Source file src/runtime/os_freebsd.go

Documentation: runtime

     1  // Copyright 2011 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  package runtime
     6  
     7  import (
     8  	"internal/abi"
     9  	"internal/goarch"
    10  	"unsafe"
    11  )
    12  
    13  type mOS struct{}
    14  
    15  //go:noescape
    16  func thr_new(param *thrparam, size int32) int32
    17  
    18  //go:noescape
    19  func sigaltstack(new, old *stackt)
    20  
    21  //go:noescape
    22  func sigprocmask(how int32, new, old *sigset)
    23  
    24  //go:noescape
    25  func setitimer(mode int32, new, old *itimerval)
    26  
    27  //go:noescape
    28  func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32
    29  
    30  func raiseproc(sig uint32)
    31  
    32  func thr_self() thread
    33  func thr_kill(tid thread, sig int)
    34  
    35  //go:noescape
    36  func sys_umtx_op(addr *uint32, mode int32, val uint32, uaddr1 uintptr, ut *umtx_time) int32
    37  
    38  func osyield()
    39  
    40  //go:nosplit
    41  func osyield_no_g() {
    42  	osyield()
    43  }
    44  
    45  func kqueue() int32
    46  
    47  //go:noescape
    48  func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32
    49  
    50  func pipe2(flags int32) (r, w int32, errno int32)
    51  func fcntl(fd, cmd, arg int32) (ret int32, errno int32)
    52  
    53  func issetugid() int32
    54  
    55  // From FreeBSD's <sys/sysctl.h>
    56  const (
    57  	_CTL_HW      = 6
    58  	_HW_PAGESIZE = 7
    59  )
    60  
    61  var sigset_all = sigset{[4]uint32{^uint32(0), ^uint32(0), ^uint32(0), ^uint32(0)}}
    62  
    63  // Undocumented numbers from FreeBSD's lib/libc/gen/sysctlnametomib.c.
    64  const (
    65  	_CTL_QUERY     = 0
    66  	_CTL_QUERY_MIB = 3
    67  )
    68  
    69  // sysctlnametomib fill mib with dynamically assigned sysctl entries of name,
    70  // return count of effected mib slots, return 0 on error.
    71  func sysctlnametomib(name []byte, mib *[_CTL_MAXNAME]uint32) uint32 {
    72  	oid := [2]uint32{_CTL_QUERY, _CTL_QUERY_MIB}
    73  	miblen := uintptr(_CTL_MAXNAME)
    74  	if sysctl(&oid[0], 2, (*byte)(unsafe.Pointer(mib)), &miblen, (*byte)(unsafe.Pointer(&name[0])), (uintptr)(len(name))) < 0 {
    75  		return 0
    76  	}
    77  	miblen /= unsafe.Sizeof(uint32(0))
    78  	if miblen <= 0 {
    79  		return 0
    80  	}
    81  	return uint32(miblen)
    82  }
    83  
    84  const (
    85  	_CPU_CURRENT_PID = -1 // Current process ID.
    86  )
    87  
    88  //go:noescape
    89  func cpuset_getaffinity(level int, which int, id int64, size int, mask *byte) int32
    90  
    91  //go:systemstack
    92  func getncpu() int32 {
    93  	// Use a large buffer for the CPU mask. We're on the system
    94  	// stack, so this is fine, and we can't allocate memory for a
    95  	// dynamically-sized buffer at this point.
    96  	const maxCPUs = 64 * 1024
    97  	var mask [maxCPUs / 8]byte
    98  	var mib [_CTL_MAXNAME]uint32
    99  
   100  	// According to FreeBSD's /usr/src/sys/kern/kern_cpuset.c,
   101  	// cpuset_getaffinity return ERANGE when provided buffer size exceed the limits in kernel.
   102  	// Querying kern.smp.maxcpus to calculate maximum buffer size.
   103  	// See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=200802
   104  
   105  	// Variable kern.smp.maxcpus introduced at Dec 23 2003, revision 123766,
   106  	// with dynamically assigned sysctl entries.
   107  	miblen := sysctlnametomib([]byte("kern.smp.maxcpus"), &mib)
   108  	if miblen == 0 {
   109  		return 1
   110  	}
   111  
   112  	// Query kern.smp.maxcpus.
