1 /* Target-dependent code for GNU/Linux x86-64.
3 Copyright (C) 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
5 Contributed by Jiri Smid, SuSE Labs.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include "arch-utils.h"
30 #include "reggroups.h"
31 #include "amd64-linux-tdep.h"
32 #include "linux-tdep.h"
34 #include "gdb_string.h"
36 #include "amd64-tdep.h"
37 #include "solib-svr4.h"
39 /* Mapping between the general-purpose registers in `struct user'
40 format and GDB's register cache layout. */
42 /* From <sys/reg.h>. */
43 static int amd64_linux_gregset_reg_offset
[] =
72 /* Support for signal handlers. */
74 #define LINUX_SIGTRAMP_INSN0 0x48 /* mov $NNNNNNNN, %rax */
75 #define LINUX_SIGTRAMP_OFFSET0 0
76 #define LINUX_SIGTRAMP_INSN1 0x0f /* syscall */
77 #define LINUX_SIGTRAMP_OFFSET1 7
79 static const gdb_byte linux_sigtramp_code
[] =
81 /* mov $__NR_rt_sigreturn, %rax */
82 LINUX_SIGTRAMP_INSN0
, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
84 LINUX_SIGTRAMP_INSN1
, 0x05
87 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
89 /* If PC is in a sigtramp routine, return the address of the start of
90 the routine. Otherwise, return 0. */
93 amd64_linux_sigtramp_start (struct frame_info
*this_frame
)
95 CORE_ADDR pc
= get_frame_pc (this_frame
);
96 gdb_byte buf
[LINUX_SIGTRAMP_LEN
];
98 /* We only recognize a signal trampoline if PC is at the start of
99 one of the two instructions. We optimize for finding the PC at
100 the start, as will be the case when the trampoline is not the
101 first frame on the stack. We assume that in the case where the
102 PC is not at the start of the instruction sequence, there will be
103 a few trailing readable bytes on the stack. */
105 if (!safe_frame_unwind_memory (this_frame
, pc
, buf
, sizeof buf
))
108 if (buf
[0] != LINUX_SIGTRAMP_INSN0
)
110 if (buf
[0] != LINUX_SIGTRAMP_INSN1
)
113 pc
-= LINUX_SIGTRAMP_OFFSET1
;
114 if (!safe_frame_unwind_memory (this_frame
, pc
, buf
, sizeof buf
))
118 if (memcmp (buf
, linux_sigtramp_code
, LINUX_SIGTRAMP_LEN
) != 0)
124 /* Return whether THIS_FRAME corresponds to a GNU/Linux sigtramp
128 amd64_linux_sigtramp_p (struct frame_info
*this_frame
)
130 CORE_ADDR pc
= get_frame_pc (this_frame
);
133 find_pc_partial_function (pc
, &name
, NULL
, NULL
);
135 /* If we have NAME, we can optimize the search. The trampoline is
136 named __restore_rt. However, it isn't dynamically exported from
137 the shared C library, so the trampoline may appear to be part of
138 the preceding function. This should always be sigaction,
139 __sigaction, or __libc_sigaction (all aliases to the same
141 if (name
== NULL
|| strstr (name
, "sigaction") != NULL
)
142 return (amd64_linux_sigtramp_start (this_frame
) != 0);
144 return (strcmp ("__restore_rt", name
) == 0);
147 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */
148 #define AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
150 /* Assuming THIS_FRAME is a GNU/Linux sigtramp routine, return the
151 address of the associated sigcontext structure. */
154 amd64_linux_sigcontext_addr (struct frame_info
*this_frame
)
156 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
157 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
161 get_frame_register (this_frame
, AMD64_RSP_REGNUM
, buf
);
162 sp
= extract_unsigned_integer (buf
, 8, byte_order
);
164 /* The sigcontext structure is part of the user context. A pointer
165 to the user context is passed as the third argument to the signal
166 handler, i.e. in %rdx. Unfortunately %rdx isn't preserved across
167 function calls so we can't use it. Fortunately the user context
168 is part of the signal frame and the unwound %rsp directly points
170 return sp
+ AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET
;
174 /* From <asm/sigcontext.h>. */
175 static int amd64_linux_sc_reg_offset
[] =
194 17 * 8, /* %eflags */
196 /* FIXME: kettenis/2002030531: The registers %cs, %fs and %gs are
