1 /* Machine-dependent ELF dynamic relocation inline functions. S390 Version.
2 Copyright (C) 2000-2021 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 "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 # See if we were run as a command with the executable file\n\
190 # name as an extra leading argument.\n\
191 l %r1,_dl_skip_args@GOT(%r12)\n\
192 l %r1,0(%r1) # load _dl_skip_args\n\
193 ltr %r1,%r1\n\
194 je 4f # Skip the arg adjustment if there were none.\n\
195 # Get the original argument count.\n\
196 l %r0,96(%r15)\n\
197 # Subtract _dl_skip_args from it.\n\
198 sr %r0,%r1\n\
199 # Store back the modified argument count.\n\
200 st %r0,96(%r15)\n\
201 # Copy argv and envp forward to account for skipped argv entries.\n\
202 # We skipped at least one argument or we would not get here.\n\
203 la %r6,100(%r15) # Destination pointer i.e. &argv[0]\n\
204 lr %r5,%r6\n\
205 lr %r0,%r1\n\
206 sll %r0,2\n # Number of skipped bytes.\n\
207 ar %r5,%r0 # Source pointer = Dest + Skipped args.\n\
208 # argv copy loop:\n\
209 1: l %r7,0(%r5) # Load a word from the source.\n\
210 st %r7,0(%r6) # Store the word in the destination.\n\
211 ahi %r5,4\n\
212 ahi %r6,4\n\
213 ltr %r7,%r7\n\
214 jne 1b # Stop after copying the NULL.\n\
215 # envp copy loop:\n\
216 2: l %r7,0(%r5) # Load a word from the source.\n\
217 st %r7,0(%r6) # Store the word in the destination.\n\
218 ahi %r5,4\n\
219 ahi %r6,4\n\
220 ltr %r7,%r7\n\
221 jne 2b # Stop after copying the NULL.\n\
222 # Now we have to zero out the envp entries after NULL to allow\n\
223 # start.S to properly find auxv by skipping zeroes.\n\
224 # zero out loop:\n\
225 lhi %r7,0\n\
226 3: st %r7,0(%r6) # Store zero.\n\
227 ahi %r6,4 # Advance dest pointer.\n\
228 ahi %r1,-1 # Subtract one from the word count.\n\
229 ltr %r1,%r1\n\
230 jne 3b # Keep copying if the word count is non-zero.\n\
231 # Adjust _dl_argv\n\
232 la %r6,100(%r15)\n\
233 l %r1,_dl_argv@GOT(%r12)\n\
234 st %r6,0(%r1)\n\
235 # The special initializer gets called with the stack just\n\
236 # as the application's entry point will see it; it can\n\
237 # switch stacks if it moves these contents over.\n\
238 " RTLD_START_SPECIAL_INIT "\n\
239 # Call the function to run the initializers.\n\
240 # Load the parameters:\n\
241 # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
242 4: l %r2,_rtld_local@GOT(%r12)\n\
243 l %r2,0(%r2)\n\
244 l %r3,96(%r15)\n\
245 la %r4,100(%r15)\n\
246 lr %r5,%r3\n\
247 sll %r5,2\n\
248 la %r5,104(%r5,%r15)\n\
249 l %r1,.Ladr4-.Llit(%r13)\n\
250 bas %r14,0(%r1,%r13)\n\
251 # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
252 l %r14,_dl_fini@GOT(%r12)\n\
253 # Free stack frame\n\
254 ahi %r15,96\n\
255 # Jump to the user's entry point (saved in %r8).\n\
256 br %r8\n\
257 .Llit:\n\
258 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
259 .Ladr1: .long _dl_start-.Llit\n\
260 .Ladr4: .long _dl_init@PLT-.Llit\n\
261 ");
262
263 #ifndef RTLD_START_SPECIAL_INIT
264 #define RTLD_START_SPECIAL_INIT /* nothing */
265 #endif
266
267 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
268 TLS variable, so undefined references should not be allowed to
269 define the value.
