[dev.typeparams] all: merge master (690a8c3) into dev.typeparams

Merge List:

+ 2021-05-18 690a8c3fb1 make.bash: fix misuse of continue
+ 2021-05-18 8b0901fd32 doc/go1.17: fix typo "avoding" -> "avoiding"
+ 2021-05-18 5e191f8f48 time: rewrite the documentation for layout strings
+ 2021-05-17 bfe3573d58 go/token: correct the interval notation used in some panic messages
+ 2021-05-17 a2c07a9a1a all: update golang.org/x/net to latest
+ 2021-05-17 b9b2bed893 syscall: some containers may fail syscall.TestSetuidEtc
+ 2021-05-17 b1aff42900 cmd/go: don't print 'go get' deprecation notices in the main module
+ 2021-05-17 bade680867 runtime/cgo: fix crosscall2 on ppc64x
+ 2021-05-15 ce92a2023c cmd/go: error out of 'go mod tidy' if the go version is newer than supported
+ 2021-05-14 02699f810a runtime: mark osyield nosplit on OpenBSD
+ 2021-05-14 3d324f127d net/http: prevent infinite wait during TestMissingStatusNoPanic
+ 2021-05-14 0eb38f2b16 cmd/go/internal/load: override Package.Root in module mode
+ 2021-05-14 a938e52986 cmd/go: fix a portability issue in the cd script command
+ 2021-05-14 d137b74539 cmd/go: fix spacing in help text of -overlay flag
+ 2021-05-14 c925e1546e cmd/internal/obj/arm64: disable AL and NV for some condition operation instructions
+ 2021-05-14 12d383c7c7 debug/macho: fix a typo in macho.go
+ 2021-05-14 3a0453514a all: fix spelling
+ 2021-05-13 b4833f7c06 cmd/link: always mark runtime.unreachableMethod symbol
+ 2021-05-13 92c189f211 cmd/link: resolve ABI alias for runtime.unreachableMethod
+ 2021-05-13 7a7624a3fa cmd/go: permit .tbd files as a linker flag
+ 2021-05-13 cde2d857fe cmd/go: be less strict about go version syntax in dependency go.mod files
+ 2021-05-13 2a61b3c590 regexp: fix repeat of preferred empty match
+ 2021-05-13 fd4631e24f cmd/compile/internal/dwarfgen: fix DWARF param DIE ordering
+ 2021-05-13 a63cded5e4 debug/dwarf: delay array type fixup to handle type cycles
+ 2021-05-13 0fa2302ee5 cmd/vendor: update golang.org/x/sys to latest
+ 2021-05-13 2c76a6f7f8 all: add //go:build lines to assembly files
+ 2021-05-12 6db7480f59 cmd/go/internal/modload: in updateLazyRoots, do not require the main module explicitly
+ 2021-05-12 f93b951f33 cmd/compile/abi-internal.md: fix table format
+ 2021-05-12 3b321a9d12 cmd/compile: add arch-specific inlining for runtime.memmove
+ 2021-05-12 07ff596404 runtime/internal/atomic: add LSE atomics instructions to arm64
+ 2021-05-12 03886707f9 runtime: fix handling of SPWRITE functions in traceback
+ 2021-05-12 e03383a2e2 cmd/link: check mmap error
+ 2021-05-12 af0f8c149e cmd/link: don't cast end address to int32
+ 2021-05-12 485474d204 cmd/go/testdata/script: fix test failing on nocgo builders
+ 2021-05-12 1a0ea1a08b runtime: fix typo in proc.go
+ 2021-05-11 9995c6b50a cmd/go: ignore implicit imports when the -find flag is set

