// 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.

// System calls and other system stuff for Linux s390x; see
// /usr/include/asm/unistd.h for the syscall number definitions.

#include "go_asm.h"
#include "go_tls.h"
#include "textflag.h"

#define SYS_exit                  1
#define SYS_read                  3
#define SYS_write                 4
#define SYS_open                  5
#define SYS_close                 6
#define SYS_getpid               20
#define SYS_kill                 37
#define SYS_brk			 45
#define SYS_mmap                 90
#define SYS_munmap               91
#define SYS_setitimer           104
#define SYS_clone               120
#define SYS_sched_yield         158
#define SYS_nanosleep           162
#define SYS_rt_sigreturn        173
#define SYS_rt_sigaction        174
#define SYS_rt_sigprocmask      175
#define SYS_sigaltstack         186
#define SYS_madvise             219
#define SYS_mincore             218
#define SYS_gettid              236
#define SYS_futex               238
#define SYS_sched_getaffinity   240
#define SYS_tgkill              241
#define SYS_exit_group          248
#define SYS_timer_create        254
#define SYS_timer_settime       255
#define SYS_timer_delete        258
#define SYS_clock_gettime       260
#define SYS_pipe2		325

TEXT runtime·exit(SB),NOSPLIT|NOFRAME,$0-4
	MOVW	code+0(FP), R2
	MOVW	$SYS_exit_group, R1
	SYSCALL
	RET

// func exitThread(wait *atomic.Uint32)
TEXT runtime·exitThread(SB),NOSPLIT|NOFRAME,$0-8
	MOVD	wait+0(FP), R1
	// We're done using the stack.
	MOVW	$0, R2
	MOVW	R2, (R1)
	MOVW	$0, R2	// exit code
	MOVW	$SYS_exit, R1
	SYSCALL
	JMP	0(PC)

TEXT runtime·open(SB),NOSPLIT|NOFRAME,$0-20
	MOVD	name+0(FP), R2
	MOVW	mode+8(FP), R3
	MOVW	perm+12(FP), R4
	MOVW	$SYS_open, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, 2(PC)
	MOVW	$-1, R2
	MOVW	R2, ret+16(FP)
	RET

TEXT runtime·closefd(SB),NOSPLIT|NOFRAME,$0-12
	MOVW	fd+0(FP), R2
	MOVW	$SYS_close, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, 2(PC)
	MOVW	$-1, R2
	MOVW	R2, ret+8(FP)
	RET

TEXT runtime·write1(SB),NOSPLIT|NOFRAME,$0-28
	MOVD	fd+0(FP), R2
	MOVD	p+8(FP), R3
	MOVW	n+16(FP), R4
	MOVW	$SYS_write, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

TEXT runtime·read(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	fd+0(FP), R2
	MOVD	p+8(FP), R3
	MOVW	n+16(FP), R4
	MOVW	$SYS_read, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

// func pipe2() (r, w int32, errno int32)
TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
	MOVD	$r+8(FP), R2
	MOVW	flags+0(FP), R3
	MOVW	$SYS_pipe2, R1
	SYSCALL
	MOVW	R2, errno+16(FP)
	RET

TEXT runtime·usleep(SB),NOSPLIT,$16-4
	MOVW	usec+0(FP), R2
	MOVD	R2, R4
	MOVW	$1000000, R3
	DIVD	R3, R2
	MOVD	R2, 8(R15)
	MULLD	R2, R3		// Convert sec to usec and subtract
	SUB	R3, R4
	MOVW	$1000, R3
	MULLD	R3, R4		// Convert remaining usec into nsec.
	MOVD	R4, 16(R15)

	// nanosleep(&ts, 0)
	ADD	$8, R15, R2
	MOVW	$0, R3
	MOVW	$SYS_nanosleep, R1
	SYSCALL
	RET

TEXT runtime·gettid(SB),NOSPLIT,$0-4
	MOVW	$SYS_gettid, R1
	SYSCALL
	MOVW	R2, ret+0(FP)
	RET

TEXT runtime·raise(SB),NOSPLIT|NOFRAME,$0
	MOVW	$SYS_getpid, R1
	SYSCALL
	MOVW	R2, R10
	MOVW	$SYS_gettid, R1
	SYSCALL
	MOVW	R2, R3	// arg 2 tid
	MOVW	R10, R2	// arg 1 pid
	MOVW	sig+0(FP), R4	// arg 2
	MOVW	$SYS_tgkill, R1
	SYSCALL
	RET

