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faf5f7ad | 1 | /* GNU/Linux on ARM target support. |
4be87837 | 2 | Copyright 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
faf5f7ad SB |
3 | |
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program 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 | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "defs.h" | |
c20f6dea SB |
22 | #include "target.h" |
23 | #include "value.h" | |
faf5f7ad | 24 | #include "gdbtypes.h" |
134e61c4 | 25 | #include "floatformat.h" |
2a451106 KB |
26 | #include "gdbcore.h" |
27 | #include "frame.h" | |
4e052eda | 28 | #include "regcache.h" |
d16aafd8 | 29 | #include "doublest.h" |
7aa1783e | 30 | #include "solib-svr4.h" |
4be87837 | 31 | #include "osabi.h" |
faf5f7ad | 32 | |
34e8f22d RE |
33 | #include "arm-tdep.h" |
34 | ||
0e18d038 | 35 | /* For shared library handling. */ |
a52e6aac SB |
36 | #include "symtab.h" |
37 | #include "symfile.h" | |
38 | #include "objfiles.h" | |
39 | ||
fdf39c9a RE |
40 | /* Under ARM GNU/Linux the traditional way of performing a breakpoint |
41 | is to execute a particular software interrupt, rather than use a | |
42 | particular undefined instruction to provoke a trap. Upon exection | |
43 | of the software interrupt the kernel stops the inferior with a | |
44 | SIGTRAP, and wakes the debugger. Since ARM GNU/Linux is little | |
45 | endian, and doesn't support Thumb at the moment we only override | |
46 | the ARM little-endian breakpoint. */ | |
66e810cd RE |
47 | |
48 | static const char arm_linux_arm_le_breakpoint[] = {0x01,0x00,0x9f,0xef}; | |
49 | ||
b1e29e33 | 50 | /* DEPRECATED_CALL_DUMMY_WORDS: |
6eb69eab RE |
51 | This sequence of words is the instructions |
52 | ||
53 | mov lr, pc | |
54 | mov pc, r4 | |
55 | swi bkpt_swi | |
56 | ||
57 | Note this is 12 bytes. */ | |
58 | ||
59 | LONGEST arm_linux_call_dummy_words[] = | |
60 | { | |
61 | 0xe1a0e00f, 0xe1a0f004, 0xef9f001 | |
62 | }; | |
63 | ||
9df628e0 | 64 | /* Description of the longjmp buffer. */ |
a6cdd8c5 RE |
65 | #define ARM_LINUX_JB_ELEMENT_SIZE INT_REGISTER_RAW_SIZE |
66 | #define ARM_LINUX_JB_PC 21 | |
faf5f7ad | 67 | |
faf5f7ad SB |
68 | /* Extract from an array REGBUF containing the (raw) register state |
69 | a function return value of type TYPE, and copy that, in virtual format, | |
70 | into VALBUF. */ | |
19d3fc80 RE |
71 | /* FIXME rearnsha/2002-02-23: This function shouldn't be necessary. |
72 | The ARM generic one should be able to handle the model used by | |
73 | linux and the low-level formatting of the registers should be | |
74 | hidden behind the regcache abstraction. */ | |
75 | static void | |
faf5f7ad | 76 | arm_linux_extract_return_value (struct type *type, |
b8b527c5 | 77 | char regbuf[], |
faf5f7ad SB |
78 | char *valbuf) |
79 | { | |
80 | /* ScottB: This needs to be looked at to handle the different | |
fdf39c9a | 81 | floating point emulators on ARM GNU/Linux. Right now the code |
faf5f7ad SB |
82 | assumes that fetch inferior registers does the right thing for |
83 | GDB. I suspect this won't handle NWFPE registers correctly, nor | |
84 | will the default ARM version (arm_extract_return_value()). */ | |
85 | ||
34e8f22d RE |
86 | int regnum = ((TYPE_CODE_FLT == TYPE_CODE (type)) |
87 | ? ARM_F0_REGNUM : ARM_A1_REGNUM); | |
faf5f7ad SB |
88 | memcpy (valbuf, ®buf[REGISTER_BYTE (regnum)], TYPE_LENGTH (type)); |
89 | } | |
90 | ||
134e61c4 SB |
91 | /* Note: ScottB |
92 | ||
93 | This function does not support passing parameters using the FPA | |