Change-Id: I843fe029b8ac09424a83e8a4e8bdcc86edd40603

56 files changed, 176 insertions, 34 deletions

diff --git a/src/runtime/asm_mips64x.s b/src/runtime/asm_mips64x.s
index c3b57e472a..d4d2280105 100644
--- a/src/runtime/asm_mips64x.s
+++ b/src/runtime/asm_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "go_asm.h"
diff --git a/src/runtime/asm_mipsx.s b/src/runtime/asm_mipsx.s
index 1d828b03cf..ea7edf20cf 100644
--- a/src/runtime/asm_mipsx.s
+++ b/src/runtime/asm_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "go_asm.h"
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 2c39b38912..942cc14f17 100644
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "go_asm.h"
diff --git a/src/runtime/atomic_mips64x.s b/src/runtime/atomic_mips64x.s
index 6f42412502..e2118e6a20 100644
--- a/src/runtime/atomic_mips64x.s
+++ b/src/runtime/atomic_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "textflag.h"
diff --git a/src/runtime/atomic_mipsx.s b/src/runtime/atomic_mipsx.s
index ed078a2d8a..1eacd273b4 100644
--- a/src/runtime/atomic_mipsx.s
+++ b/src/runtime/atomic_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "textflag.h"
diff --git a/src/runtime/atomic_ppc64x.s b/src/runtime/atomic_ppc64x.s
index 57f672f330..b63de2dbd3 100644
--- a/src/runtime/atomic_ppc64x.s
+++ b/src/runtime/atomic_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
diff --git a/src/runtime/cgo/asm_mips64x.s b/src/runtime/cgo/asm_mips64x.s
index e51cdf3d12..ba948071fa 100644
--- a/src/runtime/cgo/asm_mips64x.s
+++ b/src/runtime/cgo/asm_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "textflag.h"
diff --git a/src/runtime/cgo/asm_mipsx.s b/src/runtime/cgo/asm_mipsx.s
index 1127c8beb4..fd5d78ef97 100644
--- a/src/runtime/cgo/asm_mipsx.s
+++ b/src/runtime/cgo/asm_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "textflag.h"
diff --git a/src/runtime/cgo/asm_ppc64x.s b/src/runtime/cgo/asm_ppc64x.s
index f4efc1e67d..187b2d42f6 100644
--- a/src/runtime/cgo/asm_ppc64x.s
+++ b/src/runtime/cgo/asm_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
@@ -11,17 +12,20 @@
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
 // fn is the PC of a func(a unsafe.Pointer) function.
+// The value of R2 is saved on the new stack frame, and not
+// the caller's frame due to issue #43228.
 TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
 	// Start with standard C stack frame layout and linkage
 	MOVD	LR, R0
 	MOVD	R0, 16(R1)	// Save LR in caller's frame
 	MOVW	CR, R0		// Save CR in caller's frame
-	MOVD	R0, 8(R1)
-	MOVD	R2, 24(R1)	// Save TOC in caller's frame
+	MOVW	R0, 8(R1)
 
 	BL	saveregs2<>(SB)
 
 	MOVDU	R1, (-288-3*8-FIXED_FRAME)(R1)
+	// Save the caller's R2
+	MOVD	R2, 24(R1)
 
 	// Initialize Go ABI environment
 	BL	runtime·reginit(SB)
@@ -40,12 +44,13 @@ TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
 	MOVD	R6, FIXED_FRAME+16(R1)	// ctxt uintptr
 	BL	runtime·cgocallback(SB)
 
+	// Restore the caller's R2
+	MOVD	24(R1), R2
 	ADD	$(288+3*8+FIXED_FRAME), R1
 
 	BL	restoreregs2<>(SB)
 
-	MOVD	24(R1), R2
-	MOVD	8(R1), R0
+	MOVW	8(R1), R0
 	MOVFL	R0, $0xff
 	MOVD	16(R1), R0
 	MOVD	R0, LR
diff --git a/src/runtime/cgo/asm_riscv64.s b/src/runtime/cgo/asm_riscv64.s
index b4ddbb020f..fcd1d36ca8 100644
--- a/src/runtime/cgo/asm_riscv64.s
+++ b/src/runtime/cgo/asm_riscv64.s
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build riscv64
-
 #include "textflag.h"
 
