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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-08 11:31:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-08 11:31:16 -0700
commit3f17ea6dea8ba5668873afa54628a91aaa3fb1c0 (patch)
treeafbeb2accd4c2199ddd705ae943995b143a0af02 /arch/arm64/lib/memcpy.S
parent1860e379875dfe7271c649058aeddffe5afd9d0d (diff)
parent1a5700bc2d10cd379a795fd2bb377a190af5acd4 (diff)
Merge branch 'next' (accumulated 3.16 merge window patches) into master
Now that 3.15 is released, this merges the 'next' branch into 'master', bringing us to the normal situation where my 'master' branch is the merge window. * accumulated work in next: (6809 commits) ufs: sb mutex merge + mutex_destroy powerpc: update comments for generic idle conversion cris: update comments for generic idle conversion idle: remove cpu_idle() forward declarations nbd: zero from and len fields in NBD_CMD_DISCONNECT. mm: convert some level-less printks to pr_* MAINTAINERS: adi-buildroot-devel is moderated MAINTAINERS: add linux-api for review of API/ABI changes mm/kmemleak-test.c: use pr_fmt for logging fs/dlm/debug_fs.c: replace seq_printf by seq_puts fs/dlm/lockspace.c: convert simple_str to kstr fs/dlm/config.c: convert simple_str to kstr mm: mark remap_file_pages() syscall as deprecated mm: memcontrol: remove unnecessary memcg argument from soft limit functions mm: memcontrol: clean up memcg zoneinfo lookup mm/memblock.c: call kmemleak directly from memblock_(alloc|free) mm/mempool.c: update the kmemleak stack trace for mempool allocations lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations mm: introduce kmemleak_update_trace() mm/kmemleak.c: use %u to print ->checksum ...
Diffstat (limited to 'arch/arm64/lib/memcpy.S')
-rw-r--r--arch/arm64/lib/memcpy.S192
1 files changed, 170 insertions, 22 deletions
diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S
index 27b5003609b6..8a9a96d3ddae 100644
--- a/arch/arm64/lib/memcpy.S
+++ b/arch/arm64/lib/memcpy.S
@@ -1,5 +1,13 @@
/*
* 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
@@ -16,6 +24,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/cache.h>
/*
* Copy a buffer from src to dest (alignment handled by the hardware)
@@ -27,27 +36,166 @@
* 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(memcpy)
- mov x4, x0
- subs x2, x2, #8
- b.mi 2f
-1: ldr x3, [x1], #8
- subs x2, x2, #8
- str x3, [x4], #8
- b.pl 1b
-2: adds x2, x2, #4
- b.mi 3f
- ldr w3, [x1], #4
- sub x2, x2, #4
- str w3, [x4], #4
-3: adds x2, x2, #2
- b.mi 4f
- ldrh w3, [x1], #2
- sub x2, x2, #2
- strh w3, [x4], #2
-4: adds x2, x2, #1
- b.mi 5f
- ldrb w3, [x1]
- strb w3, [x4]
-5: ret
+ 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 overwritting 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
+ 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 .Ltiny15
+ 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
+.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
+ 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]
+ strb tmp1w, [dst]
+
+.Lexitfunc:
+ ret
+
+.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.
+ */
+ ldp A_l, A_h, [src],#16
+ stp A_l, A_h, [dst],#16
+ ldp B_l, B_h, [src],#16
+ ldp C_l, C_h, [src],#16
+ stp B_l, B_h, [dst],#16
+ stp C_l, C_h, [dst],#16
+ ldp D_l, D_h, [src],#16
+ stp D_l, D_h, [dst],#16
+
+ 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-get 64 bytes data. */
+ ldp A_l, A_h, [src],#16
+ ldp B_l, B_h, [src],#16
+ ldp C_l, C_h, [src],#16
+ ldp 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.
+ */
+ stp A_l, A_h, [dst],#16
+ ldp A_l, A_h, [src],#16
+ stp B_l, B_h, [dst],#16
+ ldp B_l, B_h, [src],#16
+ stp C_l, C_h, [dst],#16
+ ldp C_l, C_h, [src],#16
+ stp D_l, D_h, [dst],#16
+ ldp D_l, D_h, [src],#16
+ subs count, count, #64
+ b.ge 1b
+ stp A_l, A_h, [dst],#16
+ stp B_l, B_h, [dst],#16
+ stp C_l, C_h, [dst],#16
+ stp D_l, D_h, [dst],#16
+
+ tst count, #0x3f
+ b.ne .Ltail63
+ ret
ENDPROC(memcpy)