gcc_stack_unix.c

Documentation: runtime/cgo

     1// Copyright 2023 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//go:build unix && !darwin
     6
     7#ifndef _GNU_SOURCE // pthread_getattr_np
     8#define _GNU_SOURCE
     9#endif
    10
    11#include <pthread.h>
    12#include "libcgo.h"
    13
    14void
    15x_cgo_getstackbound(uintptr bounds[2])
    16{
    17	pthread_attr_t attr;
    18	void *addr;
    19	size_t size;
    20
    21	// Needed before pthread_getattr_np, too, since before glibc 2.32
    22	// it did not call pthread_attr_init in all cases (see #65625).
    23	pthread_attr_init(&attr);
    24#if defined(__GLIBC__) || (defined(__sun) && !defined(__illumos__))
    25	// pthread_getattr_np is a GNU extension supported in glibc.
    26	// Solaris is not glibc but does support pthread_getattr_np
    27	// (and the fallback doesn't work...). Illumos does not.
    28	pthread_getattr_np(pthread_self(), &attr);  // GNU extension
    29	pthread_attr_getstack(&attr, &addr, &size); // low address
    30#elif defined(__illumos__)
    31	pthread_attr_get_np(pthread_self(), &attr);
    32	pthread_attr_getstack(&attr, &addr, &size); // low address
    33#else
    34	// We don't know how to get the current stacks, so assume they are the
    35	// same as the default stack bounds.
    36	pthread_attr_getstacksize(&attr, &size);
    37	addr = __builtin_frame_address(0) + 4096 - size;
    38#endif
    39	pthread_attr_destroy(&attr);
    40
    41	// bounds points into the Go stack. TSAN can't see the synchronization
    42	// in Go around stack reuse.
    43	_cgo_tsan_acquire();
    44	bounds[0] = (uintptr)addr;
    45	bounds[1] = (uintptr)addr + size;
    46	_cgo_tsan_release();
    47}
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