runtime/internal/syscall: new package for linux

Add a generic syscall package for use by the runtime. Eventually we'd
like to clean up system calls in the runtime to use more code generation
and be moved out of the main runtime package.

The implementations of the assembly functions are based on copies of
syscall.RawSyscall6, modified slightly for more consistency between
arches. e.g., renamed trap to num, always set syscall num register
first.

For now, this package is just the bare minimum needed for
doAllThreadsSyscall to make an arbitrary syscall.

For #51087.
For #50113.

Change-Id: Ibecb5e6303279ce15286759e1cd6a2ddc52f7c72
Reviewed-on: https://go-review.googlesource.com/c/go/+/383999
Trust: Michael Pratt <[email protected]>
Run-TryBot: Michael Pratt <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Austin Clements <[email protected]>

Author: prattmic

src/cmd/compile/internal/base/base.go

@@ -62,8 +62,9 @@ func Compiling(pkgs []string) bool {
 // at best instrumentation would cause infinite recursion.
 var NoInstrumentPkgs = []string{
 	"runtime/internal/atomic",
-	"runtime/internal/sys",
 	"runtime/internal/math",
+	"runtime/internal/sys",
+	"runtime/internal/syscall",
 	"runtime",
 	"runtime/race",
 	"runtime/msan",

src/go/build/deps_test.go

@@ -88,6 +88,7 @@ var depsRules = `
 	< internal/itoa
 	< internal/unsafeheader
 	< runtime/internal/sys
+	< runtime/internal/syscall
 	< runtime/internal/atomic
 	< runtime/internal/math
 	< runtime

src/runtime/internal/syscall/asm_linux_386.s

@@ -0,0 +1,34 @@
+// Copyright 2022 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 "textflag.h"
+
+// See ../sys_linux_386.s for the reason why we always use int 0x80
+// instead of the glibc-specific "CALL 0x10(GS)".
+#define INVOKE_SYSCALL	INT	$0x80
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+//
+// Syscall # in AX, args in BX CX DX SI DI BP, return in AX
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
+	MOVL	num+0(FP), AX	// syscall entry
+	MOVL	a1+4(FP), BX
+	MOVL	a2+8(FP), CX
+	MOVL	a3+12(FP), DX
+	MOVL	a4+16(FP), SI
+	MOVL	a5+20(FP), DI
+	MOVL	a6+24(FP), BP
+	INVOKE_SYSCALL
+	CMPL	AX, $0xfffff001
+	JLS	ok
+	MOVL	$-1, r1+28(FP)
+	MOVL	$0, r2+32(FP)
+	NEGL	AX
+	MOVL	AX, errno+36(FP)
+	RET
+ok:
+	MOVL	AX, r1+28(FP)
+	MOVL	DX, r2+32(FP)
+	MOVL	$0, errno+36(FP)
+	RET

src/runtime/internal/syscall/asm_linux_amd64.s

@@ -0,0 +1,33 @@
+// Copyright 2022 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 "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+//
+// Syscall # in AX, args in DI SI DX R10 R8 R9, return in AX DX.
+//
+// Note that this differs from "standard" ABI convention, which would pass 4th
+// arg in CX, not R10.
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOVQ	num+0(FP), AX	// syscall entry
+	MOVQ	a1+8(FP), DI
+	MOVQ	a2+16(FP), SI
+	MOVQ	a3+24(FP), DX
+	MOVQ	a4+32(FP), R10
+	MOVQ	a5+40(FP), R8
+	MOVQ	a6+48(FP), R9
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	ok
+	MOVQ	$-1, r1+56(FP)
+	MOVQ	$0, r2+64(FP)
+	NEGQ	AX
+	MOVQ	AX, errno+72(FP)
+	RET
+ok:
+	MOVQ	AX, r1+56(FP)
+	MOVQ	DX, r2+64(FP)
+	MOVQ	$0, errno+72(FP)
+	RET

src/runtime/internal/syscall/asm_linux_arm.s

@@ -0,0 +1,32 @@
+// Copyright 2022 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 "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
+	MOVW	num+0(FP), R7	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	MOVW	a4+16(FP), R3
+	MOVW	a5+20(FP), R4
+	MOVW	a6+24(FP), R5
+	SWI	$0
+	MOVW	$0xfffff001, R6
+	CMP	R6, R0
+	BLS	ok
+	MOVW	$-1, R1
+	MOVW	R1, r1+28(FP)
+	MOVW	$0, R2
+	MOVW	R2, r2+32(FP)
+	RSB	$0, R0, R0
+	MOVW	R0, errno+36(FP)
+	RET
+ok:
+	MOVW	R0, r1+28(FP)
+	MOVW	R1, r2+32(FP)
+	MOVW	$0, R0
+	MOVW	R0, errno+36(FP)
+	RET

src/runtime/internal/syscall/asm_linux_arm64.s

@@ -0,0 +1,29 @@
+// Copyright 2022 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 "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOVD	num+0(FP), R8	// syscall entry
+	MOVD	a1+8(FP), R0
+	MOVD	a2+16(FP), R1
+	MOVD	a3+24(FP), R2
+	MOVD	a4+32(FP), R3
+	MOVD	a5+40(FP), R4
+	MOVD	a6+48(FP), R5
+	SVC
+	CMN	$4095, R0
+	BCC	ok
+	MOVD	$-1, R4
+	MOVD	R4, r1+56(FP)
+	MOVD	ZR, r2+64(FP)
+	NEG	R0, R0
+	MOVD	R0, errno+72(FP)
+	RET
+ok:
+	MOVD	R0, r1+56(FP)
+	MOVD	R1, r2+64(FP)
+	MOVD	ZR, errno+72(FP)
+	RET

