text: // Copyright 2010 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 "runtime.h"
  #include "arch_GOARCH.h"
  #include "defs_GOOS_GOARCH.h"
  #include "os_GOOS.h"
  #include "malloc.h"
  
  void*
  runtime·SysAlloc(uintptr n)
  {
  	void *v;
  
  	mstats.sys += n;
  	v = runtime·mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
  	if(v < (void*)4096)
  		return nil;
  	return v;
  }
  
  void
  runtime·SysUnused(void *v, uintptr n)
  {
  	// Linux's MADV_DONTNEED is like BSD's MADV_FREE.
  	runtime·madvise(v, n, MADV_FREE);
  }
  
  void
  runtime·SysFree(void *v, uintptr n)
  {
  	mstats.sys -= n;
  	runtime·munmap(v, n);
  }
  
  void*
  runtime·SysReserve(void *v, uintptr n)
  {
  	return runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
  }
  
  enum
  {
  	ENOMEM = 12,
  };
  
  void
  runtime·SysMap(void *v, uintptr n)
  {
  	void *p;
  	
  	mstats.sys += n;
  	p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
  	if(p == (void*)-ENOMEM)
  		runtime·throw("runtime: out of memory");
  	if(p != v)
  		runtime·throw("runtime: cannot map pages in arena address space");
  }
  