1 /* Machine-dependent ELF dynamic relocation inline functions. m68k version.
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 #ifndef dl_machine_h
20 #define dl_machine_h
21
22 #define ELF_MACHINE_NAME "m68k"
23
24 #include <sys/param.h>
25 #include <sysdep.h>
26 #include <dl-tls.h>
27 #include <dl-static-tls.h>
28 #include <dl-machine-rel.h>
29
30 /* Return nonzero iff ELF header is compatible with the running host. */
31 static inline int
32 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
33 {
34 return ehdr->e_machine == EM_68K;
35 }
36
37
38 /* Return the link-time address of _DYNAMIC.
39 This must be inlined in a function which uses global data. */
40 static inline Elf32_Addr
41 elf_machine_dynamic (void)
42 {
43 Elf32_Addr addr;
44
45 asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
46 : "=a" (addr));
47 return addr;
48 }
49
50
51 /* Return the run-time load address of the shared object. */
52 static inline Elf32_Addr
53 elf_machine_load_address (void)
54 {
55 Elf32_Addr addr;
56 #ifdef SHARED
57 asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
58 "sub.l _dl_start@GOT.w(%%a5), %0"
59 : "=a" (addr));
60 #else
61 asm (PCREL_OP ("lea", "_dl_relocate_static_pie", "%0", "%0", "%%pc") "\n\t"
62 "sub.l _dl_relocate_static_pie@GOT.w(%%a5), %0"
63 : "=a" (addr));
64 #endif
65 return addr;
66 }
67
68
69 /* Set up the loaded object described by L so its unrelocated PLT
70 entries will jump to the on-demand fixup code in dl-runtime.c. */
71
72 static inline int __attribute__ ((always_inline))
73 elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
74 int lazy, int profile)
75 {
76 Elf32_Addr *got;
77 extern void _dl_runtime_resolve (Elf32_Word);
78 extern void _dl_runtime_profile (Elf32_Word);
79
80 if (l->l_info[DT_JMPREL] && lazy)
81 {
82 /* The GOT entries for functions in the PLT have not yet been
83 filled in. Their initial contents will arrange when called
84 to push an offset into the .rela.plt section, push
85 _GLOBAL_OFFSET_TABLE_[1], and then jump to
86 _GLOBAL_OFFSET_TABLE_[2]. */
87 got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
88 got[1] = (Elf32_Addr) l; /* Identify this shared object. */
89
90 /* The got[2] entry contains the address of a function which gets
91 called to get the address of a so far unresolved function and
92 jump to it. The profiling extension of the dynamic linker allows
93 to intercept the calls to collect information. In this case we
94 don't store the address in the GOT so that all future calls also
95 end in this function. */
96 if (profile)
97 {
98 got[2] = (Elf32_Addr) &_dl_runtime_profile;
99
100 if (GLRO(dl_profile) != NULL
101 && _dl_name_match_p (GLRO(dl_profile), l))
102 {
103 /* This is the object we are looking for. Say that we really
104 want profiling and the timers are started. */
105 GL(dl_profile_map) = l;
106 }
107 }
108 else
109 /* This function will get called to fix up the GOT entry indicated by
110 the offset on the stack, and then jump to the resolved address. */
111 got[2] = (Elf32_Addr) &_dl_runtime_resolve;
112 }
113
114 return lazy;
115 }
116
117 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
118 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
119
120
121 /* Mask identifying addresses reserved for the user program,
122 where the dynamic linker should not map anything. */
123 #define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
124
125 /* Initial entry point code for the dynamic linker.
126 The C function `_dl_start' is the real entry point;
127 its return value is the user program's entry point. */
128
129 #define RTLD_START asm ("\
130 .text\n\
131 .globl _start\n\
132 .type _start,@function\n\
133 _start:\n\
134 sub.l %fp, %fp\n\
135 move.l %sp, -(%sp)\n\
136 jbsr _dl_start\n\
137 addq.l #4, %sp\n\
138 /* FALLTHRU */\n\
139 \n\
140 .globl _dl_start_user\n\
141 .type _dl_start_user,@function\n\
142 _dl_start_user:\n\
143 | Save the user entry point address in %a4.\n\
144 move.l %d0, %a4\n\
145 | Load the adjusted argument count.\n\
146 move.l (%sp), %d1\n\
147 # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
148 pea 8(%sp, %d1*4)\n\
149 pea 8(%sp)\n\
150 move.l %d1, -(%sp)\n\
151 " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
152 jbsr _dl_init\n\
153 addq.l #8, %sp\n\
154 addq.l #8, %sp\n\
155 | Pass our finalizer function to the user in %a1.\n\
156 " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
157 | Initialize %fp with the stack pointer.\n\
158 move.l %sp, %fp\n\
159 | Jump to the user's entry point.\n\
160 jmp (%a4)\n\
161 .size _dl_start_user, . - _dl_start_user\n\
162 .previous");
163
164 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
165 TLS variable, so undefined references should not be allowed to
166 define the value.
