gdb/nat/linux-ptrace.h

   1 /* Copyright (C) 2011-2018 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef COMMON_LINUX_PTRACE_H
  19 #define COMMON_LINUX_PTRACE_H
  20
  21 struct buffer;
  22
  23 #include "nat/gdb_ptrace.h"
  24
  25 #ifdef __UCLIBC__
  26 #if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
  27 /* PTRACE_TEXT_ADDR and friends.  */
  28 #include <asm/ptrace.h>
  29 #define HAS_NOMMU
  30 #endif
  31 #endif
  32
  33 #if !defined(PTRACE_TYPE_ARG3)
  34 #define PTRACE_TYPE_ARG3 void *
  35 #endif
  36
  37 #if !defined(PTRACE_TYPE_ARG4)
  38 #define PTRACE_TYPE_ARG4 void *
  39 #endif
  40
  41 #ifndef PTRACE_GETSIGINFO
  42 # define PTRACE_GETSIGINFO 0x4202
  43 # define PTRACE_SETSIGINFO 0x4203
  44 #endif /* PTRACE_GETSIGINF */
  45
  46 #ifndef PTRACE_GETREGSET
  47 #define PTRACE_GETREGSET        0x4204
  48 #endif
  49
  50 #ifndef PTRACE_SETREGSET
  51 #define PTRACE_SETREGSET        0x4205
  52 #endif
  53
  54 /* If the system headers did not provide the constants, hard-code the normal
  55    values.  */
  56 #ifndef PTRACE_EVENT_FORK
  57
  58 #define PTRACE_SETOPTIONS       0x4200
  59 #define PTRACE_GETEVENTMSG      0x4201
  60
  61 /* options set using PTRACE_SETOPTIONS */
  62 #define PTRACE_O_TRACESYSGOOD   0x00000001
  63 #define PTRACE_O_TRACEFORK      0x00000002
  64 #define PTRACE_O_TRACEVFORK     0x00000004
  65 #define PTRACE_O_TRACECLONE     0x00000008
  66 #define PTRACE_O_TRACEEXEC      0x00000010
  67 #define PTRACE_O_TRACEVFORKDONE 0x00000020
  68 #define PTRACE_O_TRACEEXIT      0x00000040
  69
  70 /* Wait extended result codes for the above trace options.  */
  71 #define PTRACE_EVENT_FORK       1
  72 #define PTRACE_EVENT_VFORK      2
  73 #define PTRACE_EVENT_CLONE      3
  74 #define PTRACE_EVENT_EXEC       4
  75 #define PTRACE_EVENT_VFORK_DONE 5
  76 #define PTRACE_EVENT_EXIT       6
  77
  78 #endif /* PTRACE_EVENT_FORK */
  79
  80 #ifndef PTRACE_O_EXITKILL
  81 /* Only defined in Linux Kernel 3.8 or later.  */
  82 #define PTRACE_O_EXITKILL       0x00100000
  83 #endif
  84
  85 #if (defined __bfin__ || defined __frv__ || defined __sh__) \
  86     && !defined PTRACE_GETFDPIC
  87 #define PTRACE_GETFDPIC         31
  88 #define PTRACE_GETFDPIC_EXEC    0
  89 #define PTRACE_GETFDPIC_INTERP  1
  90 #endif
  91
  92 /* We can't always assume that this flag is available, but all systems
  93    with the ptrace event handlers also have __WALL, so it's safe to use
  94    in some contexts.  */
  95 #ifndef __WALL
  96 #define __WALL          0x40000000 /* Wait for any child.  */
  97 #endif
  98
  99 /* True if whether a breakpoint/watchpoint triggered can be determined
 100    from the si_code of SIGTRAP's siginfo_t (TRAP_BRKPT/TRAP_HWBKPT).