TEXT runtime·raiseproc(SB),NOSPLIT|NOFRAME,$0
	MOVW	$SYS_getpid, R1
	SYSCALL
	MOVW	R2, R2	// arg 1 pid
	MOVW	sig+0(FP), R3	// arg 2
	MOVW	$SYS_kill, R1
	SYSCALL
	RET

TEXT ·getpid(SB),NOSPLIT|NOFRAME,$0-8
	MOVW	$SYS_getpid, R1
	SYSCALL
	MOVD	R2, ret+0(FP)
	RET

TEXT ·tgkill(SB),NOSPLIT|NOFRAME,$0-24
	MOVD	tgid+0(FP), R2
	MOVD	tid+8(FP), R3
	MOVD	sig+16(FP), R4
	MOVW	$SYS_tgkill, R1
	SYSCALL
	RET

TEXT runtime·setitimer(SB),NOSPLIT|NOFRAME,$0-24
	MOVW	mode+0(FP), R2
	MOVD	new+8(FP), R3
	MOVD	old+16(FP), R4
	MOVW	$SYS_setitimer, R1
	SYSCALL
	RET

TEXT runtime·timer_create(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	clockid+0(FP), R2
	MOVD	sevp+8(FP), R3
	MOVD	timerid+16(FP), R4
	MOVW	$SYS_timer_create, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

TEXT runtime·timer_settime(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	timerid+0(FP), R2
	MOVW	flags+4(FP), R3
	MOVD	new+8(FP), R4
	MOVD	old+16(FP), R5
	MOVW	$SYS_timer_settime, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

TEXT runtime·timer_delete(SB),NOSPLIT|NOFRAME,$0-12
	MOVW	timerid+0(FP), R2
	MOVW	$SYS_timer_delete, R1
	SYSCALL
	MOVW	R2, ret+8(FP)
	RET

TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
	MOVD	addr+0(FP), R2
	MOVD	n+8(FP), R3
	MOVD	dst+16(FP), R4
	MOVW	$SYS_mincore, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

// func walltime() (sec int64, nsec int32)
TEXT runtime·walltime(SB),NOSPLIT,$32-12
	MOVW	$0, R2			// CLOCK_REALTIME
	MOVD	R15, R7			// Backup stack pointer

	MOVD	g_m(g), R6		//m

	MOVD	runtime·vdsoClockgettimeSym(SB), R9	// Check for VDSO availability
	CMPBEQ	R9, $0, fallback

	MOVD	m_vdsoPC(R6), R4
	MOVD	R4, 16(R15)
	MOVD	m_vdsoSP(R6), R4
	MOVD	R4, 24(R15)

	MOVD	R14, R8 		// Backup return address
	MOVD	$ret-8(FP), R4 	// caller's SP

	MOVD	R8, m_vdsoPC(R6)
	MOVD	R4, m_vdsoSP(R6)

	MOVD	m_curg(R6), R5
	CMP		g, R5
	BNE		noswitch

	MOVD	m_g0(R6), R4
	MOVD	(g_sched+gobuf_sp)(R4), R15	// Set SP to g0 stack

noswitch:
	SUB		$16, R15		// reserve 2x 8 bytes for parameters
	MOVD	$~7, R4			// align to 8 bytes because of gcc ABI
	AND		R4, R15
	MOVD	R15, R3			// R15 needs to be in R3 as expected by kernel_clock_gettime

	MOVB	runtime·iscgo(SB),R12
	CMPBNE	R12, $0, nosaveg

	MOVD	m_gsignal(R6), R12	// g.m.gsignal
	CMPBEQ	R12, $0, nosaveg

	CMPBEQ	g, R12, nosaveg
	MOVD	(g_stack+stack_lo)(R12), R12 // g.m.gsignal.stack.lo
	MOVD	g, (R12)

	BL	R9 // to vdso lookup

	MOVD	$0, (R12)

	JMP	finish

nosaveg:
	BL	R9					// to vdso lookup

finish:
	MOVD	0(R15), R3		// sec
	MOVD	8(R15), R5		// nsec
	MOVD	R7, R15			// Restore SP

	// Restore vdsoPC, vdsoSP
	// We don't worry about being signaled between the two stores.
	// If we are not in a signal handler, we'll restore vdsoSP to 0,
	// and no one will care about vdsoPC. If we are in a signal handler,
	// we cannot receive another signal.
	MOVD	24(R15), R12
	MOVD	R12, m_vdsoSP(R6)
	MOVD	16(R15), R12
	MOVD	R12, m_vdsoPC(R6)

return:
	// sec is in R3, nsec in R5
	// return nsec in R3
	MOVD	R3, sec+0(FP)
	MOVW	R5, nsec+8(FP)
	RET

