| 1 | /* Target-dependent code for GNU/Linux x86-64. |
| 2 | |
| 3 | Copyright (C) 2001, 2003, 2004, 2005, 2006, 2007 |
| 4 | Free Software Foundation, Inc. |
| 5 | Contributed by Jiri Smid, SuSE Labs. |
| 6 | |
| 7 | This file is part of GDB. |
| 8 | |
| 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. |
| 13 | |
| 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. |
| 18 | |
| 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., 51 Franklin Street, Fifth Floor, |
| 22 | Boston, MA 02110-1301, USA. */ |
| 23 | |
| 24 | #include "defs.h" |
| 25 | #include "frame.h" |
| 26 | #include "gdbcore.h" |
| 27 | #include "regcache.h" |
| 28 | #include "osabi.h" |
| 29 | #include "symtab.h" |
| 30 | #include "gdbtypes.h" |
| 31 | #include "reggroups.h" |
| 32 | #include "amd64-linux-tdep.h" |
| 33 | |
| 34 | #include "gdb_string.h" |
| 35 | |
| 36 | #include "amd64-tdep.h" |
| 37 | #include "solib-svr4.h" |
| 38 | |
| 39 | /* Mapping between the general-purpose registers in `struct user' |
| 40 | format and GDB's register cache layout. */ |
| 41 | |
| 42 | /* From <sys/reg.h>. */ |
| 43 | static int amd64_linux_gregset_reg_offset[] = |
| 44 | { |
| 45 | 10 * 8, /* %rax */ |
| 46 | 5 * 8, /* %rbx */ |
| 47 | 11 * 8, /* %rcx */ |
| 48 | 12 * 8, /* %rdx */ |
| 49 | 13 * 8, /* %rsi */ |
| 50 | 14 * 8, /* %rdi */ |
| 51 | 4 * 8, /* %rbp */ |
| 52 | 19 * 8, /* %rsp */ |
| 53 | 9 * 8, /* %r8 ... */ |
| 54 | 8 * 8, |
| 55 | 7 * 8, |
| 56 | 6 * 8, |
| 57 | 3 * 8, |
| 58 | 2 * 8, |
| 59 | 1 * 8, |
| 60 | 0 * 8, /* ... %r15 */ |
| 61 | 16 * 8, /* %rip */ |
| 62 | 18 * 8, /* %eflags */ |
| 63 | 17 * 8, /* %cs */ |
| 64 | 20 * 8, /* %ss */ |
| 65 | 23 * 8, /* %ds */ |
| 66 | 24 * 8, /* %es */ |
| 67 | 25 * 8, /* %fs */ |
| 68 | 26 * 8 /* %gs */ |
| 69 | }; |
| 70 | \f |
| 71 | |
| 72 | /* Support for signal handlers. */ |
| 73 | |
| 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 |
| 78 | |
| 79 | static const gdb_byte linux_sigtramp_code[] = |
| 80 | { |
| 81 | /* mov $__NR_rt_sigreturn, %rax */ |
| 82 | LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00, |
| 83 | /* syscall */ |
| 84 | LINUX_SIGTRAMP_INSN1, 0x05 |
| 85 | }; |
| 86 | |
| 87 | #define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code) |
| 88 | |
| 89 | /* If PC is in a sigtramp routine, return the address of the start of |
| 90 | the routine. Otherwise, return 0. */ |
| 91 | |
| 92 | static CORE_ADDR |
| 93 | amd64_linux_sigtramp_start (struct frame_info *next_frame) |
| 94 | { |
| 95 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 96 | gdb_byte buf[LINUX_SIGTRAMP_LEN]; |
| 97 | |
| 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. */ |
| 104 | |
| 105 | if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf)) |
| 106 | return 0; |
| 107 | |
| 108 | if (buf[0] != LINUX_SIGTRAMP_INSN0) |
| 109 | { |
| 110 | if (buf[0] != LINUX_SIGTRAMP_INSN1) |
| 111 | return 0; |
| 112 | |
| 113 | pc -= LINUX_SIGTRAMP_OFFSET1; |
| 114 | if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf)) |
| 115 | return 0; |
| 116 | } |
| 117 | |
| 118 | if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0) |
| 119 | return 0; |
| 120 | |
| 121 | return pc; |
| 122 | } |
| 123 | |
| 124 | /* Return whether the frame preceding NEXT_FRAME corresponds to a |
| 125 | GNU/Linux sigtramp routine. */ |
| 126 | |
| 127 | static int |