94 | variant of the APCS. It passes any floating point arguments in the | |
95 | general registers and/or on the stack. | |
96 | ||
97 | FIXME: This and arm_push_arguments should be merged. However this | |
98 | function breaks on a little endian host, big endian target | |
99 | using the COFF file format. ELF is ok. | |
100 | ||
101 | ScottB. */ | |
102 | ||
103 | /* Addresses for calling Thumb functions have the bit 0 set. | |
104 | Here are some macros to test, set, or clear bit 0 of addresses. */ | |
105 | #define IS_THUMB_ADDR(addr) ((addr) & 1) | |
106 | #define MAKE_THUMB_ADDR(addr) ((addr) | 1) | |
107 | #define UNMAKE_THUMB_ADDR(addr) ((addr) & ~1) | |
108 | ||
19d3fc80 | 109 | static CORE_ADDR |
ea7c478f | 110 | arm_linux_push_arguments (int nargs, struct value **args, CORE_ADDR sp, |
134e61c4 SB |
111 | int struct_return, CORE_ADDR struct_addr) |
112 | { | |
113 | char *fp; | |
114 | int argnum, argreg, nstack_size; | |
115 | ||
116 | /* Walk through the list of args and determine how large a temporary | |
117 | stack is required. Need to take care here as structs may be | |
118 | passed on the stack, and we have to to push them. */ | |
b1e29e33 | 119 | nstack_size = -4 * DEPRECATED_REGISTER_SIZE; /* Some arguments go into A1-A4. */ |
134e61c4 SB |
120 | |
121 | if (struct_return) /* The struct address goes in A1. */ | |
b1e29e33 | 122 | nstack_size += DEPRECATED_REGISTER_SIZE; |
134e61c4 SB |
123 | |
124 | /* Walk through the arguments and add their size to nstack_size. */ | |
125 | for (argnum = 0; argnum < nargs; argnum++) | |
126 | { | |
127 | int len; | |
128 | struct type *arg_type; | |
129 | ||
130 | arg_type = check_typedef (VALUE_TYPE (args[argnum])); | |
131 | len = TYPE_LENGTH (arg_type); | |
132 | ||
133 | /* ANSI C code passes float arguments as integers, K&R code | |
134 | passes float arguments as doubles. Correct for this here. */ | |
b1e29e33 | 135 | if (TYPE_CODE_FLT == TYPE_CODE (arg_type) && DEPRECATED_REGISTER_SIZE == len) |
134e61c4 SB |
136 | nstack_size += FP_REGISTER_VIRTUAL_SIZE; |
137 | else | |
138 | nstack_size += len; | |
139 | } | |
140 | ||
141 | /* Allocate room on the stack, and initialize our stack frame | |
142 | pointer. */ | |
143 | fp = NULL; | |
144 | if (nstack_size > 0) | |
145 | { | |
146 | sp -= nstack_size; | |
147 | fp = (char *) sp; | |
148 | } | |
149 | ||
150 | /* Initialize the integer argument register pointer. */ | |
34e8f22d | 151 | argreg = ARM_A1_REGNUM; |
134e61c4 SB |
152 | |
153 | /* The struct_return pointer occupies the first parameter passing | |
154 | register. */ | |
155 | if (struct_return) | |
156 | write_register (argreg++, struct_addr); | |
157 | ||
158 | /* Process arguments from left to right. Store as many as allowed | |
159 | in the parameter passing registers (A1-A4), and save the rest on | |
160 | the temporary stack. */ | |
161 | for (argnum = 0; argnum < nargs; argnum++) | |
162 | { | |
163 | int len; | |
164 | char *val; | |
134e61c4 SB |
165 | CORE_ADDR regval; |
166 | enum type_code typecode; | |
167 | struct type *arg_type, *target_type; | |
168 | ||
169 | arg_type = check_typedef (VALUE_TYPE (args[argnum])); | |
170 | target_type = TYPE_TARGET_TYPE (arg_type); | |
171 | len = TYPE_LENGTH (arg_type); | |
172 | typecode = TYPE_CODE (arg_type); | |
173 | val = (char *) VALUE_CONTENTS (args[argnum]); | |
174 | ||
175 | /* ANSI C code passes float arguments as integers, K&R code | |
176 | passes float arguments as doubles. The .stabs record for | |
