github.com/AESNooper/go/src@v0.0.0-20220218095104-b56a4ab1bbbb/runtime/sys_linux_amd64.s (about)

     1  // Copyright 2009 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  //
     6  // System calls and other sys.stuff for AMD64, Linux
     7  //
     8  
     9  #include "go_asm.h"
    10  #include "go_tls.h"
    11  #include "textflag.h"
    12  #include "cgo/abi_amd64.h"
    13  
    14  #define AT_FDCWD -100
    15  
    16  #define SYS_read		0
    17  #define SYS_write		1
    18  #define SYS_close		3
    19  #define SYS_mmap		9
    20  #define SYS_munmap		11
    21  #define SYS_brk 		12
    22  #define SYS_rt_sigaction	13
    23  #define SYS_rt_sigprocmask	14
    24  #define SYS_rt_sigreturn	15
    25  #define SYS_pipe		22
    26  #define SYS_sched_yield 	24
    27  #define SYS_mincore		27
    28  #define SYS_madvise		28
    29  #define SYS_nanosleep		35
    30  #define SYS_setittimer		38
    31  #define SYS_getpid		39
    32  #define SYS_socket		41
    33  #define SYS_connect		42
    34  #define SYS_clone		56
    35  #define SYS_exit		60
    36  #define SYS_kill		62
    37  #define SYS_fcntl		72
    38  #define SYS_sigaltstack 	131
    39  #define SYS_arch_prctl		158
    40  #define SYS_gettid		186
    41  #define SYS_futex		202
    42  #define SYS_sched_getaffinity	204
    43  #define SYS_epoll_create	213
    44  #define SYS_timer_create	222
    45  #define SYS_timer_settime	223
    46  #define SYS_timer_delete	226
    47  #define SYS_clock_gettime	228
    48  #define SYS_exit_group		231
    49  #define SYS_epoll_ctl		233
    50  #define SYS_tgkill		234
    51  #define SYS_openat		257
    52  #define SYS_faccessat		269
    53  #define SYS_epoll_pwait		281
    54  #define SYS_epoll_create1	291
    55  #define SYS_pipe2		293
    56  
    57  TEXT runtime·exit(SB),NOSPLIT,$0-4
    58  	MOVL	code+0(FP), DI
    59  	MOVL	$SYS_exit_group, AX
    60  	SYSCALL
    61  	RET
    62  
    63  // func exitThread(wait *uint32)
    64  TEXT runtime·exitThread(SB),NOSPLIT,$0-8
    65  	MOVQ	wait+0(FP), AX
    66  	// We're done using the stack.
    67  	MOVL	$0, (AX)
    68  	MOVL	$0, DI	// exit code
    69  	MOVL	$SYS_exit, AX
    70  	SYSCALL
    71  	// We may not even have a stack any more.
    72  	INT	$3
    73  	JMP	0(PC)
    74  
    75  TEXT runtime·open(SB),NOSPLIT,$0-20
    76  	// This uses openat instead of open, because Android O blocks open.
