diff options
Diffstat (limited to 'pkg/safecopy/memcpy_amd64.s')
| -rw-r--r-- | pkg/safecopy/memcpy_amd64.s | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/pkg/safecopy/memcpy_amd64.s b/pkg/safecopy/memcpy_amd64.s new file mode 100644 index 000000000..129691d68 --- /dev/null +++ b/pkg/safecopy/memcpy_amd64.s @@ -0,0 +1,250 @@ +// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. +// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. +// Portions Copyright 2009 The Go Authors. All rights reserved. +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +// THE SOFTWARE. + +#include "textflag.h" + +// handleMemcpyFault returns (the value stored in AX, the value stored in DI). +// Control is transferred to it when memcpy below receives SIGSEGV or SIGBUS, +// with the faulting address stored in AX and the signal number stored in DI. +// +// It must have the same frame configuration as memcpy so that it can undo any +// potential call frame set up by the assembler. +TEXT handleMemcpyFault(SB), NOSPLIT, $0-36 + MOVQ AX, addr+24(FP) + MOVL DI, sig+32(FP) + RET + +// memcpy copies data from src to dst. If a SIGSEGV or SIGBUS signal is received +// during the copy, it returns the address that caused the fault and the number +// of the signal that was received. Otherwise, it returns an unspecified address +// and a signal number of 0. +// +// Data is copied in order, such that if a fault happens at address p, it is +// safe to assume that all data before p-maxRegisterSize has already been +// successfully copied. +// +// The code is derived from the forward copying part of runtime.memmove. +// +// func memcpy(dst, src unsafe.Pointer, n uintptr) (fault unsafe.Pointer, sig int32) +TEXT ·memcpy(SB), NOSPLIT, $0-36 + // Store 0 as the returned signal number. If we run to completion, + // this is the value the caller will see; if a signal is received, + // handleMemcpyFault will store a different value in this address. + MOVL $0, sig+32(FP) + + MOVQ to+0(FP), DI + MOVQ from+8(FP), SI + MOVQ n+16(FP), BX + + // REP instructions have a high startup cost, so we handle small sizes + // with some straightline code. The REP MOVSQ instruction is really fast + // for large sizes. The cutover is approximately 2K. +tail: + // move_129through256 or smaller work whether or not the source and the + // destination memory regions overlap because they load all data into + // registers before writing it back. move_256through2048 on the other + // hand can be used only when the memory regions don't overlap or the copy + // direction is forward. + TESTQ BX, BX + JEQ move_0 + CMPQ BX, $2 + JBE move_1or2 + CMPQ BX, $4 + JBE move_3or4 + CMPQ BX, $8 + JB move_5through7 + JE move_8 + CMPQ BX, $16 + JBE move_9through16 + CMPQ BX, $32 + JBE move_17through32 + CMPQ BX, $64 + JBE move_33through64 + CMPQ BX, $128 + JBE move_65through128 + CMPQ BX, $256 + JBE move_129through256 + // TODO: use branch table and BSR to make this just a single dispatch + +/* + * forward copy loop + */ + CMPQ BX, $2048 + JLS