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Diffstat (limited to 'arch/arm64/lib/copy_template.S')
| -rw-r--r-- | arch/arm64/lib/copy_template.S | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/arm64/lib/copy_template.S b/arch/arm64/lib/copy_template.S new file mode 100644 index 000000000..f5b9210f1 --- /dev/null +++ b/arch/arm64/lib/copy_template.S @@ -0,0 +1,193 @@ +/* + * 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/>. + */ + + +/* + * Copy a buffer from src to dest (alignment handled by the hardware) + * + * 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 +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 + + mov dst, dstin + cmp count, #16 + /*When memory length is less than 16, the accessed are not aligned.*/ + b.lo .Ltiny15 + + neg tmp2, src + ands tmp2, tmp2, #15/* Bytes to reach alignment. */ + b.eq .LSrcAligned + sub count, count, tmp2 + /* + * Copy the leading memory data from src to dst in an increasing + * address order.By this way,the risk of overwriting the source + * memory data is eliminated when the distance between src and + * dst is less than 16. The memory accesses here are alignment. + */ + tbz tmp2, #0, 1f + ldrb1 tmp1w, src, #1 + strb1 tmp1w, dst, #1 +1: + tbz tmp2, #1, 2f + ldrh1 tmp1w, src, #2 + strh1 tmp1w, dst, #2 +2: + tbz tmp2, #2, 3f + ldr1 tmp1w, src, #4 + str1 tmp1w, dst, #4 +3: + tbz tmp2, #3, .LSrcAligned + ldr1 tmp1, src, #8 + str1 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 .Ltiny15 + cmp tmp1w, #0x20 + b.eq 1f + b.lt 2f + ldp1 A_l, A_h, src, #16 + stp1 A_l, A_h, dst, #16 +1: + ldp1 A_l, A_h, src, #16 + stp1 A_l, A_h, dst, #16 +2: + ldp1 A_l, A_h, src, #16 + stp1 A_l, A_h, dst, #16 +.Ltiny15: + /* + * Prefer to break one ldp/stp into several load/store to access + * memory in an increasing address order,rather than to load/store 16 + * bytes from (src-16) to (dst-16) and to backward the src to aligned + * address,which way is used in original cortex memcpy. If keeping + * the original memcpy process here, memmove need to satisfy the + * precondition that src address is at least 16 bytes bigger than dst + * address,otherwise some source data will be overwritten when memove + * call memcpy directly. To make memmove simpler and decouple the + * memcpy's dependency on memmove, withdrew the original process. + */ + tbz count, #3, 1f + ldr1 tmp1, src, #8 + str1 tmp1, dst, #8 +1: + tbz count, #2, 2f + ldr1 tmp1w, src, #4 + str1 tmp1w, dst, #4 +2: + tbz count, #1, 3f + ldrh1 tmp1w, src, #2 + strh1 tmp1w, dst, #2 +3: + tbz count, #0, .Lexitfunc + ldrb1 tmp1w, src, #1 + strb1 tmp1w, dst, #1 + + b .Lexitfunc + +.Lcpy_over64: + subs count, count, #128 + b.ge .Lcpy_body_large + /* + * Less than 128 bytes to copy, so handle 64 here and then jump + * to the tail. + */ + ldp1 A_l, A_h, src, #16 + stp1 A_l, A_h, dst, #16 + ldp1 B_l, B_h, src, #16 + ldp1 C_l, C_h, src, #16 + stp1 B_l, B_h, dst, #16 + stp1 C_l, C_h, dst, #16 + ldp1 D_l, D_h, src, #16 + stp1 D_l, D_h, dst, #16 + + tst count, #0x3f + b.ne .Ltail63 + b .Lexitfunc + + /* + * 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-get 64 bytes data. */ + ldp1 A_l, A_h, src, #16 + ldp1 B_l, B_h, src, #16 + ldp1 C_l, C_h, src, #16 + ldp1 D_l, D_h, src, #16 +1: + /* + * interlace the load of next 64 bytes data block with store of the last + * loaded 64 bytes data. + */ + stp1 A_l, A_h, dst, #16 + ldp1 A_l, A_h, src, #16 + stp1 B_l, B_h, dst, #16 + ldp1 B_l, B_h, src, #16 + stp1 C_l, C_h, dst, #16 + ldp1 C_l, C_h, src, #16 + stp1 D_l, D_h, dst, #16 + ldp1 D_l, D_h, src, #16 + subs count, count, #64 + b.ge 1b + stp1 A_l, A_h, dst, #16 + stp1 B_l, B_h, dst, #16 + stp1 C_l, C_h, dst, #16 + stp1 D_l, D_h, dst, #16 + + tst count, #0x3f + b.ne .Ltail63 +.Lexitfunc: |