os_plan9.go

Documentation: runtime

     1  // Copyright 2010 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/runtime/atomic"
    10  	"internal/stringslite"
    11  	"unsafe"
    12  )
    13  
    14  type mOS struct {
    15  	waitsemacount uint32
    16  	notesig       *int8
    17  	errstr        *byte
    18  	ignoreHangup  bool
    19  }
    20  
    21  func closefd(fd int32) int32
    22  
    23  //go:noescape
    24  func open(name *byte, mode, perm int32) int32
    25  
    26  //go:noescape
    27  func pread(fd int32, buf unsafe.Pointer, nbytes int32, offset int64) int32
    28  
    29  //go:noescape
    30  func pwrite(fd int32, buf unsafe.Pointer, nbytes int32, offset int64) int32
    31  
    32  func seek(fd int32, offset int64, whence int32) int64
    33  
    34  //go:noescape
    35  func exits(msg *byte)
    36  
    37  //go:noescape
    38  func brk_(addr unsafe.Pointer) int32
    39  
    40  func sleep(ms int32) int32
    41  
    42  func rfork(flags int32) int32
    43  
    44  //go:noescape
    45  func plan9_semacquire(addr *uint32, block int32) int32
    46  
    47  //go:noescape
    48  func plan9_tsemacquire(addr *uint32, ms int32) int32
    49  
    50  //go:noescape
    51  func plan9_semrelease(addr *uint32, count int32) int32
    52  
    53  //go:noescape
    54  func notify(fn unsafe.Pointer) int32
    55  
    56  func noted(mode int32) int32
    57  
    58  //go:noescape
    59  func nsec(*int64) int64
    60  
    61  //go:noescape
    62  func sigtramp(ureg, note unsafe.Pointer)
    63  
    64  func setfpmasks()
    65  
    66  //go:noescape
    67  func tstart_plan9(newm *m)
    68  
    69  func errstr() string
    70  
    71  type _Plink uintptr
    72  
    73  func sigpanic() {
    74  	gp := getg()
    75  	if !canpanic() {
    76  		throw("unexpected signal during runtime execution")
    77  	}
    78  
    79  	note := gostringnocopy((*byte)(unsafe.Pointer(gp.m.notesig)))
    80  	switch gp.sig {
    81  	case _SIGRFAULT, _SIGWFAULT:
    82  		i := indexNoFloat(note, "addr=")
    83  		if i >= 0 {
    84  			i += 5
    85  		} else if i = indexNoFloat(note, "va="); i >= 0 {
    86  			i += 3
    87  		} else {
    88  			panicmem()
    89  		}
    90  		addr := note[i:]
    91  		gp.sigcode1 = uintptr(atolwhex(addr))
    92  		if gp.sigcode1 < 0x1000 {
    93  			panicmem()
    94  		}
    95  		if gp.paniconfault {
    96  			panicmemAddr(gp.sigcode1)
    97  		}
    98  		if inUserArenaChunk(gp.sigcode1) {
    99  			// We could check that the arena chunk is explicitly set to fault,
   100  			// but the fact that we faulted on accessing it is enough to prove
   101  			// that it is.
   102  			print("accessed data from freed user arena ", hex(gp.sigcode1), "\n")
   103  		} else {
   104  			print("unexpected fault address ", hex(gp.sigcode1), "\n")
   105  		}
   106  		throw("fault")
   107  	case _SIGTRAP:
   108  		if gp.paniconfault {
   109  			panicmem()
   110  		}
   111  		throw(note)
   112  	case _SIGINTDIV:
   113  		panicdivide()
   114  	case _SIGFLOAT:
   115  		panicfloat()
   116  	default:
   117  		panic(errorString(note))
   118  	}
   119  }
   120  
   121  // indexNoFloat is bytealg.IndexString but safe to use in a note
   122  // handler.