   113  	dstsize := uintptr(4)
   114  	maxcpus := uint32(0)
   115  	if sysctl(&mib[0], miblen, (*byte)(unsafe.Pointer(&maxcpus)), &dstsize, nil, 0) != 0 {
   116  		return 1
   117  	}
   118  
   119  	maskSize := int(maxcpus+7) / 8
   120  	if maskSize < goarch.PtrSize {
   121  		maskSize = goarch.PtrSize
   122  	}
   123  	if maskSize > len(mask) {
   124  		maskSize = len(mask)
   125  	}
   126  
   127  	if cpuset_getaffinity(_CPU_LEVEL_WHICH, _CPU_WHICH_PID, _CPU_CURRENT_PID,
   128  		maskSize, (*byte)(unsafe.Pointer(&mask[0]))) != 0 {
   129  		return 1
   130  	}
   131  	n := int32(0)
   132  	for _, v := range mask[:maskSize] {
   133  		for v != 0 {
   134  			n += int32(v & 1)
   135  			v >>= 1
   136  		}
   137  	}
   138  	if n == 0 {
   139  		return 1
   140  	}
   141  	return n
   142  }
   143  
   144  func getPageSize() uintptr {
   145  	mib := [2]uint32{_CTL_HW, _HW_PAGESIZE}
   146  	out := uint32(0)
   147  	nout := unsafe.Sizeof(out)
   148  	ret := sysctl(&mib[0], 2, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0)
   149  	if ret >= 0 {
   150  		return uintptr(out)
   151  	}
   152  	return 0
   153  }
   154  
   155  // FreeBSD's umtx_op syscall is effectively the same as Linux's futex, and
   156  // thus the code is largely similar. See Linux implementation
   157  // and lock_futex.go for comments.
   158  
   159  //go:nosplit
   160  func futexsleep(addr *uint32, val uint32, ns int64) {
   161  	systemstack(func() {
   162  		futexsleep1(addr, val, ns)
   163  	})
   164  }
   165  
   166  func futexsleep1(addr *uint32, val uint32, ns int64) {
   167  	var utp *umtx_time
   168  	if ns >= 0 {
   169  		var ut umtx_time
   170  		ut._clockid = _CLOCK_MONOTONIC
   171  		ut._timeout.setNsec(ns)
   172  		utp = &ut
   173  	}
   174  	ret := sys_umtx_op(addr, _UMTX_OP_WAIT_UINT_PRIVATE, val, unsafe.Sizeof(*utp), utp)
   175  	if ret >= 0 || ret == -_EINTR || ret == -_ETIMEDOUT {
   176  		return
   177  	}
   178  	print("umtx_wait addr=", addr, " val=", val, " ret=", ret, "\n")
   179  	*(*int32)(unsafe.Pointer(uintptr(0x1005))) = 0x1005
   180  }
   181  
   182  //go:nosplit
   183  func futexwakeup(addr *uint32, cnt uint32) {
   184  	ret := sys_umtx_op(addr, _UMTX_OP_WAKE_PRIVATE, cnt, 0, nil)
   185  	if ret >= 0 {
   186  		return
   187  	}
   188  
   189  	systemstack(func() {
   190  		print("umtx_wake_addr=", addr, " ret=", ret, "\n")
   191  	})
   192  }
   193  
   194  func thr_start()
   195  
   196  // May run with m.p==nil, so write barriers are not allowed.
   197  //
   198  //go:nowritebarrier
   199  func newosproc(mp *m) {
   200  	stk := unsafe.Pointer(mp.g0.stack.hi)
   201  	if false {
   202  		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", abi.FuncPCABI0(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
   203  	}
   204  
   205  	param := thrparam{
   206  		start_func: abi.FuncPCABI0(thr_start),
   207  		arg:        unsafe.Pointer(mp),
   208  		stack_base: mp.g0.stack.lo,
   209  		stack_size: uintptr(stk) - mp.g0.stack.lo,
   210  		child_tid:  nil, // minit will record tid
   211  		parent_tid: nil,
   212  		tls_base:   unsafe.Pointer(&mp.tls[0]),
   213  		tls_size:   unsafe.Sizeof(mp.tls),
   214  	}
   215  
   216  	var oset sigset
   217  	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
   218  	ret := retryOnEAGAIN(func() int32 {
   219  		errno := thr_new(&param, int32(unsafe.Sizeof(param)))
   220  		// thr_new returns negative errno
   221  		return -errno
   222  	})
   223  	sigprocmask(_SIG_SETMASK, &oset, nil)
   224  	if ret != 0 {
   225  		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", ret, ")\n")
   226  		throw("newosproc")
   227  	}
   228  }
   229  
   230  // Version of newosproc that doesn't require a valid G.