 // Called by C code generated by cmd/cgo.
diff --git a/src/runtime/duff_mips64x.s b/src/runtime/duff_mips64x.s
index c4e04ccc9d..a897d7fd9b 100644
--- a/src/runtime/duff_mips64x.s
+++ b/src/runtime/duff_mips64x.s
@@ -2,6 +2,7 @@
 // Run go generate from src/runtime to update.
 // See mkduff.go for comments.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "textflag.h"
diff --git a/src/runtime/duff_ppc64x.s b/src/runtime/duff_ppc64x.s
index d6b89ba940..d4e3b409d2 100644
--- a/src/runtime/duff_ppc64x.s
+++ b/src/runtime/duff_ppc64x.s
@@ -2,6 +2,7 @@
 // Run go generate from src/runtime to update.
 // See mkduff.go for comments.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
diff --git a/src/runtime/internal/atomic/atomic_arm64.go b/src/runtime/internal/atomic/atomic_arm64.go
index 131c687e1b..3c8736997f 100644
--- a/src/runtime/internal/atomic/atomic_arm64.go
+++ b/src/runtime/internal/atomic/atomic_arm64.go
@@ -7,7 +7,14 @@
 
 package atomic
 
-import "unsafe"
+import (
+	"unsafe"
+	"internal/cpu"
+)
+
+const (
+	offsetARM64HasATOMICS = unsafe.Offsetof(cpu.ARM64.HasATOMICS)
+)
 
 //go:noescape
 func Xadd(ptr *uint32, delta int32) uint32
diff --git a/src/runtime/internal/atomic/atomic_arm64.s b/src/runtime/internal/atomic/atomic_arm64.s
index 587e7f05e2..e9467afecd 100644
--- a/src/runtime/internal/atomic/atomic_arm64.s
+++ b/src/runtime/internal/atomic/atomic_arm64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+#include "go_asm.h"
 #include "textflag.h"
 
 TEXT ·Casint32(SB), NOSPLIT, $0-17
@@ -127,10 +128,15 @@ TEXT ·Store64(SB), NOSPLIT, $0-16
 TEXT ·Xchg(SB), NOSPLIT, $0-20
 	MOVD	ptr+0(FP), R0
 	MOVW	new+8(FP), R1
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	SWPALW	R1, (R0), R2
+	MOVW	R2, ret+16(FP)
+	RET
+load_store_loop:
 	LDAXRW	(R0), R2
 	STLXRW	R1, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 	MOVW	R2, ret+16(FP)
 	RET
 
@@ -142,10 +148,15 @@ again:
 TEXT ·Xchg64(SB), NOSPLIT, $0-24
 	MOVD	ptr+0(FP), R0
 	MOVD	new+8(FP), R1
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	SWPALD	R1, (R0), R2
+	MOVD	R2, ret+16(FP)
+	RET
+load_store_loop:
 	LDAXR	(R0), R2
 	STLXR	R1, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 	MOVD	R2, ret+16(FP)
 	RET
 
@@ -160,12 +171,20 @@ TEXT ·Cas(SB), NOSPLIT, $0-17
 	MOVD	ptr+0(FP), R0
 	MOVW	old+8(FP), R1
 	MOVW	new+12(FP), R2
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	MOVD	R1, R3
+	CASALW	R3, (R0), R2
+	CMP 	R1, R3
+	CSET	EQ, R0
+	MOVB	R0, ret+16(FP)
+	RET
+load_store_loop:
 	LDAXRW	(R0), R3
 	CMPW	R1, R3
 	BNE	ok
 	STLXRW	R2, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 ok:
 	CSET	EQ, R0
 	MOVB	R0, ret+16(FP)
@@ -183,12 +202,20 @@ TEXT ·Cas64(SB), NOSPLIT, $0-25
 	MOVD	ptr+0(FP), R0
 	MOVD	old+8(FP), R1
 	MOVD	new+16(FP), R2
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	MOVD	R1, R3
+	CASALD	R3, (R0), R2
+	CMP 	R1, R3
+	CSET	EQ, R0
+	MOVB	R0, ret+24(FP)
+	RET
+load_store_loop:
 	LDAXR	(R0), R3
 	CMP	R1, R3
 	BNE	ok
 	STLXR	R2, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 ok:
 	CSET	EQ, R0
 	MOVB	R0, ret+24(FP)
@@ -201,11 +228,17 @@ ok:
 TEXT ·Xadd(SB), NOSPLIT, $0-20
 	MOVD	ptr+0(FP), R0
 	MOVW	delta+8(FP), R1
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	LDADDALW	R1, (R0), R2
+	ADD 	R1, R2
+	MOVW	R2, ret+16(FP)
+	RET
+load_store_loop:
 	LDAXRW	(R0), R2
 	ADDW	R2, R1, R2
 	STLXRW	R2, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 	MOVW	R2, ret+16(FP)
 	RET
 