270 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
271 of the main executable's symbols, as for a COPY reloc. */
272 #define elf_machine_type_class(type) \
273 ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD \
274 || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF) \
275 * ELF_RTYPE_CLASS_PLT) \
276 | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
277
278 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
279 #define ELF_MACHINE_JMP_SLOT R_390_JMP_SLOT
280
281 /* We define an initialization functions. This is called very early in
282 _dl_sysdep_start. */
283 #define DL_PLATFORM_INIT dl_platform_init ()
284
285 static inline void __attribute__ ((unused))
dl_platform_init(void)286 dl_platform_init (void)
287 {
288 if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
289 /* Avoid an empty string which would disturb us. */
290 GLRO(dl_platform) = NULL;
291 }
292
293 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)294 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
295 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
296 const Elf32_Rela *reloc,
297 Elf32_Addr *reloc_addr, Elf32_Addr value)
298 {
299 return *reloc_addr = value;
300 }
301
302 /* Return the final value of a plt relocation. */
303 static inline Elf32_Addr
elf_machine_plt_value(struct link_map * map,const Elf32_Rela * reloc,Elf32_Addr value)304 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
305 Elf32_Addr value)
306 {
307 return value;
308 }
309
310 /* Names of the architecture-specific auditing callback functions. */
311 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
312 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
313
314 #endif /* !dl_machine_h */
315
316
317 #ifdef RESOLVE_MAP
318
319 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
320 MAP is the object containing the reloc. */
321
322 static inline void
323 __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)324 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
325 const Elf32_Rela *reloc, const Elf32_Sym *sym,
326 const struct r_found_version *version,
327 void *const reloc_addr_arg, int skip_ifunc)
328 {
329 Elf32_Addr *const reloc_addr = reloc_addr_arg;
330 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
331
332 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
333 if (__glibc_unlikely (r_type == R_390_RELATIVE))
334 {
335 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
336 /* This is defined in rtld.c, but nowhere in the static libc.a;
337 make the reference weak so static programs can still link.
338 This declaration cannot be done when compiling rtld.c
339 (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
340 common defn for _dl_rtld_map, which is incompatible with a
341 weak decl in the same file. */
342 # ifndef SHARED
343 weak_extern (GL(dl_rtld_map));
344 # endif
345 if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
346 # endif
347 *reloc_addr = map->l_addr + reloc->r_addend;
348 }
349 else
350 #endif
351 if (__glibc_unlikely (r_type == R_390_NONE))
352 return;
353 else
354 {
355 #if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
356 /* Only needed for R_390_COPY below. */
357 const Elf32_Sym *const refsym = sym;
358 #endif
359 struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
360 r_type);
361 Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
362
363 if (sym != NULL
364 && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
365 && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
366 && __builtin_expect (!skip_ifunc, 1))
367 value = elf_ifunc_invoke (value);
368
369 switch (r_type)
370 {
371 case R_390_IRELATIVE:
372 value = map->l_addr + reloc->r_addend;
373 if (__glibc_likely (!skip_ifunc))
374 value = elf_ifunc_invoke (value);
375 *reloc_addr = value;
376 break;
377
378 case R_390_GLOB_DAT:
379 case R_390_JMP_SLOT:
380 *reloc_addr = value + reloc->r_addend;
381 break;
382
383 #ifndef RESOLVE_CONFLICT_FIND_MAP
384 case R_390_TLS_DTPMOD:
385 # ifdef RTLD_BOOTSTRAP
386 /* During startup the dynamic linker is always the module
387 with index 1.
388 XXX If this relocation is necessary move before RESOLVE
389 call. */
390 *reloc_addr = 1;
391 # else
392 /* Get the information from the link map returned by the
393 resolv function. */
394 if (sym_map != NULL)
395 *reloc_addr = sym_map->l_tls_modid;
396 # endif
397 break;
398 case R_390_TLS_DTPOFF:
399 # ifndef RTLD_BOOTSTRAP
400 /* During relocation all TLS symbols are defined and used.
