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https://github.com/golang/go
synced 2024-10-04 20:21:22 -06:00
5bffa3b88e
There are some function pointers declared by 6c in package runtime without initialization and then also declared in package runtime/cgo with initialization, so that if runtime/cgo is linked in, the function pointers are non-nil, and otherwise they are nil. We depend on this property for implementing non-essential cgo hooks in package runtime. The declarations in package runtime are 6c-compiled and end up in .6 files. The declarations in package runtime/cgo are gcc-compiled and end up in .o files. Since 6l links the .6 and .o files together, this all works. However, when we switch to "external linking" mode, 6l will not see the .o files, and it would be up to the host linker to resolve the two into a single initialized symbol. Not all host linkers will do this (in particular OS X gcc will not). To fix this, move the cgo declarations into 6c-compiled code, so that they end up in .6 files, so that 6l gets them no matter what. R=golang-dev CC=golang-dev https://golang.org/cl/7440045
136 lines
2.9 KiB
C
136 lines
2.9 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include <string.h> /* for strerror */
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#include <pthread.h>
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#include <signal.h>
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#include "libcgo.h"
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static void* threadentry(void*);
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static pthread_key_t k1, k2;
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#define magic1 (0x23581321345589ULL)
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static void
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inittls(void)
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{
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uint64 x, y;
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pthread_key_t tofree[128], k;
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int i, ntofree;
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int havek1, havek2;
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/*
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* Same logic, code as darwin_386.c:/inittls, except that words
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* are 8 bytes long now, and the thread-local storage starts
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* at 0x60 on Leopard / Snow Leopard. So the offsets are
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* 0x60+8*0x108 = 0x8a0 and 0x60+8*0x109 = 0x8a8.
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*
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* The linker and runtime hard-code these constant offsets
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* from %gs where we expect to find m and g.
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* Known to ../../../cmd/6l/obj.c:/8a0
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* and to ../sys_darwin_amd64.s:/8a0
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*
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* As disgusting as on the 386; same justification.
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*/
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havek1 = 0;
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havek2 = 0;
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ntofree = 0;
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while(!havek1 || !havek2) {
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if(pthread_key_create(&k, nil) < 0) {
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fprintf(stderr, "runtime/cgo: pthread_key_create failed\n");
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abort();
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}
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pthread_setspecific(k, (void*)magic1);
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asm volatile("movq %%gs:0x8a0, %0" : "=r"(x));
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asm volatile("movq %%gs:0x8a8, %0" : "=r"(y));
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if(x == magic1) {
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havek1 = 1;
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k1 = k;
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} else if(y == magic1) {
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havek2 = 1;
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k2 = k;
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} else {
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if(ntofree >= nelem(tofree)) {
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fprintf(stderr, "runtime/cgo: could not obtain pthread_keys\n");
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fprintf(stderr, "\ttried");
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for(i=0; i<ntofree; i++)
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fprintf(stderr, " %#x", (unsigned)tofree[i]);
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fprintf(stderr, "\n");
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abort();
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}
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tofree[ntofree++] = k;
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}
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pthread_setspecific(k, 0);
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}
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/*
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* We got the keys we wanted. Free the others.
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*/
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for(i=0; i<ntofree; i++)
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pthread_key_delete(tofree[i]);
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}
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void
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x_cgo_init(G *g)
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{
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pthread_attr_t attr;
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size_t size;
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pthread_attr_init(&attr);
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pthread_attr_getstacksize(&attr, &size);
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g->stackguard = (uintptr)&attr - size + 4096;
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pthread_attr_destroy(&attr);
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inittls();
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}
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void
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_cgo_sys_thread_start(ThreadStart *ts)
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{
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pthread_attr_t attr;
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sigset_t ign, oset;
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pthread_t p;
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size_t size;
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int err;
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sigfillset(&ign);
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pthread_sigmask(SIG_SETMASK, &ign, &oset);
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pthread_attr_init(&attr);
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pthread_attr_getstacksize(&attr, &size);
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ts->g->stackguard = size;
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err = pthread_create(&p, &attr, threadentry, ts);
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pthread_sigmask(SIG_SETMASK, &oset, nil);
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if (err != 0) {
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fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
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abort();
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}
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}
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static void*
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threadentry(void *v)
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{
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ThreadStart ts;
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ts = *(ThreadStart*)v;
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free(v);
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ts.g->stackbase = (uintptr)&ts;
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/*
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* _cgo_sys_thread_start set stackguard to stack size;
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* change to actual guard pointer.
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*/
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ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
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pthread_setspecific(k1, (void*)ts.g);
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pthread_setspecific(k2, (void*)ts.m);
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crosscall_amd64(ts.fn);
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return nil;
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}
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