github.com/ccccaoqing/test@v0.0.0-20220510085219-3985d23445c0/src/runtime/cgo/gcc_openbsd_amd64.c (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  #include <sys/types.h>
     6  #include <dlfcn.h>
     7  #include <errno.h>
     8  #include <pthread.h>
     9  #include <signal.h>
    10  #include <string.h>
    11  #include "libcgo.h"
    12  
    13  static void* threadentry(void*);
    14  static void (*setg_gcc)(void*);
    15  
    16  // TCB_SIZE is sizeof(struct thread_control_block),
    17  // as defined in /usr/src/lib/librthread/tcb.h
    18  #define TCB_SIZE (4 * sizeof(void *))
    19  #define TLS_SIZE (2 * sizeof(void *))
    20  
    21  void *__get_tcb(void);
    22  void __set_tcb(void *);
    23  
    24  static int (*sys_pthread_create)(pthread_t *thread, const pthread_attr_t *attr,
    25  	void *(*start_routine)(void *), void *arg);
    26  
    27  struct thread_args {
    28  	void *(*func)(void *);
    29  	void *arg;
    30  };
    31  
    32  static void
    33  tcb_fixup(int mainthread)
    34  {
    35  	void *newtcb, *oldtcb;
    36  
    37  	// The OpenBSD ld.so(1) does not currently support PT_TLS. As a result,
    38  	// we need to allocate our own TLS space while preserving the existing
    39  	// TCB that has been setup via librthread.
    40  
    41  	newtcb = malloc(TCB_SIZE + TLS_SIZE);
    42  	if(newtcb == NULL)
    43  		abort();
    44  
    45  	// The signal trampoline expects the TLS slots to be zeroed.
    46  	bzero(newtcb, TLS_SIZE);
    47  
    48  	oldtcb = __get_tcb();
    49  	bcopy(oldtcb, newtcb + TLS_SIZE, TCB_SIZE);
    50  	__set_tcb(newtcb + TLS_SIZE);
    51  
    52  	// NOTE(jsing, minux): we can't free oldtcb without causing double-free
    53  	// problem. so newtcb will be memory leaks. Get rid of this when OpenBSD
    54  	// has proper support for PT_TLS.
    55  }
    56  
    57  static void *
    58  thread_start_wrapper(void *arg)
    59  {
    60  	struct thread_args args = *(struct thread_args *)arg;
    61  
    62  	free(arg);
    63  	tcb_fixup(0);
    64  
    65  	return args.func(args.arg);
    66  }
    67  
    68  static void init_pthread_wrapper(void) {
    69  	void *handle;
    70  
    71  	// Locate symbol for the system pthread_create function.
    72  	handle = dlopen("libpthread.so", RTLD_LAZY);
    73  	if(handle == NULL) {
    74  		fprintf(stderr, "runtime/cgo: dlopen failed to load libpthread: %s\n", dlerror());
    75  		abort();
    76  	}
    77  	sys_pthread_create = dlsym(handle, "pthread_create");
    78  	if(sys_pthread_create == NULL) {
    79  		fprintf(stderr, "runtime/cgo: dlsym failed to find pthread_create: %s\n", dlerror());
    80  		abort();
    81  	}
    82  	dlclose(handle);
    83  }
    84  
    85  static pthread_once_t init_pthread_wrapper_once = PTHREAD_ONCE_INIT;
    86  
    87  int
    88  pthread_create(pthread_t *thread, const pthread_attr_t *attr,
    89  	void *(*start_routine)(void *), void *arg)
    90  {
    91  	struct thread_args *p;
    92  
    93  	// we must initialize our wrapper in pthread_create, because it is valid to call
    94  	// pthread_create in a static constructor, and in fact, our test for issue 9456
    95  	// does just that.
    96  	if(pthread_once(&init_pthread_wrapper_once, init_pthread_wrapper) != 0) {
    97  		fprintf(stderr, "runtime/cgo: failed to initialize pthread_create wrapper\n");
    98  		abort();
    99  	}
   100  
   101  	p = malloc(sizeof(*p));
   102  	if(p == NULL) {
   103  		errno = ENOMEM;
   104  		return -1;
   105  	}
   106  	p->func = start_routine;
   107  	p->arg = arg;
   108  
   109  	return sys_pthread_create(thread, attr, thread_start_wrapper, p);
   110  }
   111  
   112  void
   113  x_cgo_init(G *g, void (*setg)(void*))
   114  {
   115  	pthread_attr_t attr;
   116  	size_t size;
   117  
   118  	setg_gcc = setg;
   119  	pthread_attr_init(&attr);
   120  	pthread_attr_getstacksize(&attr, &size);
   121  	g->stacklo = (uintptr)&attr - size + 4096;
   122  	pthread_attr_destroy(&attr);
   123  
   124  	if(pthread_once(&init_pthread_wrapper_once, init_pthread_wrapper) != 0) {
   125  		fprintf(stderr, "runtime/cgo: failed to initialize pthread_create wrapper\n");
   126  		abort();
   127  	}
   128  
   129  	tcb_fixup(1);
   130  }
   131  
   132  
   133  void
   134  _cgo_sys_thread_start(ThreadStart *ts)
   135  {
   136  	pthread_attr_t attr;
   137  	sigset_t ign, oset;
   138  	pthread_t p;
   139  	size_t size;
   140  	int err;
   141  
   142  	sigfillset(&ign);
   143  	pthread_sigmask(SIG_SETMASK, &ign, &oset);
   144  
   145  	pthread_attr_init(&attr);
   146  	pthread_attr_getstacksize(&attr, &size);
   147  
   148  	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
   149  	ts->g->stackhi = size;
   150  	err = sys_pthread_create(&p, &attr, threadentry, ts);
   151  
   152  	pthread_sigmask(SIG_SETMASK, &oset, nil);
   153  
   154  	if (err != 0) {
   155  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
   156  		abort();
   157  	}
   158  }
   159  
   160  static void*
   161  threadentry(void *v)
   162  {
   163  	ThreadStart ts;
   164  
   165  	tcb_fixup(0);
   166  
   167  	ts = *(ThreadStart*)v;
   168  	free(v);
   169  
   170  	/*
   171  	 * Set specific keys.
   172  	 */
   173  	setg_gcc((void*)ts.g);
   174  
   175  	crosscall_amd64(ts.fn);
   176  	return nil;
   177  }