177 | for ANSI prototype floating point arguments records the | |
178 | type as FP_INTEGER, while a K&R style (no prototype) | |
179 | .stabs records the type as FP_FLOAT. In this latter case | |
180 | the compiler converts the float arguments to double before | |
181 | calling the function. */ | |
b1e29e33 | 182 | if (TYPE_CODE_FLT == typecode && DEPRECATED_REGISTER_SIZE == len) |
134e61c4 | 183 | { |
134e61c4 | 184 | DOUBLEST dblval; |
f1908289 | 185 | dblval = deprecated_extract_floating (val, len); |
134e61c4 | 186 | len = TARGET_DOUBLE_BIT / TARGET_CHAR_BIT; |
a37b3cc0 | 187 | val = alloca (len); |
f1908289 | 188 | deprecated_store_floating (val, len, dblval); |
134e61c4 SB |
189 | } |
190 | ||
191 | /* If the argument is a pointer to a function, and it is a Thumb | |
192 | function, set the low bit of the pointer. */ | |
193 | if (TYPE_CODE_PTR == typecode | |
194 | && NULL != target_type | |
195 | && TYPE_CODE_FUNC == TYPE_CODE (target_type)) | |
196 | { | |
7c0b4a20 | 197 | CORE_ADDR regval = extract_unsigned_integer (val, len); |
134e61c4 | 198 | if (arm_pc_is_thumb (regval)) |
fbd9dcd3 | 199 | store_unsigned_integer (val, len, MAKE_THUMB_ADDR (regval)); |
134e61c4 SB |
200 | } |
201 | ||
202 | /* Copy the argument to general registers or the stack in | |
203 | register-sized pieces. Large arguments are split between | |
204 | registers and stack. */ | |
205 | while (len > 0) | |
206 | { | |
b1e29e33 | 207 | int partial_len = len < DEPRECATED_REGISTER_SIZE ? len : DEPRECATED_REGISTER_SIZE; |
134e61c4 SB |
208 | |
209 | if (argreg <= ARM_LAST_ARG_REGNUM) | |
210 | { | |
211 | /* It's an argument being passed in a general register. */ | |
7c0b4a20 | 212 | regval = extract_unsigned_integer (val, partial_len); |
134e61c4 SB |
213 | write_register (argreg++, regval); |
214 | } | |
215 | else | |
216 | { | |
217 | /* Push the arguments onto the stack. */ | |
b1e29e33 AC |
218 | write_memory ((CORE_ADDR) fp, val, DEPRECATED_REGISTER_SIZE); |
219 | fp += DEPRECATED_REGISTER_SIZE; | |
134e61c4 SB |
220 | } |
221 | ||
222 | len -= partial_len; | |
223 | val += partial_len; | |
224 | } | |
225 | } | |
226 | ||
227 | /* Return adjusted stack pointer. */ | |
228 | return sp; | |
229 | } | |
230 | ||
f38e884d | 231 | /* |
fdf39c9a RE |
232 | Dynamic Linking on ARM GNU/Linux |
233 | -------------------------------- | |
f38e884d SB |
234 | |
235 | Note: PLT = procedure linkage table | |
236 | GOT = global offset table | |
237 | ||
238 | As much as possible, ELF dynamic linking defers the resolution of | |
239 | jump/call addresses until the last minute. The technique used is | |
240 | inspired by the i386 ELF design, and is based on the following | |
241 | constraints. | |
242 | ||
243 | 1) The calling technique should not force a change in the assembly | |
244 | code produced for apps; it MAY cause changes in the way assembly | |
245 | code is produced for position independent code (i.e. shared | |
246 | libraries). | |
247 | ||
248 | 2) The technique must be such that all executable areas must not be | |
249 | modified; and any modified areas must not be executed. | |
250 | ||
251 | To do this, there are three steps involved in a typical jump: | |
252 | ||
253 | 1) in the code | |
254 | 2) through the PLT | |
255 | 3) using a pointer from the GOT | |
256 | ||
257 | When the executable or library is first loaded, each GOT entry is | |
258 | initialized to point to the code which implements dynamic name | |
259 | resolution and code finding. This is normally a function in the | |
