rt0_openbsd_arm64.s

Documentation: runtime

     1// Copyright 2019 The Go Authors. All rights reserved.
     2// Use of this source code is governed by a BSD-style
     3// license that can be found in the LICENSE file.
     4
     5#include "textflag.h"
     6#include "cgo/abi_arm64.h"
     7
     8// See comment in runtime/sys_openbsd_arm64.s re this construction.
     9#define	INVOKE_SYSCALL	\
    10	SVC;		\
    11	NOOP;		\
    12	NOOP
    13
    14TEXT _rt0_arm64_openbsd(SB),NOSPLIT|NOFRAME,$0
    15	MOVD	0(RSP), R0	// argc
    16	ADD	$8, RSP, R1	// argv
    17	BL	main(SB)
    18
    19// When building with -buildmode=c-shared, this symbol is called when the shared
    20// library is loaded.
    21TEXT _rt0_arm64_openbsd_lib(SB),NOSPLIT,$184
    22	// Preserve callee-save registers.
    23	SAVE_R19_TO_R28(24)
    24	SAVE_F8_TO_F15(104)
    25
    26	// Initialize g as null in case of using g later e.g. sigaction in cgo_sigaction.go
    27	MOVD	ZR, g
    28
    29	MOVD	R0, _rt0_arm64_openbsd_lib_argc<>(SB)
    30	MOVD	R1, _rt0_arm64_openbsd_lib_argv<>(SB)
    31
    32	// Synchronous initialization.
    33	MOVD	$runtime·libpreinit(SB), R4
    34	BL	(R4)
    35
    36	// Create a new thread to do the runtime initialization and return.
    37	MOVD	_cgo_sys_thread_create(SB), R4
    38	CBZ	R4, nocgo
    39	MOVD	$_rt0_arm64_openbsd_lib_go(SB), R0
    40	MOVD	$0, R1
    41	SUB	$16, RSP		// reserve 16 bytes for sp-8 where fp may be saved.
    42	BL	(R4)
    43	ADD	$16, RSP
    44	B	restore
    45
    46nocgo:
    47	MOVD	$0x800000, R0                     // stacksize = 8192KB
    48	MOVD	$_rt0_arm64_openbsd_lib_go(SB), R1
    49	MOVD	R0, 8(RSP)
    50	MOVD	R1, 16(RSP)
    51	MOVD	$runtime·newosproc0(SB),R4
    52	BL	(R4)
    53
    54restore:
    55	// Restore callee-save registers.
    56	RESTORE_R19_TO_R28(24)
    57	RESTORE_F8_TO_F15(104)
    58	RET
    59
    60TEXT _rt0_arm64_openbsd_lib_go(SB),NOSPLIT,$0
    61	MOVD	_rt0_arm64_openbsd_lib_argc<>(SB), R0
    62	MOVD	_rt0_arm64_openbsd_lib_argv<>(SB), R1
    63	MOVD	$runtime·rt0_go(SB),R4
    64	B       (R4)
    65
    66DATA _rt0_arm64_openbsd_lib_argc<>(SB)/8, $0
    67GLOBL _rt0_arm64_openbsd_lib_argc<>(SB),NOPTR, $8
    68DATA _rt0_arm64_openbsd_lib_argv<>(SB)/8, $0
    69GLOBL _rt0_arm64_openbsd_lib_argv<>(SB),NOPTR, $8
    70
    71
    72TEXT main(SB),NOSPLIT|NOFRAME,$0
    73	MOVD	$runtime·rt0_go(SB), R2
    74	BL	(R2)
    75exit:
    76	MOVD	$0, R0
    77	MOVD	$1, R8		// sys_exit
    78	INVOKE_SYSCALL
    79	B	exit
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