401 Therefore the offset is already correct. */
402 if (sym != NULL)
403 *reloc_addr = sym->st_value + reloc->r_addend;
404 # endif
405 break;
406 case R_390_TLS_TPOFF:
407 /* The offset is negative, forward from the thread pointer. */
408 # ifdef RTLD_BOOTSTRAP
409 *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
410 # else
411 /* We know the offset of the object the symbol is contained in.
412 It is a negative value which will be added to the
413 thread pointer. */
414 if (sym != NULL)
415 {
416 CHECK_STATIC_TLS (map, sym_map);
417 *reloc_addr = (sym->st_value + reloc->r_addend
418 - sym_map->l_tls_offset);
419 }
420 #endif
421 break;
422 #endif /* use TLS */
423
424 #ifndef RTLD_BOOTSTRAP
425 # ifndef RESOLVE_CONFLICT_FIND_MAP
426 /* Not needed in dl-conflict.c. */
427 case R_390_COPY:
428 if (sym == NULL)
429 /* This can happen in trace mode if an object could not be
430 found. */
431 break;
432 if (__builtin_expect (sym->st_size > refsym->st_size, 0)
433 || (__builtin_expect (sym->st_size < refsym->st_size, 0)
434 && __builtin_expect (GLRO(dl_verbose), 0)))
435 {
436 const char *strtab;
437
438 strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
439 _dl_error_printf ("\
440 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
441 RTLD_PROGNAME, strtab + refsym->st_name);
442 }
443 memcpy (reloc_addr_arg, (void *) value,
444 MIN (sym->st_size, refsym->st_size));
445 break;
446 # endif
447 case R_390_32:
448 *reloc_addr = value + reloc->r_addend;
449 break;
450 case R_390_16:
451 *(unsigned short *) reloc_addr = value + reloc->r_addend;
452 break;
453 case R_390_8:
454 *(char *) reloc_addr = value + reloc->r_addend;
455 break;
456 # ifndef RESOLVE_CONFLICT_FIND_MAP
457 case R_390_PC32:
458 *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
459 break;
460 case R_390_PC16DBL:
461 *(unsigned short *) reloc_addr = (unsigned short)
462 ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
463 break;
464 case R_390_PC32DBL:
465 *(unsigned int *) reloc_addr = (unsigned int)
466 ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
467 break;
468 case R_390_PC16:
469 *(unsigned short *) reloc_addr =
470 value + reloc->r_addend - (Elf32_Addr) reloc_addr;
471 break;
472 case R_390_NONE:
473 break;
474 # endif
475 #endif
476 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
477 default:
478 /* We add these checks in the version to relocate ld.so only
479 if we are still debugging. */
480 _dl_reloc_bad_type (map, r_type, 0);
481 break;
482 #endif
483 }
484 }
485 }
486
487 static inline void
488 __attribute__ ((always_inline))
elf_machine_rela_relative(Elf32_Addr l_addr,const Elf32_Rela * reloc,void * const reloc_addr_arg)489 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
490 void *const reloc_addr_arg)
491 {
492 Elf32_Addr *const reloc_addr = reloc_addr_arg;
493 *reloc_addr = l_addr + reloc->r_addend;
494 }
495
496 static inline void
497 __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)498 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
499 Elf32_Addr l_addr, const Elf32_Rela *reloc,
500 int skip_ifunc)
501 {
502 Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
503 const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
504 /* Check for unexpected PLT reloc type. */
505 if (__glibc_likely (r_type == R_390_JMP_SLOT))
506 {
507 if (__builtin_expect (map->l_mach.plt, 0) == 0)
508 *reloc_addr += l_addr;
509 else
510 *reloc_addr = map->l_mach.plt + (reloc - map->l_mach.jmprel) * 32;
511 }
512 else if (__glibc_likely (r_type == R_390_IRELATIVE))
513 {
514 Elf32_Addr value = map->l_addr + reloc->r_addend;
515 if (__glibc_likely (!skip_ifunc))
516 value = elf_ifunc_invoke (value);
517 *reloc_addr = value;
518 }
519 else
520 _dl_reloc_bad_type (map, r_type, 1);
521 }
522
523 #endif /* RESOLVE_MAP */
524