1 /* Machine-dependent ELF dynamic relocation inline functions. S390 Version.
2 Copyright (C) 2000, 2001 Free Software Foundation, Inc.
3 Contributed by Carl Pederson & Martin Schwidefsky.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
25 #define ELF_MACHINE_NAME "s390"
27 #include <sys/param.h>
31 /* This is an older, now obsolete value. */
32 #define EM_S390_OLD 0xA390
34 /* Return nonzero iff ELF header is compatible with the running host. */
36 elf_machine_matches_host (const Elf32_Ehdr
*ehdr
)
38 return (ehdr
->e_machine
== EM_S390
|| ehdr
->e_machine
== EM_S390_OLD
)
39 && ehdr
->e_ident
[EI_CLASS
] == ELFCLASS32
;
43 /* Return the link-time address of _DYNAMIC. Conveniently, this is the
44 first element of the GOT. This must be inlined in a function which
47 static inline Elf32_Addr
48 elf_machine_dynamic (void)
50 register Elf32_Addr
*got
;
53 "1: .long _GLOBAL_OFFSET_TABLE_-1b\n"
55 : "=&a" (got
) : : "0" );
61 /* Return the run-time load address of the shared object. */
62 static inline Elf32_Addr
63 elf_machine_load_address (void)
68 "1: .long _GLOBAL_OFFSET_TABLE_ - 1b\n"
69 " .long _dl_start - 1b - 0x80000000\n"
73 " sl %0,_dl_start@GOT12(1)"
74 : "=&d" (addr
) : : "1" );
78 /* Set up the loaded object described by L so its unrelocated PLT
79 entries will jump to the on-demand fixup code in dl-runtime.c. */
81 static inline int __attribute__ ((unused
))
82 elf_machine_runtime_setup (struct link_map
*l
, int lazy
, int profile
)
84 extern void _dl_runtime_resolve (Elf32_Word
);
85 extern void _dl_runtime_profile (Elf32_Word
);
87 if (l
->l_info
[DT_JMPREL
] && lazy
)
89 /* The GOT entries for functions in the PLT have not yet been filled
90 in. Their initial contents will arrange when called to push an
91 offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
92 and then jump to _GLOBAL_OFFSET_TABLE[2]. */
94 got
= (Elf32_Addr
*) D_PTR (l
, l_info
[DT_PLTGOT
]);
95 got
[1] = (Elf32_Addr
) l
; /* Identify this shared object. */
97 /* The got[2] entry contains the address of a function which gets
98 called to get the address of a so far unresolved function and
99 jump to it. The profiling extension of the dynamic linker allows
100 to intercept the calls to collect information. In this case we
101 don't store the address in the GOT so that all future calls also
102 end in this function. */
103 if (__builtin_expect (profile
, 0))
105 got
[2] = (Elf32_Addr
) &_dl_runtime_profile
;
107 if (_dl_name_match_p (_dl_profile
, l
))
108 /* This is the object we are looking for. Say that we really
109 want profiling and the timers are started. */
113 /* This function will get called to fix up the GOT entry indicated by
114 the offset on the stack, and then jump to the resolved address. */
115 got
[2] = (Elf32_Addr
) &_dl_runtime_resolve
;
121 /* This code is used in dl-runtime.c to call the `fixup' function
122 and then redirect to the address it returns. */
125 Arguments are in register.
126 r2 - r7 holds the original parameters for the function call, fixup
127 and trampoline code use r0-r5 and r14-15. For the correct function
128 call r2-r5 and r14-15 must be restored.
129 Arguments from the PLT are stored at 24(r15) and 28(r15)
130 and must be moved to r2 and r3 for the fixup call (see elf32-s390.c
131 in the binutils for the PLT code).