	// Syscall fallback
fallback:
	MOVD	$tp-16(SP), R3
	MOVW	$SYS_clock_gettime, R1
	SYSCALL
	LMG		tp-16(SP), R2, R3
	// sec is in R2, nsec in R3
	MOVD	R2, sec+0(FP)
	MOVW	R3, nsec+8(FP)
	RET

TEXT runtime·nanotime1(SB),NOSPLIT,$32-8
	MOVW	$1, R2			// CLOCK_MONOTONIC

	MOVD	R15, R7			// Backup stack pointer

	MOVD	g_m(g), R6		//m

	MOVD	runtime·vdsoClockgettimeSym(SB), R9	// Check for VDSO availability
	CMPBEQ	R9, $0, fallback

	MOVD	m_vdsoPC(R6), R4
	MOVD	R4, 16(R15)
	MOVD	m_vdsoSP(R6), R4
	MOVD	R4, 24(R15)

	MOVD	R14, R8			// Backup return address
	MOVD	$ret-8(FP), R4	// caller's SP

	MOVD	R8, m_vdsoPC(R6)
	MOVD	R4, m_vdsoSP(R6)

	MOVD	m_curg(R6), R5
	CMP		g, R5
	BNE		noswitch

	MOVD	m_g0(R6), R4
	MOVD	(g_sched+gobuf_sp)(R4), R15	// Set SP to g0 stack

noswitch:
	SUB		$16, R15		// reserve 2x 8 bytes for parameters
	MOVD	$~7, R4			// align to 8 bytes because of gcc ABI
	AND		R4, R15
	MOVD	R15, R3			// R15 needs to be in R3 as expected by kernel_clock_gettime

	MOVB	runtime·iscgo(SB),R12
	CMPBNE	R12, $0, nosaveg

	MOVD	m_gsignal(R6), R12	// g.m.gsignal
	CMPBEQ	R12, $0, nosaveg

	CMPBEQ	g, R12, nosaveg
	MOVD	(g_stack+stack_lo)(R12), R12	// g.m.gsignal.stack.lo
	MOVD	g, (R12)

	BL	R9 					// to vdso lookup

	MOVD $0, (R12)

	JMP	finish

nosaveg:
	BL	R9					// to vdso lookup

finish:
	MOVD	0(R15), R3		// sec
	MOVD	8(R15), R5		// nsec
	MOVD	R7, R15			// Restore SP

	// Restore vdsoPC, vdsoSP
	// We don't worry about being signaled between the two stores.
	// If we are not in a signal handler, we'll restore vdsoSP to 0,
	// and no one will care about vdsoPC. If we are in a signal handler,
	// we cannot receive another signal.

	MOVD	24(R15), R12
	MOVD	R12, m_vdsoSP(R6)
	MOVD	16(R15), R12
	MOVD	R12, m_vdsoPC(R6)

return:
	// sec is in R3, nsec in R5
	// return nsec in R3
	MULLD	$1000000000, R3
	ADD		R5, R3
	MOVD	R3, ret+0(FP)
	RET

	// Syscall fallback
fallback:
	MOVD	$tp-16(SP), R3
	MOVD	$SYS_clock_gettime, R1
	SYSCALL
	LMG		tp-16(SP), R2, R3
	MOVD	R3, R5
	MOVD	R2, R3
	JMP	return

TEXT runtime·rtsigprocmask(SB),NOSPLIT|NOFRAME,$0-28
	MOVW	how+0(FP), R2
	MOVD	new+8(FP), R3
	MOVD	old+16(FP), R4
	MOVW	size+24(FP), R5
	MOVW	$SYS_rt_sigprocmask, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, 2(PC)
	MOVD	R0, 0(R0) // crash
	RET

TEXT runtime·rt_sigaction(SB),NOSPLIT|NOFRAME,$0-36
	MOVD	sig+0(FP), R2
	MOVD	new+8(FP), R3
	MOVD	old+16(FP), R4
	MOVD	size+24(FP), R5
	MOVW	$SYS_rt_sigaction, R1
	SYSCALL
	MOVW	R2, ret+32(FP)
	RET

TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
	MOVW	sig+8(FP), R2
	MOVD	info+16(FP), R3
	MOVD	ctx+24(FP), R4
	MOVD	fn+0(FP), R5
	BL	R5
	RET

TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME,$160
	// initialize essential registers (just in case)
	XOR	R0, R0