    77  	MOVL	$AT_FDCWD, DI // AT_FDCWD, so this acts like open
    78  	MOVQ	name+0(FP), SI
    79  	MOVL	mode+8(FP), DX
    80  	MOVL	perm+12(FP), R10
    81  	MOVL	$SYS_openat, AX
    82  	SYSCALL
    83  	CMPQ	AX, $0xfffffffffffff001
    84  	JLS	2(PC)
    85  	MOVL	$-1, AX
    86  	MOVL	AX, ret+16(FP)
    87  	RET
    88  
    89  TEXT runtime·closefd(SB),NOSPLIT,$0-12
    90  	MOVL	fd+0(FP), DI
    91  	MOVL	$SYS_close, AX
    92  	SYSCALL
    93  	CMPQ	AX, $0xfffffffffffff001
    94  	JLS	2(PC)
    95  	MOVL	$-1, AX
    96  	MOVL	AX, ret+8(FP)
    97  	RET
    98  
    99  TEXT runtime·write1(SB),NOSPLIT,$0-28
   100  	MOVQ	fd+0(FP), DI
   101  	MOVQ	p+8(FP), SI
   102  	MOVL	n+16(FP), DX
   103  	MOVL	$SYS_write, AX
   104  	SYSCALL
   105  	MOVL	AX, ret+24(FP)
   106  	RET
   107  
   108  TEXT runtime·read(SB),NOSPLIT,$0-28
   109  	MOVL	fd+0(FP), DI
   110  	MOVQ	p+8(FP), SI
   111  	MOVL	n+16(FP), DX
   112  	MOVL	$SYS_read, AX
   113  	SYSCALL
   114  	MOVL	AX, ret+24(FP)
   115  	RET
   116  
   117  // func pipe() (r, w int32, errno int32)
   118  TEXT runtime·pipe(SB),NOSPLIT,$0-12
   119  	LEAQ	r+0(FP), DI
   120  	MOVL	$SYS_pipe, AX
   121  	SYSCALL
   122  	MOVL	AX, errno+8(FP)
   123  	RET
   124  
   125  // func pipe2(flags int32) (r, w int32, errno int32)
   126  TEXT runtime·pipe2(SB),NOSPLIT,$0-20
   127  	LEAQ	r+8(FP), DI
   128  	MOVL	flags+0(FP), SI
   129  	MOVL	$SYS_pipe2, AX
   130  	SYSCALL
   131  	MOVL	AX, errno+16(FP)
   132  	RET
   133  
   134  TEXT runtime·usleep(SB),NOSPLIT,$16
   135  	MOVL	$0, DX
   136  	MOVL	usec+0(FP), AX
   137  	MOVL	$1000000, CX
   138  	DIVL	CX
   139  	MOVQ	AX, 0(SP)
   140  	MOVL	$1000, AX	// usec to nsec
   141  	MULL	DX
   142  	MOVQ	AX, 8(SP)
   143  
   144  	// nanosleep(&ts, 0)
   145  	MOVQ	SP, DI
   146  	MOVL	$0, SI
   147  	MOVL	$SYS_nanosleep, AX
   148  	SYSCALL
   149  	RET
   150  
   151  TEXT runtime·gettid(SB),NOSPLIT,$0-4
   152  	MOVL	$SYS_gettid, AX
   153  	SYSCALL
   154  	MOVL	AX, ret+0(FP)
   155  	RET
   156  
   157  TEXT runtime·raise(SB),NOSPLIT,$0
   158  	MOVL	$SYS_getpid, AX
   159  	SYSCALL
   160  	MOVL	AX, R12
   161  	MOVL	$SYS_gettid, AX
   162  	SYSCALL
   163  	MOVL	AX, SI	// arg 2 tid
   164  	MOVL	R12, DI	// arg 1 pid
   165  	MOVL	sig+0(FP), DX	// arg 3
   166  	MOVL	$SYS_tgkill, AX
   167  	SYSCALL
   168  	RET
   169  
   170  TEXT runtime·raiseproc(SB),NOSPLIT,$0
   171  	MOVL	$SYS_getpid, AX
   172  	SYSCALL
   173  	MOVL	AX, DI	// arg 1 pid
   174  	MOVL	sig+0(FP), SI	// arg 2
   175  	MOVL	$SYS_kill, AX
   176  	SYSCALL
   177  	RET
   178  
   179  TEXT ·getpid(SB),NOSPLIT,$0-8
   180  	MOVL	$SYS_getpid, AX
   181  	SYSCALL
   182  	MOVQ	AX, ret+0(FP)
   183  	RET
   184  
   185  TEXT ·tgkill(SB),NOSPLIT,$0
   186  	MOVQ	tgid+0(FP), DI
   187  	MOVQ	tid+8(FP), SI
   188  	MOVQ	sig+16(FP), DX
   189  	MOVL	$SYS_tgkill, AX
   190  	SYSCALL
   191  	RET
   192  
   193  TEXT runtime·setitimer(SB),NOSPLIT,$0-24
   194  	MOVL	mode+0(FP), DI
