gdb/nat/linux-ptrace.h

   1 /* Copyright (C) 2011-2021 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 NAT_LINUX_PTRACE_H
  19 #define NAT_LINUX_PTRACE_H
  20
  21 struct buffer;
  22
  23 #include "nat/gdb_ptrace.h"
  24 #include "gdbsupport/gdb_wait.h"
  25
  26 #ifdef __UCLIBC__
  27 #if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
  28 /* PTRACE_TEXT_ADDR and friends.  */
  29 #include <asm/ptrace.h>
  30 #define HAS_NOMMU
  31 #endif
  32 #endif
  33
  34 #if !defined(PTRACE_TYPE_ARG3)
  35 #define PTRACE_TYPE_ARG3 void *
  36 #endif
  37
  38 #if !defined(PTRACE_TYPE_ARG4)
  39 #define PTRACE_TYPE_ARG4 void *
  40 #endif
  41
  42 #ifndef PTRACE_GETSIGINFO
  43 # define PTRACE_GETSIGINFO 0x4202
  44 # define PTRACE_SETSIGINFO 0x4203
  45 #endif /* PTRACE_GETSIGINF */
  46
  47 #ifndef PTRACE_GETREGSET
  48 #define PTRACE_GETREGSET        0x4204
  49 #endif
  50
  51 #ifndef PTRACE_SETREGSET
  52 #define PTRACE_SETREGSET        0x4205
  53 #endif
  54
  55 /* If the system headers did not provide the constants, hard-code the normal
  56    values.  */
  57 #ifndef PTRACE_EVENT_FORK
  58
  59 #define PTRACE_SETOPTIONS       0x4200
  60 #define PTRACE_GETEVENTMSG      0x4201
  61
  62 /* options set using PTRACE_SETOPTIONS */
  63 #define PTRACE_O_TRACESYSGOOD   0x00000001
  64 #define PTRACE_O_TRACEFORK      0x00000002
  65 #define PTRACE_O_TRACEVFORK     0x00000004
  66 #define PTRACE_O_TRACECLONE     0x00000008
  67 #define PTRACE_O_TRACEEXEC      0x00000010
  68 #define PTRACE_O_TRACEVFORKDONE 0x00000020
  69 #define PTRACE_O_TRACEEXIT      0x00000040
  70
  71 /* Wait extended result codes for the above trace options.  */
  72 #define PTRACE_EVENT_FORK       1
  73 #define PTRACE_EVENT_VFORK      2
  74 #define PTRACE_EVENT_CLONE      3
  75 #define PTRACE_EVENT_EXEC       4
  76 #define PTRACE_EVENT_VFORK_DONE 5
  77 #define PTRACE_EVENT_EXIT       6
  78
  79 #endif /* PTRACE_EVENT_FORK */
  80
  81 #ifndef PTRACE_O_EXITKILL
  82 /* Only defined in Linux Kernel 3.8 or later.  */
  83 #define PTRACE_O_EXITKILL       0x00100000
  84 #endif
  85
  86 #if (defined __bfin__ || defined __frv__ || defined __sh__) \
  87     && !defined PTRACE_GETFDPIC
  88 #define PTRACE_GETFDPIC         31
  89 #define PTRACE_GETFDPIC_EXEC    0
  90 #define PTRACE_GETFDPIC_INTERP  1
  91 #endif
  92
  93 /* We can't always assume that this flag is available, but all systems
  94    with the ptrace event handlers also have __WALL, so it's safe to use
  95    in some contexts.  */
  96 #ifndef __WALL
  97 #define __WALL          0x40000000 /* Wait for any child.  */
  98 #endif
  99
 100 /* True if whether a breakpoint/watchpoint triggered can be determined
 101    from the si_code of SIGTRAP's siginfo_t (TRAP_BRKPT/TRAP_HWBKPT).
