gcc_netbsd_arm64.c

Documentation: runtime/cgo

     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 <sys/types.h>
     6  #include <pthread.h>
     7  #include <signal.h>
     8  #include <string.h>
     9  #include "libcgo.h"
    10  #include "libcgo_unix.h"
    11  
    12  static void *threadentry(void*);
    13  
    14  static void (*setg_gcc)(void*);
    15  
    16  void
    17  x_cgo_init(G *g, void (*setg)(void*))
    18  {
    19  	pthread_attr_t attr;
    20  	size_t size;
    21  
    22  	setg_gcc = setg;
    23  	pthread_attr_init(&attr);
    24  	pthread_attr_getstacksize(&attr, &size);
    25  	g->stacklo = (uintptr)&attr - size + 4096;
    26  	pthread_attr_destroy(&attr);
    27  }
    28  
    29  
    30  void
    31  _cgo_sys_thread_start(ThreadStart *ts)
    32  {
    33  	pthread_attr_t attr;
    34  	sigset_t ign, oset;
    35  	pthread_t p;
    36  	size_t size;
    37  	int err;
    38  
    39  	sigfillset(&ign);
    40  	pthread_sigmask(SIG_SETMASK, &ign, &oset);
    41  
    42  	pthread_attr_init(&attr);
    43  	pthread_attr_getstacksize(&attr, &size);
    44  	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
    45  	ts->g->stackhi = size;
    46  	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
    47  
    48  	pthread_sigmask(SIG_SETMASK, &oset, nil);
    49  
    50  	if (err != 0) {
    51  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
    52  		abort();
    53  	}
    54  }
    55  
    56  extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
    57  
    58  static void*
    59  threadentry(void *v)
    60  {
    61  	ThreadStart ts;
    62  	stack_t ss;
    63  
    64  	ts = *(ThreadStart*)v;
    65  	free(v);
    66  
    67  	// On NetBSD, a new thread inherits the signal stack of the
    68  	// creating thread. That confuses minit, so we remove that
    69  	// signal stack here before calling the regular mstart. It's
    70  	// a bit baroque to remove a signal stack here only to add one
    71  	// in minit, but it's a simple change that keeps NetBSD
    72  	// working like other OS's. At this point all signals are
    73  	// blocked, so there is no race.
    74  	memset(&ss, 0, sizeof ss);
    75  	ss.ss_flags = SS_DISABLE;
    76  	sigaltstack(&ss, nil);
    77  
    78  	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
    79  	return nil;
    80  }
    81
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