   195  	MOVQ	new+8(FP), SI
   196  	MOVQ	old+16(FP), DX
   197  	MOVL	$SYS_setittimer, AX
   198  	SYSCALL
   199  	RET
   200  
   201  TEXT runtime·timer_create(SB),NOSPLIT,$0-28
   202  	MOVL	clockid+0(FP), DI
   203  	MOVQ	sevp+8(FP), SI
   204  	MOVQ	timerid+16(FP), DX
   205  	MOVL	$SYS_timer_create, AX
   206  	SYSCALL
   207  	MOVL	AX, ret+24(FP)
   208  	RET
   209  
   210  TEXT runtime·timer_settime(SB),NOSPLIT,$0-28
   211  	MOVL	timerid+0(FP), DI
   212  	MOVL	flags+4(FP), SI
   213  	MOVQ	new+8(FP), DX
   214  	MOVQ	old+16(FP), R10
   215  	MOVL	$SYS_timer_settime, AX
   216  	SYSCALL
   217  	MOVL	AX, ret+24(FP)
   218  	RET
   219  
   220  TEXT runtime·timer_delete(SB),NOSPLIT,$0-12
   221  	MOVL	timerid+0(FP), DI
   222  	MOVL	$SYS_timer_delete, AX
   223  	SYSCALL
   224  	MOVL	AX, ret+8(FP)
   225  	RET
   226  
   227  TEXT runtime·mincore(SB),NOSPLIT,$0-28
   228  	MOVQ	addr+0(FP), DI
   229  	MOVQ	n+8(FP), SI
   230  	MOVQ	dst+16(FP), DX
   231  	MOVL	$SYS_mincore, AX
   232  	SYSCALL
   233  	MOVL	AX, ret+24(FP)
   234  	RET
   235  
   236  // func nanotime1() int64
   237  TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
   238  	// We don't know how much stack space the VDSO code will need,
   239  	// so switch to g0.
   240  	// In particular, a kernel configured with CONFIG_OPTIMIZE_INLINING=n
   241  	// and hardening can use a full page of stack space in gettime_sym
   242  	// due to stack probes inserted to avoid stack/heap collisions.
   243  	// See issue #20427.
   244  
   245  	MOVQ	SP, R12	// Save old SP; R12 unchanged by C code.
   246  
   247  	MOVQ	g_m(R14), BX // BX unchanged by C code.
   248  
   249  	// Set vdsoPC and vdsoSP for SIGPROF traceback.
   250  	// Save the old values on stack and restore them on exit,
   251  	// so this function is reentrant.
   252  	MOVQ	m_vdsoPC(BX), CX
   253  	MOVQ	m_vdsoSP(BX), DX
   254  	MOVQ	CX, 0(SP)
   255  	MOVQ	DX, 8(SP)
   256  
   257  	LEAQ	ret+0(FP), DX
   258  	MOVQ	-8(DX), CX
   259  	MOVQ	CX, m_vdsoPC(BX)
   260  	MOVQ	DX, m_vdsoSP(BX)
   261  
   262  	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
   263  	JNE	noswitch
   264  
   265  	MOVQ	m_g0(BX), DX
   266  	MOVQ	(g_sched+gobuf_sp)(DX), SP	// Set SP to g0 stack
   267  
   268  noswitch:
   269  	SUBQ	$16, SP		// Space for results
   270  	ANDQ	$~15, SP	// Align for C code
   271  
   272  	MOVL	$1, DI // CLOCK_MONOTONIC
   273  	LEAQ	0(SP), SI
   274  	MOVQ	runtime·vdsoClockgettimeSym(SB), AX
   275  	CMPQ	AX, $0
   276  	JEQ	fallback
   277  	CALL	AX
   278  ret:
   279  	MOVQ	0(SP), AX	// sec
   280  	MOVQ	8(SP), DX	// nsec
   281  	MOVQ	R12, SP		// Restore real SP
   282  	// Restore vdsoPC, vdsoSP
   283  	// We don't worry about being signaled between the two stores.
   284  	// If we are not in a signal handler, we'll restore vdsoSP to 0,
   285  	// and no one will care about vdsoPC. If we are in a signal handler,
   286  	// we cannot receive another signal.