fdf39c9a RE |
260 | program interpreter (on ARM GNU/Linux this is usually |
261 | ld-linux.so.2, but it does not have to be). On the first | |
262 | invocation, the function is located and the GOT entry is replaced | |
263 | with the real function address. Subsequent calls go through steps | |
264 | 1, 2 and 3 and end up calling the real code. | |
f38e884d SB |
265 | |
266 | 1) In the code: | |
267 | ||
268 | b function_call | |
269 | bl function_call | |
270 | ||
271 | This is typical ARM code using the 26 bit relative branch or branch | |
272 | and link instructions. The target of the instruction | |
273 | (function_call is usually the address of the function to be called. | |
274 | In position independent code, the target of the instruction is | |
275 | actually an entry in the PLT when calling functions in a shared | |
276 | library. Note that this call is identical to a normal function | |
277 | call, only the target differs. | |
278 | ||
279 | 2) In the PLT: | |
280 | ||
281 | The PLT is a synthetic area, created by the linker. It exists in | |
282 | both executables and libraries. It is an array of stubs, one per | |
283 | imported function call. It looks like this: | |
284 | ||
285 | PLT[0]: | |
286 | str lr, [sp, #-4]! @push the return address (lr) | |
287 | ldr lr, [pc, #16] @load from 6 words ahead | |
288 | add lr, pc, lr @form an address for GOT[0] | |
289 | ldr pc, [lr, #8]! @jump to the contents of that addr | |
290 | ||
291 | The return address (lr) is pushed on the stack and used for | |
292 | calculations. The load on the second line loads the lr with | |
293 | &GOT[3] - . - 20. The addition on the third leaves: | |
294 | ||
295 | lr = (&GOT[3] - . - 20) + (. + 8) | |
296 | lr = (&GOT[3] - 12) | |
297 | lr = &GOT[0] | |
298 | ||
299 | On the fourth line, the pc and lr are both updated, so that: | |
300 | ||
301 | pc = GOT[2] | |
302 | lr = &GOT[0] + 8 | |
303 | = &GOT[2] | |
304 | ||
305 | NOTE: PLT[0] borrows an offset .word from PLT[1]. This is a little | |
306 | "tight", but allows us to keep all the PLT entries the same size. | |
307 | ||
308 | PLT[n+1]: | |
309 | ldr ip, [pc, #4] @load offset from gotoff | |
310 | add ip, pc, ip @add the offset to the pc | |
311 | ldr pc, [ip] @jump to that address | |
312 | gotoff: .word GOT[n+3] - . | |
313 | ||
314 | The load on the first line, gets an offset from the fourth word of | |
315 | the PLT entry. The add on the second line makes ip = &GOT[n+3], | |
316 | which contains either a pointer to PLT[0] (the fixup trampoline) or | |
317 | a pointer to the actual code. | |
318 | ||
319 | 3) In the GOT: | |
320 | ||
321 | The GOT contains helper pointers for both code (PLT) fixups and | |
322 | data fixups. The first 3 entries of the GOT are special. The next | |
323 | M entries (where M is the number of entries in the PLT) belong to | |
324 | the PLT fixups. The next D (all remaining) entries belong to | |
325 | various data fixups. The actual size of the GOT is 3 + M + D. | |
326 | ||
327 | The GOT is also a synthetic area, created by the linker. It exists | |
328 | in both executables and libraries. When the GOT is first | |
329 | initialized , all the GOT entries relating to PLT fixups are | |
330 | pointing to code back at PLT[0]. | |
331 | ||
332 | The special entries in the GOT are: | |
333 | ||
334 | GOT[0] = linked list pointer used by the dynamic loader | |
335 | GOT[1] = pointer to the reloc table for this module | |
336 | GOT[2] = pointer to the fixup/resolver code | |