@@ -216,11 +249,17 @@ again:
 TEXT ·Xadd64(SB), NOSPLIT, $0-24
 	MOVD	ptr+0(FP), R0
 	MOVD	delta+8(FP), R1
-again:
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	LDADDALD	R1, (R0), R2
+	ADD 	R1, R2
+	MOVD	R2, ret+16(FP)
+	RET
+load_store_loop:
 	LDAXR	(R0), R2
 	ADD	R2, R1, R2
 	STLXR	R2, (R0), R3
-	CBNZ	R3, again
+	CBNZ	R3, load_store_loop
 	MOVD	R2, ret+16(FP)
 	RET
 
@@ -236,37 +275,59 @@ TEXT ·Xchguintptr(SB), NOSPLIT, $0-24
 TEXT ·And8(SB), NOSPLIT, $0-9
 	MOVD	ptr+0(FP), R0
 	MOVB	val+8(FP), R1
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	MVN 	R1, R2
+	LDCLRALB	R2, (R0), R3
+	RET
+load_store_loop:
 	LDAXRB	(R0), R2
 	AND	R1, R2
 	STLXRB	R2, (R0), R3
-	CBNZ	R3, -3(PC)
+	CBNZ	R3, load_store_loop
 	RET
 
 TEXT ·Or8(SB), NOSPLIT, $0-9
 	MOVD	ptr+0(FP), R0
 	MOVB	val+8(FP), R1
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	LDORALB	R1, (R0), R2
+	RET
+load_store_loop:
 	LDAXRB	(R0), R2
 	ORR	R1, R2
 	STLXRB	R2, (R0), R3
-	CBNZ	R3, -3(PC)
+	CBNZ	R3, load_store_loop
 	RET
 
 // func And(addr *uint32, v uint32)
 TEXT ·And(SB), NOSPLIT, $0-12
 	MOVD	ptr+0(FP), R0
 	MOVW	val+8(FP), R1
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	MVN 	R1, R2
+	LDCLRALW	R2, (R0), R3
+	RET
+load_store_loop:
 	LDAXRW	(R0), R2
 	AND	R1, R2
 	STLXRW	R2, (R0), R3
-	CBNZ	R3, -3(PC)
+	CBNZ	R3, load_store_loop
 	RET
 
 // func Or(addr *uint32, v uint32)
 TEXT ·Or(SB), NOSPLIT, $0-12
 	MOVD	ptr+0(FP), R0
 	MOVW	val+8(FP), R1
+	MOVBU	internal∕cpu·ARM64+const_offsetARM64HasATOMICS(SB), R4
+	CBZ 	R4, load_store_loop
+	LDORALW	R1, (R0), R2
+	RET
+load_store_loop:
 	LDAXRW	(R0), R2
 	ORR	R1, R2
 	STLXRW	R2, (R0), R3
-	CBNZ	R3, -3(PC)
+	CBNZ	R3, load_store_loop
 	RET
diff --git a/src/runtime/internal/atomic/atomic_mips64x.s b/src/runtime/internal/atomic/atomic_mips64x.s
index 2751c6f808..fba668f94a 100644
--- a/src/runtime/internal/atomic/atomic_mips64x.s
+++ b/src/runtime/internal/atomic/atomic_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "textflag.h"
diff --git a/src/runtime/internal/atomic/atomic_mipsx.s b/src/runtime/internal/atomic/atomic_mipsx.s
index 3f61321450..c0835d66ed 100644
--- a/src/runtime/internal/atomic/atomic_mipsx.s
+++ b/src/runtime/internal/atomic/atomic_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "textflag.h"
diff --git a/src/runtime/internal/atomic/atomic_ppc64x.s b/src/runtime/internal/atomic/atomic_ppc64x.s
index 37c8515d37..dca26cb334 100644
--- a/src/runtime/internal/atomic/atomic_ppc64x.s
+++ b/src/runtime/internal/atomic/atomic_ppc64x.s
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
 
