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amd64-obsd-tdep.c
Go to the documentation of this file.
1/* Target-dependent code for OpenBSD/amd64.
2
3 Copyright (C) 2003-2023 Free Software Foundation, Inc.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20#include "defs.h"
21#include "frame.h"
22#include "frame-unwind.h"
23#include "gdbcore.h"
24#include "symtab.h"
25#include "objfiles.h"
26#include "osabi.h"
27#include "regcache.h"
28#include "regset.h"
29#include "target.h"
30#include "trad-frame.h"
31
32#include "obsd-tdep.h"
33#include "amd64-tdep.h"
34#include "i387-tdep.h"
35#include "gdbsupport/x86-xstate.h"
36#include "solib-svr4.h"
37#include "bsd-uthread.h"
38
39/* Support for signal handlers. */
40
41/* Default page size. */
42static const int amd64obsd_page_size = 4096;
43
44/* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
45 routine. */
46
47static int
49{
50 CORE_ADDR pc = get_frame_pc (this_frame);
51 CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
52 const gdb_byte osigreturn[] =
53 {
54 0x48, 0xc7, 0xc0,
55 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
56 0xcd, 0x80 /* int $0x80 */
57 };
58 const gdb_byte sigreturn[] =
59 {
60 0x48, 0xc7, 0xc0,
61 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
62 0x0f, 0x05 /* syscall */
63 };
64 size_t buflen = (sizeof sigreturn) + 1;
65 gdb_byte *buf;
66 const char *name;
67
68 /* If the function has a valid symbol name, it isn't a
69 trampoline. */
70 find_pc_partial_function (pc, &name, NULL, NULL);
71 if (name != NULL)
72 return 0;
73
74 /* If the function lives in a valid section (even without a starting
75 point) it isn't a trampoline. */
76 if (find_pc_section (pc) != NULL)
77 return 0;
78
79 /* If we can't read the instructions at START_PC, return zero. */
80 buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1);
81 if (!safe_frame_unwind_memory (this_frame, start_pc + 6, {buf, buflen}))
82 return 0;
83
84 /* Check for sigreturn(2). Depending on how the assembler encoded
85 the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
86 7. OpenBSD 5.0 and later use the `syscall' instruction. Older
87 versions use `int $0x80'. Check for both. */
88 if (memcmp (buf, sigreturn, sizeof sigreturn)
89 && memcmp (buf + 1, sigreturn, sizeof sigreturn)
90 && memcmp (buf, osigreturn, sizeof osigreturn)
91 && memcmp (buf + 1, osigreturn, sizeof osigreturn))
92 return 0;
93
94 return 1;
95}
96
97/* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
98 address of the associated sigcontext structure. */
99
100static CORE_ADDR
102{
103 CORE_ADDR pc = get_frame_pc (this_frame);
104 ULONGEST offset = (pc & (amd64obsd_page_size - 1));
105
106 /* The %rsp register points at `struct sigcontext' upon entry of a
107 signal trampoline. The relevant part of the trampoline is
108
109 call *%rax
110 movq %rsp, %rdi
111 pushq %rdi
112 movq $SYS_sigreturn,%rax
113 int $0x80
114
115 (see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq'
116 instruction clobbers %rsp, but its value is saved in `%rdi'. */
117
118 if (offset > 5)
120 else
122}
123
124/* OpenBSD 3.5 or later. */
125
126/* Mapping between the general-purpose registers in `struct reg'
127 format and GDB's register cache layout. */
128
129/* From <machine/reg.h>. */
131{
132 14 * 8, /* %rax */
133 13 * 8, /* %rbx */
134 3 * 8, /* %rcx */
135 2 * 8, /* %rdx */
136 1 * 8, /* %rsi */
137 0 * 8, /* %rdi */
138 12 * 8, /* %rbp */
139 15 * 8, /* %rsp */
140 4 * 8, /* %r8 .. */
141 5 * 8,
142 6 * 8,
143 7 * 8,
144 8 * 8,
145 9 * 8,
146 10 * 8,
147 11 * 8, /* ... %r15 */
148 16 * 8, /* %rip */
149 17 * 8, /* %eflags */
150 18 * 8, /* %cs */
151 19 * 8, /* %ss */
152 20 * 8, /* %ds */
153 21 * 8, /* %es */
154 22 * 8, /* %fs */
155 23 * 8 /* %gs */
156};
157
158/* From <machine/signal.h>. */
160{
161 14 * 8, /* %rax */
162 13 * 8, /* %rbx */
163 3 * 8, /* %rcx */
164 2 * 8, /* %rdx */
165 1 * 8, /* %rsi */
166 0 * 8, /* %rdi */
167 12 * 8, /* %rbp */
168 24 * 8, /* %rsp */
