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https://github.com/golang/go
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5cffce611a
Part 2 of CL 5601044 (cgo: Linux/ARM support) R=dave, rsc CC=golang-dev https://golang.org/cl/5989057
110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
// Copyright 2010 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 <pthread.h>
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#include <string.h>
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#include "libcgo.h"
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static void *threadentry(void*);
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// We have to resort to TLS variable to save g(R10) and
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// m(R9). One reason is that external code might trigger
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// SIGSEGV, and our runtime.sigtramp don't even know we
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// are in external code, and will continue to use R10/R9,
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// this might as well result in another SIGSEGV.
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// Note: all three functions will clobber R0, and the last
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// two can be called from 5c ABI code.
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void __aeabi_read_tp(void) __attribute__((naked));
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void cgo_tls_set_gm(void) __attribute__((naked));
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void cgo_tls_get_gm(void) __attribute__((naked));
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void __aeabi_read_tp(void) {
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// b __kuser_get_tls @ 0xffff0fe0
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__asm__ __volatile__ (
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"mvn r0, #0xf000\n\t"
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"sub pc, r0, #31\n\t"
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"nop\n\tnop\n\t"
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);
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}
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// g (R10) at 8(TP), m (R9) at 12(TP)
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void cgo_tls_get_gm(void) {
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__asm__ __volatile__ (
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"push {lr}\n\t"
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"bl __aeabi_read_tp\n\t"
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"ldr r10, [r0, #8]\n\t"
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"ldr r9, [r0, #12]\n\t"
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"pop {pc}\n\t"
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);
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}
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void cgo_tls_set_gm(void) {
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__asm__ __volatile__ (
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"push {lr}\n\t"
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"bl __aeabi_read_tp\n\t"
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"str r10, [r0, #8]\n\t"
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"str r9, [r0, #12]\n\t"
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"pop {pc}\n\t"
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);
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}
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// both cgo_tls_{get,set}_gm can be called from runtime
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void (*cgo_load_gm)(void) = cgo_tls_get_gm;
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void (*cgo_save_gm)(void) = cgo_tls_set_gm;
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static void
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xinitcgo(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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cgo_tls_set_gm(); // save g and m for the initial thread
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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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}
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void (*initcgo)(G*) = xinitcgo;
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void
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libcgo_sys_thread_start(ThreadStart *ts)
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{
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pthread_attr_t attr;
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pthread_t p;
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size_t size;
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int err;
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// Not sure why the memset is necessary here,
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// but without it, we get a bogus stack size
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// out of pthread_attr_getstacksize. C'est la Linux.
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memset(&attr, 0, sizeof attr);
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pthread_attr_init(&attr);
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size = 0;
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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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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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extern void crosscall_arm2(void (*fn)(void), void *g, void *m);
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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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* libcgo_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 * 2;
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crosscall_arm2(ts.fn, (void *)ts.g, (void *)ts.m);
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return nil;
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}
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