| 128 | amd64_linux_sigtramp_p (struct frame_info *next_frame) |
| 129 | { |
| 130 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 131 | char *name; |
| 132 | |
| 133 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 134 | |
| 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 |
| 140 | function). */ |
| 141 | if (name == NULL || strstr (name, "sigaction") != NULL) |
| 142 | return (amd64_linux_sigtramp_start (next_frame) != 0); |
| 143 | |
| 144 | return (strcmp ("__restore_rt", name) == 0); |
| 145 | } |
| 146 | |
| 147 | /* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>. */ |
| 148 | #define AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40 |
| 149 | |
| 150 | /* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp |
| 151 | routine, return the address of the associated sigcontext structure. */ |
| 152 | |
| 153 | static CORE_ADDR |
| 154 | amd64_linux_sigcontext_addr (struct frame_info *next_frame) |
| 155 | { |
| 156 | CORE_ADDR sp; |
| 157 | gdb_byte buf[8]; |
| 158 | |
| 159 | frame_unwind_register (next_frame, SP_REGNUM, buf); |
| 160 | sp = extract_unsigned_integer (buf, 8); |
| 161 | |
| 162 | /* The sigcontext structure is part of the user context. A pointer |
| 163 | to the user context is passed as the third argument to the signal |
| 164 | handler, i.e. in %rdx. Unfortunately %rdx isn't preserved across |
| 165 | function calls so we can't use it. Fortunately the user context |
| 166 | is part of the signal frame and the unwound %rsp directly points |
| 167 | at it. */ |
| 168 | return sp + AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET; |
| 169 | } |
| 170 | \f |
| 171 | |
| 172 | /* From <asm/sigcontext.h>. */ |
| 173 | static int amd64_linux_sc_reg_offset[] = |
| 174 | { |
| 175 | 13 * 8, /* %rax */ |
| 176 | 11 * 8, /* %rbx */ |
| 177 | 14 * 8, /* %rcx */ |
| 178 | 12 * 8, /* %rdx */ |
| 179 | 9 * 8, /* %rsi */ |
| 180 | 8 * 8, /* %rdi */ |
| 181 | 10 * 8, /* %rbp */ |
| 182 | 15 * 8, /* %rsp */ |
| 183 | 0 * 8, /* %r8 */ |
| 184 | 1 * 8, /* %r9 */ |
| 185 | 2 * 8, /* %r10 */ |
| 186 | 3 * 8, /* %r11 */ |
| 187 | 4 * 8, /* %r12 */ |
| 188 | 5 * 8, /* %r13 */ |
| 189 | 6 * 8, /* %r14 */ |
| 190 | 7 * 8, /* %r15 */ |
| 191 | 16 * 8, /* %rip */ |
| 192 | 17 * 8, /* %eflags */ |
| 193 | |
| 194 | /* FIXME: kettenis/2002030531: The registers %cs, %fs and %gs are |
| 195 | available in `struct sigcontext'. However, they only occupy two |
| 196 | bytes instead of four, which makes using them here rather |
| 197 | difficult. Leave them out for now. */ |
| 198 | -1, /* %cs */ |
| 199 | -1, /* %ss */ |
| 200 | -1, /* %ds */ |
| 201 | -1, /* %es */ |
| 202 | -1, /* %fs */ |
| 203 | -1 /* %gs */ |
| 204 | }; |
| 205 | |
| 206 | /* Replacement register functions which know about %orig_rax. */ |
| 207 | |
| 208 | static const char * |
| 209 | amd64_linux_register_name (int reg) |
| 210 | { |
| 211 | if (reg == AMD64_LINUX_ORIG_RAX_REGNUM) |
| 212 | return "orig_rax"; |
| 213 | |
| 214 | return amd64_register_name (reg); |
| 215 | } |
| 216 | |
| 217 | static struct type * |
| 218 | amd64_linux_register_type (struct gdbarch *gdbarch, int reg) |
| 219 | { |
| 220 | if (reg == AMD64_LINUX_ORIG_RAX_REGNUM) |
| 221 | return builtin_type_int64; |
| 222 | |
| 223 | return amd64_register_type (gdbarch, reg); |
| 224 | } |
| 225 | |
| 226 | static int |
