breakpoint.h revision 051dffaf54d2e049487bc884f3fa4346444be865
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/* Utility function that does what typically needs to be done when a 116 * breakpoint is to be inserted. It checks whether there is another 117 * breakpoint in PROC for given ADDR. If not, it allocates memory for 118 * a new breakpoint on the heap, initializes it, and calls 119 * PROC_ADD_BREAKPOINT to add the newly-created breakpoint. For newly 120 * added as well as preexisting breakpoints, it then calls 121 * BREAKPOINT_TURN_ON. If anything fails, it cleans up and returns 122 * NULL. Otherwise it returns the breakpoint for ADDR. */ 123struct breakpoint *insert_breakpoint(struct Process *proc, void *addr, 124 struct library_symbol *libsym); 125 126/* Name of a symbol associated with BP. May be NULL. */ 127const char *breakpoint_name(const struct breakpoint *bp); 128 129/* A library that this breakpoint comes from. May be NULL. */ 130struct library *breakpoint_library(const struct breakpoint *bp); 131 132/* Again, this seems to be several interfaces rolled into one: 133 * - breakpoint_disable 134 * - proc_remove_breakpoint 135 * - breakpoint_destroy 136 * XXX */ 137void delete_breakpoint(struct Process *proc, void *addr); 138 139/* XXX some of the following belongs to proc.h/proc.c. */ 140struct breakpoint *address2bpstruct(struct Process *proc, void *addr); 141void enable_all_breakpoints(struct Process *proc); 142void disable_all_breakpoints(struct Process *proc); 143int breakpoints_init(struct Process *proc); 144 145#endif /* BREAKPOINT_H */ 146