1 /* Target-dependent code for OpenBSD/amd64.
3 Copyright (C) 2003-2019 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
22 /* Local non-gdb includes. */
23 #include "amd64-tdep.h"
24 #include "bsd-uthread.h"
25 #include "common/x86-xstate.h"
26 #include "frame-unwind.h"
29 #include "i387-tdep.h"
31 #include "obsd-tdep.h"
35 #include "solib-svr4.h"
38 #include "trad-frame.h"
40 /* Support for signal handlers. */
42 /* Default page size. */
43 static const int amd64obsd_page_size = 4096;
45 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
49 amd64obsd_sigtramp_p (struct frame_info *this_frame)
51 CORE_ADDR pc = get_frame_pc (this_frame);
52 CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
53 const gdb_byte osigreturn[] =
56 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
57 0xcd, 0x80 /* int $0x80 */
59 const gdb_byte sigreturn[] =
62 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
63 0x0f, 0x05 /* syscall */
65 size_t buflen = (sizeof sigreturn) + 1;
69 /* If the function has a valid symbol name, it isn't a
71 find_pc_partial_function (pc, &name, NULL, NULL);
75 /* If the function lives in a valid section (even without a starting
76 point) it isn't a trampoline. */
77 if (find_pc_section (pc) != NULL)
80 /* If we can't read the instructions at START_PC, return zero. */
81 buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1);
82 if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
85 /* Check for sigreturn(2). Depending on how the assembler encoded
86 the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
87 7. OpenBSD 5.0 and later use the `syscall' instruction. Older
88 versions use `int $0x80'. Check for both. */
89 if (memcmp (buf, sigreturn, sizeof sigreturn)
90 && memcmp (buf + 1, sigreturn, sizeof sigreturn)
91 && memcmp (buf, osigreturn, sizeof osigreturn)
92 && memcmp (buf + 1, osigreturn, sizeof osigreturn))
98 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
99 address of the associated sigcontext structure. */
102 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
104 CORE_ADDR pc = get_frame_pc (this_frame);
105 ULONGEST offset = (pc & (amd64obsd_page_size - 1));
107 /* The %rsp register points at `struct sigcontext' upon entry of a
108 signal trampoline. The relevant part of the trampoline is
113 movq $SYS_sigreturn,%rax
116 (see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq'
117 instruction clobbers %rsp, but its value is saved in `%rdi'. */
120 return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
122 return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
125 /* OpenBSD 3.5 or later. */
127 /* Mapping between the general-purpose registers in `struct reg'
128 format and GDB's register cache layout. */
130 /* From <machine/reg.h>. */
131 int amd64obsd_r_reg_offset[] =
148 11 * 8, /* ... %r15 */
150 17 * 8, /* %eflags */
159 /* From <machine/signal.h>. */
160 static int amd64obsd_sc_reg_offset[] =
177 11 * 8, /* ... %r15 */
179 23 * 8, /* %eflags */
188 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */
189 static int amd64obsd_uthread_reg_offset[] =
199 12 * 8, /* %r8 ... */
206 5 * 8, /* ... %r15 */
217 /* Offset within the thread structure where we can find the saved
218 stack pointer (%esp). */
219 #define AMD64OBSD_UTHREAD_RSP_OFFSET 400
222 amd64obsd_supply_uthread (struct regcache *regcache,
223 int regnum, CORE_ADDR addr)
225 struct gdbarch *gdbarch = regcache->arch ();
226 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
227 CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
232 gdb_assert (regnum >= -1);
234 if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
238 /* Fetch stack pointer from thread structure. */
239 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
241 /* Adjust the stack pointer such that it looks as if we just
242 returned from _thread_machdep_switch. */
243 offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
244 store_unsigned_integer (buf, 8, byte_order, sp + offset);
245 regcache->raw_supply (AMD64_RSP_REGNUM, buf);
248 for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
250 if (amd64obsd_uthread_reg_offset[i] != -1
251 && (regnum == -1 || regnum == i))
253 /* Fetch stack pointer from thread structure (if we didn't
256 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
258 /* Read the saved register from the stack frame. */
259 read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
260 regcache->raw_supply (i, buf);
266 amd64obsd_collect_uthread (const struct regcache *regcache,
267 int regnum, CORE_ADDR addr)
269 struct gdbarch *gdbarch = regcache->arch ();
270 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
271 CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
276 gdb_assert (regnum >= -1);
278 if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
282 /* Calculate the stack pointer (frame pointer) that will be
283 stored into the thread structure. */
284 offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
