1 /* Interface for libebl.
2 Copyright (C) 2000-2010, 2013, 2014, 2015, 2016, 2017 Red Hat, Inc.
3 This file is part of elfutils.
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
8 * the GNU Lesser General Public License as published by the Free
9 Software Foundation; either version 3 of the License, or (at
10 your option) any later version
14 * the GNU General Public License as published by the Free
15 Software Foundation; either version 2 of the License, or (at
16 your option) any later version
18 or both in parallel, as here.
20 elfutils is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
25 You should have received copies of the GNU General Public License and
26 the GNU Lesser General Public License along with this program. If
27 not, see <http://www.gnu.org/licenses/>. */
30 /* This is the interface for the Elfutils Backend Library.
31 It is a completely UNSUPPORTED interface. Don't use any libebl
32 function directly. These are only for internal elfutils backends
33 and tools. There is NO source or binary compatible guarantee.
35 The ABI of the backend modules is not guaranteed. Really, no guarantee
36 whatsoever. We are enforcing this in the code. The modules and their
37 users must match. No third-party EBL module are supported or allowed.
38 The only reason there are separate modules is to not have the code for
39 all architectures in all the binaries. */
51 #include "elf-knowledge.h"
54 /* Opaque type for the handle. */
55 typedef struct ebl Ebl;
62 /* Get backend handle for object associated with ELF handle. */
63 extern Ebl *ebl_openbackend (Elf *elf);
64 /* Similar but without underlying ELF file. */
65 extern Ebl *ebl_openbackend_machine (GElf_Half machine);
66 /* Similar but with emulation name given. */
67 extern Ebl *ebl_openbackend_emulation (const char *emulation);
69 /* Free resources allocated for backend handle. */
70 extern void ebl_closebackend (Ebl *bh);
73 /* Information about the descriptor. */
75 /* Get ELF machine. */
76 extern int ebl_get_elfmachine (Ebl *ebl) __pure_attribute__;
79 extern int ebl_get_elfclass (Ebl *ebl) __pure_attribute__;
81 /* Get ELF data encoding. */
82 extern int ebl_get_elfdata (Ebl *ebl) __pure_attribute__;
85 /* Function to call the callback functions including default ELF
88 /* Return backend name. */
89 extern const char *ebl_backend_name (Ebl *ebl);
91 /* Return relocation type name. */
92 extern const char *ebl_reloc_type_name (Ebl *ebl, int reloc,
93 char *buf, size_t len);
95 /* Check relocation type. */
96 extern bool ebl_reloc_type_check (Ebl *ebl, int reloc);
98 /* Check relocation type use. */
99 extern bool ebl_reloc_valid_use (Ebl *ebl, int reloc);
101 /* Check if relocation type is for simple absolute relocations.
102 Return ELF_T_{BYTE,HALF,SWORD,SXWORD} for a simple type, else ELF_T_NUM.
103 If the relocation type is an ADD or SUB relocation, set *ADDSUB to 1 or -1,
105 extern Elf_Type ebl_reloc_simple_type (Ebl *ebl, int reloc, int *addsub);
107 /* Return true if the symbol type is that referencing the GOT. E.g.,
109 extern bool ebl_gotpc_reloc_check (Ebl *ebl, int reloc);
111 /* Return segment type name. */
112 extern const char *ebl_segment_type_name (Ebl *ebl, int segment,
113 char *buf, size_t len);
115 /* Return section type name. */
116 extern const char *ebl_section_type_name (Ebl *ebl, int section,
117 char *buf, size_t len);
119 /* Return section name. */
120 extern const char *ebl_section_name (Ebl *ebl, int section, int xsection,
121 char *buf, size_t len,
122 const char *scnnames[], size_t shnum);
124 /* Return machine flag names. */
125 extern const char *ebl_machine_flag_name (Ebl *ebl, GElf_Word flags,
126 char *buf, size_t len);
128 /* Check whether machine flag is valid. */
129 extern bool ebl_machine_flag_check (Ebl *ebl, GElf_Word flags);
131 /* Check whether SHF_MASKPROC flags are valid. */
132 extern bool ebl_machine_section_flag_check (Ebl *ebl, GElf_Xword flags);
134 /* Check whether the section with the given index, header, and name