| 227 | amd64_linux_register_reggroup_p (struct gdbarch *gdbarch, int regnum, |
| 228 | struct reggroup *group) |
| 229 | { |
| 230 | if (regnum == AMD64_LINUX_ORIG_RAX_REGNUM) |
| 231 | return (group == system_reggroup |
| 232 | || group == save_reggroup |
| 233 | || group == restore_reggroup); |
| 234 | return default_register_reggroup_p (gdbarch, regnum, group); |
| 235 | } |
| 236 | |
| 237 | /* Set the program counter for process PTID to PC. */ |
| 238 | |
| 239 | static void |
| 240 | amd64_linux_write_pc (CORE_ADDR pc, ptid_t ptid) |
| 241 | { |
| 242 | write_register_pid (AMD64_RIP_REGNUM, pc, ptid); |
| 243 | |
| 244 | /* We must be careful with modifying the program counter. If we |
| 245 | just interrupted a system call, the kernel might try to restart |
| 246 | it when we resume the inferior. On restarting the system call, |
| 247 | the kernel will try backing up the program counter even though it |
| 248 | no longer points at the system call. This typically results in a |
| 249 | SIGSEGV or SIGILL. We can prevent this by writing `-1' in the |
| 250 | "orig_rax" pseudo-register. |
| 251 | |
| 252 | Note that "orig_rax" is saved when setting up a dummy call frame. |
| 253 | This means that it is properly restored when that frame is |
| 254 | popped, and that the interrupted system call will be restarted |
| 255 | when we resume the inferior on return from a function call from |
| 256 | within GDB. In all other cases the system call will not be |
| 257 | restarted. */ |
| 258 | write_register_pid (AMD64_LINUX_ORIG_RAX_REGNUM, -1, ptid); |
| 259 | } |
| 260 | |
| 261 | static void |
| 262 | amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 263 | { |
| 264 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 265 | |
| 266 | tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset; |
| 267 | tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset); |
| 268 | tdep->sizeof_gregset = 27 * 8; |
| 269 | |
| 270 | amd64_init_abi (info, gdbarch); |
| 271 | |
| 272 | tdep->sigtramp_p = amd64_linux_sigtramp_p; |
| 273 | tdep->sigcontext_addr = amd64_linux_sigcontext_addr; |
| 274 | tdep->sc_reg_offset = amd64_linux_sc_reg_offset; |
| 275 | tdep->sc_num_regs = ARRAY_SIZE (amd64_linux_sc_reg_offset); |
| 276 | |
| 277 | /* GNU/Linux uses SVR4-style shared libraries. */ |
| 278 | set_solib_svr4_fetch_link_map_offsets |
| 279 | (gdbarch, svr4_lp64_fetch_link_map_offsets); |
| 280 | |
| 281 | /* Add the %orig_rax register used for syscall restarting. */ |
| 282 | set_gdbarch_write_pc (gdbarch, amd64_linux_write_pc); |
| 283 | set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS); |
| 284 | set_gdbarch_register_name (gdbarch, amd64_linux_register_name); |
| 285 | set_gdbarch_register_type (gdbarch, amd64_linux_register_type); |
| 286 | set_gdbarch_register_reggroup_p (gdbarch, amd64_linux_register_reggroup_p); |
| 287 | |
| 288 | /* Enable TLS support. */ |
| 289 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 290 | svr4_fetch_objfile_link_map); |
| 291 | } |
| 292 | \f |
| 293 | |
| 294 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 295 | extern void _initialize_amd64_linux_tdep (void); |
| 296 | |
| 297 | void |
| 298 | _initialize_amd64_linux_tdep (void) |
| 299 | { |
| 300 | gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, |
| 301 | GDB_OSABI_LINUX, amd64_linux_init_abi); |
| 302 | } |