1/* This test program is part of GDB, the GNU debugger.
2
3   Copyright 2011 Free Software Foundation, Inc.
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
19/* Simulate loading of JIT code.  */
20
21#include <elf.h>
22#include <link.h>
23#include <errno.h>
24#include <fcntl.h>
25#include <stdint.h>
26#include <stdio.h>
27#include <stdlib.h>
28#include <string.h>
29#include <sys/mman.h>
30#include <sys/stat.h>
31
32/* ElfW is coming from linux. On other platforms it does not exist.
33   Let us define it here. */
34#ifndef ElfW
35# if (defined  (_LP64) || defined (__LP64__))
36#   define WORDSIZE 64
37# else
38#   define WORDSIZE 32
39# endif /* _LP64 || __LP64__  */
40#define ElfW(type)      _ElfW (Elf, WORDSIZE, type)
41#define _ElfW(e,w,t)    _ElfW_1 (e, w, _##t)
42#define _ElfW_1(e,w,t)  e##w##t
43#endif /* !ElfW  */
44
45typedef enum
46{
47  JIT_NOACTION = 0,
48  JIT_REGISTER_FN,
49  JIT_UNREGISTER_FN
50} jit_actions_t;
51
52struct jit_code_entry
53{
54  struct jit_code_entry *next_entry;
55  struct jit_code_entry *prev_entry;
56  const char *symfile_addr;
57  uint64_t symfile_size;
58};
59
60struct jit_descriptor
61{
62  uint32_t version;
63  /* This type should be jit_actions_t, but we use uint32_t
64     to be explicit about the bitwidth.  */
65  uint32_t action_flag;
66  struct jit_code_entry *relevant_entry;
67  struct jit_code_entry *first_entry;
68};
69
70/* GDB puts a breakpoint in this function.  */
71void __attribute__((noinline)) __jit_debug_register_code () { }
72
73/* Make sure to specify the version statically, because the
74   debugger may check the version before we can set it.  */
75struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
76
77static void
78usage (const char *const argv0)
79{
80  fprintf (stderr, "Usage: %s library [count]\n", argv0);
81  exit (1);
82}
83
84/* Update .p_vaddr and .sh_addr as if the code was JITted to ADDR.  */
85
86static void
87update_locations (const void *const addr, int idx)
88{
89  const ElfW (Ehdr) *const ehdr = (ElfW (Ehdr) *)addr;
90  ElfW (Shdr) *const shdr = (ElfW (Shdr) *)((char *)addr + ehdr->e_shoff);
91  ElfW (Phdr) *const phdr = (ElfW (Phdr) *)((char *)addr + ehdr->e_phoff);
92  int i;
93
94  for (i = 0; i < ehdr->e_phnum; ++i)
95    if (phdr[i].p_type == PT_LOAD)
96      phdr[i].p_vaddr += (ElfW (Addr))addr;
97
98  for (i = 0; i < ehdr->e_shnum; ++i)
99    {
100      if (shdr[i].sh_type == SHT_STRTAB)
101        {
102          /* Note: we update both .strtab and .dynstr.  The latter would
103             not be correct if this were a regular shared library (.hash
104             would be wrong), but this is a simulation -- the library is
105             never exposed to the dynamic loader, so it all ends up ok.  */
106          char *const strtab = (char *)((ElfW (Addr))addr + shdr[i].sh_offset);
107          char *const strtab_end = strtab + shdr[i].sh_size;
108          char *p;
109
110          for (p = strtab; p < strtab_end; p += strlen (p) + 1)
111            if (strcmp (p, "jit_function_XXXX") == 0)
112              sprintf (p, "jit_function_%04d", idx);
113        }
114
115      if (shdr[i].sh_flags & SHF_ALLOC)
116        shdr[i].sh_addr += (ElfW (Addr))addr;
117    }
118}
119
120#ifndef MAIN
121#define MAIN main
122#endif
123
124int
125MAIN (int argc, char *argv[])
126{
127  /* These variables are here so they can easily be set from jit.exp.  */
128  const char *libname = NULL;
129  int count = 0;
130
131  count = count;  /* gdb break here 0  */
132
133  if (argc < 2)
134    usage (argv[0]);
135  else
136    {
137      int i, fd;
138      struct stat st;
139
140      if (libname == NULL)
141        /* Only set if not already set from GDB.  */
142        libname = argv[1];
143
144      if (argc > 2 && count == 0)
145        /* Only set if not already set from GDB.  */
146        count = atoi (argv[2]);
147
148      printf ("%s:%d: libname = %s, count = %d\n", __FILE__, __LINE__,
149              libname, count);
150
151      if ((fd = open (libname, O_RDONLY)) == -1)
152        {
153          fprintf (stderr, "open (\"%s\", O_RDONLY): %s\n", libname,
154                   strerror (errno));
155          exit (1);
156        }
157
158      if (fstat (fd, &st) != 0)
159        {
160          fprintf (stderr, "fstat (\"%d\"): %s\n", fd, strerror (errno));
161          exit (1);
162        }
163
164      for (i = 0; i < count; ++i)
165        {
166          const void *const addr = mmap (0, st.st_size, PROT_READ|PROT_WRITE,
167                                         MAP_PRIVATE, fd, 0);
168          struct jit_code_entry *const entry = calloc (1, sizeof (*entry));
169
170          if (addr == MAP_FAILED)
171            {
172              fprintf (stderr, "mmap: %s\n", strerror (errno));
173              exit (1);
174            }
175
176          update_locations (addr, i);
177
178          /* Link entry at the end of the list.  */
179          entry->symfile_addr = (const char *)addr;
180          entry->symfile_size = st.st_size;
181          entry->prev_entry = __jit_debug_descriptor.relevant_entry;
182          __jit_debug_descriptor.relevant_entry = entry;
183
184          if (entry->prev_entry != NULL)
185            entry->prev_entry->next_entry = entry;
186          else
187            __jit_debug_descriptor.first_entry = entry;
188
189          /* Notify GDB.  */
190          __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
191          __jit_debug_register_code ();
192        }
193
194      i = 0;  /* gdb break here 1 */
195
196      /* Now unregister them all in reverse order.  */
197      while (__jit_debug_descriptor.relevant_entry != NULL)
198        {
199          struct jit_code_entry *const entry =
200            __jit_debug_descriptor.relevant_entry;
201          struct jit_code_entry *const prev_entry = entry->prev_entry;
202
203          if (prev_entry != NULL)
204            {
205              prev_entry->next_entry = NULL;
206              entry->prev_entry = NULL;
207            }
208          else
209            __jit_debug_descriptor.first_entry = NULL;
210
211          /* Notify GDB.  */
212          __jit_debug_descriptor.action_flag = JIT_UNREGISTER_FN;
213          __jit_debug_register_code ();
214
215          __jit_debug_descriptor.relevant_entry = prev_entry;
216          free (entry);
217        }
218    }
219  return 0;  /* gdb break here 2  */
220}
221