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linux-ptrace.h
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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 */
linux_ptrace_init_warnings
void linux_ptrace_init_warnings(void)
Definition: linux-ptrace.c:586
linux_enable_event_reporting
void linux_enable_event_reporting(pid_t pid, int attached)
Definition: linux-ptrace.c:491
linux_supports_tracefork
int linux_supports_tracefork(void)
Definition: linux-ptrace.c:537
linux_ptrace_get_extended_event
int linux_ptrace_get_extended_event(int wstat)
Definition: linux-ptrace.c:600
linux_is_extended_waitstatus
int linux_is_extended_waitstatus(int wstat)
Definition: linux-ptrace.c:608
ptid_t
Definition: ptid.h:35
linux_disable_event_reporting
void linux_disable_event_reporting(pid_t pid)
Definition: linux-ptrace.c:512
linux_ptrace_attach_fail_reason_string
char * linux_ptrace_attach_fail_reason_string(ptid_t ptid, int err)
Definition: linux-ptrace.c:59
linux_ptrace_attach_fail_reason
void linux_ptrace_attach_fail_reason(pid_t pid, struct buffer *buffer)
Definition: linux-ptrace.c:40
linux_supports_traceexec
int linux_supports_traceexec(void)
Definition: linux-ptrace.c:548
linux_check_ptrace_features
void linux_check_ptrace_features(void)
Definition: linux-ptrace.c:337
buffer
Definition: buffer.h:23
linux_supports_tracevforkdone
int linux_supports_tracevforkdone(void)
Definition: linux-ptrace.c:568
gdb_ptrace.h
linux_supports_tracesysgood
int linux_supports_tracesysgood(void)
Definition: linux-ptrace.c:577
linux_wstatus_maybe_breakpoint
int linux_wstatus_maybe_breakpoint(int wstat)
Definition: linux-ptrace.c:616
linux_supports_traceclone
int linux_supports_traceclone(void)
Definition: linux-ptrace.c:559