337 | ||
338 | The first invocation of function call comes through and uses the | |
339 | fixup/resolver code. On the entry to the fixup/resolver code: | |
340 | ||
341 | ip = &GOT[n+3] | |
342 | lr = &GOT[2] | |
343 | stack[0] = return address (lr) of the function call | |
344 | [r0, r1, r2, r3] are still the arguments to the function call | |
345 | ||
346 | This is enough information for the fixup/resolver code to work | |
347 | with. Before the fixup/resolver code returns, it actually calls | |
348 | the requested function and repairs &GOT[n+3]. */ | |
349 | ||
a52e6aac SB |
350 | /* Find the minimal symbol named NAME, and return both the minsym |
351 | struct and its objfile. This probably ought to be in minsym.c, but | |
352 | everything there is trying to deal with things like C++ and | |
353 | SOFUN_ADDRESS_MAYBE_TURQUOISE, ... Since this is so simple, it may | |
354 | be considered too special-purpose for general consumption. */ | |
355 | ||
356 | static struct minimal_symbol * | |
357 | find_minsym_and_objfile (char *name, struct objfile **objfile_p) | |
358 | { | |
359 | struct objfile *objfile; | |
360 | ||
361 | ALL_OBJFILES (objfile) | |
362 | { | |
363 | struct minimal_symbol *msym; | |
364 | ||
365 | ALL_OBJFILE_MSYMBOLS (objfile, msym) | |
366 | { | |
22abf04a DC |
367 | if (DEPRECATED_SYMBOL_NAME (msym) |
368 | && strcmp (DEPRECATED_SYMBOL_NAME (msym), name) == 0) | |
a52e6aac SB |
369 | { |
370 | *objfile_p = objfile; | |
371 | return msym; | |
372 | } | |
373 | } | |
374 | } | |
375 | ||
376 | return 0; | |
377 | } | |
378 | ||
379 | ||
7aa1783e RE |
380 | /* Fetch, and possibly build, an appropriate link_map_offsets structure |
381 | for ARM linux targets using the struct offsets defined in <link.h>. | |
382 | Note, however, that link.h is not actually referred to in this file. | |
383 | Instead, the relevant structs offsets were obtained from examining | |
384 | link.h. (We can't refer to link.h from this file because the host | |
385 | system won't necessarily have it, or if it does, the structs which | |
386 | it defines will refer to the host system, not the target). */ | |
387 | ||
388 | static struct link_map_offsets * | |
389 | arm_linux_svr4_fetch_link_map_offsets (void) | |
390 | { | |
391 | static struct link_map_offsets lmo; | |
392 | static struct link_map_offsets *lmp = 0; | |
393 | ||
394 | if (lmp == 0) | |
395 | { | |
396 | lmp = &lmo; | |
397 | ||
398 | lmo.r_debug_size = 8; /* Actual size is 20, but this is all we | |
399 | need. */ | |
400 | ||
401 | lmo.r_map_offset = 4; | |
402 | lmo.r_map_size = 4; | |
403 | ||
404 | lmo.link_map_size = 20; /* Actual size is 552, but this is all we | |
405 | need. */ | |
406 | ||
407 | lmo.l_addr_offset = 0; | |
408 | lmo.l_addr_size = 4; | |
409 | ||
410 | lmo.l_name_offset = 4; | |
411 | lmo.l_name_size = 4; | |
412 | ||
413 | lmo.l_next_offset = 12; | |
414 | lmo.l_next_size = 4; | |
415 | ||
416 | lmo.l_prev_offset = 16; | |
417 | lmo.l_prev_size = 4; | |
418 | } | |
419 | ||
420 | return lmp; | |
421 | } | |
422 | ||
a52e6aac SB |
423 | static CORE_ADDR |
424 | skip_hurd_resolver (CORE_ADDR pc) | |
425 | { | |
426 | /* The HURD dynamic linker is part of the GNU C library, so many | |
427 | GNU/Linux distributions use it. (All ELF versions, as far as I | |
428 | know.) An unresolved PLT entry points to "_dl_runtime_resolve", | |
429 | which calls "fixup" to patch the PLT, and then passes control to | |
430 | the function. | |
431 | ||
432 | We look for the symbol `_dl_runtime_resolve', and find `fixup' in | |
