From f76fc28c6b31f28783b94596d6328450202c903a Mon Sep 17 00:00:00 2001
From: qmuntal <quimmuntal@gmail.com>
Date: Wed, 8 Feb 2023 14:28:18 +0100
Subject: [PATCH] runtime: use explicit NOFRAME on netbsd/amd64

This CL marks some netbsd assembly functions as NOFRAME to avoid
relying on the implicit amd64 NOFRAME heuristic, where NOSPLIT functions
without stack were also marked as NOFRAME.

While here, and thanks to CL 466355, `asm_netbsd_amd64.s` can
be deleted in favor of `asm9_unix2_amd64.s`, which makes better
use of the frame pointer.

Updates #58378

Change-Id: Iff554b664ec25f2bb6ec198c0f684590b359c383
Reviewed-on: https://go-review.googlesource.com/c/go/+/466396
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
---
 src/cmd/internal/obj/x86/obj6.go |  2 +-
 src/runtime/sys_netbsd_amd64.s   | 10 +++-----
 src/syscall/asm9_unix2_amd64.s   |  4 +--
 src/syscall/asm_netbsd_amd64.s   | 43 --------------------------------
 4 files changed, 7 insertions(+), 52 deletions(-)
 delete mode 100644 src/syscall/asm_netbsd_amd64.s

diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index 3c9e0ed3f5..c81cbf12e9 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -614,7 +614,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	var usefpheuristic bool
 	switch ctxt.Headtype {
 	case objabi.Hwindows, objabi.Hdarwin, objabi.Hlinux, objabi.Hdragonfly,
-		objabi.Hfreebsd:
+		objabi.Hfreebsd, objabi.Hnetbsd:
 	default:
 		usefpheuristic = true
 	}
diff --git a/src/runtime/sys_netbsd_amd64.s b/src/runtime/sys_netbsd_amd64.s
index 30f3f380b6..2c5dc01bb6 100644
--- a/src/runtime/sys_netbsd_amd64.s
+++ b/src/runtime/sys_netbsd_amd64.s
@@ -296,16 +296,14 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
 	MOVL	sig+8(FP),   DI
 	MOVQ	info+16(FP), SI
 	MOVQ	ctx+24(FP),  DX
-	PUSHQ	BP
-	MOVQ	SP, BP
-	ANDQ	$~15, SP     // alignment for x86_64 ABI
+	MOVQ	SP, BX		// callee-saved
+	ANDQ	$~15, SP	// alignment for x86_64 ABI
 	CALL	AX
-	MOVQ	BP, SP
-	POPQ	BP
+	MOVQ	BX, SP
 	RET
 
 // Called using C ABI.
-TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME,$0
+TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME|NOFRAME,$0
 	// Transition from C ABI to Go ABI.
 	PUSH_REGS_HOST_TO_ABI0()
 
diff --git a/src/syscall/asm9_unix2_amd64.s b/src/syscall/asm9_unix2_amd64.s
index 6daa58d386..bb4e9db15c 100644
--- a/src/syscall/asm9_unix2_amd64.s
+++ b/src/syscall/asm9_unix2_amd64.s
@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build dragonfly || freebsd
+//go:build dragonfly || freebsd || netbsd
 
 #include "textflag.h"
 #include "funcdata.h"
 
 //
-// Syscall9 support for AMD64, DragonFly and FreeBSD
+// Syscall9 support for AMD64, DragonFly, FreeBSD and NetBSD
 //
 
 // func Syscall9(trap int64, a1, a2, a3, a4, a5, a6, a7, a8, a9 int64) (r1, r2, err int64);
diff --git a/src/syscall/asm_netbsd_amd64.s b/src/syscall/asm_netbsd_amd64.s
deleted file mode 100644
index 457e207296..0000000000
--- a/src/syscall/asm_netbsd_amd64.s
+++ /dev/null
@@ -1,43 +0,0 @@
-// Copyright 2016 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"
-#include "funcdata.h"
-
-//
-// Syscall9 support for AMD64, NetBSD
-//
-
-// func Syscall9(trap int64, a1, a2, a3, a4, a5, a6, a7, a8, a9 int64) (r1, r2, err int64);
-TEXT	·Syscall9(SB),NOSPLIT,$0-104
-	CALL	runtime·entersyscall<ABIInternal>(SB)
-	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
-	MOVQ	a7+56(FP), R11
-	MOVQ	a8+64(FP), R12
-	MOVQ	a9+72(FP), R13
-	SUBQ    $32, SP
-	MOVQ	R11, 8(SP)	// arg 7
-	MOVQ	R12, 16(SP)	// arg 8
-	MOVQ	R13, 24(SP)	// arg 9
-	SYSCALL
-	JCC	ok9
-	ADDQ    $32, SP
-	MOVQ	$-1, 88(SP)	// r1
-	MOVQ	$0, 96(SP)	// r2
-	MOVQ	AX, 104(SP)	// errno
-	CALL	runtime·exitsyscall<ABIInternal>(SB)
-	RET
-ok9:
-	ADDQ    $32, SP
-	MOVQ	AX, 88(SP)	// r1
-	MOVQ	DX, 96(SP)	// r2
-	MOVQ	$0, 104(SP)	// errno
-	CALL	runtime·exitsyscall<ABIInternal>(SB)
-	RET
-- 
2.50.0