132 Fixup function address in r2.
135 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
138 .globl _dl_runtime_resolve\n\
139 .type _dl_runtime_resolve, @function\n\
141 _dl_runtime_resolve:\n\
148 # load args saved by PLT\n\
153 bas 14,0(14,1) # call fixup\n\
154 lr 1,2 # function addr returned in r2\n\
155 # restore registers\n\
161 .size _dl_runtime_resolve, .-_dl_runtime_resolve\n\
163 .globl _dl_runtime_profile\n\
164 .type _dl_runtime_profile, @function\n\
166 _dl_runtime_profile:\n\
173 # load args saved by PLT\n\
175 # load return address as third parameter\n\
180 bas 14,0(14,1) # call fixup\n\
181 lr 1,2 # function addr returned in r2\n\
182 # restore registers\n\
187 1: .long profile_fixup-1b\n\
188 .size _dl_runtime_profile, .-_dl_runtime_profile\n\
191 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
194 .globl _dl_runtime_resolve\n\
195 .globl _dl_runtime_profile\n\
196 .type _dl_runtime_resolve, @function\n\
197 .type _dl_runtime_profile, @function\n\
199 _dl_runtime_resolve:\n\
200 _dl_runtime_profile:\n\
207 # load args saved by PLT\n\
209 # load return address as third parameter\n\
214 bas 14,0(14,1) # call fixup\n\
215 lr 1,2 # function addr returned in r2\n\
216 # restore registers\n\
222 .size _dl_runtime_resolve, .-_dl_runtime_resolve\n\
223 .size _dl_runtime_profile, .-_dl_runtime_profile\n\
227 /* Mask identifying addresses reserved for the user program,
228 where the dynamic linker should not map anything. */
229 #define ELF_MACHINE_USER_ADDRESS_MASK 0xf8000000UL
231 /* Initial entry point code for the dynamic linker.
232 The C function `_dl_start' is the real entry point;
233 its return value is the user program's entry point. */
235 #define RTLD_START asm ("\n\
239 .globl _dl_start_user\n\
242 .L0: ahi %r13,.Llit-.L0\n\
244 # Alloc stack frame\n\
246 # Set the back chain to zero\n\
247 xc 0(4,%r15),0(%r15)\n\
248 # Call _dl_start with %r2 pointing to arg on stack\n\
249 l %r14,.Ladr1-.Llit(%r13)\n\
250 bas %r14,0(%r14,%r13) # call _dl_start\n\
252 # Save the user entry point address in %r8.\n\
254 # Point %r12 at the GOT.\n\
255 l %r12,.Ladr0-.Llit(%r13)\n\
257 # Store the highest stack address\n\
258 l %r1,__libc_stack_end@GOT(%r12)\n\
260 # See if we were run as a command with the executable file\n\
261 # name as an extra leading argument.\n\
262 l %r1,_dl_skip_args@GOT12(0,%r12)\n\
263 l %r1,0(%r1) # load _dl_skip_args\n\
264 # Get the original argument count.\n\
266 # Subtract _dl_skip_args from it.\n\
268 # Adjust the stack pointer to skip _dl_skip_args words.\n\
271 # Set the back chain to zero again\n\
272 xc 0(4,%r15),0(%r15)\n\
273 # Store back the modified argument count.\n\
275 # The special initializer gets called with the stack just\n\
276 # as the application's entry point will see it; it can\n\
277 # switch stacks if it moves these contents over.\n\
278 " RTLD_START_SPECIAL_INIT "\n\
279 # Call the function to run the initializers.\n\
280 # Load the parameters:\n\
281 # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
282 l %r2,_dl_loaded@GOT(%r12)\n\
288 la %r5,104(%r5,%r15)\n\
289 l %r1,.Ladr4-.Llit(%r13)\n\
290 bas %r14,0(%r1,%r13)\n\
291 # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
292 l %r14,_dl_fini@GOT(%r12)\n\
293 # Free stack frame\n\
295 # Jump to the user's entry point (saved in %r8).\n\
298 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
299 .Ladr1: .long _dl_start-.Llit\n\
300 .Ladr4: .long _dl_init@PLT-.Llit\n\
303 #ifndef RTLD_START_SPECIAL_INIT
304 #define RTLD_START_SPECIAL_INIT /* nothing */
307 /* Nonzero iff TYPE should not be allowed to resolve to one of
308 the main executable's symbols, as for a COPY reloc. */
309 #define elf_machine_lookup_noexec_p(type) ((type) == R_390_COPY)
311 /* Nonzero iff TYPE describes relocation of a PLT entry, so