169 4 * 8, /* %r8 ... */
170 5 * 8,
171 6 * 8,
172 7 * 8,
173 8 * 8,
174 9 * 8,
175 10 * 8,
176 11 * 8, /* ... %r15 */
177 21 * 8, /* %rip */
178 23 * 8, /* %eflags */
179 22 * 8, /* %cs */
180 25 * 8, /* %ss */
181 18 * 8, /* %ds */
182 17 * 8, /* %es */
183 16 * 8, /* %fs */
184 15 * 8 /* %gs */
185};
186
187/* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */
189{
190 19 * 8, /* %rax */
191 16 * 8, /* %rbx */
192 18 * 8, /* %rcx */
193 17 * 8, /* %rdx */
194 14 * 8, /* %rsi */
195 13 * 8, /* %rdi */
196 15 * 8, /* %rbp */
197 -1, /* %rsp */
198 12 * 8, /* %r8 ... */
199 11 * 8,
200 10 * 8,
201 9 * 8,
202 8 * 8,
203 7 * 8,
204 6 * 8,
205 5 * 8, /* ... %r15 */
206 20 * 8, /* %rip */
207 4 * 8, /* %eflags */
208 21 * 8, /* %cs */
209 -1, /* %ss */
210 3 * 8, /* %ds */
211 2 * 8, /* %es */
212 1 * 8, /* %fs */
213 0 * 8 /* %gs */
214};
215
216/* Offset within the thread structure where we can find the saved
217 stack pointer (%esp). */
218#define AMD64OBSD_UTHREAD_RSP_OFFSET 400
219
220static void
222 int regnum, CORE_ADDR addr)
223{
224 struct gdbarch *gdbarch = regcache->arch ();
225 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
226 CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
227 CORE_ADDR sp = 0;
228 gdb_byte buf[8];
229 int i;
230
231 gdb_assert (regnum >= -1);
232
233 if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
234 {
235 int offset;
236
237 /* Fetch stack pointer from thread structure. */
238 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
239
240 /* Adjust the stack pointer such that it looks as if we just
241 returned from _thread_machdep_switch. */
243 store_unsigned_integer (buf, 8, byte_order, sp + offset);
245 }
246
247 for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
248 {
250 && (regnum == -1 || regnum == i))
251 {
252 /* Fetch stack pointer from thread structure (if we didn't
253 do so already). */
254 if (sp == 0)
255 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
256
257 /* Read the saved register from the stack frame. */
259 regcache->raw_supply (i, buf);
260 }
261 }
262}
263
264static void
266 int regnum, CORE_ADDR addr)
267{
268 struct gdbarch *gdbarch = regcache->arch ();
269 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
270 CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
271 CORE_ADDR sp = 0;
272 gdb_byte buf[8];
273 int i;
274
275 gdb_assert (regnum >= -1);
276
277 if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
278 {
279 int offset;
280
281 /* Calculate the stack pointer (frame pointer) that will be
282 stored into the thread structure. */
285 sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
286
287 /* Store the stack pointer. */
288 write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
289
290 /* The stack pointer was (potentially) modified. Make sure we
291 build a proper stack frame. */
292 regnum = -1;
293 }
294
295 for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
296 {
298 && (regnum == -1 || regnum == i))
299 {
300 /* Fetch stack pointer from thread structure (if we didn't
301 calculate it already). */
302 if (sp == 0)
303 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
304
305 /* Write the register into the stack frame. */
306 regcache->raw_collect (i, buf);
308 }
309 }
310}
311/* Kernel debugging support. */
312
313/* From <machine/frame.h>. Easy since `struct trapframe' matches
314 `struct sigcontext'. */
315#define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
316
317static struct trad_frame_cache *
319{
320 struct gdbarch *gdbarch = get_frame_arch (this_frame);
321 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
322 struct trad_frame_cache *cache;
323 CORE_ADDR func, sp, addr;
324 ULONGEST cs;
325 const char *name;
326 int i;
327
328 if (*this_cache)
329 return (struct trad_frame_cache *) *this_cache;
330
332 *this_cache = cache;
333
336
337 find_pc_partial_function (func, &name, NULL, NULL);
338 if (name && startswith (name, "Xintr"))
339 addr = sp + 8; /* It's an interrupt frame. */