-
 // For more details about how various memory models are
 // enforced on POWER, the following paper provides more
 // details about how they enforce C/C++ like models. This
diff --git a/src/runtime/internal/atomic/sys_nonlinux_arm.s b/src/runtime/internal/atomic/sys_nonlinux_arm.s
index 57568b2238..04036ca970 100644
--- a/src/runtime/internal/atomic/sys_nonlinux_arm.s
+++ b/src/runtime/internal/atomic/sys_nonlinux_arm.s
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !linux,arm
+//go:build !linux
+// +build !linux
 
 #include "textflag.h"
 
diff --git a/src/runtime/libfuzzer_amd64.s b/src/runtime/libfuzzer_amd64.s
index 890fde341b..13645fc7af 100644
--- a/src/runtime/libfuzzer_amd64.s
+++ b/src/runtime/libfuzzer_amd64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build libfuzzer
 // +build libfuzzer
 
 #include "go_asm.h"
diff --git a/src/runtime/libfuzzer_arm64.s b/src/runtime/libfuzzer_arm64.s
index 121673e092..4ad8242804 100644
--- a/src/runtime/libfuzzer_arm64.s
+++ b/src/runtime/libfuzzer_arm64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build libfuzzer
 // +build libfuzzer
 
 #include "go_asm.h"
diff --git a/src/runtime/memclr_386.s b/src/runtime/memclr_386.s
index d2ef17f7ce..046c344119 100644
--- a/src/runtime/memclr_386.s
+++ b/src/runtime/memclr_386.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !plan9
 // +build !plan9
 
 #include "go_asm.h"
diff --git a/src/runtime/memclr_amd64.s b/src/runtime/memclr_amd64.s
index 5d2bebb901..a10f57bd8c 100644
--- a/src/runtime/memclr_amd64.s
+++ b/src/runtime/memclr_amd64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !plan9
 // +build !plan9
 
 #include "go_asm.h"
diff --git a/src/runtime/memclr_mips64x.s b/src/runtime/memclr_mips64x.s
index d7a3251e20..bc037013fe 100644
--- a/src/runtime/memclr_mips64x.s
+++ b/src/runtime/memclr_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "go_asm.h"
diff --git a/src/runtime/memclr_mipsx.s b/src/runtime/memclr_mipsx.s
index eb2a8a7219..3d21c3c414 100644
--- a/src/runtime/memclr_mipsx.s
+++ b/src/runtime/memclr_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "textflag.h"
diff --git a/src/runtime/memclr_ppc64x.s b/src/runtime/memclr_ppc64x.s
index 7512620894..65639322b2 100644
--- a/src/runtime/memclr_ppc64x.s
+++ b/src/runtime/memclr_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
diff --git a/src/runtime/memmove_386.s b/src/runtime/memmove_386.s
index d99546c633..1a43a1f724 100644
--- a/src/runtime/memmove_386.s
+++ b/src/runtime/memmove_386.s
@@ -23,6 +23,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+//go:build !plan9
 // +build !plan9
 
 #include "go_asm.h"
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index f1e3403596..24c6529f58 100644
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -23,6 +23,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+//go:build !plan9
 // +build !plan9
 
 #include "go_asm.h"
diff --git a/src/runtime/memmove_mips64x.s b/src/runtime/memmove_mips64x.s
index 8a1b88afba..fef3c6be82 100644
--- a/src/runtime/memmove_mips64x.s
+++ b/src/runtime/memmove_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "textflag.h"
diff --git a/src/runtime/memmove_mipsx.s b/src/runtime/memmove_mipsx.s
index 6c86558f8d..cd02fc25c4 100644
--- a/src/runtime/memmove_mipsx.s
+++ b/src/runtime/memmove_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "textflag.h"
diff --git a/src/runtime/memmove_ppc64x.s b/src/runtime/memmove_ppc64x.s
index dbd835506f..fd16ad8129 100644
--- a/src/runtime/memmove_ppc64x.s
+++ b/src/runtime/memmove_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "textflag.h"
diff --git a/src/runtime/mkduff.go b/src/runtime/mkduff.go
index 8632fe08a3..da191cc594 100644
--- a/src/runtime/mkduff.go
+++ b/src/runtime/mkduff.go
@@ -179,6 +179,7 @@ func copyARM64(w io.Writer) {
 
