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1 | /* Machine-dependent ELF dynamic relocation inline functions. RISC-V version. |
---|---|
2 | Copyright (C) 2011-2022 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 "RISC-V" |
23 | |
24 | #include <entry.h> |
25 | #include <elf/elf.h> |
26 | #include <sys/asm.h> |
27 | #include <dl-tls.h> |
28 | #include <dl-irel.h> |
29 | #include <dl-static-tls.h> |
30 | #include <dl-machine-rel.h> |
31 | |
32 | #ifndef _RTLD_PROLOGUE |
33 | # define _RTLD_PROLOGUE(entry) \ |
34 | ".globl\t" __STRING (entry) "\n\t" \ |
35 | ".type\t" __STRING (entry) ", @function\n" \ |
36 | __STRING (entry) ":\n\t" |
37 | #endif |
38 | |
39 | #ifndef _RTLD_EPILOGUE |
40 | # define _RTLD_EPILOGUE(entry) \ |
41 | ".size\t" __STRING (entry) ", . - " __STRING (entry) "\n\t" |
42 | #endif |
43 | |
44 | #define ELF_MACHINE_JMP_SLOT R_RISCV_JUMP_SLOT |
45 | |
46 | #define elf_machine_type_class(type) \ |
47 | ((ELF_RTYPE_CLASS_PLT * ((type) == ELF_MACHINE_JMP_SLOT \ |
48 | || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_DTPREL32) \ |
49 | || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_DTPMOD32) \ |
50 | || (__WORDSIZE == 32 && (type) == R_RISCV_TLS_TPREL32) \ |
51 | || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_DTPREL64) \ |
52 | || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_DTPMOD64) \ |
53 | || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_TPREL64))) \ |
54 | | (ELF_RTYPE_CLASS_COPY * ((type) == R_RISCV_COPY))) |
55 | |
56 | /* Return nonzero iff ELF header is compatible with the running host. */ |
57 | static inline int __attribute_used__ |
58 | elf_machine_matches_host (const ElfW(Ehdr) *ehdr) |
59 | { |
60 | /* We can only run RISC-V binaries. */ |
61 | if (ehdr->e_machine != EM_RISCV) |
62 | return 0; |
63 | |
64 | /* Ensure the library's floating-point ABI matches that of the running |
65 | system. For now we don't support mixing XLEN, so there's no need (or way) |
66 | to check it matches. */ |
67 | #ifdef __riscv_float_abi_double |
68 | if ((ehdr->e_flags & EF_RISCV_FLOAT_ABI) != EF_RISCV_FLOAT_ABI_DOUBLE) |
69 | return 0; |
70 | #else |
71 | if ((ehdr->e_flags & EF_RISCV_FLOAT_ABI) != EF_RISCV_FLOAT_ABI_SOFT) |
72 | return 0; |
73 | #endif |
74 | |
75 | return 1; |
76 | } |
77 | |
78 | /* Return the run-time load address of the shared object. */ |
79 | static inline ElfW(Addr) |
80 | elf_machine_load_address (void) |
81 | { |
82 | extern const ElfW(Ehdr) __ehdr_start attribute_hidden; |
83 | return (ElfW(Addr)) &__ehdr_start; |
84 | } |
85 | |
86 | /* Return the link-time address of _DYNAMIC. */ |
87 | static inline ElfW(Addr) |
88 | elf_machine_dynamic (void) |
89 | { |
90 | extern ElfW(Dyn) _DYNAMIC[] attribute_hidden; |
91 | return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address (); |
92 | } |
93 | |
94 | #define STRINGXP(X) __STRING (X) |
95 | #define STRINGXV(X) STRINGV_ (X) |
96 | #define STRINGV_(...) # __VA_ARGS__ |
97 | |
98 | /* Initial entry point code for the dynamic linker. |
99 | The C function `_dl_start' is the real entry point; |
100 | its return value is the user program's entry point. */ |
101 | |
102 | #define RTLD_START asm (\ |
103 | ".text\n\ |
104 | " _RTLD_PROLOGUE (ENTRY_POINT) "\ |
105 | mv a0, sp\n\ |