   287  	MOVQ	8(SP), CX
   288  	MOVQ	CX, m_vdsoSP(BX)
   289  	MOVQ	0(SP), CX
   290  	MOVQ	CX, m_vdsoPC(BX)
   291  	// sec is in AX, nsec in DX
   292  	// return nsec in AX
   293  	IMULQ	$1000000000, AX
   294  	ADDQ	DX, AX
   295  	MOVQ	AX, ret+0(FP)
   296  	RET
   297  fallback:
   298  	MOVQ	$SYS_clock_gettime, AX
   299  	SYSCALL
   300  	JMP	ret
   301  
   302  TEXT runtime·rtsigprocmask(SB),NOSPLIT,$0-28
   303  	MOVL	how+0(FP), DI
   304  	MOVQ	new+8(FP), SI
   305  	MOVQ	old+16(FP), DX
   306  	MOVL	size+24(FP), R10
   307  	MOVL	$SYS_rt_sigprocmask, AX
   308  	SYSCALL
   309  	CMPQ	AX, $0xfffffffffffff001
   310  	JLS	2(PC)
   311  	MOVL	$0xf1, 0xf1  // crash
   312  	RET
   313  
   314  TEXT runtime·rt_sigaction(SB),NOSPLIT,$0-36
   315  	MOVQ	sig+0(FP), DI
   316  	MOVQ	new+8(FP), SI
   317  	MOVQ	old+16(FP), DX
   318  	MOVQ	size+24(FP), R10
   319  	MOVL	$SYS_rt_sigaction, AX
   320  	SYSCALL
   321  	MOVL	AX, ret+32(FP)
   322  	RET
   323  
   324  // Call the function stored in _cgo_sigaction using the GCC calling convention.
   325  TEXT runtime·callCgoSigaction(SB),NOSPLIT,$16
   326  	MOVQ	sig+0(FP), DI
   327  	MOVQ	new+8(FP), SI
   328  	MOVQ	old+16(FP), DX
   329  	MOVQ	_cgo_sigaction(SB), AX
   330  	MOVQ	SP, BX	// callee-saved
   331  	ANDQ	$~15, SP	// alignment as per amd64 psABI
   332  	CALL	AX
   333  	MOVQ	BX, SP
   334  	MOVL	AX, ret+24(FP)
   335  	RET
   336  
   337  TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
   338  	MOVQ	fn+0(FP),    AX
   339  	MOVL	sig+8(FP),   DI
   340  	MOVQ	info+16(FP), SI
   341  	MOVQ	ctx+24(FP),  DX
   342  	PUSHQ	BP
   343  	MOVQ	SP, BP
   344  	ANDQ	$~15, SP     // alignment for x86_64 ABI
   345  	CALL	AX
   346  	MOVQ	BP, SP
   347  	POPQ	BP
   348  	RET
   349  
   350  // Called using C ABI.
   351  TEXT runtime·sigtramp(SB),NOSPLIT,$0
   352  	// Transition from C ABI to Go ABI.
   353  	PUSH_REGS_HOST_TO_ABI0()
   354  
   355  	// Call into the Go signal handler
   356  	NOP	SP		// disable vet stack checking
   357          ADJSP   $24
   358  	MOVQ	DI, 0(SP)	// sig
   359  	MOVQ	SI, 8(SP)	// info
   360  	MOVQ	DX, 16(SP)	// ctx
   361  	CALL	·sigtrampgo(SB)
   362  	ADJSP	$-24
   363  
   364          POP_REGS_HOST_TO_ABI0()
   365  	RET
   366  
   367  // Called using C ABI.
   368  TEXT runtime·sigprofNonGoWrapper<>(SB),NOSPLIT,$0
   369  	// Transition from C ABI to Go ABI.
   370  	PUSH_REGS_HOST_TO_ABI0()
   371  
   372  	// Call into the Go signal handler
   373  	NOP	SP		// disable vet stack checking
   374  	ADJSP	$24
   375  	MOVL	DI, 0(SP)	// sig
   376  	MOVQ	SI, 8(SP)	// info
   377  	MOVQ	DX, 16(SP)	// ctx
   378  	CALL	·sigprofNonGo(SB)
   379  	ADJSP	$-24
   380  
   381  	POP_REGS_HOST_TO_ABI0()
   382  	RET
   383  
   384  // Used instead of sigtramp in programs that use cgo.
   385  // Arguments from kernel are in DI, SI, DX.
   386  TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
   387  	// If no traceback function, do usual sigtramp.
   388  	MOVQ	runtime·cgoTraceback(SB), AX
   389  	TESTQ	AX, AX
   390  	JZ	sigtramp
   391  
   392  	// If no traceback support function, which means that
   393  	// runtime/cgo was not linked in, do usual sigtramp.
