1 /*
2 * This file is part of ltrace.
3 * Copyright (C) 2012 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2008,2009 Juan Cespedes
5 * Copyright (C) 2006 Ian Wienand
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of the
10 * License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20 * 02110-1301 USA
21 */
22
23 #include <errno.h>
24 #include <gelf.h>
25 #include <stdio.h>
26 #include <string.h>
27 #include <sys/ptrace.h>
28
29 #include "proc.h"
30 #include "common.h"
31 #include "library.h"
32
33 /* A bundle is 128 bits. */
34 #define BUNDLE_SIZE 16
35
36 /* The PLT has
37 *
38 * - 3 bundles as a header
39 *
40 * - The special reserved entry
41 *
42 * - Following that, each PLT entry has it's initial code that the GOT
43 * entry points to. Each PLT entry has one bundle allocated.
44 *
45 * - Following that, each PLT entry has two bundles of actual PLT
46 * code, i.e. load up the address from the GOT and jump to it. This
47 * is the point we want to insert the breakpoint, as this will be
48 * captured every time we jump to the PLT entry in the code.
49 */
50
51 GElf_Addr
arch_plt_sym_val(struct ltelf * lte,size_t ndx,GElf_Rela * rela)52 arch_plt_sym_val(struct ltelf *lte, size_t ndx, GElf_Rela * rela)
53 {
54 /* Find number of entires by removing header and special
55 * entry, dividing total size by three, since each PLT entry
56 * will have 3 bundles (1 for inital entry and two for the PLT
57 * code). */
58 int entries = (lte->plt_size - 4 * BUNDLE_SIZE) / (3 * BUNDLE_SIZE);
59
60 /* Now the point we want to break on is the PLT entry after
61 * all the header stuff */
62 unsigned long addr =
63 lte->plt_addr + (4 * BUNDLE_SIZE) + (BUNDLE_SIZE * entries) +
64 (2 * ndx * BUNDLE_SIZE);
65 debug(3, "Found PLT %zd entry at %lx", ndx, addr);
66
67 return addr;
68 }
69
70 void *
sym2addr(struct process * proc,struct library_symbol * sym)71 sym2addr(struct process *proc, struct library_symbol *sym)
72 {
73 return sym->enter_addr;
74 }
75
76 int
arch_translate_address_dyn(struct process * proc,arch_addr_t addr,arch_addr_t * ret)77 arch_translate_address_dyn(struct process *proc,
78 arch_addr_t addr, arch_addr_t *ret)
79 {
80 errno = 0;
81 unsigned long l = ptrace(PTRACE_PEEKTEXT, proc->pid, addr, 0);
82 if (l == -1UL && errno) {
83 fprintf(stderr, "dynamic .opd translation of %p: %s\n",
84 addr, strerror(errno));
85 return -1;
86 }
87
88 /* XXX The double cast should be removed when
89 * arch_addr_t becomes integral type. */
90 *ret = (arch_addr_t)(uintptr_t)l;
91 return 0;
92 }
93
94 int
arch_translate_address(struct ltelf * lte,arch_addr_t addr,arch_addr_t * ret)95 arch_translate_address(struct ltelf *lte,
96 arch_addr_t addr, arch_addr_t *ret)
97 {
98 *ret = addr;
99 return 0;
100 }
101