340 else
341 addr = sp;
342
343 for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
344 if (amd64obsd_tf_reg_offset[i] != -1)
346
347 /* Read %cs from trap frame. */
349 cs = read_memory_unsigned_integer (addr, 8, byte_order);
350 if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
351 {
352 /* Trap from user space; terminate backtrace. */
354 }
355 else
356 {
357 /* Construct the frame ID using the function start. */
358 trad_frame_set_id (cache, frame_id_build (sp + 16, func));
359 }
360
361 return cache;
362}
363
364static void
366 void **this_cache, struct frame_id *this_id)
367{
368 struct trad_frame_cache *cache =
370
371 trad_frame_get_id (cache, this_id);
372}
373
374static struct value *
376 void **this_cache, int regnum)
377{
378 struct trad_frame_cache *cache =
380
382}
383
384static int
387 void **this_prologue_cache)
388{
389 ULONGEST cs;
390 const char *name;
391
392 /* Check Current Privilege Level and bail out if we're not executing
393 in kernel space. */
395 if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
396 return 0;
397
399 return (name && ((strcmp (name, "calltrap") == 0)
400 || (strcmp (name, "osyscall1") == 0)
401 || (strcmp (name, "Xsyscall") == 0)
402 || (startswith (name, "Xintr"))));
403}
404
406{
407 /* FIXME: kettenis/20051219: This really is more like an interrupt
408 frame, but SIGTRAMP_FRAME would print <signal handler called>,
409 which really is not what we want here. */
410 "amd64 openbsd trap",
415 NULL,
417};
418
419
420static void
422{
423 i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
424
425 amd64_init_abi (info, gdbarch,
426 amd64_target_description (X86_XSTATE_SSE_MASK, true));
427 obsd_init_abi (info, gdbarch);
428
429 /* Initialize general-purpose register set details. */
431 tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
432 tdep->sizeof_gregset = 24 * 8;
433
434 tdep->jb_pc_offset = 7 * 8;
435
439 tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
440
441 /* OpenBSD provides a user-level threads implementation. */
444
445 /* OpenBSD uses SVR4-style shared libraries. */
448
449 /* Unwind kernel trap frames correctly. */
451}
452
454void
456{
457 /* The OpenBSD/amd64 native dependent code makes this assumption. */
458 gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
459
460 gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
462}
int regnum
const char *const name
static struct trad_frame_cache * amd64obsd_trapframe_cache(frame_info_ptr this_frame, void **this_cache)
static struct value * amd64obsd_trapframe_prev_register(frame_info_ptr this_frame, void **this_cache, int regnum)
static const int amd64obsd_page_size
#define AMD64OBSD_UTHREAD_RSP_OFFSET
static void amd64obsd_collect_uthread(const struct regcache *regcache, int regnum, CORE_ADDR addr)
static const struct frame_unwind amd64obsd_trapframe_unwind
static int amd64obsd_trapframe_sniffer(const struct frame_unwind *self, frame_info_ptr this_frame, void **this_prologue_cache)
static void amd64obsd_trapframe_this_id(frame_info_ptr this_frame, void **this_cache, struct frame_id *this_id)
static void amd64obsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
static int amd64obsd_sigtramp_p(frame_info_ptr this_frame)
int amd64obsd_r_reg_offset[]
#define amd64obsd_tf_reg_offset
static void amd64obsd_supply_uthread(struct regcache *regcache, int regnum, CORE_ADDR addr)
void _initialize_amd64obsd_tdep()
static int amd64obsd_uthread_reg_offset[]
static CORE_ADDR amd64obsd_sigcontext_addr(frame_info_ptr this_frame)
static int amd64obsd_sc_reg_offset[]
const struct target_desc * amd64_target_description(uint64_t xcr0, bool segments)
void amd64_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch, const target_desc *default_tdesc)
#define AMD64_NUM_GREGS
Definition amd64-tdep.h:87
@ AMD64_RIP_REGNUM
Definition amd64-tdep.h:51
@ AMD64_RDI_REGNUM
Definition amd64-tdep.h:40
@ AMD64_CS_REGNUM
Definition amd64-tdep.h:53
@ AMD64_RSP_REGNUM
