| 1 | /* Native-dependent code for GNU/Linux x86 (i386 and x86-64). |
| 2 | |
| 3 | Copyright (C) 1999-2019 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 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. |
| 11 | |
| 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. |
| 16 | |
| 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/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "inferior.h" |
| 22 | #include "elf/common.h" |
| 23 | #include "gdb_proc_service.h" |
| 24 | #include "nat/gdb_ptrace.h" |
| 25 | #include <sys/user.h> |
| 26 | #include <sys/procfs.h> |
| 27 | #include <sys/uio.h> |
| 28 | |
| 29 | #include "x86-nat.h" |
| 30 | #ifndef __x86_64__ |
| 31 | #include "i386-linux-nat.h" |
| 32 | #endif |
| 33 | #include "x86-linux-nat.h" |
| 34 | #include "i386-linux-tdep.h" |
| 35 | #ifdef __x86_64__ |
| 36 | #include "amd64-linux-tdep.h" |
| 37 | #endif |
| 38 | #include "gdbsupport/x86-xstate.h" |
| 39 | #include "nat/linux-btrace.h" |
| 40 | #include "nat/linux-nat.h" |
| 41 | #include "nat/x86-linux.h" |
| 42 | #include "nat/x86-linux-dregs.h" |
| 43 | #include "nat/linux-ptrace.h" |
| 44 | |
| 45 | /* linux_nat_target::low_new_fork implementation. */ |
| 46 | |
| 47 | void |
| 48 | x86_linux_nat_target::low_new_fork (struct lwp_info *parent, pid_t child_pid) |
| 49 | { |
| 50 | pid_t parent_pid; |
| 51 | struct x86_debug_reg_state *parent_state; |
| 52 | struct x86_debug_reg_state *child_state; |
| 53 | |
| 54 | /* NULL means no watchpoint has ever been set in the parent. In |
| 55 | that case, there's nothing to do. */ |
| 56 | if (parent->arch_private == NULL) |
| 57 | return; |
| 58 | |
| 59 | /* Linux kernel before 2.6.33 commit |
| 60 | 72f674d203cd230426437cdcf7dd6f681dad8b0d |
| 61 | will inherit hardware debug registers from parent |
| 62 | on fork/vfork/clone. Newer Linux kernels create such tasks with |
| 63 | zeroed debug registers. |
| 64 | |
| 65 | GDB core assumes the child inherits the watchpoints/hw |
| 66 | breakpoints of the parent, and will remove them all from the |
| 67 | forked off process. Copy the debug registers mirrors into the |
| 68 | new process so that all breakpoints and watchpoints can be |
| 69 | removed together. The debug registers mirror will become zeroed |
| 70 | in the end before detaching the forked off process, thus making |
| 71 | this compatible with older Linux kernels too. */ |
| 72 | |
| 73 | parent_pid = parent->ptid.pid (); |
| 74 | parent_state = x86_debug_reg_state (parent_pid); |
| 75 | child_state = x86_debug_reg_state (child_pid); |
| 76 | *child_state = *parent_state; |
| 77 | } |
| 78 | \f |
| 79 | |
| 80 | x86_linux_nat_target::~x86_linux_nat_target () |
| 81 | { |
| 82 | } |
| 83 | |
| 84 | void |
| 85 | x86_linux_nat_target::post_startup_inferior (ptid_t ptid) |
| 86 | { |
| 87 | x86_cleanup_dregs (); |
| 88 | linux_nat_target::post_startup_inferior (ptid); |
| 89 | } |
| 90 | |
| 91 | #ifdef __x86_64__ |
| 92 | /* Value of CS segment register: |
| 93 | 64bit process: 0x33 |
| 94 | 32bit process: 0x23 */ |
| 95 | #define AMD64_LINUX_USER64_CS 0x33 |
| 96 | |
| 97 | /* Value of DS segment register: |
| 98 | LP64 process: 0x0 |
| 99 | X32 process: 0x2b */ |
| 100 | #define AMD64_LINUX_X32_DS 0x2b |
| 101 | #endif |
| 102 | |
| 103 | /* Get Linux/x86 target description from running target. */ |
| 104 | |
| 105 | const struct target_desc * |
| 106 | x86_linux_nat_target::read_description () |
| 107 | { |
| 108 | int tid; |
| 109 | int is_64bit = 0; |
| 110 | #ifdef __x86_64__ |
| 111 | int is_x32; |
| 112 | #endif |
| 113 | static uint64_t xcr0; |
| 114 | uint64_t xcr0_features_bits; |
| 115 | |