 func tagsPPC64x(w io.Writer) {
 	fmt.Fprintln(w)
+	fmt.Fprintln(w, "//go:build ppc64 || ppc64le")
 	fmt.Fprintln(w, "// +build ppc64 ppc64le")
 	fmt.Fprintln(w)
 }
@@ -202,6 +203,7 @@ func copyPPC64x(w io.Writer) {
 
 func tagsMIPS64x(w io.Writer) {
 	fmt.Fprintln(w)
+	fmt.Fprintln(w, "//go:build mips64 || mips64le")
 	fmt.Fprintln(w, "// +build mips64 mips64le")
 	fmt.Fprintln(w)
 }
diff --git a/src/runtime/mkpreempt.go b/src/runtime/mkpreempt.go
index 3a9e6cc478..6c980540f5 100644
--- a/src/runtime/mkpreempt.go
+++ b/src/runtime/mkpreempt.go
@@ -123,6 +123,7 @@ func header(arch string) {
 	fmt.Fprintf(out, "// Code generated by mkpreempt.go; DO NOT EDIT.\n\n")
 	if beLe[arch] {
 		base := arch[:len(arch)-1]
+		fmt.Fprintf(out, "//go:build %s || %sle\n", base, base)
 		fmt.Fprintf(out, "// +build %s %sle\n\n", base, base)
 	}
 	fmt.Fprintf(out, "#include \"go_asm.h\"\n")
diff --git a/src/runtime/msan_amd64.s b/src/runtime/msan_amd64.s
index 669e9ca73f..1bb57a3b7e 100644
--- a/src/runtime/msan_amd64.s
+++ b/src/runtime/msan_amd64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build msan
 // +build msan
 
 #include "go_asm.h"
diff --git a/src/runtime/msan_arm64.s b/src/runtime/msan_arm64.s
index f19906cfc8..93ade8dd89 100644
--- a/src/runtime/msan_arm64.s
+++ b/src/runtime/msan_arm64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build msan
 // +build msan
 
 #include "go_asm.h"
diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go
index 372185266f..1d5aae1363 100644
--- a/src/runtime/preempt.go
+++ b/src/runtime/preempt.go
@@ -413,6 +413,8 @@ func isAsyncSafePoint(gp *g, pc, sp, lr uintptr) (bool, uintptr) {
 		//
 		// TODO: Are there cases that are safe but don't have a
 		// locals pointer map, like empty frame functions?
+		// It might be possible to preempt any assembly functions
+		// except the ones that have funcFlag_SPWRITE set in f.flag.
 		return false, 0
 	}
 	name := funcname(f)
diff --git a/src/runtime/preempt_mips64x.s b/src/runtime/preempt_mips64x.s
index 0d0c157c36..b755425bc5 100644
--- a/src/runtime/preempt_mips64x.s
+++ b/src/runtime/preempt_mips64x.s
@@ -1,5 +1,6 @@
 // Code generated by mkpreempt.go; DO NOT EDIT.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "go_asm.h"
diff --git a/src/runtime/preempt_mipsx.s b/src/runtime/preempt_mipsx.s
index 86d3a918d3..c1bff60859 100644
--- a/src/runtime/preempt_mipsx.s
+++ b/src/runtime/preempt_mipsx.s
@@ -1,5 +1,6 @@
 // Code generated by mkpreempt.go; DO NOT EDIT.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "go_asm.h"
diff --git a/src/runtime/preempt_ppc64x.s b/src/runtime/preempt_ppc64x.s
index 90634386db..70bd91982b 100644
--- a/src/runtime/preempt_ppc64x.s
+++ b/src/runtime/preempt_ppc64x.s
@@ -1,5 +1,6 @@
 // Code generated by mkpreempt.go; DO NOT EDIT.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "go_asm.h"
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 378d5e32f5..ded406cc28 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -3136,7 +3136,7 @@ func checkIdleGCNoP() (*p, *g) {
 	// an available P and available worker G.
 	//
 	// We can attempt to acquire these in either order, though both have
-	// synchonization concerns (see below). Workers are almost always
+	// synchronization concerns (see below). Workers are almost always
 	// available (see comment in findRunnableGCWorker for the one case
 	// there may be none). Since we're slightly less likely to find a P,
 	// check for that first.
@@ -3570,6 +3570,21 @@ func preemptPark(gp *g) {
 		throw("bad g status")
 	}
 	gp.waitreason = waitReasonPreempted
+
+	if gp.asyncSafePoint {
+		// Double-check that async preemption does not
+		// happen in SPWRITE assembly functions.
+		// isAsyncSafePoint must exclude this case.
+		f := findfunc(gp.sched.pc)
+		if !f.valid() {
+			throw("preempt at unknown pc")
+		}
+		if f.flag&funcFlag_SPWRITE != 0 {
+			println("runtime: unexpected SPWRITE function", funcname(f), "in async preempt")
+			throw("preempt SPWRITE")
+		}
+	}
+
 	// Transition from _Grunning to _Gscan|_Gpreempted. We can't
 	// be in _Grunning when we dropg because then we'd be running
 	// without an M, but the moment we're in _Gpreempted,
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 58a919efe8..8d4813eadd 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build race
 // +build race
 
