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Unified Diff: src/pkg/runtime/cgo/gcc_openbsd_386.c

Issue 6853059: code review 6853059: cgo: enable cgo on openbsd (Closed)
Patch Set: diff -r e08535d6901d https://go.googlecode.com/hg/ Created 11 years, 3 months ago
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Index: src/pkg/runtime/cgo/gcc_openbsd_386.c
===================================================================
copy from src/pkg/runtime/cgo/gcc_netbsd_386.c
copy to src/pkg/runtime/cgo/gcc_openbsd_386.c
--- a/src/pkg/runtime/cgo/gcc_netbsd_386.c
+++ b/src/pkg/runtime/cgo/gcc_openbsd_386.c
@@ -3,6 +3,8 @@
// license that can be found in the LICENSE file.
#include <sys/types.h>
+#include <dlfcn.h>
+#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <string.h>
@@ -10,16 +12,101 @@
static void* threadentry(void*);
+// TCB_SIZE is sizeof(struct thread_control_block),
+// as defined in /usr/src/lib/librthread/tcb.h
+#define TCB_SIZE (4 * sizeof(void *))
+#define TLS_SIZE (2 * sizeof(void *))
+
+void *__get_tcb(void);
+void __set_tcb(void *);
+
+static int (*sys_pthread_create)(pthread_t *thread, const pthread_attr_t *attr,
+ void *(*start_routine)(void *), void *arg);
+
+struct thread_args {
+ void *(*func)(void *);
+ void *arg;
+};
+
+static void
+tcb_fixup(int mainthread)
+{
+ void *newtcb, *oldtcb;
+
+ // The OpenBSD ld.so(1) does not currently support PT_TLS. As a result,
+ // we need to allocate our own TLS space while preserving the existing
+ // TCB that has been setup via librthread.
+
+ newtcb = malloc(TCB_SIZE + TLS_SIZE);
+ if(newtcb == NULL)
+ abort();
+
+ // The signal trampoline expects the TLS slots to be zeroed.
+ bzero(newtcb, TLS_SIZE);
+
+ oldtcb = __get_tcb();
+ bcopy(oldtcb, newtcb + TLS_SIZE, TCB_SIZE);
+ __set_tcb(newtcb + TLS_SIZE);
+
+ // The main thread TCB is a static allocation - do not try to free it.
+ if(!mainthread)
+ free(oldtcb);
+}
+
+static void *
+thread_start_wrapper(void *arg)
+{
+ struct thread_args args = *(struct thread_args *)arg;
+
+ free(arg);
+ tcb_fixup(0);
+
+ return args.func(args.arg);
+}
+
+int
+pthread_create(pthread_t *thread, const pthread_attr_t *attr,
+ void *(*start_routine)(void *), void *arg)
+{
+ struct thread_args *p;
+
+ p = malloc(sizeof(*p));
+ if(p == NULL) {
+ errno = ENOMEM;
+ return -1;
+ }
+ p->func = start_routine;
+ p->arg = arg;
+
+ return sys_pthread_create(thread, attr, thread_start_wrapper, p);
+}
+
static void
xinitcgo(G *g)
{
pthread_attr_t attr;
size_t size;
+ void *handle;
pthread_attr_init(&attr);
pthread_attr_getstacksize(&attr, &size);
g->stackguard = (uintptr)&attr - size + 4096;
pthread_attr_destroy(&attr);
+
+ // Locate symbol for the system pthread_create function.
+ handle = dlopen("libpthread.so", RTLD_LAZY);
+ if(handle == NULL) {
+ fprintf(stderr, "dlopen: failed to load libpthread: %s\n", dlerror());
+ abort();
+ }
+ sys_pthread_create = dlsym(handle, "pthread_create");
+ if(sys_pthread_create == NULL) {
+ fprintf(stderr, "dlsym: failed to find pthread_create: %s\n", dlerror());
+ abort();
+ }
+ dlclose(handle);
+
+ tcb_fixup(1);
}
void (*initcgo)(G*) = xinitcgo;
@@ -39,7 +126,7 @@
pthread_attr_init(&attr);
pthread_attr_getstacksize(&attr, &size);
ts->g->stackguard = size;
- err = pthread_create(&p, &attr, threadentry, ts);
+ err = sys_pthread_create(&p, &attr, threadentry, ts);
sigprocmask(SIG_SETMASK, &oset, nil);
@@ -54,6 +141,8 @@
{
ThreadStart ts;
+ tcb_fixup(0);
+
ts = *(ThreadStart*)v;
free(v);
@@ -66,7 +155,7 @@
ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
/*
- * Set specific keys. On NetBSD/ELF, the thread local storage
+ * Set specific keys. On OpenBSD/ELF, the thread local storage
* is just before %gs:0. Our dynamic 8.out's reserve 8 bytes
* for the two words g and m at %gs:-8 and %gs:-4.
*/
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