197 available in `struct sigcontext'. However, they only occupy two
198 bytes instead of four, which makes using them here rather
199 difficult. Leave them out for now. */
208 /* Replacement register functions which know about %orig_rax. */
211 amd64_linux_register_name (struct gdbarch
*gdbarch
, int reg
)
213 if (reg
== AMD64_LINUX_ORIG_RAX_REGNUM
)
216 return amd64_register_name (gdbarch
, reg
);
220 amd64_linux_register_type (struct gdbarch
*gdbarch
, int reg
)
222 if (reg
== AMD64_LINUX_ORIG_RAX_REGNUM
)
223 return builtin_type (gdbarch
)->builtin_int64
;
225 return amd64_register_type (gdbarch
, reg
);
229 amd64_linux_register_reggroup_p (struct gdbarch
*gdbarch
, int regnum
,
230 struct reggroup
*group
)
232 if (regnum
== AMD64_LINUX_ORIG_RAX_REGNUM
)
233 return (group
== system_reggroup
234 || group
== save_reggroup
235 || group
== restore_reggroup
);
236 return default_register_reggroup_p (gdbarch
, regnum
, group
);
239 /* Set the program counter for process PTID to PC. */
242 amd64_linux_write_pc (struct regcache
*regcache
, CORE_ADDR pc
)
244 regcache_cooked_write_unsigned (regcache
, AMD64_RIP_REGNUM
, pc
);
246 /* We must be careful with modifying the program counter. If we
247 just interrupted a system call, the kernel might try to restart
248 it when we resume the inferior. On restarting the system call,
249 the kernel will try backing up the program counter even though it
250 no longer points at the system call. This typically results in a
251 SIGSEGV or SIGILL. We can prevent this by writing `-1' in the
252 "orig_rax" pseudo-register.
254 Note that "orig_rax" is saved when setting up a dummy call frame.
255 This means that it is properly restored when that frame is
256 popped, and that the interrupted system call will be restarted
257 when we resume the inferior on return from a function call from
258 within GDB. In all other cases the system call will not be
260 regcache_cooked_write_unsigned (regcache
, AMD64_LINUX_ORIG_RAX_REGNUM
, -1);
264 amd64_linux_init_abi (struct gdbarch_info info
, struct gdbarch
*gdbarch
)
266 struct gdbarch_tdep
*tdep
= gdbarch_tdep (gdbarch
);
268 tdep
->gregset_reg_offset
= amd64_linux_gregset_reg_offset
;
269 tdep
->gregset_num_regs
= ARRAY_SIZE (amd64_linux_gregset_reg_offset
);
270 tdep
->sizeof_gregset
= 27 * 8;
272 amd64_init_abi (info
, gdbarch
);
274 tdep
->sigtramp_p
= amd64_linux_sigtramp_p
;
275 tdep
->sigcontext_addr
= amd64_linux_sigcontext_addr
;
276 tdep
->sc_reg_offset
= amd64_linux_sc_reg_offset
;
277 tdep
->sc_num_regs
= ARRAY_SIZE (amd64_linux_sc_reg_offset
);
279 /* GNU/Linux uses SVR4-style shared libraries. */
280 set_solib_svr4_fetch_link_map_offsets
281 (gdbarch
, svr4_lp64_fetch_link_map_offsets
);
283 /* Add the %orig_rax register used for syscall restarting. */
284 set_gdbarch_write_pc (gdbarch
, amd64_linux_write_pc
);
285 set_gdbarch_num_regs (gdbarch
, AMD64_LINUX_NUM_REGS
);
286 set_gdbarch_register_name (gdbarch
, amd64_linux_register_name
);
287 set_gdbarch_register_type (gdbarch
, amd64_linux_register_type
);
288 set_gdbarch_register_reggroup_p (gdbarch
, amd64_linux_register_reggroup_p
);
290 /* Enable TLS support. */
291 set_gdbarch_fetch_tls_load_module_address (gdbarch
,
292 svr4_fetch_objfile_link_map
);
294 /* Displaced stepping. */
295 set_gdbarch_displaced_step_copy_insn (gdbarch
,
296 amd64_displaced_step_copy_insn
);
297 set_gdbarch_displaced_step_fixup (gdbarch
, amd64_displaced_step_fixup
);
298 set_gdbarch_displaced_step_free_closure (gdbarch
,
299 simple_displaced_step_free_closure
);
300 set_gdbarch_displaced_step_location (gdbarch
,
301 displaced_step_at_entry_point
);
303 set_gdbarch_get_siginfo_type (gdbarch
, linux_get_siginfo_type
);
307 /* Provide a prototype to silence -Wmissing-prototypes. */
308 extern void _initialize_amd64_linux_tdep (void);
311 _initialize_amd64_linux_tdep (void)
313 gdbarch_register_osabi (bfd_arch_i386
, bfd_mach_x86_64
,
314 GDB_OSABI_LINUX
, amd64_linux_init_abi
);