	MOVD	R6, 32(R15)
	MOVD	R7, 40(R15)
	MOVD	R8, 48(R15)
	MOVD	R9, 56(R15)
	MOVD	R10, 64(R15)
	MOVD	R11, 72(R15)
	MOVD	R12, 80(R15)
	MOVD	g, 88(R15)
	FMOVD	F8, 96(R15)
	FMOVD	F9, 104(R15)
	FMOVD	F10, 112(R15)
	FMOVD	F11, 120(R15)
	FMOVD	F12, 128(R15)
	FMOVD	F13, 136(R15)
	FMOVD	F14, 144(R15)
	FMOVD	F15, 152(R15)

	// this might be called in external code context,
	// where g is not set.
	MOVB	runtime·iscgo(SB), R6
	CMPBEQ	R6, $0, 2(PC)
	BL	runtime·load_g(SB)

	MOVW	R2, 8(R15)
	MOVD	R3, 16(R15)
	MOVD	R4, 24(R15)
	MOVD	$runtime·sigtrampgo(SB), R5
	BL	R5

	MOVD	32(R15), R6
	MOVD	40(R15), R7
	MOVD	48(R15), R8
	MOVD	56(R15), R9
	MOVD	64(R15), R10
	MOVD	72(R15), R11
	MOVD	80(R15), R12
	MOVD	88(R15), g
	FMOVD	96(R15), F8
	FMOVD	104(R15), F9
	FMOVD	112(R15), F10
	FMOVD	120(R15), F11
	FMOVD	128(R15), F12
	FMOVD	136(R15), F13
	FMOVD	144(R15), F14
	FMOVD	152(R15), F15
	RET

TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
	BR	runtime·sigtramp(SB)

// func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer
TEXT runtime·mmap(SB),NOSPLIT,$48-48
	MOVD	addr+0(FP), R2
	MOVD	n+8(FP), R3
	MOVW	prot+16(FP), R4
	MOVW	flags+20(FP), R5
	MOVW	fd+24(FP), R6
	MOVWZ	off+28(FP), R7

	// s390x uses old_mmap, so the arguments need to be placed into
	// a struct and a pointer to the struct passed to mmap.
	MOVD	R2, addr-48(SP)
	MOVD	R3, n-40(SP)
	MOVD	R4, prot-32(SP)
	MOVD	R5, flags-24(SP)
	MOVD	R6, fd-16(SP)
	MOVD	R7, off-8(SP)

	MOVD	$addr-48(SP), R2
	MOVW	$SYS_mmap, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, ok
	NEG	R2
	MOVD	$0, p+32(FP)
	MOVD	R2, err+40(FP)
	RET
ok:
	MOVD	R2, p+32(FP)
	MOVD	$0, err+40(FP)
	RET

TEXT runtime·munmap(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R2
	MOVD	n+8(FP), R3
	MOVW	$SYS_munmap, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, 2(PC)
	MOVD	R0, 0(R0) // crash
	RET

TEXT runtime·madvise(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R2
	MOVD	n+8(FP), R3
	MOVW	flags+16(FP), R4
	MOVW	$SYS_madvise, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

// int64 futex(int32 *uaddr, int32 op, int32 val,
//	struct timespec *timeout, int32 *uaddr2, int32 val2);
TEXT runtime·futex(SB),NOSPLIT|NOFRAME,$0
	MOVD	addr+0(FP), R2
	MOVW	op+8(FP), R3
	MOVW	val+12(FP), R4
	MOVD	ts+16(FP), R5
	MOVD	addr2+24(FP), R6
	MOVW	val3+32(FP),  R7
	MOVW	$SYS_futex, R1
	SYSCALL
	MOVW	R2, ret+40(FP)
	RET

// int32 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
TEXT runtime·clone(SB),NOSPLIT|NOFRAME,$0
	MOVW	flags+0(FP), R3
	MOVD	stk+8(FP), R2

	// Copy mp, gp, fn off parent stack for use by child.
	// Careful: Linux system call clobbers ???.
	MOVD	mp+16(FP), R7
	MOVD	gp+24(FP), R8
	MOVD	fn+32(FP), R9

	MOVD	R7, -8(R2)
	MOVD	R8, -16(R2)
	MOVD	R9, -24(R2)
	MOVD	$1234, R7
	MOVD	R7, -32(R2)