106 | jal _dl_start\n\ |
107 | " _RTLD_PROLOGUE (_dl_start_user) "\ |
108 | # Stash user entry point in s0.\n\ |
109 | mv s0, a0\n\ |
110 | # See if we were run as a command with the executable file\n\ |
111 | # name as an extra leading argument.\n\ |
112 | lw a0, _dl_skip_args\n\ |
113 | # Load the original argument count.\n\ |
114 | " STRINGXP (REG_L) " a1, 0(sp)\n\ |
115 | # Subtract _dl_skip_args from it.\n\ |
116 | sub a1, a1, a0\n\ |
117 | # Adjust the stack pointer to skip _dl_skip_args words.\n\ |
118 | sll a0, a0, " STRINGXP (PTRLOG) "\n\ |
119 | add sp, sp, a0\n\ |
120 | # Save back the modified argument count.\n\ |
121 | " STRINGXP (REG_S) " a1, 0(sp)\n\ |
122 | # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env) \n\ |
123 | " STRINGXP (REG_L) " a0, _rtld_local\n\ |
124 | add a2, sp, " STRINGXP (SZREG) "\n\ |
125 | sll a3, a1, " STRINGXP (PTRLOG) "\n\ |
126 | add a3, a3, a2\n\ |
127 | add a3, a3, " STRINGXP (SZREG) "\n\ |
128 | # Stash the stack pointer in s1.\n\ |
129 | mv s1, sp\n\ |
130 | # Align stack to 128 bits for the _dl_init call.\n\ |
131 | andi sp, sp,-16\n\ |
132 | # Call the function to run the initializers.\n\ |
133 | jal _dl_init\n\ |
134 | # Restore the stack pointer for _start.\n\ |
135 | mv sp, s1\n\ |
136 | # Pass our finalizer function to _start.\n\ |
137 | lla a0, _dl_fini\n\ |
138 | # Jump to the user entry point.\n\ |
139 | jr s0\n\ |
140 | " _RTLD_EPILOGUE (ENTRY_POINT) \ |
141 | _RTLD_EPILOGUE (_dl_start_user) "\ |
142 | .previous" \ |
143 | ); |
144 | |
145 | /* Names of the architecture-specific auditing callback functions. */ |
146 | #define ARCH_LA_PLTENTER riscv_gnu_pltenter |
147 | #define ARCH_LA_PLTEXIT riscv_gnu_pltexit |
148 | |
149 | /* Bias .got.plt entry by the offset requested by the PLT header. */ |
150 | #define elf_machine_plt_value(map, reloc, value) (value) |
151 | |
152 | static inline ElfW(Addr) |
153 | elf_machine_fixup_plt (struct link_map *map, lookup_t t, |
154 | const ElfW(Sym) *refsym, const ElfW(Sym) *sym, |
155 | const ElfW(Rela) *reloc, |
156 | ElfW(Addr) *reloc_addr, ElfW(Addr) value) |
157 | { |
158 | return *reloc_addr = value; |
159 | } |
160 | |
161 | #endif /* !dl_machine_h */ |
162 | |
163 | #ifdef RESOLVE_MAP |
164 | |
165 | /* Perform a relocation described by R_INFO at the location pointed to |
166 | by RELOC_ADDR. SYM is the relocation symbol specified by R_INFO and |
167 | MAP is the object containing the reloc. */ |
168 | |
169 | static inline void |
170 | __attribute__ ((always_inline)) |
171 | elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[], |
172 | const ElfW(Rela) *reloc, const ElfW(Sym) *sym, |
173 | const struct r_found_version *version, |
174 | void *const reloc_addr, int skip_ifunc) |
175 | { |
176 | ElfW(Addr) r_info = reloc->r_info; |
177 | const unsigned long int r_type = ELFW (R_TYPE) (r_info); |
178 | ElfW(Addr) *addr_field = (ElfW(Addr) *) reloc_addr; |
179 | const ElfW(Sym) *const __attribute__ ((unused)) refsym = sym; |
180 | struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version, r_type); |
181 | ElfW(Addr) value = 0; |
182 | if (sym_map != NULL) |
183 | value = SYMBOL_ADDRESS (sym_map, sym, true) + reloc->r_addend; |
184 | |
185 | if (sym != NULL |
186 | && __glibc_unlikely (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC) |