   231  //
   232  //go:nosplit
   233  func newosproc0(stacksize uintptr, fn unsafe.Pointer) {
   234  	stack := sysAlloc(stacksize, &memstats.stacks_sys)
   235  	if stack == nil {
   236  		writeErrStr(failallocatestack)
   237  		exit(1)
   238  	}
   239  	// This code "knows" it's being called once from the library
   240  	// initialization code, and so it's using the static m0 for the
   241  	// tls and procid (thread) pointers. thr_new() requires the tls
   242  	// pointers, though the tid pointers can be nil.
   243  	// However, newosproc0 is currently unreachable because builds
   244  	// utilizing c-shared/c-archive force external linking.
   245  	param := thrparam{
   246  		start_func: uintptr(fn),
   247  		arg:        nil,
   248  		stack_base: uintptr(stack), //+stacksize?
   249  		stack_size: stacksize,
   250  		child_tid:  nil, // minit will record tid
   251  		parent_tid: nil,
   252  		tls_base:   unsafe.Pointer(&m0.tls[0]),
   253  		tls_size:   unsafe.Sizeof(m0.tls),
   254  	}
   255  
   256  	var oset sigset
   257  	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
   258  	ret := thr_new(&param, int32(unsafe.Sizeof(param)))
   259  	sigprocmask(_SIG_SETMASK, &oset, nil)
   260  	if ret < 0 {
   261  		writeErrStr(failthreadcreate)
   262  		exit(1)
   263  	}
   264  }
   265  
   266  // Called to do synchronous initialization of Go code built with
   267  // -buildmode=c-archive or -buildmode=c-shared.
   268  // None of the Go runtime is initialized.
   269  //
   270  //go:nosplit
   271  //go:nowritebarrierrec
   272  func libpreinit() {
   273  	initsig(true)
   274  }
   275  
   276  func osinit() {
   277  	ncpu = getncpu()
   278  	if physPageSize == 0 {
   279  		physPageSize = getPageSize()
   280  	}
   281  }
   282  
   283  var urandom_dev = []byte("/dev/urandom\x00")
   284  
   285  //go:nosplit
   286  func readRandom(r []byte) int {
   287  	fd := open(&urandom_dev[0], 0 /* O_RDONLY */, 0)
   288  	n := read(fd, unsafe.Pointer(&r[0]), int32(len(r)))
   289  	closefd(fd)
   290  	return int(n)
   291  }
   292  
   293  func goenvs() {
   294  	goenvs_unix()
   295  }
   296  
   297  // Called to initialize a new m (including the bootstrap m).
   298  // Called on the parent thread (main thread in case of bootstrap), can allocate memory.
   299  func mpreinit(mp *m) {
   300  	mp.gsignal = malg(32 * 1024)
   301  	mp.gsignal.m = mp
   302  }
   303  
   304  // Called to initialize a new m (including the bootstrap m).
   305  // Called on the new thread, cannot allocate memory.
   306  func minit() {
   307  	getg().m.procid = uint64(thr_self())
   308  
   309  	// On FreeBSD before about April 2017 there was a bug such
   310  	// that calling execve from a thread other than the main
   311  	// thread did not reset the signal stack. That would confuse
   312  	// minitSignals, which calls minitSignalStack, which checks
   313  	// whether there is currently a signal stack and uses it if
   314  	// present. To avoid this confusion, explicitly disable the
   315  	// signal stack on the main thread when not running in a
   316  	// library. This can be removed when we are confident that all
   317  	// FreeBSD users are running a patched kernel. See issue #15658.
   318  	if gp := getg(); !isarchive && !islibrary && gp.m == &m0 && gp == gp.m.g0 {
   319  		st := stackt{ss_flags: _SS_DISABLE}
   320  		sigaltstack(&st, nil)
   321  	}
   322  
   323  	minitSignals()
   324  }
   325  
   326  // Called from dropm to undo the effect of an minit.
   327  //
   328  //go:nosplit
   329  func unminit() {
   330  	unminitSignals()
   331  	getg().m.procid = 0
   332  }
   333  
   334  // Called from exitm, but not from drop, to undo the effect of thread-owned
   335  // resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
   336  func mdestroy(mp *m) {
   337  }
   338  
   339  func sigtramp()
   340  
   341  type sigactiont struct {
   342  	sa_handler uintptr
   343  	sa_flags   int32
   344  	sa_mask    sigset
   345  }
   346  
   347  // See os_freebsd2.go, os_freebsd_amd64.go for setsig function
   348  
   349  //go:nosplit
   350  //go:nowritebarrierrec
   351  func setsigstack(i uint32) {
   352  	var sa sigactiont
   353  	sigaction(i, nil, &sa)
   354  	if sa.sa_flags&_SA_ONSTACK != 0 {
   355  		return
   356  	}
   357  	sa.sa_flags |= _SA_ONSTACK
   358  	sigaction(i, &sa, nil)
   359  }
   360  
   361  //go:nosplit
   362  //go:nowritebarrierrec
   363  func getsig(i uint32) uintptr {
   364  	var sa sigactiont
   365  	sigaction(i, nil, &sa)
   366  	return sa.sa_handler
   367  }
   368  
   369  // setSignalstackSP sets the ss_sp field of a stackt.
