1/* Copyright (C) 2009-2020 Free Software Foundation, Inc.
2
3   This file is part of GDB.
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 3 of the License, or
8   (at your option) any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
17
18#include <assert.h>
19#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <unistd.h>
23
24#include <sys/mman.h>
25
26#include JIT_READER_H  /* Please see jit-reader.exp for an explanation.  */
27#include "jit-reader-host.h"
28#include "jit-protocol.h"
29
30struct jit_code_entry only_entry;
31
32typedef void (jit_function_stack_mangle_t) (void);
33typedef long (jit_function_add_t) (long a, long b);
34
35/* The code of the jit_function_00 function that is copied into an
36   mmapped buffer in the inferior at run time.
37
38   The second instruction mangles the stack pointer, meaning that when
39   stopped at the third instruction, GDB needs assistance from the JIT
40   unwinder in order to be able to unwind successfully.  */
41static const unsigned char jit_function_stack_mangle_code[] = {
42  0xcc,				/* int3 */
43  0x48, 0x83, 0xf4, 0xff,	/* xor $0xffffffffffffffff, %rsp */
44  0x48, 0x83, 0xf4, 0xff,	/* xor $0xffffffffffffffff, %rsp */
45  0xc3				/* ret */
46};
47
48/* And another "JIT-ed" function, with the prototype `jit_function_add_t`.  */
49static const unsigned char jit_function_add_code[] = {
50  0x48, 0x01, 0xfe,		/* add %rdi,%rsi */
51  0x48, 0x89, 0xf0,		/* mov %rsi,%rax */
52  0xc3,				/* retq */
53};
54
55int
56main (int argc, char **argv)
57{
58  struct jithost_abi *symfile = malloc (sizeof (struct jithost_abi));
59  char *code = mmap (NULL, getpagesize (), PROT_WRITE | PROT_EXEC,
60		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
61  char *code_end = code;
62
63  assert (code != MAP_FAILED);
64
65  /* "JIT" function_stack_mangle.  */
66  memcpy (code_end, jit_function_stack_mangle_code,
67	  sizeof (jit_function_stack_mangle_code));
68  jit_function_stack_mangle_t *function_stack_mangle
69    = (jit_function_stack_mangle_t *) code_end;
70  symfile->function_stack_mangle.begin = code_end;
71  code_end += sizeof (jit_function_stack_mangle_code);
72  symfile->function_stack_mangle.end = code_end;
73
74  /* "JIT" function_add.  */
75  memcpy (code_end, jit_function_add_code, sizeof (jit_function_add_code));
76  jit_function_add_t *function_add = (jit_function_add_t *) code_end;
77  symfile->function_add.begin = code_end;
78  code_end += sizeof (jit_function_add_code);
79  symfile->function_add.end = code_end;
80
81  /* Bounds of the whole object.  */
82  symfile->object.begin = code;
83  symfile->object.end = code_end;
84
85  only_entry.symfile_addr = symfile;
86  only_entry.symfile_size = sizeof (struct jithost_abi);
87
88  __jit_debug_descriptor.first_entry = &only_entry;
89  __jit_debug_descriptor.relevant_entry = &only_entry;
90  __jit_debug_descriptor.action_flag = JIT_REGISTER;
91  __jit_debug_descriptor.version = 1;
92  __jit_debug_register_code ();
93
94  function_stack_mangle ();
95  function_add (5, 6);
96
97  return 0;
98}
99