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runtime: use kernel-supplied cas on linux/arm
Using the kernel-supplied compare-and-swap code on linux/arm means that runtime doesn't have to care whether this is GOARM=5 or GOARM=6 anymore. Fixes #1494. R=r, r2 CC=golang-dev https://golang.org/cl/4245043
This commit is contained in:
Russ Cox
parent
12b7875bf2
commit
9ad9742157
@ -40,11 +40,8 @@ OFILES_386=\
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vlop.$O\
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vlrt.$O\
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GOARM?=6
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# arm-specific object files
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OFILES_arm=\
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cas$(GOARM).$O\
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memset.$O\
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softfloat.$O\
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vlop.$O\
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@ -274,3 +274,34 @@ TEXT runtime·abort(SB),7,$-4
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TEXT runtime·runcgocallback(SB),7,$0
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MOVW $0, R0
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MOVW (R0), R1
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// bool armcas(int32 *val, int32 old, int32 new)
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// Atomically:
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// if(*val == old){
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// *val = new;
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// return 1;
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// }else
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// return 0;
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//
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// To implement runtime·cas in ../$GOOS/arm/sys.s
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// using the native instructions, use:
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//
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// TEXT runtime·cas(SB),7,$0
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// B runtime·armcas(SB)
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//
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TEXT runtime·armcas(SB),7,$0
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MOVW valptr+0(FP), R1
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MOVW old+4(FP), R2
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MOVW new+8(FP), R3
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casl:
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LDREX (R1), R0
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CMP R0, R2
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BNE casfail
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STREX R3, (R1), R0
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CMP $0, R0
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BNE casl
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MOVW $1, R0
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RET
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casfail:
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MOVW $0, R0
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RET
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@ -1,74 +0,0 @@
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "arm/asm.h"
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// This version works on pre v6 architectures
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// bool cas(int32 *val, int32 old, int32 new)
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// Atomically:
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// if(*val == old){
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// *val = new;
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// return 1;
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// }else
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// return 0;
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TEXT runtime·cas(SB),7,$0
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MOVW 0(FP), R0 // *val
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MOVW 4(FP), R1 // old
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MOVW 8(FP), R2 // new
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MOVW $1, R3
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MOVW $runtime·cas_mutex(SB), R4
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SWPW (R4), R3 // acquire mutex
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CMP $0, R3
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BNE fail0
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MOVW (R0), R5
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CMP R1, R5
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BNE fail1
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MOVW R2, (R0)
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MOVW R3, (R4) // release mutex
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MOVW $1, R0
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RET
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fail1:
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MOVW R3, (R4) // release mutex
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fail0:
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MOVW $0, R0
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RET
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// bool casp(void **p, void *old, void *new)
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// Atomically:
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// if(*p == old){
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// *p = new;
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// return 1;
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// }else
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// return 0;
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TEXT runtime·casp(SB),7,$0
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MOVW 0(FP), R0 // *p
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MOVW 4(FP), R1 // old
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MOVW 8(FP), R2 // new
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MOVW $1, R3
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MOVW $runtime·cas_mutex(SB), R4
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SWPW (R4), R3 // acquire mutex
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CMP $0, R3
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BNE failp0
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MOVW (R0), R5
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CMP R1, R5
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BNE failp1
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MOVW R2, (R0)
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MOVW R3, (R4) // release mutex
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MOVW $1, R0
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RET
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failp1:
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MOVW R3, (R4) // release mutex
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failp0:
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MOVW $0, R0
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RET
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DATA runtime·cas_mutex(SB)/4, $0
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GLOBL runtime·cas_mutex(SB), $4
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@ -1,52 +0,0 @@
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// bool cas(int32 *val, int32 old, int32 new)
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// Atomically:
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// if(*val == old){
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// *val = new;
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// return 1;
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// }else
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// return 0;
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TEXT runtime·cas(SB),7,$0
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MOVW 0(FP), R1 // *val
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MOVW 4(FP), R2 // old
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MOVW 8(FP), R3 // new
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l:
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LDREX (R1), R0
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CMP R0, R2
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BNE fail
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STREX R3, (R1), R0
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CMP $0, R0
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BNE l
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MOVW $1, R0
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RET
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fail:
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MOVW $0, R0
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RET
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// bool casp(void **p, void *old, void *new)
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// Atomically:
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// if(*p == old){
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// *p = new;
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// return 1;
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// }else
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// return 0;
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TEXT runtime·casp(SB), 7, $0
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MOVW 0(FP), R1 // *p
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MOVW 4(FP), R2 // old
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MOVW 8(FP), R3 // new
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lp:
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LDREX (R1), R0
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CMP R0, R2
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BNE failp
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STREX R3, (R1), R0
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CMP $0, R0
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BNE lp
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MOVW $1, R0
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RET
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failp:
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MOVW $0, R0
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RET
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@ -230,3 +230,21 @@ TEXT runtime·sigreturn(SB),7,$0
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MOVW $SYS_rt_sigreturn, R7
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SWI $0
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RET
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// Use kernel version instead of native armcas in ../../arm.s.
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// See ../../../sync/atomic/asm_linux_arm.s for details.
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TEXT cas<>(SB),7,$0
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MOVW $0xffff0fc0, PC
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TEXT runtime·cas(SB),7,$0
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MOVW valptr+0(FP), R2
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MOVW old+4(FP), R0
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MOVW new+8(FP), R1
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BL cas<>(SB)
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MOVW $0, R0
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MOVW.CS $1, R0
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RET
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TEXT runtime·casp(SB),7,$0
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B runtime·cas(SB)
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