   370  //
   371  //go:nosplit
   372  func setSignalstackSP(s *stackt, sp uintptr) {
   373  	s.ss_sp = sp
   374  }
   375  
   376  //go:nosplit
   377  //go:nowritebarrierrec
   378  func sigaddset(mask *sigset, i int) {
   379  	mask.__bits[(i-1)/32] |= 1 << ((uint32(i) - 1) & 31)
   380  }
   381  
   382  func sigdelset(mask *sigset, i int) {
   383  	mask.__bits[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
   384  }
   385  
   386  //go:nosplit
   387  func (c *sigctxt) fixsigcode(sig uint32) {
   388  }
   389  
   390  func setProcessCPUProfiler(hz int32) {
   391  	setProcessCPUProfilerTimer(hz)
   392  }
   393  
   394  func setThreadCPUProfiler(hz int32) {
   395  	setThreadCPUProfilerHz(hz)
   396  }
   397  
   398  //go:nosplit
   399  func validSIGPROF(mp *m, c *sigctxt) bool {
   400  	return true
   401  }
   402  
   403  func sysargs(argc int32, argv **byte) {
   404  	n := argc + 1
   405  
   406  	// skip over argv, envp to get to auxv
   407  	for argv_index(argv, n) != nil {
   408  		n++
   409  	}
   410  
   411  	// skip NULL separator
   412  	n++
   413  
   414  	// now argv+n is auxv
   415  	auxvp := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*goarch.PtrSize))
   416  	pairs := sysauxv(auxvp[:])
   417  	auxv = auxvp[: pairs*2 : pairs*2]
   418  }
   419  
   420  const (
   421  	_AT_NULL     = 0  // Terminates the vector
   422  	_AT_PAGESZ   = 6  // Page size in bytes
   423  	_AT_PLATFORM = 15 // string identifying platform
   424  	_AT_TIMEKEEP = 22 // Pointer to timehands.
   425  	_AT_HWCAP    = 25 // CPU feature flags
   426  	_AT_HWCAP2   = 26 // CPU feature flags 2
   427  )
   428  
   429  func sysauxv(auxv []uintptr) (pairs int) {
   430  	var i int
   431  	for i = 0; auxv[i] != _AT_NULL; i += 2 {
   432  		tag, val := auxv[i], auxv[i+1]
   433  		switch tag {
   434  		// _AT_NCPUS from auxv shouldn't be used due to golang.org/issue/15206
   435  		case _AT_PAGESZ:
   436  			physPageSize = val
   437  		case _AT_TIMEKEEP:
   438  			timekeepSharedPage = (*vdsoTimekeep)(unsafe.Pointer(val))
   439  		}
   440  
   441  		archauxv(tag, val)
   442  	}
   443  	return i / 2
   444  }
   445  
   446  // sysSigaction calls the sigaction system call.
   447  //
   448  //go:nosplit
   449  func sysSigaction(sig uint32, new, old *sigactiont) {
   450  	// Use system stack to avoid split stack overflow on amd64
   451  	if asmSigaction(uintptr(sig), new, old) != 0 {
   452  		systemstack(func() {
   453  			throw("sigaction failed")
   454  		})
   455  	}
   456  }
   457  
   458  // asmSigaction is implemented in assembly.
   459  //
   460  //go:noescape
   461  func asmSigaction(sig uintptr, new, old *sigactiont) int32
   462  
   463  // raise sends a signal to the calling thread.
   464  //
   465  // It must be nosplit because it is used by the signal handler before
   466  // it definitely has a Go stack.
   467  //
   468  //go:nosplit
   469  func raise(sig uint32) {
   470  	thr_kill(thr_self(), int(sig))
   471  }
   472  
   473  func signalM(mp *m, sig int) {
   474  	thr_kill(thread(mp.procid), sig)
   475  }
   476  
   477  // sigPerThreadSyscall is only used on linux, so we assign a bogus signal
   478  // number.
   479  const sigPerThreadSyscall = 1 << 31
   480  
   481  //go:nosplit
   482  func runPerThreadSyscall() {
   483  	throw("runPerThreadSyscall only valid on linux")
   484  }
   485  

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