167 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
168 of the main executable's symbols, as for a COPY reloc. */
169 #define elf_machine_type_class(type) \
170 ((((type) == R_68K_JMP_SLOT \
171 || (type) == R_68K_TLS_DTPMOD32 \
172 || (type) == R_68K_TLS_DTPREL32 \
173 || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT) \
174 | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
175
176 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
177 #define ELF_MACHINE_JMP_SLOT R_68K_JMP_SLOT
178
179 static inline Elf32_Addr
180 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
181 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
182 const Elf32_Rela *reloc,
183 Elf32_Addr *reloc_addr, Elf32_Addr value)
184 {
185 return *reloc_addr = value;
186 }
187
188 /* Return the final value of a plt relocation. On the m68k the JMP_SLOT
189 relocation ignores the addend. */
190 static inline Elf32_Addr
191 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
192 Elf32_Addr value)
193 {
194 return value;
195 }
196
197 /* Names of the architecture-specific auditing callback functions. */
198 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
199 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
200
201 #endif /* !dl_machine_h */
202
203 #ifdef RESOLVE_MAP
204
205 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
206 MAP is the object containing the reloc. */
207
208 static inline void __attribute__ ((unused, always_inline))
209 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
210 const Elf32_Rela *reloc, const Elf32_Sym *sym,
211 const struct r_found_version *version,
212 void *const reloc_addr_arg, int skip_ifunc)
213 {
214 Elf32_Addr *const reloc_addr = reloc_addr_arg;
215 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
216
217 if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
218 *reloc_addr = map->l_addr + reloc->r_addend;
219 else
220 {
221 const Elf32_Sym *const refsym = sym;
222 struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
223 r_type);
224 Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
225
226 switch (r_type)
227 {
228 case R_68K_GLOB_DAT:
229 case R_68K_JMP_SLOT:
230 *reloc_addr = value;
231 break;
232 #ifndef RTLD_BOOTSTRAP
233 case R_68K_COPY:
234 if (sym == NULL)
235 /* This can happen in trace mode if an object could not be
236 found. */
237 break;
238 if (sym->st_size > refsym->st_size
239 || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
240 {
241 const char *strtab;
242
243 strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
244 _dl_error_printf ("\
245 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
246 RTLD_PROGNAME, strtab + refsym->st_name);
247 }
248 memcpy (reloc_addr_arg, (void *) value,
249 MIN (sym->st_size, refsym->st_size));
250 break;
251 case R_68K_8:
252 *(char *) reloc_addr = value + reloc->r_addend;
253 break;
254 case R_68K_16:
255 *(short *) reloc_addr = value + reloc->r_addend;
256 break;
257 case R_68K_32:
258 *reloc_addr = value + reloc->r_addend;
259 break;
260 case R_68K_PC8:
261 *(char *) reloc_addr
262 = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
263 break;
264 case R_68K_PC16:
265 *(short *) reloc_addr
266 = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
267 break;
268 case R_68K_PC32:
269 *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
270 break;
271 case R_68K_TLS_DTPMOD32:
272 /* Get the information from the link map returned by the
273 resolv function. */
274 if (sym_map != NULL)
275 *reloc_addr = sym_map->l_tls_modid;
276 break;
277 case R_68K_TLS_DTPREL32:
278 if (sym != NULL)
279 *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
280 break;
281 case R_68K_TLS_TPREL32:
282 if (sym != NULL)
283 {
284 CHECK_STATIC_TLS (map, sym_map);
285 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
286 }
287 break;
288 case R_68K_NONE: /* Alright, Wilbur. */
289 break;
290 #endif /* !RTLD_BOOTSTRAP */
291 default:
292 _dl_reloc_bad_type (map, r_type, 0);
293 break;
294 }
295 }
296 }
297
298 static inline void __attribute__ ((unused, always_inline))
299 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
300 void *const reloc_addr_arg)
301 {
302 Elf32_Addr *const reloc_addr = reloc_addr_arg;
303 *reloc_addr = l_addr + reloc->r_addend;
304 }
305
306 static inline void __attribute__ ((unused, always_inline))
307 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
308 Elf32_Addr l_addr, const Elf32_Rela *reloc,
309 int skip_ifunc)
310 {
311 Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
312 if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
313 *reloc_addr += l_addr;
314 else
315 _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
316 }
317
318 #endif /* RESOLVE_MAP */