1 /* Machine-dependent ELF dynamic relocation inline functions. Stub version.
2 Copyright (C) 1995-2023 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 #define ELF_MACHINE_NAME "stub"
20
21 #include <string.h>
22 #include <link.h>
23 #include <dl-static-tls.h>
24 #include <dl-machine-rel.h>
25
26
27 /* Return nonzero iff ELF header is compatible with the running host. */
28 static inline int
29 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
30 {
31 switch (ehdr->e_machine)
32 {
33 default:
34 return 0;
35 }
36 }
37
38
39 /* Return the link-time address of _DYNAMIC. */
40 static inline Elf32_Addr
41 elf_machine_dynamic (void)
42 {
43 #error "Damn, no _DYNAMIC"
44 }
45
46
47 /* Return the run-time load address of the shared object. */
48 static inline Elf32_Addr
49 elf_machine_load_address (void)
50 {
51 #error "Where am I?"
52 }
53
54 /* Fixup a PLT entry to bounce directly to the function at VALUE. */
55
56 static inline ElfW(Addr)
57 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
58 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
59 const ElfW(Rel) *reloc,
60 ElfW(Addr) *reloc_addr, ElfW(Addr) value)
61 {
62 return *reloc_addr = value;
63 }
64
65 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
66 LOADADDR is the load address of the object; INFO is an array indexed
67 by DT_* of the .dynamic section info. */
68
69 auto inline void
70 __attribute__ ((always_inline))
71 elf_machine_rel (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM],
72 const Elf32_Rel *reloc, const Elf32_Sym *sym,
73 Elf32_Addr (*resolve) (const Elf32_Sym **ref,
74 Elf32_Addr reloc_addr,
75 int noplt))
76 {
77 Elf32_Addr *const reloc_addr = (Elf32_Addr *) reloc->r_offset;
78 Elf32_Addr loadbase;
79
80 switch (ELF32_R_TYPE (reloc->r_info))
81 {
82 case R_MACHINE_COPY:
83 loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
84 memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
85 break;
86 default:
87 _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 0);
88 break;
89 }
90 }
91
92
93 auto inline Elf32_Addr
94 __attribute__ ((always_inline))
95 elf_machine_rela (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM],
96 const Elf32_Rel *reloc, const Elf32_Sym *sym,
97 Elf32_Addr (*resolve) (const Elf32_Sym **ref,
98 Elf32_Addr reloc_addr,
99 int noplt))
100 {
101 _dl_signal_error (0, "Elf32_Rela relocation requested -- unused on "
102 NULL, ELF_MACHINE_NAME);
103 }
104
105
106 /* Set up the loaded object described by L so its unrelocated PLT
107 entries will jump to the on-demand fixup code in dl-runtime.c. */
108
109 static inline int
110 elf_machine_runtime_setup (struct link_map *l, int lazy)
111 {
112 extern void _dl_runtime_resolve (Elf32_Word);
113
114 if (lazy)
115 {
116 /* The GOT entries for functions in the PLT have not yet been filled
117 in. Their initial contents will arrange when called to push an
118 offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
119 and then jump to _GLOBAL_OFFSET_TABLE[2]. */
120 Elf32_Addr *got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
121 got[1] = (Elf32_Addr) l; /* Identify this shared object. */
122
123 /* This function will get called to fix up the GOT entry indicated by
124 the offset on the stack, and then jump to the resolved address. */
125 got[2] = (Elf32_Addr) &_dl_runtime_resolve;
126 }
127
128 return lazy;
129 }
130
131
132 /* Initial entry point code for the dynamic linker.
133 The C function `_dl_start' is the real entry point;
134 its return value is the user program's entry point. */
135
136 #define RTLD_START #error need some startup code