| 116 | /* GNU/Linux LWP ID's are process ID's. */ |
| 117 | tid = inferior_ptid.lwp (); |
| 118 | if (tid == 0) |
| 119 | tid = inferior_ptid.pid (); /* Not a threaded program. */ |
| 120 | |
| 121 | #ifdef __x86_64__ |
| 122 | { |
| 123 | unsigned long cs; |
| 124 | unsigned long ds; |
| 125 | |
| 126 | /* Get CS register. */ |
| 127 | errno = 0; |
| 128 | cs = ptrace (PTRACE_PEEKUSER, tid, |
| 129 | offsetof (struct user_regs_struct, cs), 0); |
| 130 | if (errno != 0) |
| 131 | perror_with_name (_("Couldn't get CS register")); |
| 132 | |
| 133 | is_64bit = cs == AMD64_LINUX_USER64_CS; |
| 134 | |
| 135 | /* Get DS register. */ |
| 136 | errno = 0; |
| 137 | ds = ptrace (PTRACE_PEEKUSER, tid, |
| 138 | offsetof (struct user_regs_struct, ds), 0); |
| 139 | if (errno != 0) |
| 140 | perror_with_name (_("Couldn't get DS register")); |
| 141 | |
| 142 | is_x32 = ds == AMD64_LINUX_X32_DS; |
| 143 | |
| 144 | if (sizeof (void *) == 4 && is_64bit && !is_x32) |
| 145 | error (_("Can't debug 64-bit process with 32-bit GDB")); |
| 146 | } |
| 147 | #elif HAVE_PTRACE_GETFPXREGS |
| 148 | if (have_ptrace_getfpxregs == -1) |
| 149 | { |
| 150 | elf_fpxregset_t fpxregs; |
| 151 | |
| 152 | if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0) |
| 153 | { |
| 154 | have_ptrace_getfpxregs = 0; |
| 155 | have_ptrace_getregset = TRIBOOL_FALSE; |
| 156 | return i386_linux_read_description (X86_XSTATE_X87_MASK); |
| 157 | } |
| 158 | } |
| 159 | #endif |
| 160 | |
| 161 | if (have_ptrace_getregset == TRIBOOL_UNKNOWN) |
| 162 | { |
| 163 | uint64_t xstateregs[(X86_XSTATE_SSE_SIZE / sizeof (uint64_t))]; |
| 164 | struct iovec iov; |
| 165 | |
| 166 | iov.iov_base = xstateregs; |
| 167 | iov.iov_len = sizeof (xstateregs); |
| 168 | |
| 169 | /* Check if PTRACE_GETREGSET works. */ |
| 170 | if (ptrace (PTRACE_GETREGSET, tid, |
| 171 | (unsigned int) NT_X86_XSTATE, &iov) < 0) |
| 172 | have_ptrace_getregset = TRIBOOL_FALSE; |
| 173 | else |
| 174 | { |
| 175 | have_ptrace_getregset = TRIBOOL_TRUE; |
| 176 | |
| 177 | /* Get XCR0 from XSAVE extended state. */ |
| 178 | xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET |
| 179 | / sizeof (uint64_t))]; |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | /* Check the native XCR0 only if PTRACE_GETREGSET is available. If |
| 184 | PTRACE_GETREGSET is not available then set xcr0_features_bits to |
| 185 | zero so that the "no-features" descriptions are returned by the |
| 186 | switches below. */ |
| 187 | if (have_ptrace_getregset == TRIBOOL_TRUE) |
| 188 | xcr0_features_bits = xcr0 & X86_XSTATE_ALL_MASK; |
| 189 | else |
| 190 | xcr0_features_bits = 0; |
| 191 | |
| 192 | if (is_64bit) |
| 193 | { |
| 194 | #ifdef __x86_64__ |
| 195 | return amd64_linux_read_description (xcr0_features_bits, is_x32); |
| 196 | #endif |
| 197 | } |
| 198 | else |
| 199 | { |
| 200 | const struct target_desc * tdesc |
| 201 | = i386_linux_read_description (xcr0_features_bits); |
| 202 | |
| 203 | if (tdesc == NULL) |
| 204 | tdesc = i386_linux_read_description (X86_XSTATE_SSE_MASK); |
| 205 | |
| 206 | return tdesc; |
| 207 | } |
| 208 | |
| 209 | gdb_assert_not_reached ("failed to return tdesc"); |
| 210 | } |
| 211 | \f |
| 212 | |
| 213 | /* Enable branch tracing. */ |
| 214 | |
| 215 | struct btrace_target_info * |
| 216 | x86_linux_nat_target::enable_btrace (ptid_t ptid, |
| 217 | const struct btrace_config *conf) |
| 218 | { |
| 219 | struct btrace_target_info *tinfo = nullptr; |
| 220 | try |
| 221 | { |
| 222 | tinfo = linux_enable_btrace (ptid, conf); |
| 223 | } |
| 224 | catch (const gdb_exception_error &exception) |
| 225 | { |
| 226 | error (_("Could not enable branch tracing for %s: %s"), |