   123  func indexNoFloat(s, t string) int {
   124  	if len(t) == 0 {
   125  		return 0
   126  	}
   127  	for i := 0; i < len(s); i++ {
   128  		if s[i] == t[0] && stringslite.HasPrefix(s[i:], t) {
   129  			return i
   130  		}
   131  	}
   132  	return -1
   133  }
   134  
   135  func atolwhex(p string) int64 {
   136  	for stringslite.HasPrefix(p, " ") || stringslite.HasPrefix(p, "\t") {
   137  		p = p[1:]
   138  	}
   139  	neg := false
   140  	if stringslite.HasPrefix(p, "-") || stringslite.HasPrefix(p, "+") {
   141  		neg = p[0] == '-'
   142  		p = p[1:]
   143  		for stringslite.HasPrefix(p, " ") || stringslite.HasPrefix(p, "\t") {
   144  			p = p[1:]
   145  		}
   146  	}
   147  	var n int64
   148  	switch {
   149  	case stringslite.HasPrefix(p, "0x"), stringslite.HasPrefix(p, "0X"):
   150  		p = p[2:]
   151  		for ; len(p) > 0; p = p[1:] {
   152  			if '0' <= p[0] && p[0] <= '9' {
   153  				n = n*16 + int64(p[0]-'0')
   154  			} else if 'a' <= p[0] && p[0] <= 'f' {
   155  				n = n*16 + int64(p[0]-'a'+10)
   156  			} else if 'A' <= p[0] && p[0] <= 'F' {
   157  				n = n*16 + int64(p[0]-'A'+10)
   158  			} else {
   159  				break
   160  			}
   161  		}
   162  	case stringslite.HasPrefix(p, "0"):
   163  		for ; len(p) > 0 && '0' <= p[0] && p[0] <= '7'; p = p[1:] {
   164  			n = n*8 + int64(p[0]-'0')
   165  		}
   166  	default:
   167  		for ; len(p) > 0 && '0' <= p[0] && p[0] <= '9'; p = p[1:] {
   168  			n = n*10 + int64(p[0]-'0')
   169  		}
   170  	}
   171  	if neg {
   172  		n = -n
   173  	}
   174  	return n
   175  }
   176  
   177  type sigset struct{}
   178  
   179  // Called to initialize a new m (including the bootstrap m).
   180  // Called on the parent thread (main thread in case of bootstrap), can allocate memory.
   181  func mpreinit(mp *m) {
   182  	// Initialize stack and goroutine for note handling.
   183  	mp.gsignal = malg(32 * 1024)
   184  	mp.gsignal.m = mp
   185  	mp.notesig = (*int8)(mallocgc(_ERRMAX, nil, true))
   186  	// Initialize stack for handling strings from the
   187  	// errstr system call, as used in package syscall.
   188  	mp.errstr = (*byte)(mallocgc(_ERRMAX, nil, true))
   189  }
   190  
   191  func sigsave(p *sigset) {
   192  }
   193  
   194  func msigrestore(sigmask sigset) {
   195  }
   196  
   197  //go:nosplit
   198  //go:nowritebarrierrec
   199  func clearSignalHandlers() {
   200  }
   201  
   202  func sigblock(exiting bool) {
   203  }
   204  
   205  // Called to initialize a new m (including the bootstrap m).
   206  // Called on the new thread, cannot allocate memory.
   207  func minit() {
   208  	if atomic.Load(&exiting) != 0 {
   209  		exits(&emptystatus[0])
   210  	}
   211  	// Mask all SSE floating-point exceptions
   212  	// when running on the 64-bit kernel.
   213  	setfpmasks()
   214  }
   215  
   216  // Called from dropm to undo the effect of an minit.
   217  func unminit() {
   218  }
   219  
   220  // Called from exitm, but not from drop, to undo the effect of thread-owned
   221  // resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
   222  func mdestroy(mp *m) {
   223  }
   224  
   225  var sysstat = []byte("/dev/sysstat\x00")
   226  
   227  func getproccount() int32 {
   228  	var buf [2048]byte
   229  	fd := open(&sysstat[0], _OREAD, 0)
   230  	if fd < 0 {
   231  		return 1
   232  	}
   233  	ncpu := int32(0)
   234  	for {
   235  		n := read(fd, unsafe.Pointer(&buf), int32(len(buf)))
   236  		if n <= 0 {
   237  			break
   238  		}
   239  		for i := int32(0); i < n; i++ {
   240  			if buf[i] == '\n' {
   241  				ncpu++
   242  			}
   243  		}
   244  	}
   245  	closefd(fd)
   246  	if ncpu == 0 {
   247  		ncpu = 1
   248  	}
   249  	return ncpu
   250  }
   251  
   252  var devswap = []byte("/dev/swap\x00")
   253  var pagesize = []byte(" pagesize\n")
   254  
   255  func getPageSize() uintptr {
   256  	var buf [2048]byte
   257  	var pos int
   258  	fd := open(&devswap[0], _OREAD, 0)
   259  	if fd < 0 {
   260  		// There's not much we can do if /dev/swap doesn't
   261  		// exist. However, nothing in the memory manager uses
   262  		// this on Plan 9, so it also doesn't really matter.