433 | the same objfile. If we are at the entry point of `fixup', then | |
434 | we set a breakpoint at the return address (at the top of the | |
435 | stack), and continue. | |
436 | ||
437 | It's kind of gross to do all these checks every time we're | |
438 | called, since they don't change once the executable has gotten | |
439 | started. But this is only a temporary hack --- upcoming versions | |
fdf39c9a | 440 | of GNU/Linux will provide a portable, efficient interface for |
a52e6aac SB |
441 | debugging programs that use shared libraries. */ |
442 | ||
443 | struct objfile *objfile; | |
444 | struct minimal_symbol *resolver | |
445 | = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile); | |
446 | ||
447 | if (resolver) | |
448 | { | |
449 | struct minimal_symbol *fixup | |
9b27852e | 450 | = lookup_minimal_symbol ("fixup", NULL, objfile); |
a52e6aac SB |
451 | |
452 | if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc) | |
6913c89a | 453 | return (DEPRECATED_SAVED_PC_AFTER_CALL (get_current_frame ())); |
a52e6aac SB |
454 | } |
455 | ||
456 | return 0; | |
457 | } | |
458 | ||
459 | /* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c. | |
460 | This function: | |
461 | 1) decides whether a PLT has sent us into the linker to resolve | |
462 | a function reference, and | |
463 | 2) if so, tells us where to set a temporary breakpoint that will | |
464 | trigger when the dynamic linker is done. */ | |
465 | ||
f38e884d | 466 | CORE_ADDR |
a52e6aac | 467 | arm_linux_skip_solib_resolver (CORE_ADDR pc) |
f38e884d | 468 | { |
a52e6aac SB |
469 | CORE_ADDR result; |
470 | ||
471 | /* Plug in functions for other kinds of resolvers here. */ | |
472 | result = skip_hurd_resolver (pc); | |
e1d6e81f | 473 | |
a52e6aac SB |
474 | if (result) |
475 | return result; | |
a52e6aac | 476 | |
f38e884d SB |
477 | return 0; |
478 | } | |
479 | ||
2a451106 KB |
480 | /* The constants below were determined by examining the following files |
481 | in the linux kernel sources: | |
482 | ||
483 | arch/arm/kernel/signal.c | |
484 | - see SWI_SYS_SIGRETURN and SWI_SYS_RT_SIGRETURN | |
485 | include/asm-arm/unistd.h | |
486 | - see __NR_sigreturn, __NR_rt_sigreturn, and __NR_SYSCALL_BASE */ | |
487 | ||
488 | #define ARM_LINUX_SIGRETURN_INSTR 0xef900077 | |
489 | #define ARM_LINUX_RT_SIGRETURN_INSTR 0xef9000ad | |
490 | ||
491 | /* arm_linux_in_sigtramp determines if PC points at one of the | |
492 | instructions which cause control to return to the Linux kernel upon | |
493 | return from a signal handler. FUNC_NAME is unused. */ | |
494 | ||
495 | int | |
496 | arm_linux_in_sigtramp (CORE_ADDR pc, char *func_name) | |
497 | { | |
498 | unsigned long inst; | |
499 | ||
500 | inst = read_memory_integer (pc, 4); | |
501 | ||
502 | return (inst == ARM_LINUX_SIGRETURN_INSTR | |
503 | || inst == ARM_LINUX_RT_SIGRETURN_INSTR); | |
504 | ||
505 | } | |
506 | ||
507 | /* arm_linux_sigcontext_register_address returns the address in the | |
508 | sigcontext of register REGNO given a stack pointer value SP and | |
509 | program counter value PC. The value 0 is returned if PC is not | |
510 | pointing at one of the signal return instructions or if REGNO is | |
511 | not saved in the sigcontext struct. */ | |
512 | ||
513 | CORE_ADDR | |
514 | arm_linux_sigcontext_register_address (CORE_ADDR sp, CORE_ADDR pc, int regno) | |
515 | { | |
516 | unsigned long inst; | |
517 | CORE_ADDR reg_addr = 0; | |
518 | ||
519 | inst = read_memory_integer (pc, 4); | |
