gcc_stack_unix.c

     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  
    14  void
    15  x_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  }
    48
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