| 1 | /* Target-dependent code for GNU/Linux x86-64. |
| 2 | |
| 3 | Copyright (C) 2001, 2003, 2004, 2005 Free Software Foundation, Inc. |
| 4 | Contributed by Jiri Smid, SuSE Labs. |
| 5 | |
| 6 | This file is part of GDB. |
| 7 | |
| 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 2 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program; if not, write to the Free Software |
| 20 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 21 | Boston, MA 02110-1301, USA. */ |
| 22 | |
| 23 | #include "defs.h" |
| 24 | #include "frame.h" |
| 25 | #include "gdbcore.h" |
| 26 | #include "regcache.h" |
| 27 | #include "osabi.h" |
| 28 | #include "symtab.h" |
| 29 | |
| 30 | #include "gdb_string.h" |
| 31 | |
| 32 | #include "amd64-tdep.h" |
| 33 | #include "solib-svr4.h" |
| 34 | |
| 35 | /* Mapping between the general-purpose registers in `struct user' |
| 36 | format and GDB's register cache layout. */ |
| 37 | |
| 38 | /* From <sys/reg.h>. */ |
| 39 | static int amd64_linux_gregset_reg_offset[] = |
| 40 | { |
| 41 | 10 * 8, /* %rax */ |
| 42 | 5 * 8, /* %rbx */ |
| 43 | 11 * 8, /* %rcx */ |
| 44 | 12 * 8, /* %rdx */ |
| 45 | 13 * 8, /* %rsi */ |
| 46 | 14 * 8, /* %rdi */ |
| 47 | 4 * 8, /* %rbp */ |
| 48 | 19 * 8, /* %rsp */ |
| 49 | 9 * 8, /* %r8 ... */ |
| 50 | 8 * 8, |
| 51 | 7 * 8, |
| 52 | 6 * 8, |
| 53 | 3 * 8, |
| 54 | 2 * 8, |
| 55 | 1 * 8, |
| 56 | 0 * 8, /* ... %r15 */ |
| 57 | 16 * 8, /* %rip */ |
| 58 | 18 * 8, /* %eflags */ |
| 59 | 17 * 8, /* %cs */ |
| 60 | 20 * 8, /* %ss */ |
| 61 | 23 * 8, /* %ds */ |
| 62 | 24 * 8, /* %es */ |
| 63 | 25 * 8, /* %fs */ |
| 64 | 26 * 8 /* %gs */ |
| 65 | }; |
| 66 | \f |
| 67 | |
| 68 | /* Support for signal handlers. */ |
| 69 | |
| 70 | #define LINUX_SIGTRAMP_INSN0 0x48 /* mov $NNNNNNNN, %rax */ |
| 71 | #define LINUX_SIGTRAMP_OFFSET0 0 |
| 72 | #define LINUX_SIGTRAMP_INSN1 0x0f /* syscall */ |
| 73 | #define LINUX_SIGTRAMP_OFFSET1 7 |
| 74 | |
| 75 | static const gdb_byte linux_sigtramp_code[] = |
| 76 | { |
| 77 | /* mov $__NR_rt_sigreturn, %rax */ |
| 78 | LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00, |
| 79 | /* syscall */ |
| 80 | LINUX_SIGTRAMP_INSN1, 0x05 |
| 81 | }; |
| 82 | |
| 83 | #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code) |
| 84 | |
| 85 | /* If PC is in a sigtramp routine, return the address of the start of |
| 86 | the routine. Otherwise, return 0. */ |
| 87 | |
| 88 | static CORE_ADDR |
| 89 | amd64_linux_sigtramp_start (struct frame_info *next_frame) |
| 90 | { |
| 91 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 92 | gdb_byte buf[LINUX_SIGTRAMP_LEN]; |
| 93 | |
| 94 | /* We only recognize a signal trampoline if PC is at the start of |
| 95 | one of the two instructions. We optimize for finding the PC at |
| 96 | the start, as will be the case when the trampoline is not the |
| 97 | first frame on the stack. We assume that in the case where the |
| 98 | PC is not at the start of the instruction sequence, there will be |
| 99 | a few trailing readable bytes on the stack. */ |
| 100 | |
| 101 | if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf)) |
| 102 | return 0; |
| 103 | |
| 104 | if (buf[0] != LINUX_SIGTRAMP_INSN0) |
| 105 | { |
| 106 | if (buf[0] != LINUX_SIGTRAMP_INSN1) |
| 107 | return 0; |
| 108 | |
| 109 | pc -= LINUX_SIGTRAMP_OFFSET1; |
| 110 | if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf)) |
| 111 | return 0; |
| 112 | } |
| 113 | |
| 114 | if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0) |
| 115 | return 0; |
| 116 | |
| 117 | return pc; |
| 118 | } |
| 119 | |
| 120 | /* Return whether the frame preceding NEXT_FRAME corresponds to a |
| 121 | GNU/Linux sigtramp routine. */ |
| 122 | |
| 123 | static int |
| 124 | amd64_linux_sigtramp_p (struct frame_info *next_frame) |
| 125 | { |
| 126 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 127 | char *name; |
| 128 | |
| 129 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 130 | |
| 131 | /* If we have NAME, we can optimize the search. The trampoline is |
