github.com/aloncn/graphics-go@v0.0.1/src/runtime/cgo/gcc_android_386.c (about)

     1  // Copyright 2015 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  // +build cgo
     6  
     7  #include <string.h> /* for strerror */
     8  #include <pthread.h>
     9  #include <signal.h>
    10  #include "libcgo.h"
    11  
    12  static void* threadentry(void*);
    13  static pthread_key_t k1;
    14  
    15  #define magic1 (0x23581321U)
    16  
    17  static void
    18  inittls(void)
    19  {
    20  	uint32 x;
    21  	pthread_key_t tofree[128], k;
    22  	int i, ntofree;
    23  
    24  	/*
    25  	 * Same logic, code as gcc_android_amd64.c:/inittls.
    26  	 * Note that this is a temporary hack that should be fixed soon.
    27  	 *
    28  	 * TODO: fix this.
    29  	 *
    30  	 * The linker and runtime hard-code this constant offset
    31  	 * from %gs where we expect to find g. Disgusting.
    32  	 *
    33  	 * Known to src/cmd/link/internal/ld/sym.go:/0xf8
    34  	 * and to src/runtime/sys_linux_386.s:/0xf8 or /GOOS_android.
    35  	 * TODO(hyangah): check 0xb0 works with API23+
    36  	 *
    37  	 * As disgusting as on the darwin/386, darwin/amd64.
    38  	 */
    39  	ntofree = 0;
    40  	for(;;) {
    41  		if(pthread_key_create(&k, nil) < 0) {
    42  			fprintf(stderr, "runtime/cgo: pthread_key_create failed\n");
    43  			abort();
    44  		}
    45  		pthread_setspecific(k, (void*)magic1);
    46  		asm volatile("movl %%gs:0xf8, %0" : "=r"(x));
    47  		pthread_setspecific(k, 0);
    48  		if (x == magic1) {
    49  			k1 = k;
    50  			break;
    51  		}
    52  		if(ntofree >= nelem(tofree)) {
    53  			fprintf(stderr, "runtime/cgo: could not obtain pthread_keys\n");
    54  			fprintf(stderr, "\ttried");
    55  			for(i=0; i<ntofree; i++)
    56  				fprintf(stderr, " %#x", (unsigned)tofree[i]);
    57  			fprintf(stderr, "\n");
    58  			abort();
    59  		}
    60  		tofree[ntofree++] = k;
    61  	}
    62  	// TODO: output to stderr is not useful for apps.
    63  	// Can we fall back to Android's log library?
    64  
    65  	/*
    66  	 * We got the key we wanted.  Free the others.
    67  	 */
    68  	for(i=0; i<ntofree; i++) {
    69  		pthread_key_delete(tofree[i]);
    70  	}
    71  }
    72  
    73  
    74  static void*
    75  threadentry(void *v)
    76  {
    77  	ThreadStart ts;
    78  
    79  	ts = *(ThreadStart*)v;
    80  	free(v);
    81  
    82  	pthread_setspecific(k1, (void*)ts.g);
    83  
    84  	crosscall_386(ts.fn);
    85  	return nil;
    86  }
    87  
    88  void (*x_cgo_inittls)(void) = inittls;
    89  void* (*x_cgo_threadentry)(void*) = threadentry;