135 is a special machine section that is valid despite a combination
136 of flags or other details that are not generically valid. */
137 extern bool ebl_check_special_section (Ebl *ebl, int ndx,
138 const GElf_Shdr *shdr, const char *name);
140 /* Return symbol type name. */
141 extern const char *ebl_symbol_type_name (Ebl *ebl, int symbol,
142 char *buf, size_t len);
144 /* Return symbol binding name. */
145 extern const char *ebl_symbol_binding_name (Ebl *ebl, int binding,
146 char *buf, size_t len);
148 /* Return dynamic tag name. */
149 extern const char *ebl_dynamic_tag_name (Ebl *ebl, int64_t tag,
150 char *buf, size_t len);
152 /* Check dynamic tag. */
153 extern bool ebl_dynamic_tag_check (Ebl *ebl, int64_t tag);
155 /* Check whether given symbol's st_value and st_size are OK despite failing
157 extern bool ebl_check_special_symbol (Ebl *ebl,
158 const GElf_Sym *sym, const char *name,
159 const GElf_Shdr *destshdr);
161 /* Check if this is a data marker symbol. e.g. '$d' symbols for ARM. */
162 extern bool ebl_data_marker_symbol (Ebl *ebl, const GElf_Sym *sym,
165 /* Check whether only valid bits are set on the st_other symbol flag. */
166 extern bool ebl_check_st_other_bits (Ebl *ebl, unsigned char st_other);
168 /* Return symbolic representation of OS ABI. */
169 extern const char *ebl_osabi_name (Ebl *ebl, int osabi, char *buf, size_t len);
172 /* Return name of the note section type for a core file. */
173 extern const char *ebl_core_note_type_name (Ebl *ebl, uint32_t type, char *buf,
176 /* Return name of the note section type for an object file. */
177 extern const char *ebl_object_note_type_name (Ebl *ebl, const char *name,
178 uint32_t type, char *buf,
181 /* Print information about object note if available. */
182 extern void ebl_object_note (Ebl *ebl, const char *name, uint32_t type,
183 uint32_t descsz, const char *desc);
185 /* Check whether an attribute in a .gnu_attributes section is recognized.
186 Fills in *TAG_NAME with the name for this tag.
187 If VALUE is a known value for that tag, also fills in *VALUE_NAME. */
188 extern bool ebl_check_object_attribute (Ebl *ebl, const char *vendor,
189 int tag, uint64_t value,
190 const char **tag_name,
191 const char **value_name);
193 /* Check whether a section type is a valid reloc target. */
194 extern bool ebl_check_reloc_target_type (Ebl *ebl, Elf64_Word sh_type);
197 /* Check section name for being that of a debug informatino section. */
198 extern bool ebl_debugscn_p (Ebl *ebl, const char *name);
200 /* Check whether given relocation is a copy relocation. */
201 extern bool ebl_copy_reloc_p (Ebl *ebl, int reloc);
203 /* Check whether given relocation is a no-op relocation. */
204 extern bool ebl_none_reloc_p (Ebl *ebl, int reloc);
206 /* Check whether given relocation is a relative relocation. */
207 extern bool ebl_relative_reloc_p (Ebl *ebl, int reloc);
209 /* Check whether section should be stripped. */
210 extern bool ebl_section_strip_p (Ebl *ebl,
211 const GElf_Shdr *shdr, const char *name,
212 bool remove_comment, bool only_remove_debug);
214 /* Check if backend uses a bss PLT in this file. */
215 extern bool ebl_bss_plt_p (Ebl *ebl);
217 /* Return size of entry in SysV-style hash table. */
218 extern int ebl_sysvhash_entrysize (Ebl *ebl);
220 /* Return location expression to find return value given a
221 DW_TAG_subprogram, DW_TAG_subroutine_type, or similar DIE describing
222 function itself (whose DW_AT_type attribute describes its return type).
223 Returns -1 for a libdw error (see dwarf_errno).
224 Returns -2 for an unrecognized type formation.
225 Returns zero if the function has no return value (e.g. "void" in C).
226 Otherwise, *LOCOPS gets a location expression to find the return value,
227 and returns the number of operations in the expression. The pointer is
228 permanently allocated at least as long as the Ebl handle is open. */
229 extern int ebl_return_value_location (Ebl *ebl,
230 Dwarf_Die *functypedie,
231 const Dwarf_Op **locops);
233 /* Fill in register information given DWARF register numbers.