 #include "go_asm.h"
diff --git a/src/runtime/race_arm64.s b/src/runtime/race_arm64.s
index 82e3caadc8..c6d5b91edc 100644
--- a/src/runtime/race_arm64.s
+++ b/src/runtime/race_arm64.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build race
 // +build race
 
 #include "go_asm.h"
diff --git a/src/runtime/race_ppc64le.s b/src/runtime/race_ppc64le.s
index 069e4d86dd..963e57099c 100644
--- a/src/runtime/race_ppc64le.s
+++ b/src/runtime/race_ppc64le.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build race
 // +build race
 
 #include "go_asm.h"
diff --git a/src/runtime/rt0_linux_mips64x.s b/src/runtime/rt0_linux_mips64x.s
index 55506755df..fabd8570b5 100644
--- a/src/runtime/rt0_linux_mips64x.s
+++ b/src/runtime/rt0_linux_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (mips64 || mips64le)
 // +build linux
 // +build mips64 mips64le
 
diff --git a/src/runtime/rt0_linux_mipsx.s b/src/runtime/rt0_linux_mipsx.s
index 74b8f50b73..9f5842b51a 100644
--- a/src/runtime/rt0_linux_mipsx.s
+++ b/src/runtime/rt0_linux_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (mips || mipsle)
 // +build linux
 // +build mips mipsle
 
diff --git a/src/runtime/sys_aix_ppc64.s b/src/runtime/sys_aix_ppc64.s
index a56d043f42..c171c191c0 100644
--- a/src/runtime/sys_aix_ppc64.s
+++ b/src/runtime/sys_aix_ppc64.s
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build aix
-// +build ppc64 ppc64le
-
 //
 // System calls and other sys.stuff for ppc64, Aix
 //
diff --git a/src/runtime/sys_linux_mips64x.s b/src/runtime/sys_linux_mips64x.s
index 0206cb88bd..e18d291445 100644
--- a/src/runtime/sys_linux_mips64x.s
+++ b/src/runtime/sys_linux_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (mips64 || mips64le)
 // +build linux
 // +build mips64 mips64le
 
diff --git a/src/runtime/sys_linux_mipsx.s b/src/runtime/sys_linux_mipsx.s
index d5317d3957..b3970be9cf 100644
--- a/src/runtime/sys_linux_mipsx.s
+++ b/src/runtime/sys_linux_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (mips || mipsle)
 // +build linux
 // +build mips mipsle
 
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index 46387288d5..05b5916db4 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (ppc64 || ppc64le)
 // +build linux
 // +build ppc64 ppc64le
 
diff --git a/src/runtime/sys_openbsd1.go b/src/runtime/sys_openbsd1.go
index 6f9ad356d4..cb5d35879c 100644
--- a/src/runtime/sys_openbsd1.go
+++ b/src/runtime/sys_openbsd1.go
@@ -23,6 +23,7 @@ func thrwakeup(ident uintptr, n int32) int32 {
 }
 func thrwakeup_trampoline()
 
