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

diff --git a/src/pkg/runtime/Makefile b/src/pkg/runtime/Makefile
index 185397f5708aacf4702806761d6f19f28859dbb7..e4cc0817514cc8003b152a8d0c1e7e339fdda59c 100644 (file)
--- a/src/pkg/runtime/Makefile
+++ b/src/pkg/runtime/Makefile
@@ -40,11 +40,8 @@ OFILES_386=\
        vlop.$O\
        vlrt.$O\
 
-GOARM?=6
-
 # arm-specific object files
 OFILES_arm=\
-       cas$(GOARM).$O\
        memset.$O\
        softfloat.$O\
        vlop.$O\

diff --git a/src/pkg/runtime/arm/asm.s b/src/pkg/runtime/arm/asm.s
index 93c4d4cd1614f3fc278a99c0bcf07ec22f21b326..f9fe7e62833a019b76db54cd85091478b19c59df 100644 (file)
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/arm/asm.s
@@ -274,3 +274,34 @@ TEXT runtime·abort(SB),7,$-4
 TEXT runtime·runcgocallback(SB),7,$0
        MOVW    $0, R0
        MOVW    (R0), R1
+
+// bool armcas(int32 *val, int32 old, int32 new)
+// Atomically:
+//     if(*val == old){
+//             *val = new;
+//             return 1;
+//     }else
+//             return 0;
+//
+// To implement runtime·cas in ../$GOOS/arm/sys.s
+// using the native instructions, use:
+//
+//     TEXT runtime·cas(SB),7,$0
+//             B       runtime·armcas(SB)
+//
+TEXT runtime·armcas(SB),7,$0
+       MOVW    valptr+0(FP), R1
+       MOVW    old+4(FP), R2
+       MOVW    new+8(FP), R3
+casl:
+       LDREX   (R1), R0
+       CMP             R0, R2
+       BNE             casfail
+       STREX   R3, (R1), R0
+       CMP             $0, R0
+       BNE             casl
+       MOVW    $1, R0
+       RET
+casfail:
+       MOVW    $0, R0
+       RET

diff --git a/src/pkg/runtime/arm/cas5.s b/src/pkg/runtime/arm/cas5.s
deleted file mode 100644 (file)
index d46cdf9..0000000
--- a/src/pkg/runtime/arm/cas5.s
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#include "arm/asm.h"
-
-// This version works on pre v6 architectures
-
-// bool cas(int32 *val, int32 old, int32 new)
-// Atomically:
-//     if(*val == old){
-//             *val = new;
-//             return 1;
-//     }else
-//             return 0;
-
-TEXT runtime·cas(SB),7,$0
-       MOVW    0(FP), R0       // *val
-       MOVW    4(FP), R1       // old
-       MOVW    8(FP), R2       // new
-       MOVW    $1, R3
-       MOVW    $runtime·cas_mutex(SB), R4
-       SWPW    (R4), R3        // acquire mutex
-       CMP             $0, R3
-       BNE             fail0
-       
-       MOVW    (R0), R5
-       CMP             R1, R5
-       BNE             fail1
-       
-       MOVW    R2, (R0)        
-       MOVW    R3, (R4)        // release mutex
-       MOVW    $1, R0
-       RET
-fail1: 
-       MOVW    R3, (R4)        // release mutex
-fail0:
-       MOVW    $0, R0
-       RET
-
-// bool casp(void **p, void *old, void *new)
-// Atomically:
-//     if(*p == old){
-//             *p = new;
-//             return 1;
-//     }else
-//             return 0;
-
-TEXT runtime·casp(SB),7,$0
-       MOVW    0(FP), R0       // *p
-       MOVW    4(FP), R1       // old
-       MOVW    8(FP), R2       // new
-       MOVW    $1, R3
-       MOVW    $runtime·cas_mutex(SB), R4
-       SWPW    (R4), R3        // acquire mutex
-       CMP             $0, R3
-       BNE             failp0
-       
-       MOVW    (R0), R5
-       CMP             R1, R5
-       BNE             failp1
-       
-       MOVW    R2, (R0)        
-       MOVW    R3, (R4)        // release mutex
-       MOVW    $1, R0
-       RET
-failp1:        
-       MOVW    R3, (R4)        // release mutex
-failp0:
-       MOVW    $0, R0
-       RET
-
-DATA runtime·cas_mutex(SB)/4, $0
-GLOBL runtime·cas_mutex(SB), $4

diff --git a/src/pkg/runtime/arm/cas6.s b/src/pkg/runtime/arm/cas6.s
deleted file mode 100644 (file)
index ba97771..0000000
--- a/src/pkg/runtime/arm/cas6.s
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// bool cas(int32 *val, int32 old, int32 new)
-// Atomically:
-//     if(*val == old){
-//             *val = new;
-//             return 1;
-//     }else
-//             return 0;
-
-TEXT runtime·cas(SB),7,$0
-       MOVW    0(FP), R1       // *val
-       MOVW    4(FP), R2       // old
-       MOVW    8(FP), R3       // new
-l:
-       LDREX   (R1), R0
-       CMP             R0, R2
-       BNE             fail
-       STREX   R3, (R1), R0
-       CMP             $0, R0
-       BNE             l
-       MOVW    $1, R0
-       RET
-fail:
-       MOVW    $0, R0
-       RET
-
-// bool casp(void **p, void *old, void *new)
-// Atomically:
-//     if(*p == old){
-//             *p = new;
-//             return 1;
-//     }else
-//             return 0;
-TEXT runtime·casp(SB), 7, $0
-       MOVW    0(FP), R1       // *p
-       MOVW    4(FP), R2       // old
-       MOVW    8(FP), R3       // new
-lp:
-       LDREX   (R1), R0
-       CMP             R0, R2
-       BNE             failp
-       STREX   R3, (R1), R0
-       CMP             $0, R0
-       BNE             lp
-       MOVW    $1, R0
-       RET
-failp:
-       MOVW    $0, R0
-       RET

diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/linux/arm/sys.s
index 6c222fc8aa00d1347ac013a2e50441b92924ce4c..9daf9c2e4dd657c1999d5af75337f3510e1243a7 100644 (file)
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/linux/arm/sys.s
@@ -230,3 +230,21 @@ TEXT runtime·sigreturn(SB),7,$0
        MOVW    $SYS_rt_sigreturn, R7
        SWI     $0
        RET
+
+// Use kernel version instead of native armcas in ../../arm.s.
+// See ../../../sync/atomic/asm_linux_arm.s for details.
+TEXT cas<>(SB),7,$0
+       MOVW    $0xffff0fc0, PC
+
+TEXT runtime·cas(SB),7,$0
+       MOVW    valptr+0(FP), R2
+       MOVW    old+4(FP), R0
+       MOVW    new+8(FP), R1
+       BL      cas<>(SB)
+       MOVW    $0, R0
+       MOVW.CS $1, R0
+       RET
+
+TEXT runtime·casp(SB),7,$0
+       B       runtime·cas(SB)
+