Home | History | Annotate | Download | only in cgo 
      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 <string.h> /* for strerror */
      6 #include <pthread.h>
      7 #include <signal.h>
      8 #include "libcgo.h"
      9 #include "libcgo_unix.h"
     10 
     11 static void* threadentry(void*);
     12 static pthread_key_t k1;
     13 
     14 #define magic1 (0x23581321345589ULL)
     15 
     16 static void
     17 inittls(void)
     18 {
     19 	uint64 x;
     20 	pthread_key_t tofree[128], k;
     21 	int i, ntofree;
     22 
     23 	/*
     24 	 * Same logic, code as darwin_386.c:/inittls, except that words
     25 	 * are 8 bytes long now, and the thread-local storage starts
     26 	 * at 0x60 on Leopard / Snow Leopard. So the offset is
     27 	 * 0x60+8*0x108 = 0x8a0.
     28 	 *
     29 	 * The linker and runtime hard-code this constant offset
     30 	 * from %gs where we expect to find g.
     31 	 * Known to src/cmd/link/internal/ld/sym.go:/0x8a0
     32 	 * and to src/runtime/sys_darwin_amd64.s:/0x8a0
     33 	 *
     34 	 * As disgusting as on the 386; same justification.
     35 	 */
     36 	ntofree = 0;
     37 	for(;;) {
     38 		if(pthread_key_create(&k, nil) != 0) {
     39 			fprintf(stderr, "runtime/cgo: pthread_key_create failed\n");
     40 			abort();
     41 		}
     42 		pthread_setspecific(k, (void*)magic1);
     43 		asm volatile("movq %%gs:0x8a0, %0" : "=r"(x));
     44 		pthread_setspecific(k, 0);
     45 		if(x == magic1) {
     46 			k1 = k;
     47 			break;
     48 		}
     49 		if(ntofree >= nelem(tofree)) {
     50 			fprintf(stderr, "runtime/cgo: could not obtain pthread_keys\n");
     51 			fprintf(stderr, "\ttried");
     52 			for(i=0; i<ntofree; i++)
     53 				fprintf(stderr, " %#x", (unsigned)tofree[i]);
     54 			fprintf(stderr, "\n");
     55 			abort();
     56 		}
     57 		tofree[ntofree++] = k;
     58 	}
     59 
     60 	/*
     61 	 * We got the key we wanted.  Free the others.
     62 	 */
     63 	for(i=0; i<ntofree; i++)
     64 		pthread_key_delete(tofree[i]);
     65 }
     66 
     67 void
     68 x_cgo_init(G *g)
     69 {
     70 	pthread_attr_t attr;
     71 	size_t size;
     72 
     73 	pthread_attr_init(&attr);
     74 	pthread_attr_getstacksize(&attr, &size);
     75 	g->stacklo = (uintptr)&attr - size + 4096;
     76 	pthread_attr_destroy(&attr);
     77 
     78 	inittls();
     79 }
     80 
     81 
     82 void
     83 _cgo_sys_thread_start(ThreadStart *ts)
     84 {
     85 	pthread_attr_t attr;
     86 	sigset_t ign, oset;
     87 	pthread_t p;
     88 	size_t size;
     89 	int err;
     90 
     91 	sigfillset(&ign);
     92 	pthread_sigmask(SIG_SETMASK, &ign, &oset);
     93 
     94 	pthread_attr_init(&attr);
     95 	pthread_attr_getstacksize(&attr, &size);
     96 	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
     97 	ts->g->stackhi = size;
     98 	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
     99 
    100 	pthread_sigmask(SIG_SETMASK, &oset, nil);
    101 
    102 	if (err != 0) {
    103 		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
    104 		abort();
    105 	}
    106 }
    107 
    108 static void*
    109 threadentry(void *v)
    110 {
    111 	ThreadStart ts;
    112 
    113 	ts = *(ThreadStart*)v;
    114 	free(v);
    115 
    116 	if (pthread_setspecific(k1, (void*)ts.g) != 0) {
    117 		fprintf(stderr, "runtime/cgo: pthread_setspecific failed\n");
    118 		abort();
    119 	}
    120 
    121 	crosscall_amd64(ts.fn);
    122 	return nil;
    123 }
    124