| 132 | named __restore_rt. However, it isn't dynamically exported from |
| 133 | the shared C library, so the trampoline may appear to be part of |
| 134 | the preceding function. This should always be sigaction, |
| 135 | __sigaction, or __libc_sigaction (all aliases to the same |
| 136 | function). */ |
| 137 | if (name == NULL || strstr (name, "sigaction") != NULL) |
| 138 | return (amd64_linux_sigtramp_start (next_frame) != 0); |
| 139 | |
| 140 | return (strcmp ("__restore_rt", name) == 0); |
| 141 | } |
| 142 | |
| 143 | /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */ |
| 144 | #define AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40 |
| 145 | |
| 146 | /* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp |
| 147 | routine, return the address of the associated sigcontext structure. */ |
| 148 | |
| 149 | static CORE_ADDR |
| 150 | amd64_linux_sigcontext_addr (struct frame_info *next_frame) |
| 151 | { |
| 152 | CORE_ADDR sp; |
| 153 | gdb_byte buf[8]; |
| 154 | |
| 155 | frame_unwind_register (next_frame, SP_REGNUM, buf); |
| 156 | sp = extract_unsigned_integer (buf, 8); |
| 157 | |
| 158 | /* The sigcontext structure is part of the user context. A pointer |
| 159 | to the user context is passed as the third argument to the signal |
| 160 | handler, i.e. in %rdx. Unfortunately %rdx isn't preserved across |
| 161 | function calls so we can't use it. Fortunately the user context |
| 162 | is part of the signal frame and the unwound %rsp directly points |
| 163 | at it. */ |
| 164 | return sp + AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET; |
| 165 | } |
| 166 | \f |
| 167 | |
| 168 | /* From <asm/sigcontext.h>. */ |
| 169 | static int amd64_linux_sc_reg_offset[] = |
| 170 | { |
| 171 | 13 * 8, /* %rax */ |
| 172 | 11 * 8, /* %rbx */ |
| 173 | 14 * 8, /* %rcx */ |
| 174 | 12 * 8, /* %rdx */ |
| 175 | 9 * 8, /* %rsi */ |
| 176 | 8 * 8, /* %rdi */ |
| 177 | 10 * 8, /* %rbp */ |
| 178 | 15 * 8, /* %rsp */ |
| 179 | 0 * 8, /* %r8 */ |
| 180 | 1 * 8, /* %r9 */ |
| 181 | 2 * 8, /* %r10 */ |
| 182 | 3 * 8, /* %r11 */ |
| 183 | 4 * 8, /* %r12 */ |
| 184 | 5 * 8, /* %r13 */ |
| 185 | 6 * 8, /* %r14 */ |
| 186 | 7 * 8, /* %r15 */ |
| 187 | 16 * 8, /* %rip */ |
| 188 | 17 * 8, /* %eflags */ |
| 189 | |
| 190 | /* FIXME: kettenis/2002030531: The registers %cs, %fs and %gs are |
| 191 | available in `struct sigcontext'. However, they only occupy two |
| 192 | bytes instead of four, which makes using them here rather |
| 193 | difficult. Leave them out for now. */ |
| 194 | -1, /* %cs */ |
| 195 | -1, /* %ss */ |
| 196 | -1, /* %ds */ |
| 197 | -1, /* %es */ |
| 198 | -1, /* %fs */ |
| 199 | -1 /* %gs */ |
| 200 | }; |
| 201 | |
| 202 | static void |
| 203 | amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 204 | { |
| 205 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 206 | |
| 207 | tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset; |
| 208 | tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset); |
| 209 | tdep->sizeof_gregset = 27 * 8; |
| 210 | |
| 211 | amd64_init_abi (info, gdbarch); |
| 212 | |
| 213 | tdep->sigtramp_p = amd64_linux_sigtramp_p; |
| 214 | tdep->sigcontext_addr = amd64_linux_sigcontext_addr; |
| 215 | tdep->sc_reg_offset = amd64_linux_sc_reg_offset; |
| 216 | tdep->sc_num_regs = ARRAY_SIZE (amd64_linux_sc_reg_offset); |
| 217 | |
| 218 | /* GNU/Linux uses SVR4-style shared libraries. */ |
| 219 | set_solib_svr4_fetch_link_map_offsets |
| 220 | (gdbarch, svr4_lp64_fetch_link_map_offsets); |
| 221 | |
| 222 | /* Enable TLS support. */ |
| 223 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 224 | svr4_fetch_objfile_link_map); |
| 225 | } |
| 226 | \f |
| 227 | |
| 228 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 229 | extern void _initialize_amd64_linux_tdep (void); |
| 230 | |
| 231 | void |
| 232 | _initialize_amd64_linux_tdep (void) |
| 233 | { |
| 234 | gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, |
| 235 | GDB_OSABI_LINUX, amd64_linux_init_abi); |
| 236 | } |