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Diffstat (limited to 'arch/arm64/lib/memmove.S')
| -rw-r--r-- | arch/arm64/lib/memmove.S | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/arm64/lib/memmove.S b/arch/arm64/lib/memmove.S new file mode 100644 index 000000000..57b19ea2d --- /dev/null +++ b/arch/arm64/lib/memmove.S @@ -0,0 +1,197 @@ +/* + * 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> +#include <asm/cache.h> + +/* + * Move a buffer from src to test (alignment handled by the hardware). + * If dest <= src, call memcpy, otherwise copy in reverse order. + * + * Parameters: + * x0 - dest + * x1 - src + * x2 - n + * Returns: + * x0 - dest + */ +dstin .req x0 +src .req x1 +count .req x2 +tmp1 .req x3 +tmp1w .req w3 +tmp2 .req x4 +tmp2w .req w4 +tmp3 .req x5 +tmp3w .req w5 +dst .req x6 + +A_l .req x7 +A_h .req x8 +B_l .req x9 +B_h .req x10 +C_l .req x11 +C_h .req x12 +D_l .req x13 +D_h .req x14 + +ENTRY(memmove) + cmp dstin, src + b.lo memcpy + add tmp1, src, count + cmp dstin, tmp1 + b.hs memcpy /* No overlap. */ + + add dst, dstin, count + add src, src, count + cmp count, #16 + b.lo .Ltail15 /*probably non-alignment accesses.*/ + + ands tmp2, src, #15 /* Bytes to reach alignment. */ + b.eq .LSrcAligned + sub count, count, tmp2 + /* + * process the aligned offset length to make the src aligned firstly. + * those extra instructions' cost is acceptable. It also make the + * coming accesses are based on aligned address. + */ + tbz tmp2, #0, 1f + ldrb tmp1w, [src, #-1]! + strb tmp1w, [dst, #-1]! +1: + tbz tmp2, #1, 2f + ldrh tmp1w, [src, #-2]! + strh tmp1w, [dst, #-2]! +2: + tbz tmp2, #2, 3f + ldr tmp1w, [src, #-4]! + str tmp1w, [dst, #-4]! +3: + tbz tmp2, #3, .LSrcAligned + ldr tmp1, [src, #-8]! + str tmp1, [dst, #-8]! + +.LSrcAligned: + cmp count, #64 + b.ge .Lcpy_over64 + + /* + * Deal with small copies quickly by dropping straight into the + * exit block. + */ +.Ltail63: + /* + * Copy up to 48 bytes of data. At this point we only need the + * bottom 6 bits of count to be accurate. + */ + ands tmp1, count, #0x30 + b.eq .Ltail15 + cmp tmp1w, #0x20 + b.eq 1f + b.lt 2f + ldp A_l, A_h, [src, #-16]! + stp A_l, A_h, [dst, #-16]! +1: + ldp A_l, A_h, [src, #-16]! + stp A_l, A_h, [dst, #-16]! +2: + ldp A_l, A_h, [src, #-16]! + stp A_l, A_h, [dst, #-16]! + +.Ltail15: + tbz count, #3, 1f + ldr tmp1, [src, #-8]! + str tmp1, [dst, #-8]! +1: + tbz count, #2, 2f + ldr tmp1w, [src, #-4]! + str tmp1w, [dst, #-4]! +2: + tbz count, #1, 3f + ldrh tmp1w, [src, #-2]! + strh tmp1w, [dst, #-2]! +3: + tbz count, #0, .Lexitfunc + ldrb tmp1w, [src, #-1] + strb tmp1w, [dst, #-1] + +.Lexitfunc: + ret + +.Lcpy_over64: + subs count, count, #128 + b.ge .Lcpy_body_large + /* + * Less than 128 bytes to copy, so handle 64 bytes here and then jump + * to the tail. + */ + ldp A_l, A_h, [src, #-16] + stp A_l, A_h, [dst, #-16] + ldp B_l, B_h, [src, #-32] + ldp C_l, C_h, [src, #-48] + stp B_l, B_h, [dst, #-32] + stp C_l, C_h, [dst, #-48] + ldp D_l, D_h, [src, #-64]! + stp D_l, D_h, [dst, #-64]! + + tst count, #0x3f + b.ne .Ltail63 + ret + + /* + * Critical loop. Start at a new cache line boundary. Assuming + * 64 bytes per line this ensures the entire loop is in one line. + */ + .p2align L1_CACHE_SHIFT +.Lcpy_body_large: + /* pre-load 64 bytes data. */ + ldp A_l, A_h, [src, #-16] + ldp B_l, B_h, [src, #-32] + ldp C_l, C_h, [src, #-48] + ldp D_l, D_h, [src, #-64]! +1: + /* + * interlace the load of next 64 bytes data block with store of the last + * loaded 64 bytes data. + */ + stp A_l, A_h, [dst, #-16] + ldp A_l, A_h, [src, #-16] + stp B_l, B_h, [dst, #-32] + ldp B_l, B_h, [src, #-32] + stp C_l, C_h, [dst, #-48] + ldp C_l, C_h, [src, #-48] + stp D_l, D_h, [dst, #-64]! + ldp D_l, D_h, [src, #-64]! + subs count, count, #64 + b.ge 1b + stp A_l, A_h, [dst, #-16] + stp B_l, B_h, [dst, #-32] + stp C_l, C_h, [dst, #-48] + stp D_l, D_h, [dst, #-64]! + + tst count, #0x3f + b.ne .Ltail63 + ret +ENDPROC(memmove) |