285 regcache->raw_collect (AMD64_RSP_REGNUM, buf);
286 sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
288 /* Store the stack pointer. */
289 write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
291 /* The stack pointer was (potentially) modified. Make sure we
292 build a proper stack frame. */
296 for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
298 if (amd64obsd_uthread_reg_offset[i] != -1
299 && (regnum == -1 || regnum == i))
301 /* Fetch stack pointer from thread structure (if we didn't
302 calculate it already). */
304 sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
306 /* Write the register into the stack frame. */
307 regcache->raw_collect (i, buf);
308 write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
312 /* Kernel debugging support. */
314 /* From <machine/frame.h>. Easy since `struct trapframe' matches
315 `struct sigcontext'. */
316 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
318 static struct trad_frame_cache *
319 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
321 struct gdbarch *gdbarch = get_frame_arch (this_frame);
322 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
323 struct trad_frame_cache *cache;
324 CORE_ADDR func, sp, addr;
330 return (struct trad_frame_cache *) *this_cache;
332 cache = trad_frame_cache_zalloc (this_frame);
335 func = get_frame_func (this_frame);
336 sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
338 find_pc_partial_function (func, &name, NULL, NULL);
339 if (name && startswith (name, "Xintr"))
340 addr = sp + 8; /* It's an interrupt frame. */
344 for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
345 if (amd64obsd_tf_reg_offset[i] != -1)
346 trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
348 /* Read %cs from trap frame. */
349 addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
350 cs = read_memory_unsigned_integer (addr, 8, byte_order);
351 if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
353 /* Trap from user space; terminate backtrace. */
354 trad_frame_set_id (cache, outer_frame_id);
358 /* Construct the frame ID using the function start. */
359 trad_frame_set_id (cache, frame_id_build (sp + 16, func));
366 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
367 void **this_cache, struct frame_id *this_id)
369 struct trad_frame_cache *cache =
370 amd64obsd_trapframe_cache (this_frame, this_cache);
372 trad_frame_get_id (cache, this_id);
375 static struct value *
376 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
377 void **this_cache, int regnum)
379 struct trad_frame_cache *cache =
380 amd64obsd_trapframe_cache (this_frame, this_cache);
382 return trad_frame_get_register (cache, this_frame, regnum);
386 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
387 struct frame_info *this_frame,
388 void **this_prologue_cache)
393 /* Check Current Privilege Level and bail out if we're not executing
395 cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
396 if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
399 find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
400 return (name && ((strcmp (name, "calltrap") == 0)
401 || (strcmp (name, "osyscall1") == 0)
402 || (strcmp (name, "Xsyscall") == 0)
403 || (startswith (name, "Xintr"))));
406 static const struct frame_unwind amd64obsd_trapframe_unwind = {
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. */
411 default_frame_unwind_stop_reason,
412 amd64obsd_trapframe_this_id,
413 amd64obsd_trapframe_prev_register,
415 amd64obsd_trapframe_sniffer
420 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
422 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
424 amd64_init_abi (info, gdbarch,
425 amd64_target_description (X86_XSTATE_SSE_MASK, true));
426 obsd_init_abi (info, gdbarch);
428 /* Initialize general-purpose register set details. */
429 tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
430 tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
431 tdep->sizeof_gregset = 24 * 8;
433 tdep->jb_pc_offset = 7 * 8;
435 tdep->sigtramp_p = amd64obsd_sigtramp_p;
436 tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
437 tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
438 tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
440 /* OpenBSD provides a user-level threads implementation. */
441 bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
442 bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
444 /* OpenBSD uses SVR4-style shared libraries. */
445 set_solib_svr4_fetch_link_map_offsets
446 (gdbarch, svr4_lp64_fetch_link_map_offsets);
448 /* Unwind kernel trap frames correctly. */
449 frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
453 _initialize_amd64obsd_tdep (void)
455 /* The OpenBSD/amd64 native dependent code makes this assumption. */
456 gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
458 gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
459 GDB_OSABI_OPENBSD, amd64obsd_init_abi);