1 /* Machine-dependent ELF dynamic relocation inline functions. S390 Version.
2 Copyright (C) 2000-2022 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 "s390"
23
24 #include <sys/param.h>
25 #include <string.h>
26 #include <link.h>
27 #include <sysdeps/s390/dl-procinfo.h>
28 #include <dl-irel.h>
29 #include <dl-static-tls.h>
30 #include <dl-machine-rel.h>
31
32 /* This is an older, now obsolete value. */
33 #define EM_S390_OLD 0xA390
34
35 /* Return nonzero iff ELF header is compatible with the running host. */
36 static inline int
elf_machine_matches_host(const Elf32_Ehdr * ehdr)37 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
38 {
39 /* Check if the kernel provides the high gpr facility if needed by
40 the binary. */
41 if ((ehdr->e_flags & EF_S390_HIGH_GPRS)
42 && !(GLRO (dl_hwcap) & HWCAP_S390_HIGH_GPRS))
43 return 0;
44
45 return (ehdr->e_machine == EM_S390 || ehdr->e_machine == EM_S390_OLD)
46 && ehdr->e_ident[EI_CLASS] == ELFCLASS32;
47 }
48
49
50 /* Return the link-time address of _DYNAMIC. Conveniently, this is the
51 first element of the GOT. This must be inlined in a function which
52 uses global data. */
53
54 static inline Elf32_Addr
elf_machine_dynamic(void)55 elf_machine_dynamic (void)
56 {
57 register Elf32_Addr *got;
58
59 __asm__( " bras %0,2f\n"
60 "1: .long _GLOBAL_OFFSET_TABLE_-1b\n"
61 "2: al %0,0(%0)"
62 : "=&a" (got) : : "0" );
63
64 return *got;
65 }
66
67
68 /* Return the run-time load address of the shared object. */
69 static inline Elf32_Addr
elf_machine_load_address(void)70 elf_machine_load_address (void)
71 {
72 Elf32_Addr addr;
73
74 __asm__( " bras 1,2f\n"
75 "1: .long _GLOBAL_OFFSET_TABLE_ - 1b\n"
76 " .long (_dl_start - 1b - 0x80000000) & 0x00000000ffffffff\n"
77 "2: l %0,4(1)\n"
78 " ar %0,1\n"
79 " al 1,0(1)\n"
80 " sl %0,_dl_start@GOT(1)"
81 : "=&d" (addr) : : "1" );
82 return addr;
83 }
84
85 /* Set up the loaded object described by L so its unrelocated PLT
86 entries will jump to the on-demand fixup code in dl-runtime.c. */
87
88 static inline int __attribute__ ((unused))
elf_machine_runtime_setup(struct link_map * l,struct r_scope_elem * scope[],int lazy,int profile)89 elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
90 int lazy, int profile)
91 {
92 extern void _dl_runtime_resolve (Elf32_Word);
93 extern void _dl_runtime_profile (Elf32_Word);
94 #if defined HAVE_S390_VX_ASM_SUPPORT
95 extern void _dl_runtime_resolve_vx (Elf32_Word);
96 extern void _dl_runtime_profile_vx (Elf32_Word);
97 #endif
98
99
100 if (l->l_info[DT_JMPREL] && lazy)
101 {
102 /* The GOT entries for functions in the PLT have not yet been filled
103 in. Their initial contents will arrange when called to push an
104 offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
105 and then jump to _GLOBAL_OFFSET_TABLE[2]. */
106 Elf32_Addr *got;
107 got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
108 /* If a library is prelinked but we have to relocate anyway,
109 we have to be able to undo the prelinking of .got.plt.
