1 /* Target-dependent code for GNU/Linux running on x86-64, for GDB.
3 Copyright 2001, 2003 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 2 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, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
30 #include "gdb_string.h"
32 #include "x86-64-tdep.h"
34 #define LINUX_SIGTRAMP_INSN0 0x48 /* mov $NNNNNNNN, %rax */
35 #define LINUX_SIGTRAMP_OFFSET0 0
36 #define LINUX_SIGTRAMP_INSN1 0x0f /* syscall */
37 #define LINUX_SIGTRAMP_OFFSET1 7
39 static const unsigned char linux_sigtramp_code[] =
41 /* mov $__NR_rt_sigreturn, %rax */
42 LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,
44 LINUX_SIGTRAMP_INSN1, 0x05
47 #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
49 /* If PC is in a sigtramp routine, return the address of the start of
50 the routine. Otherwise, return 0. */
53 x86_64_linux_sigtramp_start (CORE_ADDR pc)
55 unsigned char buf[LINUX_SIGTRAMP_LEN];
57 /* We only recognize a signal trampoline if PC is at the start of
58 one of the two instructions. We optimize for finding the PC at
59 the start, as will be the case when the trampoline is not the
60 first frame on the stack. We assume that in the case where the
61 PC is not at the start of the instruction sequence, there will be
62 a few trailing readable bytes on the stack. */
64 if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
67 if (buf[0] != LINUX_SIGTRAMP_INSN0)
69 if (buf[0] != LINUX_SIGTRAMP_INSN1)
72 pc -= LINUX_SIGTRAMP_OFFSET1;
74 if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
78 if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
84 /* Return whether PC is in a GNU/Linux sigtramp routine. */
87 x86_64_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
89 /* If we have NAME, we can optimize the search. The trampoline is
90 named __restore_rt. However, it isn't dynamically exported from
91 the shared C library, so the trampoline may appear to be part of
92 the preceding function. This should always be sigaction,
93 __sigaction, or __libc_sigaction (all aliases to the same
95 if (name == NULL || strstr (name, "sigaction") != NULL)
96 return (x86_64_linux_sigtramp_start (pc) != 0);
98 return (strcmp ("__restore_rt", name) == 0);
101 /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */
102 #define X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40
104 /* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp
105 routine, return the address of the associated sigcontext structure. */
108 x86_64_linux_sigcontext_addr (struct frame_info *next_frame)
113 frame_unwind_register (next_frame, SP_REGNUM, buf);
114 sp = extract_unsigned_integer (buf, 8);
116 /* The sigcontext structure is part of the user context. A pointer
117 to the user context is passed as the third argument to the signal
118 handler, i.e. in %rdx. Unfortunately %rdx isn't preserved across
119 function calls so we can't use it. Fortunately the user context
120 is part of the signal frame and the unwound %rsp directly points
122 return sp + X86_64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET;
127 x86_64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
129 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
130 x86_64_init_abi (info, gdbarch);
132 set_gdbarch_pc_in_sigtramp (gdbarch, x86_64_linux_pc_in_sigtramp);
134 tdep->sigcontext_addr = x86_64_linux_sigcontext_addr;
135 tdep->sc_pc_offset = 16 * 8; /* From <asm/sigcontext.h>. */
136 tdep->sc_sp_offset = 15 * 8;
140 /* Provide a prototype to silence -Wmissing-prototypes. */
141 extern void _initialize_x86_64_linux_tdep (void);
144 _initialize_x86_64_linux_tdep (void)
146 gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_LINUX,
147 x86_64_linux_init_abi);