runtime: use explicit NOFRAME on dragonfly/amd64

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

Updates golang#58378

Change-Id: I832a1a78d68a49f11df3b03fa9d50d4796bcac03
Reviewed-on: https://go-review.googlesource.com/c/go/+/466355
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

src/cmd/internal/obj/x86/obj6.go

@@ -613,7 +613,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 
 	var usefpheuristic bool
 	switch ctxt.Headtype {
-	case objabi.Hwindows, objabi.Hdarwin, objabi.Hlinux:
+	case objabi.Hwindows, objabi.Hdarwin, objabi.Hlinux, objabi.Hdragonfly:
 	default:
 		usefpheuristic = true
 	}

src/runtime/sys_dragonfly_amd64.s

@@ -213,16 +213,14 @@ 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()
 

src/syscall/asm9_unix2_amd64.s

@@ -12,7 +12,8 @@
 //
 
 // func Syscall9(trap int64, a1, a2, a3, a4, a5, a6, a7, a8, a9 int64) (r1, r2, err int64);
-TEXT	·Syscall9(SB),NOSPLIT,$0-104
+TEXT	·Syscall9(SB),NOSPLIT,$32-104
+	NO_LOCAL_POINTERS
 	CALL	runtime·entersyscall<ABIInternal>(SB)
 	MOVQ	num+0(FP), AX	// syscall entry
 	MOVQ	a1+8(FP), DI
@@ -21,17 +22,15 @@ TEXT	·Syscall9(SB),NOSPLIT,$0-104
 	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
 
-	// shift around the last three arguments so they're at the
-	// top of the stack when the syscall is called.
-	// note that we are scribbling over the Go arguments now.
-	MOVQ	SP, CX	// hide (SP) writes from vet
-	MOVQ	a7+56(FP), R11 // arg 7
-	MOVQ	R11, 8(CX)
-	MOVQ	a8+64(FP), R11 // arg 8
-	MOVQ	R11, 16(CX)
-	MOVQ	a9+72(FP), R11 // arg 9
-	MOVQ	R11, 24(CX)
+	// only the first 6 arguments can be passed in registers,
+	// the last three should be placed at the top of the stack.
+	MOVQ	R11, 8(SP)	// arg 7
+	MOVQ	R12, 16(SP)	// arg 8
+	MOVQ	R13, 24(SP)	// arg 9
 
 	SYSCALL
 	JCC	ok9