   394  	MOVQ	_cgo_callers(SB), AX
   395  	TESTQ	AX, AX
   396  	JZ	sigtramp
   397  
   398  	// Figure out if we are currently in a cgo call.
   399  	// If not, just do usual sigtramp.
   400  	get_tls(CX)
   401  	MOVQ	g(CX),AX
   402  	TESTQ	AX, AX
   403  	JZ	sigtrampnog     // g == nil
   404  	MOVQ	g_m(AX), AX
   405  	TESTQ	AX, AX
   406  	JZ	sigtramp        // g.m == nil
   407  	MOVL	m_ncgo(AX), CX
   408  	TESTL	CX, CX
   409  	JZ	sigtramp        // g.m.ncgo == 0
   410  	MOVQ	m_curg(AX), CX
   411  	TESTQ	CX, CX
   412  	JZ	sigtramp        // g.m.curg == nil
   413  	MOVQ	g_syscallsp(CX), CX
   414  	TESTQ	CX, CX
   415  	JZ	sigtramp        // g.m.curg.syscallsp == 0
   416  	MOVQ	m_cgoCallers(AX), R8
   417  	TESTQ	R8, R8
   418  	JZ	sigtramp        // g.m.cgoCallers == nil
   419  	MOVL	m_cgoCallersUse(AX), CX
   420  	TESTL	CX, CX
   421  	JNZ	sigtramp	// g.m.cgoCallersUse != 0
   422  
   423  	// Jump to a function in runtime/cgo.
   424  	// That function, written in C, will call the user's traceback
   425  	// function with proper unwind info, and will then call back here.
   426  	// The first three arguments, and the fifth, are already in registers.
   427  	// Set the two remaining arguments now.
   428  	MOVQ	runtime·cgoTraceback(SB), CX
   429  	MOVQ	$runtime·sigtramp(SB), R9
   430  	MOVQ	_cgo_callers(SB), AX
   431  	JMP	AX
   432  
   433  sigtramp:
   434  	JMP	runtime·sigtramp(SB)
   435  
   436  sigtrampnog:
   437  	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
   438  	// stack trace.
   439  	CMPL	DI, $27 // 27 == SIGPROF
   440  	JNZ	sigtramp
   441  
   442  	// Lock sigprofCallersUse.
   443  	MOVL	$0, AX
   444  	MOVL	$1, CX
   445  	MOVQ	$runtime·sigprofCallersUse(SB), R11
   446  	LOCK
   447  	CMPXCHGL	CX, 0(R11)
   448  	JNZ	sigtramp  // Skip stack trace if already locked.
   449  
   450  	// Jump to the traceback function in runtime/cgo.
   451  	// It will call back to sigprofNonGo, via sigprofNonGoWrapper, to convert
   452  	// the arguments to the Go calling convention.
   453  	// First three arguments to traceback function are in registers already.
   454  	MOVQ	runtime·cgoTraceback(SB), CX
   455  	MOVQ	$runtime·sigprofCallers(SB), R8
   456  	MOVQ	$runtime·sigprofNonGoWrapper<>(SB), R9
   457  	MOVQ	_cgo_callers(SB), AX
   458  	JMP	AX
   459  
   460  // For cgo unwinding to work, this function must look precisely like
   461  // the one in glibc.  The glibc source code is:
   462  // https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c
   463  // The code that cares about the precise instructions used is:
   464  // https://gcc.gnu.org/viewcvs/gcc/trunk/libgcc/config/i386/linux-unwind.h?revision=219188&view=markup
   465  TEXT runtime·sigreturn(SB),NOSPLIT,$0
   466  	MOVQ	$SYS_rt_sigreturn, AX
   467  	SYSCALL
   468  	INT $3	// not reached
   469  
   470  TEXT runtime·sysMmap(SB),NOSPLIT,$0
   471  	MOVQ	addr+0(FP), DI
   472  	MOVQ	n+8(FP), SI
   473  	MOVL	prot+16(FP), DX
   474  	MOVL	flags+20(FP), R10
   475  	MOVL	fd+24(FP), R8
   476  	MOVL	off+28(FP), R9
   477  
   478  	MOVL	$SYS_mmap, AX
   479  	SYSCALL
   480  	CMPQ	AX, $0xfffffffffffff001
   481  	JLS	ok
   482  	NOTQ	AX
   483  	INCQ	AX
   484  	MOVQ	$0, p+32(FP)
   485  	MOVQ	AX, err+40(FP)
   486  	RET
   487  ok:
   488  	MOVQ	AX, p+32(FP)
   489  	MOVQ	$0, err+40(FP)
   490  	RET
   491  
   492  // Call the function stored in _cgo_mmap using the GCC calling convention.