   263  		return minPhysPageSize
   264  	}
   265  	for pos < len(buf) {
   266  		n := read(fd, unsafe.Pointer(&buf[pos]), int32(len(buf)-pos))
   267  		if n <= 0 {
   268  			break
   269  		}
   270  		pos += int(n)
   271  	}
   272  	closefd(fd)
   273  	text := buf[:pos]
   274  	// Find "<n> pagesize" line.
   275  	bol := 0
   276  	for i, c := range text {
   277  		if c == '\n' {
   278  			bol = i + 1
   279  		}
   280  		if bytesHasPrefix(text[i:], pagesize) {
   281  			// Parse number at the beginning of this line.
   282  			return uintptr(_atoi(text[bol:]))
   283  		}
   284  	}
   285  	// Again, the page size doesn't really matter, so use a fallback.
   286  	return minPhysPageSize
   287  }
   288  
   289  func bytesHasPrefix(s, prefix []byte) bool {
   290  	if len(s) < len(prefix) {
   291  		return false
   292  	}
   293  	for i, p := range prefix {
   294  		if s[i] != p {
   295  			return false
   296  		}
   297  	}
   298  	return true
   299  }
   300  
   301  var pid = []byte("#c/pid\x00")
   302  
   303  func getpid() uint64 {
   304  	var b [20]byte
   305  	fd := open(&pid[0], 0, 0)
   306  	if fd >= 0 {
   307  		read(fd, unsafe.Pointer(&b), int32(len(b)))
   308  		closefd(fd)
   309  	}
   310  	c := b[:]
   311  	for c[0] == ' ' || c[0] == '\t' {
   312  		c = c[1:]
   313  	}
   314  	return uint64(_atoi(c))
   315  }
   316  
   317  func osinit() {
   318  	physPageSize = getPageSize()
   319  	initBloc()
   320  	ncpu = getproccount()
   321  	getg().m.procid = getpid()
   322  }
   323  
   324  //go:nosplit
   325  func crash() {
   326  	notify(nil)
   327  	*(*int)(nil) = 0
   328  }
   329  
   330  //go:nosplit
   331  func readRandom(r []byte) int {
   332  	return 0
   333  }
   334  
   335  func initsig(preinit bool) {
   336  	if !preinit {
   337  		notify(unsafe.Pointer(abi.FuncPCABI0(sigtramp)))
   338  	}
   339  }
   340  
   341  //go:nosplit
   342  func osyield() {
   343  	sleep(0)
   344  }
   345  
   346  //go:nosplit
   347  func osyield_no_g() {
   348  	osyield()
   349  }
   350  
   351  //go:nosplit
   352  func usleep(µs uint32) {
   353  	ms := int32(µs / 1000)
   354  	if ms == 0 {
   355  		ms = 1
   356  	}
   357  	sleep(ms)
   358  }
   359  
   360  //go:nosplit
   361  func usleep_no_g(usec uint32) {
   362  	usleep(usec)
   363  }
   364  
   365  //go:nosplit
   366  func nanotime1() int64 {
   367  	var scratch int64
   368  	ns := nsec(&scratch)
   369  	// TODO(aram): remove hack after I fix _nsec in the pc64 kernel.
   370  	if ns == 0 {
   371  		return scratch
   372  	}
   373  	return ns
   374  }
   375  
   376  var goexits = []byte("go: exit ")
   377  var emptystatus = []byte("\x00")
   378  var exiting uint32
   379  
   380  func goexitsall(status *byte) {
   381  	var buf [_ERRMAX]byte
   382  	if !atomic.Cas(&exiting, 0, 1) {
   383  		return
   384  	}
   385  	getg().m.locks++
   386  	n := copy(buf[:], goexits)
   387  	n = copy(buf[n:], gostringnocopy(status))
   388  	pid := getpid()
   389  	for mp := (*m)(atomic.Loadp(unsafe.Pointer(&allm))); mp != nil; mp = mp.alllink {
   390  		if mp.procid != 0 && mp.procid != pid {
   391  			postnote(mp.procid, buf[:])
   392  		}
   393  	}
   394  	getg().m.locks--
   395  }
   396  
   397  var procdir = []byte("/proc/")
   398  var notefile = []byte("/note\x00")
   399  
   400  func postnote(pid uint64, msg []byte) int {
   401  	var buf [128]byte
   402  	var tmp [32]byte
   403  	n := copy(buf[:], procdir)
   404  	n += copy(buf[n:], itoa(tmp[:], pid))
   405  	copy(buf[n:], notefile)
   406  	fd := open(&buf[0], _OWRITE, 0)
   407  	if fd < 0 {
   408  		return -1
   409  	}
   410  	len := findnull(&msg[0])
   411  	if write1(uintptr(fd), unsafe.Pointer(&msg[0]), int32(len)) != int32(len) {
   412  		closefd(fd)
   413  		return -1
   414  	}
   415  	closefd(fd)
   416  	return 0
   417  }
   418  
   419  //go:nosplit
   420  func exit(e int32) {
   421  	var status []byte
   422  	if e == 0 {
   423  		status = emptystatus
   424  	} else {
   425  		// build error string
   426  		var tmp [32]byte
   427  		sl := itoa(tmp[:len(tmp)-1], uint64(e))
   428  		// Don't append, rely on the existing data being zero.