+//go:nosplit
 func osyield() {
 	libcCall(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
 }
diff --git a/src/runtime/tls_arm.s b/src/runtime/tls_arm.s
index e42de8deb4..879caac9e1 100644
--- a/src/runtime/tls_arm.s
+++ b/src/runtime/tls_arm.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 #include "go_asm.h"
diff --git a/src/runtime/tls_mips64x.s b/src/runtime/tls_mips64x.s
index 888c0efec6..779d64ba31 100644
--- a/src/runtime/tls_mips64x.s
+++ b/src/runtime/tls_mips64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 #include "go_asm.h"
diff --git a/src/runtime/tls_mipsx.s b/src/runtime/tls_mipsx.s
index d2ffcd954c..ada8d06a9e 100644
--- a/src/runtime/tls_mipsx.s
+++ b/src/runtime/tls_mipsx.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 #include "go_asm.h"
diff --git a/src/runtime/tls_ppc64x.s b/src/runtime/tls_ppc64x.s
index 25d796fcc6..7e935d0eb2 100644
--- a/src/runtime/tls_ppc64x.s
+++ b/src/runtime/tls_ppc64x.s
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc64 || ppc64le
 // +build ppc64 ppc64le
 
 #include "go_asm.h"
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 167d51c452..89780edc1f 100644
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -219,18 +219,25 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
 			// This function marks the top of the stack. Stop the traceback.
 			frame.lr = 0
 			flr = funcInfo{}
-		} else if flag&funcFlag_SPWRITE != 0 {
+		} else if flag&funcFlag_SPWRITE != 0 && (callback == nil || n > 0) {
 			// The function we are in does a write to SP that we don't know
 			// how to encode in the spdelta table. Examples include context
 			// switch routines like runtime.gogo but also any code that switches
 			// to the g0 stack to run host C code. Since we can't reliably unwind
 			// the SP (we might not even be on the stack we think we are),
 			// we stop the traceback here.
+			// This only applies for profiling signals (callback == nil).
+			//
+			// For a GC stack traversal (callback != nil), we should only see
+			// a function when it has voluntarily preempted itself on entry
+			// during the stack growth check. In that case, the function has
+			// not yet had a chance to do any writes to SP and is safe to unwind.
+			// isAsyncSafePoint does not allow assembly functions to be async preempted,
+			// and preemptPark double-checks that SPWRITE functions are not async preempted.
+			// So for GC stack traversal we leave things alone (this if body does not execute for n == 0)
+			// at the bottom frame of the stack. But farther up the stack we'd better not
+			// find any.
 			if callback != nil {
-				// Finding an SPWRITE should only happen for a profiling signal, which can
-				// arrive at any time. For a GC stack traversal (callback != nil),
-				// we shouldn't see this case, and we must be sure to walk the
-				// entire stack or the GC is invalid. So crash.
 				println("traceback: unexpected SPWRITE function", funcname(f))
 				throw("traceback")
 			}
diff --git a/src/runtime/wincallback.go b/src/runtime/wincallback.go
index 8411c98412..a7a787d8f6 100644
--- a/src/runtime/wincallback.go
+++ b/src/runtime/wincallback.go
@@ -22,7 +22,9 @@ func genasm386Amd64() {
 
 	buf.WriteString(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
 
+//go:build 386 || amd64
 // +build 386 amd64
+
 // runtime·callbackasm is called by external code to
 // execute Go implemented callback function. It is not
 // called from the start, instead runtime·compilecallback
diff --git a/src/runtime/zcallback_windows.s b/src/runtime/zcallback_windows.s
index 37ffb38aca..e451c2b9d0 100644
--- a/src/runtime/zcallback_windows.s
+++ b/src/runtime/zcallback_windows.s
@@ -1,6 +1,8 @@
 // Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
 
+//go:build 386 || amd64
 // +build 386 amd64
+
 // runtime·callbackasm is called by external code to
 // execute Go implemented callback function. It is not
 // called from the start, instead runtime·compilecallback