| 227 | target_pid_to_str (ptid).c_str (), exception.what ()); |
| 228 | } |
| 229 | |
| 230 | return tinfo; |
| 231 | } |
| 232 | |
| 233 | /* Disable branch tracing. */ |
| 234 | |
| 235 | void |
| 236 | x86_linux_nat_target::disable_btrace (struct btrace_target_info *tinfo) |
| 237 | { |
| 238 | enum btrace_error errcode = linux_disable_btrace (tinfo); |
| 239 | |
| 240 | if (errcode != BTRACE_ERR_NONE) |
| 241 | error (_("Could not disable branch tracing.")); |
| 242 | } |
| 243 | |
| 244 | /* Teardown branch tracing. */ |
| 245 | |
| 246 | void |
| 247 | x86_linux_nat_target::teardown_btrace (struct btrace_target_info *tinfo) |
| 248 | { |
| 249 | /* Ignore errors. */ |
| 250 | linux_disable_btrace (tinfo); |
| 251 | } |
| 252 | |
| 253 | enum btrace_error |
| 254 | x86_linux_nat_target::read_btrace (struct btrace_data *data, |
| 255 | struct btrace_target_info *btinfo, |
| 256 | enum btrace_read_type type) |
| 257 | { |
| 258 | return linux_read_btrace (data, btinfo, type); |
| 259 | } |
| 260 | |
| 261 | /* See to_btrace_conf in target.h. */ |
| 262 | |
| 263 | const struct btrace_config * |
| 264 | x86_linux_nat_target::btrace_conf (const struct btrace_target_info *btinfo) |
| 265 | { |
| 266 | return linux_btrace_conf (btinfo); |
| 267 | } |
| 268 | |
| 269 | \f |
| 270 | |
| 271 | /* Helper for ps_get_thread_area. Sets BASE_ADDR to a pointer to |
| 272 | the thread local storage (or its descriptor) and returns PS_OK |
| 273 | on success. Returns PS_ERR on failure. */ |
| 274 | |
| 275 | ps_err_e |
| 276 | x86_linux_get_thread_area (pid_t pid, void *addr, unsigned int *base_addr) |
| 277 | { |
| 278 | /* NOTE: cagney/2003-08-26: The definition of this buffer is found |
| 279 | in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x |
| 280 | 4 byte integers in size: `entry_number', `base_addr', `limit', |
| 281 | and a bunch of status bits. |
| 282 | |
| 283 | The values returned by this ptrace call should be part of the |
| 284 | regcache buffer, and ps_get_thread_area should channel its |
| 285 | request through the regcache. That way remote targets could |
| 286 | provide the value using the remote protocol and not this direct |
| 287 | call. |
| 288 | |
| 289 | Is this function needed? I'm guessing that the `base' is the |
| 290 | address of a descriptor that libthread_db uses to find the |
| 291 | thread local address base that GDB needs. Perhaps that |
| 292 | descriptor is defined by the ABI. Anyway, given that |
| 293 | libthread_db calls this function without prompting (gdb |
| 294 | requesting tls base) I guess it needs info in there anyway. */ |
| 295 | unsigned int desc[4]; |
| 296 | |
| 297 | /* This code assumes that "int" is 32 bits and that |
| 298 | GET_THREAD_AREA returns no more than 4 int values. */ |
| 299 | gdb_assert (sizeof (int) == 4); |
| 300 | |
| 301 | #ifndef PTRACE_GET_THREAD_AREA |
| 302 | #define PTRACE_GET_THREAD_AREA 25 |
| 303 | #endif |
| 304 | |
| 305 | if (ptrace (PTRACE_GET_THREAD_AREA, pid, addr, &desc) < 0) |
| 306 | return PS_ERR; |
| 307 | |
| 308 | *base_addr = desc[1]; |
| 309 | return PS_OK; |
| 310 | } |
| 311 | \f |
| 312 | |
| 313 | void |
| 314 | _initialize_x86_linux_nat () |
| 315 | { |
| 316 | /* Initialize the debug register function vectors. */ |
| 317 | x86_dr_low.set_control = x86_linux_dr_set_control; |
| 318 | x86_dr_low.set_addr = x86_linux_dr_set_addr; |
| 319 | x86_dr_low.get_addr = x86_linux_dr_get_addr; |
| 320 | x86_dr_low.get_status = x86_linux_dr_get_status; |
| 321 | x86_dr_low.get_control = x86_linux_dr_get_control; |
| 322 | x86_set_debug_register_length (sizeof (void *)); |
| 323 | } |