   429  		status = sl[:len(sl)+1]
   430  	}
   431  	goexitsall(&status[0])
   432  	exits(&status[0])
   433  }
   434  
   435  // May run with m.p==nil, so write barriers are not allowed.
   436  //
   437  //go:nowritebarrier
   438  func newosproc(mp *m) {
   439  	if false {
   440  		print("newosproc mp=", mp, " ostk=", &mp, "\n")
   441  	}
   442  	pid := rfork(_RFPROC | _RFMEM | _RFNOWAIT)
   443  	if pid < 0 {
   444  		throw("newosproc: rfork failed")
   445  	}
   446  	if pid == 0 {
   447  		tstart_plan9(mp)
   448  	}
   449  }
   450  
   451  func exitThread(wait *atomic.Uint32) {
   452  	// We should never reach exitThread on Plan 9 because we let
   453  	// the OS clean up threads.
   454  	throw("exitThread")
   455  }
   456  
   457  //go:nosplit
   458  func semacreate(mp *m) {
   459  }
   460  
   461  //go:nosplit
   462  func semasleep(ns int64) int {
   463  	gp := getg()
   464  	if ns >= 0 {
   465  		ms := timediv(ns, 1000000, nil)
   466  		if ms == 0 {
   467  			ms = 1
   468  		}
   469  		ret := plan9_tsemacquire(&gp.m.waitsemacount, ms)
   470  		if ret == 1 {
   471  			return 0 // success
   472  		}
   473  		return -1 // timeout or interrupted
   474  	}
   475  	for plan9_semacquire(&gp.m.waitsemacount, 1) < 0 {
   476  		// interrupted; try again (c.f. lock_sema.go)
   477  	}
   478  	return 0 // success
   479  }
   480  
   481  //go:nosplit
   482  func semawakeup(mp *m) {
   483  	plan9_semrelease(&mp.waitsemacount, 1)
   484  }
   485  
   486  //go:nosplit
   487  func read(fd int32, buf unsafe.Pointer, n int32) int32 {
   488  	return pread(fd, buf, n, -1)
   489  }
   490  
   491  //go:nosplit
   492  func write1(fd uintptr, buf unsafe.Pointer, n int32) int32 {
   493  	return pwrite(int32(fd), buf, n, -1)
   494  }
   495  
   496  var _badsignal = []byte("runtime: signal received on thread not created by Go.\n")
   497  
   498  // This runs on a foreign stack, without an m or a g. No stack split.
   499  //
   500  //go:nosplit
   501  func badsignal2() {
   502  	pwrite(2, unsafe.Pointer(&_badsignal[0]), int32(len(_badsignal)), -1)
   503  	exits(&_badsignal[0])
   504  }
   505  
   506  func raisebadsignal(sig uint32) {
   507  	badsignal2()
   508  }
   509  
   510  func _atoi(b []byte) int {
   511  	n := 0
   512  	for len(b) > 0 && '0' <= b[0] && b[0] <= '9' {
   513  		n = n*10 + int(b[0]) - '0'
   514  		b = b[1:]
   515  	}
   516  	return n
   517  }
   518  
   519  func signame(sig uint32) string {
   520  	if sig >= uint32(len(sigtable)) {
   521  		return ""
   522  	}
   523  	return sigtable[sig].name
   524  }
   525  
   526  const preemptMSupported = false
   527  
   528  func preemptM(mp *m) {
   529  	// Not currently supported.
   530  	//
   531  	// TODO: Use a note like we use signals on POSIX OSes
   532  }
   533
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