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0f61f6be1f
Now that we have SYM_FUNC_ALIAS() and SYM_FUNC_ALIAS_WEAK(), use those
to simplify and more consistently define function aliases across
arch/arm64.
Aliases are now defined in terms of a canonical function name. For
position-independent functions I've made the __pi_<func> name the
canonical name, and defined other alises in terms of this.
The SYM_FUNC_{START,END}_PI(func) macros obscure the __pi_<func> name,
and make this hard to seatch for. The SYM_FUNC_START_WEAK_PI() macro
also obscures the fact that the __pi_<func> fymbol is global and the
<func> symbol is weak. For clarity, I have removed these macros and used
SYM_FUNC_{START,END}() directly with the __pi_<func> name.
For example:
SYM_FUNC_START_WEAK_PI(func)
... asm insns ...
SYM_FUNC_END_PI(func)
EXPORT_SYMBOL(func)
... becomes:
SYM_FUNC_START(__pi_func)
... asm insns ...
SYM_FUNC_END(__pi_func)
SYM_FUNC_ALIAS_WEAK(func, __pi_func)
EXPORT_SYMBOL(func)
For clarity, where there are multiple annotations such as
EXPORT_SYMBOL(), I've tried to keep annotations grouped by symbol. For
example, where a function has a name and an alias which are both
exported, this is organised as:
SYM_FUNC_START(func)
... asm insns ...
SYM_FUNC_END(func)
EXPORT_SYMBOL(func)
SYM_FUNC_ALIAS(alias, func)
EXPORT_SYMBOL(alias)
For consistency with the other string functions, I've defined strrchr as
a position-independent function, as it can safely be used as such even
though we have no users today.
As we no longer use SYM_FUNC_{START,END}_ALIAS(), our local copies are
removed. The common versions will be removed by a subsequent patch.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220216162229.1076788-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
254 lines
5.8 KiB
ArmAsm
254 lines
5.8 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2012-2021, Arm Limited.
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*
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* Adapted from the original at:
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* https://github.com/ARM-software/optimized-routines/blob/afd6244a1f8d9229/string/aarch64/memcpy.S
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/* Assumptions:
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*
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* ARMv8-a, AArch64, unaligned accesses.
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*
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*/
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#define L(label) .L ## label
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#define dstin x0
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#define src x1
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#define count x2
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#define dst x3
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#define srcend x4
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#define dstend x5
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#define A_l x6
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#define A_lw w6
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#define A_h x7
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#define B_l x8
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#define B_lw w8
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#define B_h x9
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#define C_l x10
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#define C_lw w10
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#define C_h x11
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#define D_l x12
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#define D_h x13
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#define E_l x14
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#define E_h x15
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#define F_l x16
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#define F_h x17
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#define G_l count
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#define G_h dst
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#define H_l src
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#define H_h srcend
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#define tmp1 x14
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/* This implementation handles overlaps and supports both memcpy and memmove
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from a single entry point. It uses unaligned accesses and branchless
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sequences to keep the code small, simple and improve performance.
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Copies are split into 3 main cases: small copies of up to 32 bytes, medium
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copies of up to 128 bytes, and large copies. The overhead of the overlap
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check is negligible since it is only required for large copies.
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Large copies use a software pipelined loop processing 64 bytes per iteration.
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The destination pointer is 16-byte aligned to minimize unaligned accesses.
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The loop tail is handled by always copying 64 bytes from the end.
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*/
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SYM_FUNC_START(__pi_memcpy)
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add srcend, src, count
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add dstend, dstin, count
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cmp count, 128
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b.hi L(copy_long)
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cmp count, 32
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b.hi L(copy32_128)
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/* Small copies: 0..32 bytes. */
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cmp count, 16
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b.lo L(copy16)
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ldp A_l, A_h, [src]
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ldp D_l, D_h, [srcend, -16]
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stp A_l, A_h, [dstin]
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stp D_l, D_h, [dstend, -16]
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ret
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/* Copy 8-15 bytes. */
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L(copy16):
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tbz count, 3, L(copy8)
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ldr A_l, [src]
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ldr A_h, [srcend, -8]
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str A_l, [dstin]
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str A_h, [dstend, -8]
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ret
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.p2align 3
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/* Copy 4-7 bytes. */
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L(copy8):
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tbz count, 2, L(copy4)
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ldr A_lw, [src]
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ldr B_lw, [srcend, -4]
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str A_lw, [dstin]
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str B_lw, [dstend, -4]
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ret
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/* Copy 0..3 bytes using a branchless sequence. */
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L(copy4):
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cbz count, L(copy0)
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lsr tmp1, count, 1
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ldrb A_lw, [src]
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ldrb C_lw, [srcend, -1]
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ldrb B_lw, [src, tmp1]
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strb A_lw, [dstin]
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strb B_lw, [dstin, tmp1]
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strb C_lw, [dstend, -1]
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L(copy0):
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ret
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.p2align 4
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/* Medium copies: 33..128 bytes. */
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L(copy32_128):
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ldp A_l, A_h, [src]
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ldp B_l, B_h, [src, 16]
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ldp C_l, C_h, [srcend, -32]
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ldp D_l, D_h, [srcend, -16]
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cmp count, 64
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b.hi L(copy128)
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stp A_l, A_h, [dstin]
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stp B_l, B_h, [dstin, 16]