 101    That is, if the kernel can tell us whether the thread executed a
 102    software breakpoint, we trust it.  The kernel will be determining
 103    that from the hardware (e.g., from which exception was raised in
 104    the CPU).  Relying on whether a breakpoint is planted in memory at
 105    the time the SIGTRAP is processed to determine whether the thread
 106    stopped for a software breakpoint can be too late.  E.g., the
 107    breakpoint could have been removed since.  Or the thread could have
 108    stepped an instruction the size of a breakpoint instruction, and
 109    before the stop is processed a breakpoint is inserted at its
 110    address.  Getting these wrong is disastrous on decr_pc_after_break
 111    architectures.  The moribund location mechanism helps with that
 112    somewhat but it is an heuristic, and can well fail.  Getting that
 113    information out of the kernel and ultimately out of the CPU is the
 114    way to go.  That said, some architecture may get the si_code wrong,
 115    and as such we're leaving fallback code in place.  We'll remove
 116    this after a while if no problem is reported.  */
 117 #define USE_SIGTRAP_SIGINFO 1
 118
 119 /* The x86 kernel gets some of the si_code values backwards, like
 120    this:
 121
 122    | what                                     | si_code     |
 123    |------------------------------------------+-------------|
 124    | software breakpoints (int3)              | SI_KERNEL   |
 125    | single-steps                             | TRAP_TRACE  |
 126    | single-stepping a syscall                | TRAP_BRKPT  |
 127    | user sent SIGTRAP                        | 0           |
 128    | exec SIGTRAP (when no PTRACE_EVENT_EXEC) | 0           |
 129    | hardware breakpoints/watchpoints         | TRAP_HWBKPT |
 130
 131    That is, it reports SI_KERNEL for software breakpoints (and only
 132    for those), and TRAP_BRKPT for single-stepping a syscall...  If the
 133    kernel is ever fixed, we'll just have to detect it like we detect
 134    optional ptrace features: by forking and debugging ourselves,
 135    running to a breakpoint and checking what comes out of
 136    siginfo->si_code.
 137
 138    The ppc kernel does use TRAP_BRKPT for software breakpoints
 139    in PowerPC code, but it uses SI_KERNEL for software breakpoints
 140    in SPU code on a Cell/B.E.  However, SI_KERNEL is never seen
 141    on a SIGTRAP for any other reason.
 142
 143    The MIPS kernel up until 4.5 used SI_KERNEL for all kernel
 144    generated traps.  Since:
 145
 146      - MIPS doesn't do hardware single-step.
 147      - We don't need to care about exec SIGTRAPs --- we assume
 148        PTRACE_EVENT_EXEC is available.
 149      - The MIPS kernel doesn't support hardware breakpoints.
 150
 151    on MIPS, all we need to care about is distinguishing between
 152    software breakpoints and hardware watchpoints, which can be done by
 153    peeking the debug registers.
 154
 155    Beginning with Linux 4.6, the MIPS port reports proper TRAP_BRKPT and
 156    TRAP_HWBKPT codes, so we also match them.
 157
 158    The Alpha kernel uses TRAP_BRKPT for all traps.
 159
 160    The generic Linux target code should use GDB_ARCH_IS_TRAP_* instead
 161    of TRAP_* to abstract out these peculiarities.  */
 162 #if defined __i386__ || defined __x86_64__
 163 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
 164 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 165 #elif defined __powerpc__
 166 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
 167 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 168 #elif defined __mips__
 169 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
 170 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == SI_KERNEL || (X) == TRAP_HWBKPT)
 171 #elif defined __alpha__
 172 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
 173 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_BRKPT)
 174 #else
 175 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
 176 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 177 #endif
 178
 179 #ifndef TRAP_HWBKPT
 180 # define TRAP_HWBKPT 4
 181 #endif
 182
 183 extern void linux_ptrace_attach_fail_reason (pid_t pid, struct buffer *buffer);
 184
 185 /* Find all possible reasons we could have failed to attach to PTID
 186    and return them as a string.  ERR is the error PTRACE_ATTACH failed
 187    with (an errno).  The result is stored in a static buffer.  This
 188    string should be copied into a buffer by the client if the string
 189    will not be immediately used, or if it must persist.  */
 190 extern char *linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err);
 191
 192 extern void linux_ptrace_init_warnings (void);
 193 extern void linux_check_ptrace_features (void);
 194 extern void linux_enable_event_reporting (pid_t pid, int attached);
 195 extern void linux_disable_event_reporting (pid_t pid);
 196 extern int linux_supports_tracefork (void);
 197 extern int linux_supports_traceexec (void);
 198 extern int linux_supports_traceclone (void);
 199 extern int linux_supports_tracevforkdone (void);
 200 extern int linux_supports_tracesysgood (void);
 201 extern int linux_ptrace_get_extended_event (int wstat);
 202 extern int linux_is_extended_waitstatus (int wstat);
 203 extern int linux_wstatus_maybe_breakpoint (int wstat);
 204
 205 #endif /* COMMON_LINUX_PTRACE_H */