110 The prelinker saved us here address of .plt + 0x2c. */
111 if (got[1])
112 {
113 l->l_mach.plt = got[1] + l->l_addr;
114 l->l_mach.jmprel = (const Elf32_Rela *) D_PTR (l, l_info[DT_JMPREL]);
115 }
116 got[1] = (Elf32_Addr) l; /* Identify this shared object. */
117
118 /* The got[2] entry contains the address of a function which gets
119 called to get the address of a so far unresolved function and
120 jump to it. The profiling extension of the dynamic linker allows
121 to intercept the calls to collect information. In this case we
122 don't store the address in the GOT so that all future calls also
123 end in this function. */
124 if (__glibc_unlikely (profile))
125 {
126 #if defined HAVE_S390_VX_ASM_SUPPORT
127 if (GLRO(dl_hwcap) & HWCAP_S390_VX)
128 got[2] = (Elf32_Addr) &_dl_runtime_profile_vx;
129 else
130 got[2] = (Elf32_Addr) &_dl_runtime_profile;
131 #else
132 got[2] = (Elf32_Addr) &_dl_runtime_profile;
133 #endif
134
135 if (GLRO(dl_profile) != NULL
136 && _dl_name_match_p (GLRO(dl_profile), l))
137 /* This is the object we are looking for. Say that we really
138 want profiling and the timers are started. */
139 GL(dl_profile_map) = l;
140 }
141 else
142 {
143 /* This function will get called to fix up the GOT entry indicated by
144 the offset on the stack, and then jump to the resolved address. */
145 #if defined HAVE_S390_VX_ASM_SUPPORT
146 if (GLRO(dl_hwcap) & HWCAP_S390_VX)
147 got[2] = (Elf32_Addr) &_dl_runtime_resolve_vx;
148 else
149 got[2] = (Elf32_Addr) &_dl_runtime_resolve;
150 #else
151 got[2] = (Elf32_Addr) &_dl_runtime_resolve;
152 #endif
153 }
154 }
155
156 return lazy;
157 }
158
159 /* Mask identifying addresses reserved for the user program,
160 where the dynamic linker should not map anything. */
161 #define ELF_MACHINE_USER_ADDRESS_MASK 0xf8000000UL
162
163 /* Initial entry point code for the dynamic linker.
164 The C function `_dl_start' is the real entry point;
165 its return value is the user program's entry point. */
166
167 #define RTLD_START __asm__ ("\n\
168 .text\n\
169 .align 4\n\
170 .globl _start\n\
171 .globl _dl_start_user\n\
172 _start:\n\
173 basr %r13,0\n\
174 0: ahi %r13,.Llit-0b\n\
175 lr %r2,%r15\n\
176 # Alloc stack frame\n\
177 ahi %r15,-96\n\
178 # Set the back chain to zero\n\
179 xc 0(4,%r15),0(%r15)\n\
180 # Call _dl_start with %r2 pointing to arg on stack\n\
181 l %r14,.Ladr1-.Llit(%r13)\n\
182 bas %r14,0(%r14,%r13) # call _dl_start\n\
183 _dl_start_user:\n\
184 # Save the user entry point address in %r8.\n\
185 lr %r8,%r2\n\
186 # Point %r12 at the GOT.\n\
187 l %r12,.Ladr0-.Llit(%r13)\n\
188 ar %r12,%r13\n\
189 # The special initializer gets called with the stack just\n\
190 # as the application's entry point will see it; it can\n\
191 # switch stacks if it moves these contents over.\n\
192 " RTLD_START_SPECIAL_INIT "\n\
193 # Call the function to run the initializers.\n\
194 # Load the parameters:\n\
195 # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
196 4: l %r2,_rtld_local@GOT(%r12)\n\
197 l %r2,0(%r2)\n\
198 l %r3,96(%r15)\n\
199 la %r4,100(%r15)\n\
200 lr %r5,%r3\n\
201 sll %r5,2\n\
202 la %r5,104(%r5,%r15)\n\
203 l %r1,.Ladr4-.Llit(%r13)\n\
204 bas %r14,0(%r1,%r13)\n\
205 # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
206 l %r14,_dl_fini@GOT(%r12)\n\
207 # Free stack frame\n\
208 ahi %r15,96\n\
209 # Jump to the user's entry point (saved in %r8).\n\
210 br %r8\n\
211 .Llit:\n\
212 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
213 .Ladr1: .long _dl_start-.Llit\n\
214 .Ladr4: .long _dl_init@PLT-.Llit\n\
215 ");
216
217 #ifndef RTLD_START_SPECIAL_INIT
218 #define RTLD_START_SPECIAL_INIT /* nothing */
219 #endif
220
221 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
222 TLS variable, so undefined references should not be allowed to
223 define the value.
