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