187 | && __glibc_likely (sym->st_shndx != SHN_UNDEF) |
188 | && __glibc_likely (!skip_ifunc)) |
189 | value = elf_ifunc_invoke (value); |
190 | |
191 | |
192 | switch (r_type) |
193 | { |
194 | #ifndef RTLD_BOOTSTRAP |
195 | case __WORDSIZE == 64 ? R_RISCV_TLS_DTPMOD64 : R_RISCV_TLS_DTPMOD32: |
196 | if (sym_map) |
197 | *addr_field = sym_map->l_tls_modid; |
198 | break; |
199 | |
200 | case __WORDSIZE == 64 ? R_RISCV_TLS_DTPREL64 : R_RISCV_TLS_DTPREL32: |
201 | if (sym != NULL) |
202 | *addr_field = TLS_DTPREL_VALUE (sym) + reloc->r_addend; |
203 | break; |
204 | |
205 | case __WORDSIZE == 64 ? R_RISCV_TLS_TPREL64 : R_RISCV_TLS_TPREL32: |
206 | if (sym != NULL) |
207 | { |
208 | CHECK_STATIC_TLS (map, sym_map); |
209 | *addr_field = TLS_TPREL_VALUE (sym_map, sym) + reloc->r_addend; |
210 | } |
211 | break; |
212 | |
213 | case R_RISCV_COPY: |
214 | { |
215 | if (__glibc_unlikely (sym == NULL)) |
216 | /* This can happen in trace mode if an object could not be |
217 | found. */ |
218 | break; |
219 | |
220 | /* Handle TLS copy relocations. */ |
221 | if (__glibc_unlikely (ELFW (ST_TYPE) (sym->st_info) == STT_TLS)) |
222 | { |
223 | /* There's nothing to do if the symbol is in .tbss. */ |
224 | if (__glibc_likely (sym->st_value >= sym_map->l_tls_initimage_size)) |
225 | break; |
226 | value += (ElfW(Addr)) sym_map->l_tls_initimage - sym_map->l_addr; |
227 | } |
228 | |
229 | size_t size = sym->st_size; |
230 | if (__glibc_unlikely (sym->st_size != refsym->st_size)) |
231 | { |
232 | const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); |
233 | if (sym->st_size > refsym->st_size) |
234 | size = refsym->st_size; |
235 | if (sym->st_size > refsym->st_size || GLRO(dl_verbose)) |
236 | _dl_error_printf ("\ |
237 | %s: Symbol `%s' has different size in shared object, consider re-linking\n", |
238 | rtld_progname ?: "<program name unknown>", |
239 | strtab + refsym->st_name); |
240 | } |
241 | |
242 | memcpy (reloc_addr, (void *)value, size); |
243 | break; |
244 | } |
245 | #endif |
246 | |
247 | #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC |
248 | case R_RISCV_RELATIVE: |
249 | { |
250 | # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC |
251 | /* This is defined in rtld.c, but nowhere in the static libc.a; |
252 | make the reference weak so static programs can still link. |
253 | This declaration cannot be done when compiling rtld.c |
254 | (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the |
255 | common defn for _dl_rtld_map, which is incompatible with a |
256 | weak decl in the same file. */ |
257 | # ifndef SHARED |
258 | weak_extern (GL(dl_rtld_map)); |
259 | # endif |
260 | if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */ |
261 | # endif |
262 | *addr_field = map->l_addr + reloc->r_addend; |
263 | break; |
264 | } |
265 | #endif |
266 | |
267 | case R_RISCV_IRELATIVE: |
268 | value = map->l_addr + reloc->r_addend; |
269 | if (__glibc_likely (!skip_ifunc)) |
270 | value = elf_ifunc_invoke (value); |
271 | *addr_field = value; |
272 | break; |
273 | |
274 | case R_RISCV_JUMP_SLOT: |
275 | case __WORDSIZE == 64 ? R_RISCV_64 : R_RISCV_32: |
276 | *addr_field = value; |
277 | break; |
278 | |
279 | case R_RISCV_NONE: |
280 | break; |
281 | |