234 If NAME is null, return the maximum REGNO + 1 that has a name.
235 Otherwise, store in NAME the name for DWARF register number REGNO
236 and return the number of bytes written (including '\0' terminator).
237 Return -1 if NAMELEN is too short or REGNO is negative or too large.
238 Return 0 if REGNO is unused (a gap in the DWARF number assignment).
239 On success, set *SETNAME to a description like "integer" or "FPU"
240 fit for "%s registers" title display, and *PREFIX to the string
241 that precedes NAME in canonical assembler syntax (e.g. "%" or "$").
242 The NAME string contains identifier characters only (maybe just digits). */
243 extern ssize_t ebl_register_info (Ebl *ebl,
244 int regno, char *name, size_t namelen,
245 const char **prefix, const char **setname,
246 int *bits, int *type);
248 /* Fill in the DWARF register numbers for the registers used in system calls.
249 The SP and PC are what kernel reports call the user stack pointer and PC.
250 The CALLNO and ARGS are the system call number and incoming arguments.
251 Each of these is filled with the DWARF register number corresponding,
252 or -1 if there is none. Returns zero when the information is available. */
253 extern int ebl_syscall_abi (Ebl *ebl, int *sp, int *pc,
254 int *callno, int args[6]);
256 /* Supply the ABI-specified state of DWARF CFI before CIE initial programs.
258 The DWARF 3.0 spec says that the default initial states of all registers
259 are "undefined", unless otherwise specified by the machine/compiler ABI.
261 This default is wrong for every machine with the CFI generated by GCC.
262 The EH unwinder does not really distinguish "same_value" and "undefined",
263 since it doesn't matter for unwinding (in either case there is no change
264 to make for that register). GCC generates CFI that says nothing at all
265 about registers it hasn't spilled somewhere. For our unwinder to give
266 the true story, the backend must supply an initial state that uses
267 "same_value" rules for all the callee-saves registers.
269 This can fill in the initial_instructions, initial_instructions_end
270 members of *ABI_INFO to point at a CFI instruction stream to process
271 before each CIE's initial instructions. It should set the
272 data_alignment_factor member if it affects the initial instructions.
274 The callback should not use the register rules DW_CFA_expression or
275 DW_CFA_val_expression. Defining the CFA using DW_CFA_def_cfa_expression
276 is allowed. This is an implementation detail since register rules
277 store expressions as offsets from the .eh_frame or .debug_frame data.
279 As a shorthand for some common cases, for this instruction stream
280 we overload some CFI instructions that cannot be used in a CIE:
282 DW_CFA_restore -- Change default rule for all unmentioned
283 registers from undefined to same_value.
285 This function can also fill in ABI_INFO->return_address_register with the
286 DWARF register number that identifies the actual PC in machine state.
287 If there is no canonical DWARF register number with that meaning, it's
288 left unchanged (callers usually initialize with (Dwarf_Word) -1).
289 This value is not used by CFI per se.
291 Function returns 0 on success and -1 for error or unsupported by the
293 extern int ebl_abi_cfi (Ebl *ebl, Dwarf_CIE *abi_info)
294 __nonnull_attribute__ (2);
296 /* Register map info. */
299 Dwarf_Half offset; /* Byte offset in register data block. */
300 Dwarf_Half regno; /* DWARF register number. */
301 uint8_t bits; /* Bits of data for one register. */
302 uint8_t pad; /* Bytes of padding after register's data. */
303 Dwarf_Half count; /* Consecutive register numbers here. */
305 } Ebl_Register_Location;
307 /* Non-register data items in core notes. */
310 const char *name; /* Printable identifier. */
311 const char *group; /* Identifier for category of related items. */
312 Dwarf_Half offset; /* Byte offset in note data. */
316 bool thread_identifier;
320 /* Describe the format of a core file note with the given header and NAME.
321 NAME is not guaranteed terminated, it's NHDR->n_namesz raw bytes. */
322 extern int ebl_core_note (Ebl *ebl, const GElf_Nhdr *nhdr, const char *name,
323 GElf_Word *regs_offset, size_t *nregloc,
324 const Ebl_Register_Location **reglocs,
325 size_t *nitems, const Ebl_Core_Item **items)
326 __nonnull_attribute__ (1, 2, 3, 4, 5, 6, 7, 8);
328 /* Describe the auxv type number. */
329 extern int ebl_auxv_info (Ebl *ebl, GElf_Xword a_type,
330 const char **name, const char **format)
331 __nonnull_attribute__ (1, 3, 4);
333 /* Callback type for ebl_set_initial_registers_tid.
