1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2012,2013,2014 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2009 Juan Cespedes
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
19 * 02110-1301 USA
20 */
21
22#ifndef BREAKPOINT_H
23#define BREAKPOINT_H
24
25/* XXX This is currently a very weak abstraction.  We would like to
26 * much expand this to allow things like breakpoints on SDT probes and
27 * such.
28 *
29 * In particular, we would like to add a tracepoint abstraction.
30 * Tracepoint is a traceable feature--e.g. an exact address, a DWARF
31 * symbol, an ELF symbol, a PLT entry, or an SDT probe.  Tracepoints
32 * are named and the user can configure which of them he wants to
33 * enable.  Realized tracepoints enable breakpoints, which are a
34 * low-level realization of high-level tracepoint.
35 *
36 * Service breakpoints like the handling of dlopen would be a
37 * low-level breakpoint, likely without tracepoint attached.
38 *
39 * So that's for sometimes.
40 */
41
42#include "sysdep.h"
43#include "library.h"
44#include "forward.h"
45
46struct bp_callbacks {
47	void (*on_hit)(struct breakpoint *bp, struct process *proc);
48	void (*on_continue)(struct breakpoint *bp, struct process *proc);
49	void (*on_install)(struct breakpoint *bp, struct process *proc);
50	void (*on_retract)(struct breakpoint *bp, struct process *proc);
51
52	/* Create a new breakpoint that should handle return from the
53	 * function.  BP is the breakpoint that was just hit and for
54	 * which we wish to find the corresponding return breakpoint.
55	 * This returns 0 on success (in which case *RET will have
56	 * been initialized to desired breakpoint object, or NULL if
57	 * none is necessary) or a negative value on failure.  */
58	int (*get_return_bp)(struct breakpoint **ret,
59			     struct breakpoint *bp, struct process *proc);
60};
61
62struct breakpoint {
63	struct bp_callbacks *cbs;
64	struct library_symbol *libsym;
65	void *addr;
66	unsigned char orig_value[BREAKPOINT_LENGTH];
67	int enabled;
68	struct arch_breakpoint_data arch;
69	struct os_breakpoint_data os;
70};
71
72/* Call ON_HIT handler of BP, if any is set.  */
73void breakpoint_on_hit(struct breakpoint *bp, struct process *proc);
74
75/* Call ON_CONTINUE handler of BP.  If none is set, call
76 * continue_after_breakpoint.  */
77void breakpoint_on_continue(struct breakpoint *bp, struct process *proc);
78
79/* Call ON_RETRACT handler of BP, if any is set.  This should be
80 * called before the breakpoints are destroyed.  The reason for a
81 * separate interface is that breakpoint_destroy has to be callable
82 * without PROC.  ON_DISABLE might be useful as well, but that would
83 * be called every time we disable the breakpoint, which is too often
84 * (a breakpoint has to be disabled every time that we need to execute
85 * the instruction underneath it).  */
86void breakpoint_on_retract(struct breakpoint *bp, struct process *proc);
87
88/* Call ON_INSTALL handler of BP, if any is set.  This should be
89 * called after the breakpoint is enabled for the first time, not
90 * every time it's enabled (such as after stepping over a site of a
91 * temporarily disabled breakpoint).  */
92void breakpoint_on_install(struct breakpoint *bp, struct process *proc);
93
94/* Call GET_RETURN_BP handler of BP, if any is set.  If none is set,
95 * call CREATE_DEFAULT_RETURN_BP to obtain one.  */
96int breakpoint_get_return_bp(struct breakpoint **ret,
97			     struct breakpoint *bp, struct process *proc);
98
99/* Initialize a breakpoint structure.  That doesn't actually realize
100 * the breakpoint.  The breakpoint is initially assumed to be
101 * disabled.  orig_value has to be set separately.  CBS may be
102 * NULL.  */
103int breakpoint_init(struct breakpoint *bp, struct process *proc,
104		    arch_addr_t addr, struct library_symbol *libsym);
105
106/* Make a clone of breakpoint BP into the area of memory pointed to by
107 * RETP.  Symbols of cloned breakpoint are looked up in NEW_PROC.
108 * Returns 0 on success or a negative value on failure.  */
109int breakpoint_clone(struct breakpoint *retp, struct process *new_proc,
110		     struct breakpoint *bp);
111
112/* Set callbacks.  If CBS is non-NULL, then BP->cbs shall be NULL.  */
113void breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs);
114
115/* Destroy a breakpoint structure.   */
116void breakpoint_destroy(struct breakpoint *bp);
117
118/* Call enable_breakpoint the first time it's called.  Returns 0 on
119 * success and a negative value on failure.  */
120int breakpoint_turn_on(struct breakpoint *bp, struct process *proc);
121
122/* Call disable_breakpoint when turned off the same number of times
123 * that it was turned on.  Returns 0 on success and a negative value
124 * on failure.  */
125int breakpoint_turn_off(struct breakpoint *bp, struct process *proc);
126
127/* Allocate and initialize a default return breakpoint.  Returns NULL
128 * on failure.  */
129struct breakpoint *create_default_return_bp(struct process *proc);
130
131/* This allocates and initializes new breakpoint at ADDR, then calls
132 * INSERT_BREAKPOINT.  Returns the new breakpoint or NULL if there are
133 * errors.  */
134struct breakpoint *insert_breakpoint_at(struct process *proc, arch_addr_t addr,
135					struct library_symbol *libsym);
136
137/* Check if there is a breakpoint on this address already.  If yes,
138 * return that breakpoint instead (BP was not added).  If no, try to
139 * PROC_ADD_BREAKPOINT and BREAKPOINT_TURN_ON.  If it all works,
140 * return BP.  Otherwise return NULL.  */
141struct breakpoint *insert_breakpoint(struct process *proc,
142				     struct breakpoint *bp);
143
144/* Name of a symbol associated with BP.  May be NULL.  */
145const char *breakpoint_name(const struct breakpoint *bp);
146
147/* A library that this breakpoint comes from.  May be NULL.  */
148struct library *breakpoint_library(const struct breakpoint *bp);
149
150/* Again, this seems to be several interfaces rolled into one:
151 *  - breakpoint_disable
152 *  - proc_remove_breakpoint
153 *  - breakpoint_destroy
154 * XXX */
155void delete_breakpoint_at(struct process *proc, void *addr);
156int delete_breakpoint(struct process *proc, struct breakpoint *bp);
157
158/* XXX some of the following belongs to proc.h/proc.c.  */
159struct breakpoint *address2bpstruct(struct process *proc, void *addr);
160void disable_all_breakpoints(struct process *proc);
161int breakpoints_init(struct process *proc);
162
163#endif /* BREAKPOINT_H */
164