282 | default: |
283 | _dl_reloc_bad_type (map, r_type, 0); |
284 | break; |
285 | } |
286 | } |
287 | |
288 | static inline void |
289 | __attribute__ ((always_inline)) |
290 | elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
291 | void *const reloc_addr) |
292 | { |
293 | *(ElfW(Addr) *) reloc_addr = l_addr + reloc->r_addend; |
294 | } |
295 | |
296 | static inline void |
297 | __attribute__ ((always_inline)) |
298 | elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], |
299 | ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
300 | int skip_ifunc) |
301 | { |
302 | ElfW(Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset); |
303 | const unsigned int r_type = ELFW (R_TYPE) (reloc->r_info); |
304 | |
305 | /* Check for unexpected PLT reloc type. */ |
306 | if (__glibc_likely (r_type == R_RISCV_JUMP_SLOT)) |
307 | { |
308 | if (__glibc_unlikely (map->l_mach.plt == 0)) |
309 | { |
310 | if (l_addr) |
311 | *reloc_addr += l_addr; |
312 | } |
313 | else |
314 | *reloc_addr = map->l_mach.plt; |
315 | } |
316 | else if (__glibc_unlikely (r_type == R_RISCV_IRELATIVE)) |
317 | { |
318 | ElfW(Addr) value = map->l_addr + reloc->r_addend; |
319 | if (__glibc_likely (!skip_ifunc)) |
320 | value = elf_ifunc_invoke (value); |
321 | *reloc_addr = value; |
322 | } |
323 | else |
324 | _dl_reloc_bad_type (map, r_type, 1); |
325 | } |
326 | |
327 | /* Set up the loaded object described by L so its stub function |
328 | will jump to the on-demand fixup code __dl_runtime_resolve. */ |
329 | |
330 | static inline int |
331 | __attribute__ ((always_inline)) |
332 | elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[], |
333 | int lazy, int profile) |
334 | { |
335 | #ifndef RTLD_BOOTSTRAP |
336 | /* If using PLTs, fill in the first two entries of .got.plt. */ |
337 | if (l->l_info[DT_JMPREL]) |
338 | { |
339 | extern void _dl_runtime_resolve (void) __attribute__ ((visibility ("hidden"))); |
340 | ElfW(Addr) *gotplt = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]); |
341 | /* If a library is prelinked but we have to relocate anyway, |
342 | we have to be able to undo the prelinking of .got.plt. |
343 | The prelinker saved the address of .plt for us here. */ |
344 | if (gotplt[1]) |
345 | l->l_mach.plt = gotplt[1] + l->l_addr; |
346 | gotplt[0] = (ElfW(Addr)) &_dl_runtime_resolve; |
347 | gotplt[1] = (ElfW(Addr)) l; |
348 | } |
349 | |
350 | if (l->l_type == lt_executable) |
351 | { |
352 | /* The __global_pointer$ may not be defined by the linker if the |
353 | $gp register does not be used to access the global variable |
354 | in the executable program. Therefore, the search symbol is |
355 | set to a weak symbol to avoid we error out if the |
356 | __global_pointer$ is not found. */ |
357 | ElfW(Sym) gp_sym = { 0 }; |
358 | gp_sym.st_info = (unsigned char) ELFW (ST_INFO (STB_WEAK, STT_NOTYPE)); |
359 | |
360 | const ElfW(Sym) *ref = &gp_sym; |
361 | _dl_lookup_symbol_x ("__global_pointer$", l, &ref, |
362 | l->l_scope, NULL, 0, 0, NULL); |
363 | if (ref) |
364 | asm ( |
365 | "mv gp, %0\n" |
366 | : |
367 | : "r" (ref->st_value) |
368 | ); |
369 | } |
370 | #endif |
371 | return lazy; |
372 | } |
373 | |
374 | #endif /* RESOLVE_MAP */ |
375 |
Warning: This file is not a C or C++ file. It does not have highlighting.