breakpoint.h revision 929bd57ca202fd2f2e8485ebf65d683e664f67b5 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2012 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_retract)(struct breakpoint *bp, struct process *proc);
50};
51
52struct breakpoint {
53	struct bp_callbacks *cbs;
54	struct library_symbol *libsym;
55	void *addr;
56	unsigned char orig_value[BREAKPOINT_LENGTH];
57	int enabled;
58	struct arch_breakpoint_data arch;
59};
60
61/* Call on-hit handler of BP, if any is set.  */
62void breakpoint_on_hit(struct breakpoint *bp, struct process *proc);
63
64/* Call on-continue handler of BP.  If none is set, call
65 * continue_after_breakpoint.  */
66void breakpoint_on_continue(struct breakpoint *bp, struct process *proc);
67
68/* Call on-retract handler of BP, if any is set.  This should be
69 * called before the breakpoints are destroyed.  The reason for a
70 * separate interface is that breakpoint_destroy has to be callable
71 * without PROC.  ON_DISABLE might be useful as well, but that would
72 * be called every time we disable the breakpoint, which is too often
73 * (a breakpoint has to be disabled every time that we need to execute
74 * the instruction underneath it).  */
75void breakpoint_on_retract(struct breakpoint *bp, struct process *proc);
76
77/* Initialize a breakpoint structure.  That doesn't actually realize
78 * the breakpoint.  The breakpoint is initially assumed to be
79 * disabled.  orig_value has to be set separately.  CBS may be
80 * NULL.  */
81int breakpoint_init(struct breakpoint *bp, struct process *proc,
82		    arch_addr_t addr, struct library_symbol *libsym);
83
84/* Make a clone of breakpoint BP into the area of memory pointed to by
85 * RETP.  The original breakpoint was assigned to process OLD_PROC,
86 * the cloned breakpoint will be attached to process NEW_PROC.
87 * Returns 0 on success or a negative value on failure.  */
88int breakpoint_clone(struct breakpoint *retp, struct process *new_proc,
89		     struct breakpoint *bp, struct process *old_proc);
90
91/* Set callbacks.  If CBS is non-NULL, then BP->cbs shall be NULL.  */
92void breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs);
93
94/* Destroy a breakpoint structure.   */
95void breakpoint_destroy(struct breakpoint *bp);
96
97/* Call enable_breakpoint the first time it's called.  Returns 0 on
98 * success and a negative value on failure.  */
99int breakpoint_turn_on(struct breakpoint *bp, struct process *proc);
100
101/* Call disable_breakpoint when turned off the same number of times
102 * that it was turned on.  Returns 0 on success and a negative value
103 * on failure.  */
104int breakpoint_turn_off(struct breakpoint *bp, struct process *proc);
105
106/* Utility function that does what typically needs to be done when a
107 * breakpoint is to be inserted.  It checks whether there is another
108 * breakpoint in PROC->LEADER for given ADDR.  If not, it allocates
109 * memory for a new breakpoint on the heap, initializes it, and calls
110 * PROC_ADD_BREAKPOINT to add the newly-created breakpoint.  For newly
111 * added as well as preexisting breakpoints, it then calls
112 * BREAKPOINT_TURN_ON.  If anything fails, it cleans up and returns
113 * NULL.  Otherwise it returns the breakpoint for ADDR.  */
114struct breakpoint *insert_breakpoint(struct process *proc, void *addr,
115				     struct library_symbol *libsym);
116
117/* Name of a symbol associated with BP.  May be NULL.  */
118const char *breakpoint_name(const struct breakpoint *bp);
119
120/* A library that this breakpoint comes from.  May be NULL.  */
121struct library *breakpoint_library(const struct breakpoint *bp);
122
123/* Again, this seems to be several interfaces rolled into one:
124 *  - breakpoint_disable
125 *  - proc_remove_breakpoint
126 *  - breakpoint_destroy
127 * XXX */
128void delete_breakpoint(struct process *proc, void *addr);
129
130/* XXX some of the following belongs to proc.h/proc.c.  */
131struct breakpoint *address2bpstruct(struct process *proc, void *addr);
132void enable_all_breakpoints(struct process *proc);
133void disable_all_breakpoints(struct process *proc);
134int breakpoints_init(struct process *proc);
135
136#endif /* BREAKPOINT_H */
137