312 PLT entries should not be allowed to define the value. */
313 #define elf_machine_lookup_noplt_p(type) ((type) == R_390_JMP_SLOT)
315 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
316 #define ELF_MACHINE_JMP_SLOT R_390_JMP_SLOT
318 /* The S390 never uses Elf32_Rel relocations. */
319 #define ELF_MACHINE_NO_REL 1
321 /* The S390 overlaps DT_RELA and DT_PLTREL. */
322 #define ELF_MACHINE_PLTREL_OVERLAP 1
324 /* We define an initialization functions. This is called very early in
326 #define DL_PLATFORM_INIT dl_platform_init ()
328 extern const char *_dl_platform
;
330 static inline void __attribute__ ((unused
))
331 dl_platform_init (void)
333 if (_dl_platform
!= NULL
&& *_dl_platform
== '\0')
334 /* Avoid an empty string which would disturb us. */
338 static inline Elf32_Addr
339 elf_machine_fixup_plt (struct link_map
*map
, lookup_t t
,
340 const Elf32_Rela
*reloc
,
341 Elf32_Addr
*reloc_addr
, Elf32_Addr value
)
343 return *reloc_addr
= value
;
346 /* Return the final value of a plt relocation. */
347 static inline Elf32_Addr
348 elf_machine_plt_value (struct link_map
*map
, const Elf32_Rela
*reloc
,
354 #endif /* !dl_machine_h */
359 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
360 MAP is the object containing the reloc. */
363 elf_machine_rela (struct link_map
*map
, const Elf32_Rela
*reloc
,
364 const Elf32_Sym
*sym
, const struct r_found_version
*version
,
365 Elf32_Addr
*const reloc_addr
)
367 const unsigned int r_type
= ELF32_R_TYPE (reloc
->r_info
);
369 if (__builtin_expect (r_type
== R_390_RELATIVE
, 0))
370 *reloc_addr
= map
->l_addr
+ reloc
->r_addend
;
371 #ifndef RTLD_BOOTSTRAP
372 else if (__builtin_expect (r_type
== R_390_NONE
, 0))
377 const Elf32_Sym
*const refsym
= sym
;
378 Elf32_Addr value
= RESOLVE (&sym
, version
, r_type
);
380 value
+= sym
->st_value
;
386 /* This can happen in trace mode if an object could not be
389 if (__builtin_expect (sym
->st_size
> refsym
->st_size
, 0)
390 || (__builtin_expect (sym
->st_size
< refsym
->st_size
, 0)
391 && __builtin_expect (_dl_verbose
, 0)))
395 strtab
= (const char *) D_PTR(map
,l_info
[DT_STRTAB
]);
397 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
398 _dl_argv
[0] ?: "<program name unknown>",
399 strtab
+ refsym
->st_name
);
401 memcpy (reloc_addr
, (void *) value
, MIN (sym
->st_size
,
410 #ifndef RTLD_BOOTSTRAP
411 /* This is defined in rtld.c, but nowhere in the static
412 libc.a; make the reference weak so static programs can
413 still link. This declaration cannot be done when
414 compiling rtld.c (i.e. #ifdef RTLD_BOOTSTRAP) because
415 rtld.c contains the common defn for _dl_rtld_map, which
416 is incompatible with a weak decl in the same file. */
417 weak_extern (_dl_rtld_map
);
418 if (map
== &_dl_rtld_map
)
419 /* Undo the relocation done here during bootstrapping.
420 Now we will relocate it anew, possibly using a
421 binding found in the user program or a loaded library
422 rather than the dynamic linker's built-in definitions
423 used while loading those libraries. */
424 value
-= map
->l_addr
+ refsym
->st_value
;
426 *reloc_addr
= value
+ reloc
->r_addend
;
431 *reloc_addr
= value
+ reloc
->r_addend
- (Elf32_Addr
) reloc_addr
;
436 _dl_reloc_bad_type (map
, r_type
, 0);
443 elf_machine_rela_relative (Elf32_Addr l_addr
, const Elf32_Rela
*reloc
,
444 Elf32_Addr
*const reloc_addr
)
446 *reloc_addr
= l_addr
+ reloc
->r_addend
;
450 elf_machine_lazy_rel (struct link_map
*map
,
451 Elf32_Addr l_addr
, const Elf32_Rela
*reloc
)
453 Elf32_Addr
*const reloc_addr
= (void *) (l_addr
+ reloc
->r_offset
);
454 const unsigned int r_type
= ELF32_R_TYPE (reloc
->r_info
);
455 /* Check for unexpected PLT reloc type. */
456 if (__builtin_expect (r_type
== R_390_JMP_SLOT
, 1)))
457 *reloc_addr
+= l_addr
;
459 _dl_reloc_bad_type (map
, r_type
, 1);