   493  // This must be called on the system stack.
   494  TEXT runtime·callCgoMmap(SB),NOSPLIT,$16
   495  	MOVQ	addr+0(FP), DI
   496  	MOVQ	n+8(FP), SI
   497  	MOVL	prot+16(FP), DX
   498  	MOVL	flags+20(FP), CX
   499  	MOVL	fd+24(FP), R8
   500  	MOVL	off+28(FP), R9
   501  	MOVQ	_cgo_mmap(SB), AX
   502  	MOVQ	SP, BX
   503  	ANDQ	$~15, SP	// alignment as per amd64 psABI
   504  	MOVQ	BX, 0(SP)
   505  	CALL	AX
   506  	MOVQ	0(SP), SP
   507  	MOVQ	AX, ret+32(FP)
   508  	RET
   509  
   510  TEXT runtime·sysMunmap(SB),NOSPLIT,$0
   511  	MOVQ	addr+0(FP), DI
   512  	MOVQ	n+8(FP), SI
   513  	MOVQ	$SYS_munmap, AX
   514  	SYSCALL
   515  	CMPQ	AX, $0xfffffffffffff001
   516  	JLS	2(PC)
   517  	MOVL	$0xf1, 0xf1  // crash
   518  	RET
   519  
   520  // Call the function stored in _cgo_munmap using the GCC calling convention.
   521  // This must be called on the system stack.
   522  TEXT runtime·callCgoMunmap(SB),NOSPLIT,$16-16
   523  	MOVQ	addr+0(FP), DI
   524  	MOVQ	n+8(FP), SI
   525  	MOVQ	_cgo_munmap(SB), AX
   526  	MOVQ	SP, BX
   527  	ANDQ	$~15, SP	// alignment as per amd64 psABI
   528  	MOVQ	BX, 0(SP)
   529  	CALL	AX
   530  	MOVQ	0(SP), SP
   531  	RET
   532  
   533  TEXT runtime·madvise(SB),NOSPLIT,$0
   534  	MOVQ	addr+0(FP), DI
   535  	MOVQ	n+8(FP), SI
   536  	MOVL	flags+16(FP), DX
   537  	MOVQ	$SYS_madvise, AX
   538  	SYSCALL
   539  	MOVL	AX, ret+24(FP)
   540  	RET
   541  
   542  // int64 futex(int32 *uaddr, int32 op, int32 val,
   543  //	struct timespec *timeout, int32 *uaddr2, int32 val2);
   544  TEXT runtime·futex(SB),NOSPLIT,$0
   545  	MOVQ	addr+0(FP), DI
   546  	MOVL	op+8(FP), SI
   547  	MOVL	val+12(FP), DX
   548  	MOVQ	ts+16(FP), R10
   549  	MOVQ	addr2+24(FP), R8
   550  	MOVL	val3+32(FP), R9
   551  	MOVL	$SYS_futex, AX
   552  	SYSCALL
   553  	MOVL	AX, ret+40(FP)
   554  	RET
   555  
   556  // int32 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
   557  TEXT runtime·clone(SB),NOSPLIT,$0
   558  	MOVL	flags+0(FP), DI
   559  	MOVQ	stk+8(FP), SI
   560  	MOVQ	$0, DX
   561  	MOVQ	$0, R10
   562  	MOVQ    $0, R8
   563  	// Copy mp, gp, fn off parent stack for use by child.
   564  	// Careful: Linux system call clobbers CX and R11.
   565  	MOVQ	mp+16(FP), R13
   566  	MOVQ	gp+24(FP), R9
   567  	MOVQ	fn+32(FP), R12
   568  	CMPQ	R13, $0    // m
   569  	JEQ	nog1
   570  	CMPQ	R9, $0    // g
   571  	JEQ	nog1
   572  	LEAQ	m_tls(R13), R8
   573  #ifdef GOOS_android
   574  	// Android stores the TLS offset in runtime·tls_g.