Definition amd64-tdep.h:42
bool find_pc_partial_function(CORE_ADDR pc, const char **name, CORE_ADDR *address, CORE_ADDR *endaddr, const struct block **block)
Definition blockframe.c:373
void bsd_uthread_set_collect_uthread(struct gdbarch *gdbarch, void(*collect_uthread)(const struct regcache *, int, CORE_ADDR))
void bsd_uthread_set_supply_uthread(struct gdbarch *gdbarch, void(*supply_uthread)(struct regcache *, int, CORE_ADDR))
Definition bsd-uthread.c:98
gdbarch * arch() const
Definition regcache.c:231
void raw_collect(int regnum, void *buf) const override
Definition regcache.c:1127
void raw_supply(int regnum, const void *buf) override
Definition regcache.c:1062
void write_memory(CORE_ADDR memaddr, const bfd_byte *myaddr, ssize_t len)
Definition corefile.c:347
ULONGEST read_memory_unsigned_integer(CORE_ADDR memaddr, int len, enum bfd_endian byte_order)
Definition corefile.c:306
void write_memory_unsigned_integer(CORE_ADDR addr, int len, enum bfd_endian byte_order, ULONGEST value)
Definition corefile.c:380
void read_memory(CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
Definition corefile.c:238
static void store_unsigned_integer(gdb_byte *addr, int len, enum bfd_endian byte_order, ULONGEST val)
Definition defs.h:515
static ULONGEST extract_unsigned_integer(gdb::array_view< const gdb_byte > buf, enum bfd_endian byte_order)
Definition defs.h:480
const struct frame_id outer_frame_id
Definition frame.c:689
void frame_unwind_prepend_unwinder(struct gdbarch *gdbarch, const struct frame_unwind *unwinder)
enum unwind_stop_reason default_frame_unwind_stop_reason(frame_info_ptr this_frame, void **this_cache)
ULONGEST get_frame_register_unsigned(frame_info_ptr frame, int regnum)
Definition frame.c:1399
CORE_ADDR get_frame_pc(frame_info_ptr frame)
Definition frame.c:2712
struct frame_id frame_id_build(CORE_ADDR stack_addr, CORE_ADDR code_addr)
Definition frame.c:736
struct gdbarch * get_frame_arch(frame_info_ptr this_frame)
Definition frame.c:3027
CORE_ADDR get_frame_func(frame_info_ptr this_frame)
Definition frame.c:1098
bool safe_frame_unwind_memory(frame_info_ptr this_frame, CORE_ADDR addr, gdb::array_view< gdb_byte > buffer)
Definition frame.c:3017
@ NORMAL_FRAME
Definition frame.h:187
enum bfd_endian gdbarch_byte_order(struct gdbarch *gdbarch)
Definition gdbarch.c:1396
#define I386_SEL_UPL
Definition i386-tdep.h:394
#define I386_SEL_RPL
Definition i386-tdep.h:393
struct obj_section * find_pc_section(CORE_ADDR pc)
Definition objfiles.c:1128
void obsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
Definition obsd-tdep.c:294
void gdbarch_register_osabi(enum bfd_architecture arch, unsigned long machine, enum gdb_osabi osabi, void(*init_osabi)(struct gdbarch_info, struct gdbarch *))
Definition osabi.c:146
@ GDB_OSABI_OPENBSD
Definition osabi.h:35
void(* func)(remote_target *remote, char *)
void set_solib_svr4_fetch_link_map_offsets(struct gdbarch *gdbarch, struct link_map_offsets *(*flmo)(void))
struct link_map_offsets * svr4_lp64_fetch_link_map_offsets(void)
int * gregset_reg_offset
Definition i386-tdep.h:64
int(* sigtramp_p)(frame_info_ptr)
Definition i386-tdep.h:230
CORE_ADDR(* sigcontext_addr)(frame_info_ptr)
Definition i386-tdep.h:233
size_t sizeof_gregset
Definition i386-tdep.h:66
struct frame_id this_id
Definition trad-frame.c:35
frame_info_ptr this_frame
Definition trad-frame.c:32
Definition value.h:130
struct trad_frame_cache * trad_frame_cache_zalloc(frame_info_ptr this_frame)
Definition trad-frame.c:39
void trad_frame_set_reg_addr(struct trad_frame_cache *this_trad_cache, int regnum, CORE_ADDR addr)
Definition trad-frame.c:110
void trad_frame_get_id(struct trad_frame_cache *this_trad_cache, struct frame_id *this_id)
Definition trad-frame.c:227
void trad_frame_set_id(struct trad_frame_cache *this_trad_cache, struct frame_id this_id)
Definition trad-frame.c:220
struct value * trad_frame_get_register(struct trad_frame_cache *this_trad_cache, frame_info_ptr this_frame, int regnum)
Definition trad-frame.c:211