point.
+ */
+ bic src1, src1, #7
+ bic src2, src2, #7
+ ldr data1, [src1], #8
+ ldr data2, [src2], #8
+ sub limit_wd, limit, #1/* limit != 0, so no underflow. */
+ and tmp3, limit_wd, #7
+ lsr limit_wd, limit_wd, #3
+ add tmp3, tmp3, tmp1
+ add limit_wd, limit_wd, tmp3, lsr #3
+ add limit, limit, tmp1/* Adjust the limit for the extra. */
+ lsl tmp1, tmp1, #3/* Bytes beyond alignment -> bits.*/
+ neg tmp1, tmp1/* Bits to alignment -64. */
+ mov tmp2, #~0
+#ifdef __ARM64EB__
+ /* Big-endian. Early bytes are at MSB. */
+ lsl tmp2, tmp2, tmp1/* Shift (tmp1 & 63). */
+#else
+ /* Little-endian. Early bytes are at LSB. */
+ lsr tmp2, tmp2, tmp1/* Shift (tmp1 & 63). */
+#endif
+ orr data1, data1, tmp2
+ orr data2, data2, tmp2
+ b .Lstart_realigned
+
+.Lmisaligned8:
+ cmp limit, #8
+ b.lo .Ltiny8proc /*limit < 8... */
+ /*
+ * Get the align offset length to compare per byte first.
+ * After this process, one string's address will be aligned.
+ */
+ and tmp1, src1, #7
+ neg tmp1, tmp1
+ add tmp1, tmp1, #8
+ and tmp2, src2, #7
+ neg tmp2, tmp2
+ add tmp2, tmp2, #8
+ subs tmp3, tmp1, tmp2
+ csel pos, tmp1, tmp2, hi /*Choose the maximum. */
+ /*
+ * Here, limit is not less than 8,
+ * so directly run .Ltinycmp without checking the limit.*/
+ sub limit, limit, pos
+.Ltinycmp:
+ ldrb data1w, [src1], #1
+ ldrb data2w, [src2], #1
+ subs pos, pos, #1
+ ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */
+ b.eq .Ltinycmp
+ cbnz pos, 1f /*find the unequal...*/
+ cmp data1w, data2w
+ b.eq .Lstart_align /*the last bytes are equal....*/
+1:
+ sub result, data1, data2
+ ret
+
+.Lstart_align:
+ lsr limit_wd, limit, #3
+ cbz limit_wd, .Lremain8
+ ands xzr, src1, #7
+ /*
+ * eq means tmp1 bytes finished the compare in the Ltinycmp,
+ * tmp3 is positive here
+ */
+ b.eq .Lrecal_offset
+ add src1, src1, tmp3
+ add src2, src2, tmp3
+ sub limit, limit, tmp3
+ lsr limit_wd, limit, #3
+ cbz limit_wd, .Lremain8
+ ldr data1, [src1], #8
+ ldr data2, [src2], #8
+
+ subs limit_wd, limit_wd, #1
+ eor diff, data1, data2 /*Non-zero if differences found.*/
+ csinv endloop, diff, xzr, ne
+ cbnz endloop, .Lunequal_proc
+ and tmp3, tmp3, #7 /*tmp3 = 8 + tmp3 ( old tmp3 is negative)*/
+ /*
+ * src1 is aligned and src1 is in the right of src2.
+ * Remain count is not less than 8 here.
+ */
+.Lrecal_offset:
+ neg pos, tmp3
+.Lloopcmp_proc:
+ /*
+ * Fall back pos bytes, get the first bytes segment of
+ * one Dword of src1. pos is negative here. We also can use :
+ * ldr data1, [src1]
+ * ldr data2, [src2, pos]
+ * These two instructions will read data with aligned address,then
+ * do the compare.But if we adapt this method, have to add some
+ * shift and mask out some bits from these two Dword to construct
+ * two Dwords to compare.Some more instructions will be added,
+ * and most important, it will need more time cost.
+ */
+ ldr data1, [src1,pos]
+ ldr data2, [src2,pos]
+ eor diff, data1, data2 /* Non-zero if differences found.*/
+ cbnz diff, .Lnot_limit
+
+ /*The second part process*/
+ ldr data1, [src1], #8
+ ldr data2, [src2], #8
+ eor diff, data1, data2 /* Non-zero if differences found.*/
+ subs limit_wd, limit_wd, #1
+ csinv endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/
+ cbz endloop, .Lloopcmp_proc
+.Lunequal_proc:
+ /*whether unequal occurred?*/
+ cbz diff, .Lremain8
+.Lnot_limit:
+#ifndef __ARM64EB__
+ rev diff, diff
+ rev data1, data1
+ rev data2, data2
+#endif
+ /*
+ * The MS-non-zero bit of DIFF marks either the first bit
+ * that is different, or the end of the significant data.
+ * Shifting left now will bring the critical information into the
+ * top bits.
+ */
+ clz pos, diff
+ lsl data1, data1, pos
+ lsl data2, data2, pos
+ /* But we need to zero-extend (char is unsigned) the value and then
+ perform a signed 32-bit subtraction. */
+ lsr data1, data1, #56
+ sub result, data1, data2, lsr #56
+ ret
+
+ .p2align 6
+.Lremain8:
+ /* Limit % 8 == 0 => all bytes significant. */
+ ands limit, limit, #7
+ b.eq .Lret0
+
+.Ltiny8proc:
+ /*Perhaps we can do better than this.*/
+ ldrb data1w, [src1], #1
+ ldrb data2w, [src2], #1
+ subs limit, limit, #1
+ /*
+ * ne satisfied means current limit > 0. Z=1 will make cs =0,
+ * lead to next ccmp use ZERO to set flags,so break the loop.*/
+ ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */
+ b.eq .Ltiny8proc
+ sub result, data1, data2
+ ret
+.Lret0:
+ mov result, #0
+ ret
+ENDPROC(memcmp)