   575  	SUBQ	runtime·tls_g(SB), R8
   576  #else
   577  	ADDQ	$8, R8	// ELF wants to use -8(FS)
   578  #endif
   579  	ORQ 	$0x00080000, DI //add flag CLONE_SETTLS(0x00080000) to call clone
   580  nog1:
   581  	MOVL	$SYS_clone, AX
   582  	SYSCALL
   583  
   584  	// In parent, return.
   585  	CMPQ	AX, $0
   586  	JEQ	3(PC)
   587  	MOVL	AX, ret+40(FP)
   588  	RET
   589  
   590  	// In child, on new stack.
   591  	MOVQ	SI, SP
   592  
   593  	// If g or m are nil, skip Go-related setup.
   594  	CMPQ	R13, $0    // m
   595  	JEQ	nog2
   596  	CMPQ	R9, $0    // g
   597  	JEQ	nog2
   598  
   599  	// Initialize m->procid to Linux tid
   600  	MOVL	$SYS_gettid, AX
   601  	SYSCALL
   602  	MOVQ	AX, m_procid(R13)
   603  
   604  	// In child, set up new stack
   605  	get_tls(CX)
   606  	MOVQ	R13, g_m(R9)
   607  	MOVQ	R9, g(CX)
   608  	MOVQ	R9, R14 // set g register
   609  	CALL	runtime·stackcheck(SB)
   610  
   611  nog2:
   612  	// Call fn. This is the PC of an ABI0 function.
   613  	CALL	R12
   614  
   615  	// It shouldn't return. If it does, exit that thread.
   616  	MOVL	$111, DI
   617  	MOVL	$SYS_exit, AX
   618  	SYSCALL
   619  	JMP	-3(PC)	// keep exiting
   620  
   621  TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
   622  	MOVQ	new+0(FP), DI
   623  	MOVQ	old+8(FP), SI
   624  	MOVQ	$SYS_sigaltstack, AX
   625  	SYSCALL
   626  	CMPQ	AX, $0xfffffffffffff001
   627  	JLS	2(PC)
   628  	MOVL	$0xf1, 0xf1  // crash
   629  	RET
   630  
   631  // set tls base to DI
   632  TEXT runtime·settls(SB),NOSPLIT,$32
   633  #ifdef GOOS_android
   634  	// Android stores the TLS offset in runtime·tls_g.
   635  	SUBQ	runtime·tls_g(SB), DI
   636  #else
   637  	ADDQ	$8, DI	// ELF wants to use -8(FS)
   638  #endif
   639  	MOVQ	DI, SI
   640  	MOVQ	$0x1002, DI	// ARCH_SET_FS
   641  	MOVQ	$SYS_arch_prctl, AX
   642  	SYSCALL
   643  	CMPQ	AX, $0xfffffffffffff001
   644  	JLS	2(PC)
   645  	MOVL	$0xf1, 0xf1  // crash
   646  	RET
   647  
   648  TEXT runtime·osyield(SB),NOSPLIT,$0
   649  	MOVL	$SYS_sched_yield, AX
   650  	SYSCALL
   651  	RET
   652  
   653  TEXT runtime·sched_getaffinity(SB),NOSPLIT,$0
   654  	MOVQ	pid+0(FP), DI
   655  	MOVQ	len+8(FP), SI
   656  	MOVQ	buf+16(FP), DX
   657  	MOVL	$SYS_sched_getaffinity, AX
   658  	SYSCALL
   659  	MOVL	AX, ret+24(FP)
   660  	RET
   661  
   662  // int32 runtime·epollcreate(int32 size);
   663  TEXT runtime·epollcreate(SB),NOSPLIT,$0
   664  	MOVL    size+0(FP), DI
   665  	MOVL    $SYS_epoll_create, AX
   666  	SYSCALL
   667  	MOVL	AX, ret+8(FP)
   668  	RET
   669  
   670  // int32 runtime·epollcreate1(int32 flags);
   671  TEXT runtime·epollcreate1(SB),NOSPLIT,$0
   672  	MOVL	flags+0(FP), DI
   673  	MOVL	$SYS_epoll_create1, AX
   674  	SYSCALL
   675  	MOVL	AX, ret+8(FP)
   676  	RET
   677  
   678  // func epollctl(epfd, op, fd int32, ev *epollEvent) int
   679  TEXT runtime·epollctl(SB),NOSPLIT,$0
   680  	MOVL	epfd+0(FP), DI
   681  	MOVL	op+4(FP), SI
   682  	MOVL	fd+8(FP), DX
   683  	MOVQ	ev+16(FP), R10
   684  	MOVL	$SYS_epoll_ctl, AX
   685  	SYSCALL
   686  	MOVL	AX, ret+24(FP)
   687  	RET
   688  
   689  // int32 runtime·epollwait(int32 epfd, EpollEvent *ev, int32 nev, int32 timeout);
   690  TEXT runtime·epollwait(SB),NOSPLIT,$0
   691  	// This uses pwait instead of wait, because Android O blocks wait.