 102    That is, if the kernel can tell us whether the thread executed a
 103    software breakpoint, we trust it.  The kernel will be determining
 104    that from the hardware (e.g., from which exception was raised in
 105    the CPU).  Relying on whether a breakpoint is planted in memory at
 106    the time the SIGTRAP is processed to determine whether the thread
 107    stopped for a software breakpoint can be too late.  E.g., the
 108    breakpoint could have been removed since.  Or the thread could have
 109    stepped an instruction the size of a breakpoint instruction, and
 110    before the stop is processed a breakpoint is inserted at its
 111    address.  Getting these wrong is disastrous on decr_pc_after_break
 112    architectures.  The moribund location mechanism helps with that
 113    somewhat but it is an heuristic, and can well fail.  Getting that
 114    information out of the kernel and ultimately out of the CPU is the
 115    way to go.  That said, some architecture may get the si_code wrong,
 116    and as such we're leaving fallback code in place.  We'll remove
 117    this after a while if no problem is reported.  */
 118 #define USE_SIGTRAP_SIGINFO 1
 119
 120 /* The x86 kernel gets some of the si_code values backwards, like
 121    this:
 122
 123    | what                                     | si_code     |
 124    |------------------------------------------+-------------|
 125    | software breakpoints (int3)              | SI_KERNEL   |
 126    | single-steps                             | TRAP_TRACE  |
 127    | single-stepping a syscall                | TRAP_BRKPT  |
 128    | user sent SIGTRAP                        | 0           |
 129    | exec SIGTRAP (when no PTRACE_EVENT_EXEC) | 0           |
 130    | hardware breakpoints/watchpoints         | TRAP_HWBKPT |
 131
 132    That is, it reports SI_KERNEL for software breakpoints (and only
 133    for those), and TRAP_BRKPT for single-stepping a syscall...  If the
 134    kernel is ever fixed, we'll just have to detect it like we detect
 135    optional ptrace features: by forking and debugging ourselves,
 136    running to a breakpoint and checking what comes out of
 137    siginfo->si_code.
 138
 139    The ppc kernel does use TRAP_BRKPT for software breakpoints
 140    in PowerPC code, but it uses SI_KERNEL for software breakpoints
 141    in SPU code on a Cell/B.E.  However, SI_KERNEL is never seen
 142    on a SIGTRAP for any other reason.
 143
 144    The MIPS kernel up until 4.5 used SI_KERNEL for all kernel
 145    generated traps.  Since:
 146
 147      - MIPS doesn't do hardware single-step.
 148      - We don't need to care about exec SIGTRAPs --- we assume
 149        PTRACE_EVENT_EXEC is available.
 150      - The MIPS kernel doesn't support hardware breakpoints.
 151
 152    on MIPS, all we need to care about is distinguishing between
 153    software breakpoints and hardware watchpoints, which can be done by
 154    peeking the debug registers.
 155
 156    Beginning with Linux 4.6, the MIPS port reports proper TRAP_BRKPT and
 157    TRAP_HWBKPT codes, so we also match them.
 158
 159    The generic Linux target code should use GDB_ARCH_IS_TRAP_* instead
 160    of TRAP_* to abstract out these peculiarities.  */
 161 #if defined __i386__ || defined __x86_64__
 162 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
 163 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 164 #elif defined __powerpc__
 165 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
 166 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 167 #elif defined __mips__
 168 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
 169 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == SI_KERNEL || (X) == TRAP_HWBKPT)
 170 #else
 171 # define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
 172 # define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
 173 #endif
 174
 175 #ifndef TRAP_HWBKPT
 176 # define TRAP_HWBKPT 4
 177 #endif
 178
 179 extern std::string linux_ptrace_attach_fail_reason (pid_t pid);
 180
 181 /* Find all possible reasons we could have failed to attach to PTID
 182    and return them as a string.  ERR is the error PTRACE_ATTACH failed
 183    with (an errno).  */
 184 extern std::string linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err);
 185
 186 extern void linux_ptrace_init_warnings (void);
 187 extern void linux_check_ptrace_features (void);
 188 extern void linux_enable_event_reporting (pid_t pid, int attached);
 189 extern void linux_disable_event_reporting (pid_t pid);
 190 extern int linux_supports_tracefork (void);
 191 extern int linux_supports_traceexec (void);
 192 extern int linux_supports_traceclone (void);
 193 extern int linux_supports_tracevforkdone (void);
 194 extern int linux_supports_tracesysgood (void);
 195 extern int linux_ptrace_get_extended_event (int wstat);
 196 extern int linux_is_extended_waitstatus (int wstat);
 197 extern int linux_wstatus_maybe_breakpoint (int wstat);
 198
 199 #endif /* NAT_LINUX_PTRACE_H */