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stp C_l, C_h, [dstend, -32]
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stp D_l, D_h, [dstend, -16]
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ret
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.p2align 4
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/* Copy 65..128 bytes. */
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L(copy128):
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ldp E_l, E_h, [src, 32]
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ldp F_l, F_h, [src, 48]
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cmp count, 96
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b.ls L(copy96)
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ldp G_l, G_h, [srcend, -64]
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ldp H_l, H_h, [srcend, -48]
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stp G_l, G_h, [dstend, -64]
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stp H_l, H_h, [dstend, -48]
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L(copy96):
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stp A_l, A_h, [dstin]
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stp B_l, B_h, [dstin, 16]
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stp E_l, E_h, [dstin, 32]
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stp F_l, F_h, [dstin, 48]
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stp C_l, C_h, [dstend, -32]
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stp D_l, D_h, [dstend, -16]
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ret
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.p2align 4
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/* Copy more than 128 bytes. */
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L(copy_long):
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/* Use backwards copy if there is an overlap. */
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sub tmp1, dstin, src
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cbz tmp1, L(copy0)
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cmp tmp1, count
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b.lo L(copy_long_backwards)
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/* Copy 16 bytes and then align dst to 16-byte alignment. */
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ldp D_l, D_h, [src]
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and tmp1, dstin, 15
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bic dst, dstin, 15
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sub src, src, tmp1
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add count, count, tmp1 /* Count is now 16 too large. */
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ldp A_l, A_h, [src, 16]
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stp D_l, D_h, [dstin]
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ldp B_l, B_h, [src, 32]
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ldp C_l, C_h, [src, 48]
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ldp D_l, D_h, [src, 64]!
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subs count, count, 128 + 16 /* Test and readjust count. */
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b.ls L(copy64_from_end)
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L(loop64):
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stp A_l, A_h, [dst, 16]
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ldp A_l, A_h, [src, 16]
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stp B_l, B_h, [dst, 32]
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ldp B_l, B_h, [src, 32]
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stp C_l, C_h, [dst, 48]
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ldp C_l, C_h, [src, 48]
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stp D_l, D_h, [dst, 64]!
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ldp D_l, D_h, [src, 64]!
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subs count, count, 64
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b.hi L(loop64)
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/* Write the last iteration and copy 64 bytes from the end. */
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L(copy64_from_end):
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ldp E_l, E_h, [srcend, -64]
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stp A_l, A_h, [dst, 16]
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ldp A_l, A_h, [srcend, -48]
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stp B_l, B_h, [dst, 32]
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ldp B_l, B_h, [srcend, -32]
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stp C_l, C_h, [dst, 48]
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ldp C_l, C_h, [srcend, -16]
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stp D_l, D_h, [dst, 64]
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stp E_l, E_h, [dstend, -64]
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stp A_l, A_h, [dstend, -48]
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stp B_l, B_h, [dstend, -32]
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stp C_l, C_h, [dstend, -16]
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ret
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.p2align 4
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/* Large backwards copy for overlapping copies.
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Copy 16 bytes and then align dst to 16-byte alignment. */
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L(copy_long_backwards):
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ldp D_l, D_h, [srcend, -16]
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and tmp1, dstend, 15
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sub srcend, srcend, tmp1
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sub count, count, tmp1
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ldp A_l, A_h, [srcend, -16]
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stp D_l, D_h, [dstend, -16]
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ldp B_l, B_h, [srcend, -32]
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ldp C_l, C_h, [srcend, -48]
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ldp D_l, D_h, [srcend, -64]!
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sub dstend, dstend, tmp1
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subs count, count, 128
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b.ls L(copy64_from_start)
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L(loop64_backwards):
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stp A_l, A_h, [dstend, -16]
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ldp A_l, A_h, [srcend, -16]
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stp B_l, B_h, [dstend, -32]
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ldp B_l, B_h, [srcend, -32]
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stp C_l, C_h, [dstend, -48]
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ldp C_l, C_h, [srcend, -48]
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stp D_l, D_h, [dstend, -64]!
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ldp D_l, D_h, [srcend, -64]!
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subs count, count, 64
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b.hi L(loop64_backwards)
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/* Write the last iteration and copy 64 bytes from the start. */
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L(copy64_from_start):
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ldp G_l, G_h, [src, 48]
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stp A_l, A_h, [dstend, -16]
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ldp A_l, A_h, [src, 32]
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stp B_l, B_h, [dstend, -32]
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ldp B_l, B_h, [src, 16]
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stp C_l, C_h, [dstend, -48]
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ldp C_l, C_h, [src]
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stp D_l, D_h, [dstend, -64]
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stp G_l, G_h, [dstin, 48]
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stp A_l, A_h, [dstin, 32]
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stp B_l, B_h, [dstin, 16]
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stp C_l, C_h, [dstin]
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ret
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SYM_FUNC_END(__pi_memcpy)
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SYM_FUNC_ALIAS(__memcpy, __pi_memcpy)
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EXPORT_SYMBOL(__memcpy)
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SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
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EXPORT_SYMBOL(memcpy)
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SYM_FUNC_ALIAS(__pi_memmove, __pi_memcpy)
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SYM_FUNC_ALIAS(__memmove, __pi_memmove)
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EXPORT_SYMBOL(__memmove)
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SYM_FUNC_ALIAS_WEAK(memmove, __memmove)
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EXPORT_SYMBOL(memmove)
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