// will clobber the test pattern created by the caller
	ADD	$(1024*8), X2

	// Ask signaller to setgid
	MOV	$1, X5
	FENCE
	MOVW	X5, ·Baton(SB)
	FENCE

	// Wait for setgid completion
loop:
	FENCE
	MOVW	·Baton(SB), X5
	OR	X6, X6, X6	// hint that we're in a spin loop
	BNE	ZERO, X5, loop
	FENCE

	// Restore stack
	ADD	$(-1024*8), X2

	// Rewind stack pointer so anything that happens on the stack
	// will clobber the test pattern created by the caller
	ADDQ	$(1024 * 8), SP

	// Ask signaller to setgid
	MOVL	$1, ·Baton(SB)

	// Wait for setgid completion
loop:
	PAUSE
	MOVL	·Baton(SB), AX
	CMPL	AX, $0
	JNE	loop

	// Restore stack
	SUBQ	$(1024 * 8), SP

	// will clobber the test pattern created by the caller
	ADDU	$(1024*8), R29

	// Ask signaller to setgid
	MOVW	$1, R1
	SYNC
	MOVW	R1, ·Baton(SB)
	SYNC

	// Wait for setgid completion
loop:
	SYNC
	MOVW	·Baton(SB), R1
	OR	R2, R2, R2	// hint that we're in a spin loop
	BNE	R1, loop
	SYNC

	// Restore stack
	ADDU	$(-1024*8), R29

	// will clobber the test pattern created by the caller
	ADD	$(1024 * 8), R1

	// Ask signaller to setgid
	MOVW	$1, R3
	SYNC
	MOVW	R3, ·Baton(SB)

	// Wait for setgid completion
loop:
	SYNC
	MOVW	·Baton(SB), R3
	CMP	R3, $0
	// Hint that we're in a spin loop
	OR	R1, R1, R1
	BNE	loop
	ISYNC

	// Restore stack
	SUB	$(1024 * 8), R1

	// will clobber the test pattern created by the caller
	ADD	$(1024 * 8), R15

	// Ask signaller to setgid
	MOVD	$·Baton(SB), R5
	MOVW	$1, 0(R5)

	// Wait for setgid completion
loop:
	SYNC
	MOVW	·Baton(SB), R3
	CMPBNE	R3, $0, loop

	// Restore stack
	SUB	$(1024 * 8), R15

	// will clobber the test pattern created by the caller
	ADDV	$(1024*8), R3

	// Ask signaller to setgid
	MOVW	$1, R12
	DBAR
	MOVW	R12, ·Baton(SB)
	DBAR

	// Wait for setgid completion
loop:
	DBAR
	MOVW	·Baton(SB), R12
	OR	R13, R13, R13	// hint that we're in a spin loop
	BNE	R12, loop
	DBAR

	// Restore stack
	ADDV	$(-1024*8), R3

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build gc

#include "textflag.h"

TEXT ·RewindAndSetgid(SB),NOSPLIT,$0-0
	MOVL	$·Baton(SB), BX
	// Rewind stack pointer so anything that happens on the stack
	// will clobber the test pattern created by the caller
	ADDL	$(1024 * 8), SP

	// Ask signaller to setgid
	MOVL	$1, (BX)

	MOVD	R30, R9

	// Rewind stack pointer so anything that happens on the stack
	// will clobber the test pattern created by the caller
	ADD	$(1024 * 8), RSP

	// Ask signaller to setgid
	MOVD	$·Baton(SB), R0
	MOVD	$1, R1
storeloop:
	LDAXRW	(R0), R2
	STLXRW	R1, (R0), R3
	CBNZ	R3, storeloop

	// Wait for setgid completion
	MOVW	$0, R1
	MOVW	$0, R2
loop:
	LDAXRW	(R0), R3
	CMPW	R1, R3
	BNE	loop

	// will clobber the test pattern created by the caller
	ADDV	$(1024*8), R29

	// Ask signaller to setgid
	MOVW	$1, R1
	SYNC
	MOVW	R1, ·Baton(SB)
	SYNC

	// Wait for setgid completion
loop:
	SYNC
	MOVW	·Baton(SB), R1
	OR	R2, R2, R2	// hint that we're in a spin loop
	BNE	R1, loop
	SYNC

	// Restore stack
	ADDV	$(-1024*8), R29

	MOVW	R14, R4

	// Rewind stack pointer so anything that happens on the stack
	// will clobber the test pattern created by the caller
	ADD	$(1024 * 8), R13

	// Ask signaller to setgid
	MOVW	$·Baton(SB), R2
storeloop:
	MOVW	0(R2), R0
	MOVW	$1, R1
	BL	cas<>(SB)
	BCC	storeloop

	// Wait for setgid completion
loop:
	MOVW	$0, R0
	MOVW	$0, R1
	BL	cas<>(SB)
	BCC	loop

	// Restore stack