src/runtime/internal/syscall/asm_linux_mips64x.s

@@ -0,0 +1,29 @@
+// Copyright 2022 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.
+
+//go:build linux && (mips64 || mips64le)
+
+#include "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOVV	num+0(FP), R2	// syscall entry
+	MOVV	a1+8(FP), R4
+	MOVV	a2+16(FP), R5
+	MOVV	a3+24(FP), R6
+	MOVV	a4+32(FP), R7
+	MOVV	a5+40(FP), R8
+	MOVV	a6+48(FP), R9
+	SYSCALL
+	BEQ	R7, ok
+	MOVV	$-1, R1
+	MOVV	R1, r1+56(FP)
+	MOVV	R0, r2+64(FP)
+	MOVV	R2, errno+72(FP)
+	RET
+ok:
+	MOVV	R2, r1+56(FP)
+	MOVV	R3, r2+64(FP)
+	MOVV	R0, errno+72(FP)
+	RET

src/runtime/internal/syscall/asm_linux_mipsx.s

@@ -0,0 +1,34 @@
+// Copyright 2022 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.
+
+//go:build linux && (mips || mipsle)
+
+#include "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+//
+// The 5th and 6th arg go at sp+16, sp+20.
+// Note that frame size of 20 means that 24 bytes gets reserved on stack.
+TEXT ·Syscall6(SB),NOSPLIT,$20-40
+	MOVW	num+0(FP), R2	// syscall entry
+	MOVW	a1+4(FP), R4
+	MOVW	a2+8(FP), R5
+	MOVW	a3+12(FP), R6
+	MOVW	a4+16(FP), R7
+	MOVW	a5+20(FP), R8
+	MOVW	a6+24(FP), R9
+	MOVW	R8, 16(R29)
+	MOVW	R9, 20(R29)
+	SYSCALL
+	BEQ	R7, ok
+	MOVW	$-1, R1
+	MOVW	R1, r1+28(FP)
+	MOVW	R0, r2+32(FP)
+	MOVW	R2, errno+36(FP)
+	RET
+ok:
+	MOVW	R2, r1+28(FP)
+	MOVW	R3, r2+32(FP)
+	MOVW	R0, errno+36(FP)
+	RET

src/runtime/internal/syscall/asm_linux_ppc64x.s

@@ -0,0 +1,29 @@
+// Copyright 2022 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.
+
+//go:build linux && (ppc64 || ppc64le)
+
+#include "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOVD	num+0(FP), R9	// syscall entry
+	MOVD	a1+8(FP), R3
+	MOVD	a2+16(FP), R4
+	MOVD	a3+24(FP), R5
+	MOVD	a4+32(FP), R6
+	MOVD	a5+40(FP), R7
+	MOVD	a6+48(FP), R8
+	SYSCALL	R9
+	BVC	ok
+	MOVD	$-1, R4
+	MOVD	R4, r1+56(FP)
+	MOVD	R0, r2+64(FP)
+	MOVD	R3, errno+72(FP)
+	RET
+ok:
+	MOVD	R3, r1+56(FP)
+	MOVD	R4, r2+64(FP)
+	MOVD	R0, errno+72(FP)
+	RET

src/runtime/internal/syscall/asm_linux_riscv64.s

@@ -0,0 +1,29 @@
+// Copyright 2022 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 "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOV	num+0(FP), A7	// syscall entry
+	MOV	a1+8(FP), A0
+	MOV	a2+16(FP), A1
+	MOV	a3+24(FP), A2
+	MOV	a4+32(FP), A3
+	MOV	a5+40(FP), A4
+	MOV	a6+48(FP), A5
+	ECALL
+	MOV	$-4096, T0
+	BLTU	T0, A0, err
+	MOV	A0, r1+56(FP)
+	MOV	A1, r2+64(FP)
+	MOV	ZERO, errno+72(FP)
+	RET
+err:
+	MOV	$-1, T0
+	MOV	T0, r1+56(FP)
+	MOV	ZERO, r2+64(FP)
+	SUB	A0, ZERO, A0
+	MOV	A0, errno+72(FP)
+	RET

src/runtime/internal/syscall/asm_linux_s390x.s

@@ -0,0 +1,28 @@
+// Copyright 2022 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 "textflag.h"
+
+// func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	MOVD	num+0(FP), R1	// syscall entry
+	MOVD	a1+8(FP), R2
+	MOVD	a2+16(FP), R3
+	MOVD	a3+24(FP), R4
+	MOVD	a4+32(FP), R5
+	MOVD	a5+40(FP), R6
+	MOVD	a6+48(FP), R7
+	SYSCALL
+	MOVD	$0xfffffffffffff001, R8
+	CMPUBLT	R2, R8, ok
+	MOVD	$-1, r1+56(FP)
+	MOVD	$0, r2+64(FP)
+	NEG	R2, R2
+	MOVD	R2, errno+72(FP)
+	RET
+ok:
+	MOVD	R2, r1+56(FP)
+	MOVD	R3, r2+64(FP)
+	MOVD	$0, errno+72(FP)
+	RET

src/runtime/internal/syscall/syscall_linux.go

@@ -0,0 +1,12 @@
+// Copyright 2022 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.
+
+// Package syscall provides the syscall primitives required for the runtime.
+package syscall
+
+// TODO(https://go.dev/issue/51087): This package is incomplete and currently
+// only contains very minimal support for Linux.
+
+// Syscall6 calls system call number 'num' with arguments a1-6.
+func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)