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 #58378

Change-Id: I832a1a78d68a49f11df3b03fa9d50d4796bcac03
Reviewed-on: https://go-review.googlesource.com/c/go/+/466355
Run-TryBot: Quim Muntal <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: qmuntal

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