224 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
225 of the main executable's symbols, as for a COPY reloc. */
226 #define elf_machine_type_class(type) \
227 ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD \
228 || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF) \
229 * ELF_RTYPE_CLASS_PLT) \
230 | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
231
232 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
233 #define ELF_MACHINE_JMP_SLOT R_390_JMP_SLOT
234
235 /* We define an initialization functions. This is called very early in
236 _dl_sysdep_start. */
237 #define DL_PLATFORM_INIT dl_platform_init ()
238
239 static inline void __attribute__ ((unused))
dl_platform_init(void)240 dl_platform_init (void)
241 {
242 if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
243 /* Avoid an empty string which would disturb us. */
244 GLRO(dl_platform) = NULL;
245 }
246
247 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)248 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
249 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
250 const Elf32_Rela *reloc,
251 Elf32_Addr *reloc_addr, Elf32_Addr value)
252 {
253 return *reloc_addr = value;
254 }
255
256 /* Return the final value of a plt relocation. */
257 static inline Elf32_Addr
elf_machine_plt_value(struct link_map * map,const Elf32_Rela * reloc,Elf32_Addr value)258 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
259 Elf32_Addr value)
260 {
261 return value;
262 }
263
264 /* Names of the architecture-specific auditing callback functions. */
265 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
266 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
267
268 #endif /* !dl_machine_h */
269
270
271 #ifdef RESOLVE_MAP
272
273 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
274 MAP is the object containing the reloc. */
275
276 static inline void
277 __attribute__ ((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)278 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
279 const Elf32_Rela *reloc, const Elf32_Sym *sym,
280 const struct r_found_version *version,
281 void *const reloc_addr_arg, int skip_ifunc)
282 {
283 Elf32_Addr *const reloc_addr = reloc_addr_arg;
284 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
285
286 #if !defined RTLD_BOOTSTRAP
287 if (__glibc_unlikely (r_type == R_390_RELATIVE))
288 *reloc_addr = map->l_addr + reloc->r_addend;
289 else
290 #endif
291 if (__glibc_unlikely (r_type == R_390_NONE))
292 return;
293 else
294 {
295 #if !defined RTLD_BOOTSTRAP
296 /* Only needed for R_390_COPY below. */
297 const Elf32_Sym *const refsym = sym;
298 #endif
299 struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
300 r_type);
301 Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
302
303 if (sym != NULL
304 && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
305 && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
306 && __builtin_expect (!skip_ifunc, 1))
307 value = elf_ifunc_invoke (value);
308
309 switch (r_type)
310 {
311 case R_390_IRELATIVE:
312 value = map->l_addr + reloc->r_addend;
313 if (__glibc_likely (!skip_ifunc))
314 value = elf_ifunc_invoke (value);
315 *reloc_addr = value;
316 break;
317
318 case R_390_GLOB_DAT:
319 case R_390_JMP_SLOT:
320 *reloc_addr = value + reloc->r_addend;
321 break;
322
323 case R_390_TLS_DTPMOD:
324 #ifdef RTLD_BOOTSTRAP
325 /* During startup the dynamic linker is always the module
326 with index 1.
327 XXX If this relocation is necessary move before RESOLVE
328 call. */
329 *reloc_addr = 1;
330 #else
331 /* Get the information from the link map returned by the
332 resolv function. */
333 if (sym_map != NULL)
334 *reloc_addr = sym_map->l_tls_modid;
335 #endif
336 break;
337 case R_390_TLS_DTPOFF:
338 #ifndef RTLD_BOOTSTRAP
339 /* During relocation all TLS symbols are defined and used.