	SYSCALL $SYS_clone

	// In parent, return.
	CMPBEQ	R2, $0, 3(PC)
	MOVW	R2, ret+40(FP)
	RET

	// In child, on new stack.
	// initialize essential registers
	XOR	R0, R0
	MOVD	-32(R15), R7
	CMP	R7, $1234
	BEQ	2(PC)
	MOVD	R0, 0(R0)

	// Initialize m->procid to Linux tid
	SYSCALL $SYS_gettid

	MOVD	-24(R15), R9        // fn
	MOVD	-16(R15), R8        // g
	MOVD	-8(R15), R7         // m

	CMPBEQ	R7, $0, nog
	CMP	R8, $0
	BEQ	nog

	MOVD	R2, m_procid(R7)

	// In child, set up new stack
	MOVD	R7, g_m(R8)
	MOVD	R8, g
	//CALL	runtime·stackcheck(SB)

nog:
	// Call fn
	BL	R9

	// It shouldn't return.	 If it does, exit that thread.
	MOVW	$111, R2
	MOVW	$SYS_exit, R1
	SYSCALL
	BR	-2(PC)	// keep exiting

TEXT runtime·sigaltstack(SB),NOSPLIT|NOFRAME,$0
	MOVD	new+0(FP), R2
	MOVD	old+8(FP), R3
	MOVW	$SYS_sigaltstack, R1
	SYSCALL
	MOVD	$-4095, R3
	CMPUBLT	R2, R3, 2(PC)
	MOVD	R0, 0(R0) // crash
	RET

TEXT runtime·osyield(SB),NOSPLIT|NOFRAME,$0
	MOVW	$SYS_sched_yield, R1
	SYSCALL
	RET

TEXT runtime·sched_getaffinity(SB),NOSPLIT|NOFRAME,$0
	MOVD	pid+0(FP), R2
	MOVD	len+8(FP), R3
	MOVD	buf+16(FP), R4
	MOVW	$SYS_sched_getaffinity, R1
	SYSCALL
	MOVW	R2, ret+24(FP)
	RET

// func sbrk0() uintptr
TEXT runtime·sbrk0(SB),NOSPLIT|NOFRAME,$0-8
	// Implemented as brk(NULL).
	MOVD	$0, R2
	MOVW	$SYS_brk, R1
	SYSCALL
	MOVD	R2, ret+0(FP)
	RET

TEXT runtime·access(SB),$0-20
	MOVD	$0, 2(R0) // unimplemented, only needed for android; declared in stubs_linux.go
	MOVW	R0, ret+16(FP)
	RET

TEXT runtime·connect(SB),$0-28
	MOVD	$0, 2(R0) // unimplemented, only needed for android; declared in stubs_linux.go
	MOVW	R0, ret+24(FP)
	RET

TEXT runtime·socket(SB),$0-20
	MOVD	$0, 2(R0) // unimplemented, only needed for android; declared in stubs_linux.go
	MOVW	R0, ret+16(FP)
	RET

// func vgetrandom1(buf *byte, length uintptr, flags uint32, state uintptr, stateSize uintptr) int
TEXT runtime·vgetrandom1(SB),NOSPLIT,$16-48
	MOVD	buf+0(FP), R2
	MOVD	length+8(FP), R3
	MOVW	flags+16(FP), R4
	MOVD	state+24(FP), R5
	MOVD	stateSize+32(FP), R6

	MOVD	R15, R7

	MOVD	runtime·vdsoGetrandomSym(SB), R1
	MOVD	g_m(g), R9

	MOVD	m_vdsoPC(R9), R12
	MOVD	R12, 8(R15)
	MOVD	m_vdsoSP(R9), R12
	MOVD	R12, 16(R15)
	MOVD	R14, m_vdsoPC(R9)
	MOVD	$buf+0(FP), R12
	MOVD	R12, m_vdsoSP(R9)

	SUB	$160, R15
	MOVD	$~7, R12
	AND	R12, R15

	MOVB	runtime·iscgo(SB), R12
	CMPBNE	R12, $0, nosaveg
	MOVD	m_gsignal(R9), R12
	CMPBEQ	R12, $0, nosaveg
	CMPBEQ	g, R12, nosaveg
	MOVD	(g_stack+stack_lo)(R12), R12
	MOVD	g, (R12)

	BL	R1

	MOVD	$0, (R12)
	JMP	restore

nosaveg:
	BL	R1

restore:
	MOVD	R7, R15
	MOVD	16(R15), R12
	MOVD	R12, m_vdsoSP(R9)
	MOVD	8(R15), R12
	MOVD	R12, m_vdsoPC(R9)
	MOVD	R2, ret+40(FP)
	RET