1 /* Machine-dependent ELF dynamic relocation inline functions. m68k version.
2 Copyright (C) 1996-2021 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
elf_machine_matches_host(const Elf32_Ehdr * ehdr)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
elf_machine_dynamic(void)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
elf_machine_load_address(void)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))
elf_machine_runtime_setup(struct link_map * l,struct r_scope_elem * scope[],int lazy,int profile)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 | See if we were run as a command with the executable file\n\
146 | name as an extra leading argument.\n\
147 " PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
148 | Pop the original argument count\n\
149 move.l (%sp)+, %d1\n\
150 | Subtract _dl_skip_args from it.\n\
151 sub.l %d0, %d1\n\
152 | Adjust the stack pointer to skip _dl_skip_args words.\n\
153 lea (%sp, %d0*4), %sp\n\
154 | Push back the modified argument count.\n\
155 move.l %d1, -(%sp)\n\
156 # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
157 pea 8(%sp, %d1*4)\n\
158 pea 8(%sp)\n\
159 move.l %d1, -(%sp)\n\
160 " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
161 jbsr _dl_init\n\
162 addq.l #8, %sp\n\
163 addq.l #8, %sp\n\
164 | Pass our finalizer function to the user in %a1.\n\
165 " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
166 | Initialize %fp with the stack pointer.\n\
167 move.l %sp, %fp\n\
168 | Jump to the user's entry point.\n\
169 jmp (%a4)\n\
170 .size _dl_start_user, . - _dl_start_user\n\
171 .previous");
172
173 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
174 TLS variable, so undefined references should not be allowed to
175 define the value.
176 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
177 of the main executable's symbols, as for a COPY reloc. */
178 #define elf_machine_type_class(type) \
179 ((((type) == R_68K_JMP_SLOT \
180 || (type) == R_68K_TLS_DTPMOD32 \
181 || (type) == R_68K_TLS_DTPREL32 \
182 || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT) \
183 | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
184
185 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
186 #define ELF_MACHINE_JMP_SLOT R_68K_JMP_SLOT
187
188 static inline Elf32_Addr
elf_machine_fixup_plt(struct link_map * map,lookup_t t,const ElfW (Sym)* refsym,const ElfW (Sym)* sym,const Elf32_Rela * reloc,Elf32_Addr * reloc_addr,Elf32_Addr value)189 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
190 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
191 const Elf32_Rela *reloc,
192 Elf32_Addr *reloc_addr, Elf32_Addr value)
193 {
194 return *reloc_addr = value;
195 }
196
197 /* Return the final value of a plt relocation. On the m68k the JMP_SLOT
198 relocation ignores the addend. */
199 static inline Elf32_Addr
elf_machine_plt_value(struct link_map * map,const Elf32_Rela * reloc,Elf32_Addr value)200 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
201 Elf32_Addr value)
202 {
203 return value;
204 }
205
206 /* Names of the architecture-specific auditing callback functions. */
207 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
208 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
209
210 #endif /* !dl_machine_h */
211
212 #ifdef RESOLVE_MAP
213
214 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
215 MAP is the object containing the reloc. */
216
217 static inline void __attribute__ ((unused, always_inline))
elf_machine_rela(struct link_map * map,struct r_scope_elem * scope[],const Elf32_Rela * reloc,const Elf32_Sym * sym,const struct r_found_version * version,void * const reloc_addr_arg,int skip_ifunc)218 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
219 const Elf32_Rela *reloc, const Elf32_Sym *sym,
220 const struct r_found_version *version,
221 void *const reloc_addr_arg, int skip_ifunc)
222 {
223 Elf32_Addr *const reloc_addr = reloc_addr_arg;
224 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
225
226 if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
227 *reloc_addr = map->l_addr + reloc->r_addend;
228 else
229 {
230 const Elf32_Sym *const refsym = sym;
231 struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
232 r_type);
233 Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
234
235 switch (r_type)
236 {
237 case R_68K_COPY:
238 if (sym == NULL)
239 /* This can happen in trace mode if an object could not be
240 found. */
241 break;
242 if (sym->st_size > refsym->st_size
243 || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
244 {
245 const char *strtab;
246
247 strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
248 _dl_error_printf ("\
249 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
250 RTLD_PROGNAME, strtab + refsym->st_name);
251 }
252 memcpy (reloc_addr_arg, (void *) value,
253 MIN (sym->st_size, refsym->st_size));
254 break;
255 case R_68K_GLOB_DAT:
256 case R_68K_JMP_SLOT:
257 *reloc_addr = value;
258 break;
259 case R_68K_8:
260 *(char *) reloc_addr = value + reloc->r_addend;
261 break;
262 case R_68K_16:
263 *(short *) reloc_addr = value + reloc->r_addend;
264 break;
265 case R_68K_32:
266 *reloc_addr = value + reloc->r_addend;
267 break;
268 case R_68K_PC8:
269 *(char *) reloc_addr
270 = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
271 break;
272 case R_68K_PC16:
273 *(short *) reloc_addr
274 = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
275 break;
276 case R_68K_PC32:
277 *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
278 break;
279 #ifndef RTLD_BOOTSTRAP
280 case R_68K_TLS_DTPMOD32:
281 /* Get the information from the link map returned by the
282 resolv function. */
283 if (sym_map != NULL)
284 *reloc_addr = sym_map->l_tls_modid;
285 break;
286 case R_68K_TLS_DTPREL32:
287 if (sym != NULL)
288 *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
289 break;
290 case R_68K_TLS_TPREL32:
291 if (sym != NULL)
292 {
293 CHECK_STATIC_TLS (map, sym_map);
294 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
295 }
296 break;
297 #endif /* !RTLD_BOOTSTRAP */
298 case R_68K_NONE: /* Alright, Wilbur. */
299 break;
300 default:
301 _dl_reloc_bad_type (map, r_type, 0);
302 break;
303 }
304 }
305 }
306
307 static inline void __attribute__ ((unused, always_inline))
elf_machine_rela_relative(Elf32_Addr l_addr,const Elf32_Rela * reloc,void * const reloc_addr_arg)308 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
309 void *const reloc_addr_arg)
310 {
311 Elf32_Addr *const reloc_addr = reloc_addr_arg;
312 *reloc_addr = l_addr + reloc->r_addend;
313 }
314
315 static inline void __attribute__ ((unused, always_inline))
elf_machine_lazy_rel(struct link_map * map,struct r_scope_elem * scope[],Elf32_Addr l_addr,const Elf32_Rela * reloc,int skip_ifunc)316 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
317 Elf32_Addr l_addr, const Elf32_Rela *reloc,
318 int skip_ifunc)
319 {
320 Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
321 if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
322 *reloc_addr += l_addr;
323 else
324 _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
325 }
326
327 #endif /* RESOLVE_MAP */
328