340 Therefore the offset is already correct. */
341 if (sym != NULL)
342 *reloc_addr = sym->st_value + reloc->r_addend;
343 #endif
344 break;
345 case R_390_TLS_TPOFF:
346 /* The offset is negative, forward from the thread pointer. */
347 #ifdef RTLD_BOOTSTRAP
348 *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
349 #else
350 /* We know the offset of the object the symbol is contained in.
351 It is a negative value which will be added to the
352 thread pointer. */
353 if (sym != NULL)
354 {
355 CHECK_STATIC_TLS (map, sym_map);
356 *reloc_addr = (sym->st_value + reloc->r_addend
357 - sym_map->l_tls_offset);
358 }
359 #endif
360 break;
361
362 #ifndef RTLD_BOOTSTRAP
363 /* Not needed in dl-conflict.c. */
364 case R_390_COPY:
365 if (sym == NULL)
366 /* This can happen in trace mode if an object could not be
367 found. */
368 break;
369 if (__builtin_expect (sym->st_size > refsym->st_size, 0)
370 || (__builtin_expect (sym->st_size < refsym->st_size, 0)
371 && __builtin_expect (GLRO(dl_verbose), 0)))
372 {
373 const char *strtab;
374
375 strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
376 _dl_error_printf ("\
377 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
378 RTLD_PROGNAME, strtab + refsym->st_name);
379 }
380 memcpy (reloc_addr_arg, (void *) value,
381 MIN (sym->st_size, refsym->st_size));
382 break;
383 case R_390_32:
384 *reloc_addr = value + reloc->r_addend;
385 break;
386 case R_390_16:
387 *(unsigned short *) reloc_addr = value + reloc->r_addend;
388 break;
389 case R_390_8:
390 *(char *) reloc_addr = value + reloc->r_addend;
391 break;
392 case R_390_PC32:
393 *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
394 break;
395 case R_390_PC16DBL:
396 *(unsigned short *) reloc_addr = (unsigned short)
397 ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
398 break;
399 case R_390_PC32DBL:
400 *(unsigned int *) reloc_addr = (unsigned int)
401 ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
402 break;
403 case R_390_PC16:
404 *(unsigned short *) reloc_addr =
405 value + reloc->r_addend - (Elf32_Addr) reloc_addr;
406 break;
407 case R_390_NONE:
408 break;
409 #endif
410 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
411 default:
412 /* We add these checks in the version to relocate ld.so only
413 if we are still debugging. */
414 _dl_reloc_bad_type (map, r_type, 0);
415 break;
416 #endif
417 }
418 }
419 }
420
421 static inline void
422 __attribute__ ((always_inline))
elf_machine_rela_relative(Elf32_Addr l_addr,const Elf32_Rela * reloc,void * const reloc_addr_arg)423 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
424 void *const reloc_addr_arg)
425 {
426 Elf32_Addr *const reloc_addr = reloc_addr_arg;
427 *reloc_addr = l_addr + reloc->r_addend;
428 }
429
430 static inline void
431 __attribute__ ((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)432 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
433 Elf32_Addr l_addr, const Elf32_Rela *reloc,
434 int skip_ifunc)
435 {
436 Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
437 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
438 /* Check for unexpected PLT reloc type. */
439 if (__glibc_likely (r_type == R_390_JMP_SLOT))
440 {
441 if (__builtin_expect (map->l_mach.plt, 0) == 0)
442 *reloc_addr += l_addr;
443 else
444 *reloc_addr = map->l_mach.plt + (reloc - map->l_mach.jmprel) * 32;
445 }
446 else if (__glibc_likely (r_type == R_390_IRELATIVE))
447 {
448 Elf32_Addr value = map->l_addr + reloc->r_addend;
449 if (__glibc_likely (!skip_ifunc))
450 value = elf_ifunc_invoke (value);
451 *reloc_addr = value;
452 }
453 else
454 _dl_reloc_bad_type (map, r_type, 1);
455 }
456
457 #endif /* RESOLVE_MAP */
458