move_256through2048 + + // Check alignment + MOVL SI, AX + ORL DI, AX + TESTL $7, AX + JEQ fwdBy8 + + // Do 1 byte at a time + MOVQ BX, CX + REP; MOVSB + RET + +fwdBy8: + // Do 8 bytes at a time + MOVQ BX, CX + SHRQ $3, CX + ANDQ $7, BX + REP; MOVSQ + JMP tail + +move_1or2: + MOVB (SI), AX + MOVB AX, (DI) + MOVB -1(SI)(BX*1), CX + MOVB CX, -1(DI)(BX*1) + RET +move_0: + RET +move_3or4: + MOVW (SI), AX + MOVW AX, (DI) + MOVW -2(SI)(BX*1), CX + MOVW CX, -2(DI)(BX*1) + RET +move_5through7: + MOVL (SI), AX + MOVL AX, (DI) + MOVL -4(SI)(BX*1), CX + MOVL CX, -4(DI)(BX*1) + RET +move_8: + // We need a separate case for 8 to make sure we write pointers atomically. + MOVQ (SI), AX + MOVQ AX, (DI) + RET +move_9through16: + MOVQ (SI), AX + MOVQ AX, (DI) + MOVQ -8(SI)(BX*1), CX + MOVQ CX, -8(DI)(BX*1) + RET +move_17through32: + MOVOU (SI), X0 + MOVOU X0, (DI) + MOVOU -16(SI)(BX*1), X1 + MOVOU X1, -16(DI)(BX*1) + RET +move_33through64: + MOVOU (SI), X0 + MOVOU X0, (DI) + MOVOU 16(SI), X1 + MOVOU X1, 16(DI) + MOVOU -32(SI)(BX*1), X2 + MOVOU X2, -32(DI)(BX*1) + MOVOU -16(SI)(BX*1), X3 + MOVOU X3, -16(DI)(BX*1) + RET +move_65through128: + MOVOU (SI), X0 + MOVOU X0, (DI) + MOVOU 16(SI), X1 + MOVOU X1, 16(DI) + MOVOU 32(SI), X2 + MOVOU X2, 32(DI) + MOVOU 48(SI), X3 + MOVOU X3, 48(DI) + MOVOU -64(SI)(BX*1), X4 + MOVOU X4, -64(DI)(BX*1) + MOVOU -48(SI)(BX*1), X5 + MOVOU X5, -48(DI)(BX*1) + MOVOU -32(SI)(BX*1), X6 + MOVOU X6, -32(DI)(BX*1) + MOVOU -16(SI)(BX*1), X7 + MOVOU X7, -16(DI)(BX*1) + RET +move_129through256: + MOVOU (SI), X0 + MOVOU X0, (DI) + MOVOU 16(SI), X1 + MOVOU X1, 16(DI) + MOVOU 32(SI), X2 + MOVOU X2, 32(DI) + MOVOU 48(SI), X3 + MOVOU X3, 48(DI) + MOVOU 64(SI), X4 + MOVOU X4, 64(DI) + MOVOU 80(SI), X5 + MOVOU X5, 80(DI) + MOVOU 96(SI), X6 + MOVOU X6, 96(DI) + MOVOU 112(SI), X7 + MOVOU X7, 112(DI) + MOVOU -128(SI)(BX*1), X8 + MOVOU X8, -128(DI)(BX*1) + MOVOU -112(SI)(BX*1), X9 + MOVOU X9, -112(DI)(BX*1) + MOVOU -96(SI)(BX*1), X10 + MOVOU X10, -96(DI)(BX*1) + MOVOU -80(SI)(BX*1), X11 + MOVOU X11, -80(DI)(BX*1) + MOVOU -64(SI)(BX*1), X12 + MOVOU X12, -64(DI)(BX*1) + MOVOU -48(SI)(BX*1), X13 + MOVOU X13, -48(DI)(BX*1) + MOVOU -32(SI)(BX*1), X14 + MOVOU X14, -32(DI)(BX*1) + MOVOU -16(SI)(BX*1), X15 + MOVOU X15, -16(DI)(BX*1) + RET +move_256through2048: + SUBQ $256, BX + MOVOU (SI), X0 + MOVOU X0, (DI) + MOVOU 16(SI), X1 + MOVOU X1, 16(DI) + MOVOU 32(SI), X2 + MOVOU X2, 32(DI) + MOVOU 48(SI), X3 + MOVOU X3, 48(DI) + MOVOU 64(SI), X4 + MOVOU X4, 64(DI) + MOVOU 80(SI), X5 + MOVOU X5, 80(DI) + MOVOU 96(SI), X6 + MOVOU X6, 96(DI) + MOVOU 112(SI), X7 + MOVOU X7, 112(DI) + MOVOU 128(SI), X8 + MOVOU X8, 128(DI) + MOVOU 144(SI), X9 + MOVOU X9, 144(DI) + MOVOU 160(SI), X10 + MOVOU X10, 160(DI) + MOVOU 176(SI), X11 + MOVOU X11, 176(DI) + MOVOU 192(SI), X12 + MOVOU X12, 192(DI) + MOVOU 208(SI), X13 + MOVOU X13, 208(DI) + MOVOU 224(SI), X14 + MOVOU X14, 224(DI) + MOVOU 240(SI), X15 + MOVOU X15, 240(DI) + CMPQ BX, $256 + LEAQ 256(SI), SI + LEAQ 256(DI), DI + JGE move_256through2048 + JMP tail |