blob: 43003e81c93f0408b7f8063595be32dacb088359 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
/* go-trampoline.c -- allocate a trampoline for a nested function.
Copyright 2009 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 "config.h"
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#include "go-alloc.h"
#include "go-assert.h"
/* In order to build a trampoline we need space which is both writable
and executable. We currently just allocate a whole page. This
needs to be more system dependent. */
void *
__go_allocate_trampoline (size_t size, void *closure)
{
unsigned int page_size;
void *ret;
size_t off;
page_size = getpagesize ();
__go_assert (page_size >= size);
ret = __go_alloc (2 * page_size - 1);
ret = (void *) (((uintptr_t) ret + page_size - 1)
& ~ ((uintptr_t) page_size - 1));
/* Because the garbage collector only looks at correct address
offsets, we need to ensure that it will see the closure
address. */
off = ((size + sizeof (void *) - 1) / sizeof (void *)) * sizeof (void *);
__go_assert (size + off + sizeof (void *) <= page_size);
__builtin_memcpy (ret + off, &closure, sizeof (void *));
#ifdef HAVE_SYS_MMAN_H
{
int i;
i = mprotect (ret, size, PROT_READ | PROT_WRITE | PROT_EXEC);
__go_assert (i == 0);
}
#endif
return ret;
}
|
