breakpoint.h revision 0fe76c64833e09b382d40ee26ba23f02c63d6eb5 
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 * Tracepoints are provided by the main binary as well as by any
37 * opened libraries: every time an ELF file is mapped into the address
38 * space, a new set of tracepoints is extracted, and filtered
39 * according to user settings.  Those tracepoints that are left are
40 * then realized, and the tracing starts.
41 *
42 * A scheme like this would take care of gradually introducing
43 * breakpoints when the library is mapped, and therefore ready, and
44 * would avoid certain hacks.  For example on PPC64, we don't actually
45 * add breakpoints to PLT.  Instead, we read the PLT (which contains
46 * addresses, not code), to figure out where to put the breakpoints.
47 * In prelinked code, that address is non-zero, and points to an
48 * address that's not yet mapped.  ptrace then fails when we try to
49 * add the breakpoint.
50 *
51 * Ideally, return breakpoints would be just a special kind of
52 * tracepoint that has attached some magic.  Or a feature of a
53 * tracepoint.  Service breakpoints like the handling of dlopen would
54 * be a low-level breakpoint, likely without tracepoint attached.
55 *
56 * So that's for sometimes.
57 */
58
59#include "sysdep.h"
60#include "library.h"
61
62struct Process;
63struct breakpoint;
64
65struct bp_callbacks {
66	void (*on_hit)(struct breakpoint *bp, struct Process *proc);
67	void (*on_continue)(struct breakpoint *bp, struct Process *proc);
68};
69
70struct breakpoint {
71	struct bp_callbacks *cbs;
72	struct library_symbol *libsym;
73	void *addr;
74	unsigned char orig_value[BREAKPOINT_LENGTH];
75	int enabled;
76	struct arch_breakpoint_data arch;
77};
78
79/* Call on-hit handler of BP, if any is set.  */
80void breakpoint_on_hit(struct breakpoint *bp, struct Process *proc);
81
82/* Call on-continue handler of BP.  If none is set, call
83 * continue_after_breakpoint.  */
84void breakpoint_on_continue(struct breakpoint *bp, struct Process *proc);
85
86/* Initialize a breakpoint structure.  That doesn't actually realize
87 * the breakpoint.  The breakpoint is initially assumed to be
88 * disabled.  orig_value has to be set separately.  CBS may be
89 * NULL.  */
90int breakpoint_init(struct breakpoint *bp, struct Process *proc,
91		    target_address_t addr, struct library_symbol *libsym);
92
93/* Make a clone of breakpoint BP into the area of memory pointed to by
94 * RETP.  The original breakpoint was assigned to process OLD_PROC,
95 * the cloned breakpoint will be attached to process NEW_PROC.
96 * Returns 0 on success or a negative value on failure.  */
97int breakpoint_clone(struct breakpoint *retp, struct Process *new_proc,
98		     struct breakpoint *bp, struct Process *old_proc);
99
100/* Set callbacks.  If CBS is non-NULL, then BP->cbs shall be NULL.  */
101void breakpoint_set_callbacks(struct breakpoint *bp, struct bp_callbacks *cbs);
102
103/* Destroy a breakpoint structure.   */
104void breakpoint_destroy(struct breakpoint *bp);
105
106/* Call enable_breakpoint the first time it's called.  Returns 0 on
107 * success and a negative value on failure.  */
108int breakpoint_turn_on(struct breakpoint *bp, struct Process *proc);
109
110/* Call disable_breakpoint when turned off the same number of times
111 * that it was turned on.  Returns 0 on success and a negative value
112 * on failure.  */
113int breakpoint_turn_off(struct breakpoint *bp, struct Process *proc);
114
115/* This is actually several functions rolled in one:
116 *  - malloc
117 *  - breakpoint_init
118 *  - proc_add_breakpoint
119 *  - breakpoint_enable
120 * XXX I think it should be broken up somehow.  */
121struct breakpoint *insert_breakpoint(struct Process *proc, void *addr,
122				     struct library_symbol *libsym);
123
124/* Name of a symbol associated with BP.  May be NULL.  */
125const char *breakpoint_name(const struct breakpoint *bp);
126
127/* A library that this breakpoint comes from.  May be NULL.  */
128struct library *breakpoint_library(const struct breakpoint *bp);
129
130/* Again, this seems to be several interfaces rolled into one:
131 *  - breakpoint_disable
132 *  - proc_remove_breakpoint
133 *  - breakpoint_destroy
134 * XXX */
135void delete_breakpoint(struct Process *proc, void *addr);
136
137/* XXX some of the following belongs to proc.h/proc.c.  */
138struct breakpoint *address2bpstruct(struct Process *proc, void *addr);
139void enable_all_breakpoints(struct Process *proc);
140void disable_all_breakpoints(struct Process *proc);
141int breakpoints_init(struct Process *proc);
142
143#endif /* BREAKPOINT_H */
144