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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include <sys/types.h>
#include <machine/sysarch.h>
#include <pthread.h>
#include <string.h>
#include "libcgo.h"
static void *threadentry(void*);
// We have to resort to TLS variable to save g(R10) and
// m(R9). One reason is that external code might trigger
// SIGSEGV, and our runtime.sigtramp don't even know we
// are in external code, and will continue to use R10/R9,
// this might as well result in another SIGSEGV.
// Note: all three functions will clobber R0, and the last
// two can be called from 5c ABI code.
void __aeabi_read_tp(void) __attribute__((naked));
void x_cgo_save_gm(void) __attribute__((naked));
void x_cgo_load_gm(void) __attribute__((naked));
void
__aeabi_read_tp(void)
{
__asm__ __volatile__ (
#ifdef ARM_TP_ADDRESS
// ARM_TP_ADDRESS is (ARM_VECTORS_HIGH + 0x1000) or 0xffff1000
// GCC inline asm doesn't provide a way to provide a constant
// to "ldr r0, =??" pseudo instruction, so we hardcode the value
// and check it with cpp.
#if ARM_TP_ADDRESS != 0xffff1000
#error Wrong ARM_TP_ADDRESS!
#endif
"ldr r0, =0xffff1000\n\t"
"ldr r0, [r0]\n\t"
#else
"mrc p15, 0, r0, c13, c0, 3\n\t"
#endif
"mov pc, lr\n\t"
);
}
// g (R10) at 8(TP), m (R9) at 12(TP)
void
x_cgo_load_gm(void)
{
__asm__ __volatile__ (
"push {lr}\n\t"
"bl __aeabi_read_tp\n\t"
"ldr r10, [r0, #8]\n\t"
"ldr r9, [r0, #12]\n\t"
"pop {pc}\n\t"
);
}
void
x_cgo_save_gm(void)
{
__asm__ __volatile__ (
"push {lr}\n\t"
"bl __aeabi_read_tp\n\t"
"str r10, [r0, #8]\n\t"
"str r9, [r0, #12]\n\t"
"pop {pc}\n\t"
);
}
void
x_cgo_init(G *g)
{
pthread_attr_t attr;
size_t size;
x_cgo_save_gm(); // save g and m for the initial thread
pthread_attr_init(&attr);
pthread_attr_getstacksize(&attr, &size);
g->stackguard = (uintptr)&attr - size + 4096;
pthread_attr_destroy(&attr);
}
void
_cgo_sys_thread_start(ThreadStart *ts)
{
pthread_attr_t attr;
pthread_t p;
size_t size;
int err;
// Not sure why the memset is necessary here,
// but without it, we get a bogus stack size
// out of pthread_attr_getstacksize. C'est la Linux.
memset(&attr, 0, sizeof attr);
pthread_attr_init(&attr);
size = 0;
pthread_attr_getstacksize(&attr, &size);
ts->g->stackguard = size;
err = pthread_create(&p, &attr, threadentry, ts);
if (err != 0) {
fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
abort();
}
}
extern void crosscall_arm2(void (*fn)(void), void *g, void *m);
static void*
threadentry(void *v)
{
ThreadStart ts;
ts = *(ThreadStart*)v;
free(v);
ts.g->stackbase = (uintptr)&ts;
/*
* _cgo_sys_thread_start set stackguard to stack size;
* change to actual guard pointer.
*/
ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096 * 2;
crosscall_arm2(ts.fn, (void *)ts.g, (void *)ts.m);
return nil;
}
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