1/* Communicate dynamic linker state to the debugger at runtime.
2 Copyright (C) 1996-2023 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/* Update the `r_map' member and return the address of `struct r_debug'
34 of the namespace NS. */
35
36struct r_debug *
37_dl_debug_update (Lmid_t ns)
38{
39 struct r_debug_extended *r;
40 if (ns == LM_ID_BASE)
41 r = &_r_debug_extended;
42 else
43 r = &GL(dl_ns)[ns]._ns_debug;
44 if (r->base.r_map == NULL)
45 atomic_store_release (&r->base.r_map,
46 (void *) GL(dl_ns)[ns]._ns_loaded);
47 return &r->base;
48}
49
50/* Initialize _r_debug_extended for the namespace NS. LDBASE is the
51 run-time load address of the dynamic linker, to be put in
52 _r_debug_extended.r_ldbase. Return the address of _r_debug. */
53
54struct r_debug *
55_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
56{
57 struct r_debug_extended *r, **pp = NULL;
58
59 if (ns == LM_ID_BASE)
60 {
61 r = &_r_debug_extended;
62 /* Initialize r_version to 1. */
63 if (_r_debug_extended.base.r_version == 0)
64 _r_debug_extended.base.r_version = 1;
65 }
66 else if (DL_NNS > 1)
67 {
68 r = &GL(dl_ns)[ns]._ns_debug;
69 if (r->base.r_brk == 0)
70 {
71 /* Add the new namespace to the linked list. After a namespace
72 is initialized, r_brk becomes non-zero. A namespace becomes
73 empty (r_map == NULL) when it is unused. But it is never
74 removed from the linked list. */
75 struct r_debug_extended *p;
76 for (pp = &_r_debug_extended.r_next;
77 (p = *pp) != NULL;
78 pp = &p->r_next)
79 ;
80
81 r->base.r_version = 2;
82 }
83 }
84
85 if (r->base.r_brk == 0)
86 {
87 /* Tell the debugger where to find the map of loaded objects.
88 This function is called from dlopen. Initialize the namespace
89 only once. */
90 r->base.r_ldbase = ldbase ?: _r_debug_extended.base.r_ldbase;
91 r->base.r_brk = (ElfW(Addr)) &_dl_debug_state;
92 r->r_next = NULL;
93 }
94
95 if (r->base.r_map == NULL)
96 atomic_store_release (&r->base.r_map,
97 (void *) GL(dl_ns)[ns]._ns_loaded);
98
99 if (pp != NULL)
100 {
101 atomic_store_release (pp, r);
102 /* Bump r_version to 2 for the new namespace. */
103 atomic_store_release (&_r_debug_extended.base.r_version, 2);
104 }
105
106 return &r->base;
107}
108
109
110/* This function exists solely to have a breakpoint set on it by the
111 debugger. The debugger is supposed to find this function's address by
112 examining the r_brk member of struct r_debug, but GDB 4.15 in fact looks
113 for this particular symbol name in the PT_INTERP file. */
114void
115_dl_debug_state (void)
116{
117}
118rtld_hidden_def (_dl_debug_state)
119