334 Register -1 is mapped to PC (if arch PC has no DWARF number).
335 If FIRSTREG is -1 then NREGS has to be 1. */
336 typedef bool (ebl_tid_registers_t) (int firstreg, unsigned nregs,
337 const Dwarf_Word *regs, void *arg)
338 __nonnull_attribute__ (3);
340 /* Callback to fetch process data from live TID.
341 EBL architecture has to have EBL_FRAME_NREGS > 0, otherwise the
342 backend doesn't support unwinding and this function call may crash. */
343 extern bool ebl_set_initial_registers_tid (Ebl *ebl,
345 ebl_tid_registers_t *setfunc,
347 __nonnull_attribute__ (1, 3);
349 /* Number of registers to allocate for ebl_set_initial_registers_tid.
350 EBL architecture can unwind iff EBL_FRAME_NREGS > 0. */
351 extern size_t ebl_frame_nregs (Ebl *ebl)
352 __nonnull_attribute__ (1);
354 /* Offset to apply to the value of the return_address_register, as
355 fetched from a Dwarf CFI. This is used by some backends, where the
356 return_address_register actually contains the call address. */
357 extern int ebl_ra_offset (Ebl *ebl)
358 __nonnull_attribute__ (1);
360 /* Mask to use for function symbol or unwind return addresses in case
361 the architecture adds some extra non-address bits to it. This is
362 different from ebl_resolve_sym_value which only works for actual
363 symbol addresses (in non-ET_REL files) that might resolve to an
364 address in a different section. ebl_func_addr_mask is called to
365 turn a given function value into the a real address or offset (the
366 original value might not be a real address). This works for all
367 cases where an actual function address (or offset in ET_REL symbol
368 tables) is needed. */
369 extern GElf_Addr ebl_func_addr_mask (Ebl *ebl);
371 /* Convert *REGNO as is in DWARF to a lower range suitable for
372 Dwarf_Frame->REGS indexing. */
373 extern bool ebl_dwarf_to_regno (Ebl *ebl, unsigned *regno)
374 __nonnull_attribute__ (1, 2);
376 /* Modify PC as fetched from inferior data into valid PC. */
377 extern void ebl_normalize_pc (Ebl *ebl, Dwarf_Addr *pc)
378 __nonnull_attribute__ (1, 2);
380 /* Callback type for ebl_unwind's parameter getfunc. */
381 typedef bool (ebl_tid_registers_get_t) (int firstreg, unsigned nregs,
382 Dwarf_Word *regs, void *arg)
383 __nonnull_attribute__ (3);
385 /* Callback type for ebl_unwind's parameter readfunc. */
386 typedef bool (ebl_pid_memory_read_t) (Dwarf_Addr addr, Dwarf_Word *data,
388 __nonnull_attribute__ (3);
390 /* Get previous frame state for an existing frame state. Method is called only
391 if unwinder could not find CFI for current PC. PC is for the
392 existing frame. SETFUNC sets register in the previous frame. GETFUNC gets
393 register from the existing frame. Note that GETFUNC vs. SETFUNC act on
394 a disjunct set of registers. READFUNC reads memory. ARG has to be passed
395 for SETFUNC, GETFUNC and READFUNC. *SIGNAL_FRAMEP is initialized to false,
396 it can be set to true if existing frame is a signal frame. SIGNAL_FRAMEP is
398 extern bool ebl_unwind (Ebl *ebl, Dwarf_Addr pc, ebl_tid_registers_t *setfunc,
399 ebl_tid_registers_get_t *getfunc,
400 ebl_pid_memory_read_t *readfunc, void *arg,
402 __nonnull_attribute__ (1, 3, 4, 5, 7);
404 /* Returns true if the value can be resolved to an address in an
405 allocated section, which will be returned in *ADDR
406 (e.g. function descriptor resolving) */
407 extern bool ebl_resolve_sym_value (Ebl *ebl, GElf_Addr *addr)
408 __nonnull_attribute__ (2);
414 #endif /* libebl.h */