   692  	MOVL	epfd+0(FP), DI
   693  	MOVQ	ev+8(FP), SI
   694  	MOVL	nev+16(FP), DX
   695  	MOVL	timeout+20(FP), R10
   696  	MOVQ	$0, R8
   697  	MOVL	$SYS_epoll_pwait, AX
   698  	SYSCALL
   699  	MOVL	AX, ret+24(FP)
   700  	RET
   701  
   702  // void runtime·closeonexec(int32 fd);
   703  TEXT runtime·closeonexec(SB),NOSPLIT,$0
   704  	MOVL    fd+0(FP), DI  // fd
   705  	MOVQ    $2, SI  // F_SETFD
   706  	MOVQ    $1, DX  // FD_CLOEXEC
   707  	MOVL	$SYS_fcntl, AX
   708  	SYSCALL
   709  	RET
   710  
   711  // func runtime·setNonblock(int32 fd)
   712  TEXT runtime·setNonblock(SB),NOSPLIT,$0-4
   713  	MOVL    fd+0(FP), DI  // fd
   714  	MOVQ    $3, SI  // F_GETFL
   715  	MOVQ    $0, DX
   716  	MOVL	$SYS_fcntl, AX
   717  	SYSCALL
   718  	MOVL	fd+0(FP), DI // fd
   719  	MOVQ	$4, SI // F_SETFL
   720  	MOVQ	$0x800, DX // O_NONBLOCK
   721  	ORL	AX, DX
   722  	MOVL	$SYS_fcntl, AX
   723  	SYSCALL
   724  	RET
   725  
   726  // int access(const char *name, int mode)
   727  TEXT runtime·access(SB),NOSPLIT,$0
   728  	// This uses faccessat instead of access, because Android O blocks access.
   729  	MOVL	$AT_FDCWD, DI // AT_FDCWD, so this acts like access
   730  	MOVQ	name+0(FP), SI
   731  	MOVL	mode+8(FP), DX
   732  	MOVL	$0, R10
   733  	MOVL	$SYS_faccessat, AX
   734  	SYSCALL
   735  	MOVL	AX, ret+16(FP)
   736  	RET
   737  
   738  // int connect(int fd, const struct sockaddr *addr, socklen_t addrlen)
   739  TEXT runtime·connect(SB),NOSPLIT,$0-28
   740  	MOVL	fd+0(FP), DI
   741  	MOVQ	addr+8(FP), SI
   742  	MOVL	len+16(FP), DX
   743  	MOVL	$SYS_connect, AX
   744  	SYSCALL
   745  	MOVL	AX, ret+24(FP)
   746  	RET
   747  
   748  // int socket(int domain, int type, int protocol)
   749  TEXT runtime·socket(SB),NOSPLIT,$0-20
   750  	MOVL	domain+0(FP), DI
   751  	MOVL	typ+4(FP), SI
   752  	MOVL	prot+8(FP), DX
   753  	MOVL	$SYS_socket, AX
   754  	SYSCALL
   755  	MOVL	AX, ret+16(FP)
   756  	RET
   757  
   758  // func sbrk0() uintptr
   759  TEXT runtime·sbrk0(SB),NOSPLIT,$0-8
   760  	// Implemented as brk(NULL).
   761  	MOVQ	$0, DI
   762  	MOVL	$SYS_brk, AX
   763  	SYSCALL
   764  	MOVQ	AX, ret+0(FP)
   765  	RET