520 | ||
fdf39c9a RE |
521 | if (inst == ARM_LINUX_SIGRETURN_INSTR |
522 | || inst == ARM_LINUX_RT_SIGRETURN_INSTR) | |
2a451106 KB |
523 | { |
524 | CORE_ADDR sigcontext_addr; | |
525 | ||
526 | /* The sigcontext structure is at different places for the two | |
527 | signal return instructions. For ARM_LINUX_SIGRETURN_INSTR, | |
528 | it starts at the SP value. For ARM_LINUX_RT_SIGRETURN_INSTR, | |
529 | it is at SP+8. For the latter instruction, it may also be | |
530 | the case that the address of this structure may be determined | |
531 | by reading the 4 bytes at SP, but I'm not convinced this is | |
532 | reliable. | |
533 | ||
534 | In any event, these magic constants (0 and 8) may be | |
535 | determined by examining struct sigframe and struct | |
536 | rt_sigframe in arch/arm/kernel/signal.c in the Linux kernel | |
537 | sources. */ | |
538 | ||
539 | if (inst == ARM_LINUX_RT_SIGRETURN_INSTR) | |
540 | sigcontext_addr = sp + 8; | |
541 | else /* inst == ARM_LINUX_SIGRETURN_INSTR */ | |
542 | sigcontext_addr = sp + 0; | |
543 | ||
544 | /* The layout of the sigcontext structure for ARM GNU/Linux is | |
545 | in include/asm-arm/sigcontext.h in the Linux kernel sources. | |
546 | ||
547 | There are three 4-byte fields which precede the saved r0 | |
548 | field. (This accounts for the 12 in the code below.) The | |
549 | sixteen registers (4 bytes per field) follow in order. The | |
550 | PSR value follows the sixteen registers which accounts for | |
551 | the constant 19 below. */ | |
552 | ||
34e8f22d | 553 | if (0 <= regno && regno <= ARM_PC_REGNUM) |
2a451106 | 554 | reg_addr = sigcontext_addr + 12 + (4 * regno); |
34e8f22d | 555 | else if (regno == ARM_PS_REGNUM) |
2a451106 KB |
556 | reg_addr = sigcontext_addr + 19 * 4; |
557 | } | |
558 | ||
559 | return reg_addr; | |
560 | } | |
561 | ||
97e03143 RE |
562 | static void |
563 | arm_linux_init_abi (struct gdbarch_info info, | |
564 | struct gdbarch *gdbarch) | |
565 | { | |
566 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); | |
567 | ||
568 | tdep->lowest_pc = 0x8000; | |
66e810cd RE |
569 | tdep->arm_breakpoint = arm_linux_arm_le_breakpoint; |
570 | tdep->arm_breakpoint_size = sizeof (arm_linux_arm_le_breakpoint); | |
9df628e0 | 571 | |
fd50bc42 RE |
572 | tdep->fp_model = ARM_FLOAT_FPA; |
573 | ||
a6cdd8c5 RE |
574 | tdep->jb_pc = ARM_LINUX_JB_PC; |
575 | tdep->jb_elt_size = ARM_LINUX_JB_ELEMENT_SIZE; | |
19d3fc80 | 576 | |
7aa1783e RE |
577 | set_solib_svr4_fetch_link_map_offsets |
578 | (gdbarch, arm_linux_svr4_fetch_link_map_offsets); | |
579 | ||
b1e29e33 AC |
580 | set_gdbarch_deprecated_call_dummy_words (gdbarch, arm_linux_call_dummy_words); |
581 | set_gdbarch_deprecated_sizeof_call_dummy_words (gdbarch, sizeof (arm_linux_call_dummy_words)); | |
19d3fc80 RE |
582 | |
583 | /* The following two overrides shouldn't be needed. */ | |
26e9b323 | 584 | set_gdbarch_deprecated_extract_return_value (gdbarch, arm_linux_extract_return_value); |
b81774d8 | 585 | set_gdbarch_deprecated_push_arguments (gdbarch, arm_linux_push_arguments); |
0e18d038 RE |
586 | |
587 | /* Shared library handling. */ | |
588 | set_gdbarch_in_solib_call_trampoline (gdbarch, in_plt_section); | |
589 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); | |
97e03143 RE |
590 | } |
591 | ||
faf5f7ad SB |
592 | void |
593 | _initialize_arm_linux_tdep (void) | |
594 | { | |
05816f70 MK |
595 | gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_LINUX, |
596 | arm_linux_init_abi); | |
faf5f7ad | 597 | } |