1/* Communicate dynamic linker state to the debugger at runtime.
2 Copyright (C) 1996-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <ldsodefs.h>
20
21
22/* These are the members in the public `struct link_map' type.
23 Sanity check that the internal type and the public type match. */
24#define VERIFY_MEMBER(name) \
25 (offsetof (struct link_map_public, name) == offsetof (struct link_map, name))
26extern const int verify_link_map_members[(VERIFY_MEMBER (l_addr)
27 && VERIFY_MEMBER (l_name)
28 && VERIFY_MEMBER (l_ld)
29 && VERIFY_MEMBER (l_next)
30 && VERIFY_MEMBER (l_prev))
31 ? 1 : -1];
32
33/* This structure communicates dl state to the debugger. The debugger
34 normally finds it via the DT_DEBUG entry in the dynamic section, but in
35 a statically-linked program there is no dynamic section for the debugger
36 to examine and it looks for this particular symbol name. */
37struct r_debug _r_debug;
38
39
40/* Initialize _r_debug if it has not already been done. The argument is
41 the run-time load address of the dynamic linker, to be put in
42 _r_debug.r_ldbase. Returns the address of _r_debug. */
43
44struct r_debug *
45_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
46{
47 struct r_debug *r;
48
49 if (ns == LM_ID_BASE)
50 r = &_r_debug;
51 else
52 r = &GL(dl_ns)[ns]._ns_debug;
53
54 if (r->r_map == NULL || ldbase != 0)
55 {
56 /* Tell the debugger where to find the map of loaded objects. */
57 r->r_version = 1 /* R_DEBUG_VERSION XXX */;
58 r->r_ldbase = ldbase ?: _r_debug.r_ldbase;
59 r->r_map = (void *) GL(dl_ns)[ns]._ns_loaded;
60 r->r_brk = (ElfW(Addr)) &_dl_debug_state;
61 }
62
63 return r;
64}
65
66
67/* This function exists solely to have a breakpoint set on it by the
68 debugger. The debugger is supposed to find this function's address by
69 examining the r_brk member of struct r_debug, but GDB 4.15 in fact looks
70 for this particular symbol name in the PT_INTERP file. */
71void
72_dl_debug_state (void)
73{
74}
75rtld_hidden_def (_dl_debug_state)
76