1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 #include <libdisasm.h>
30 #include <stdlib.h>
31 #include <stdio.h>
32
33 #include "dis_tables.h"
34 #include "libdisasm_impl.h"
35
36 struct dis_handle {
37 void *dh_data;
38 int dh_flags;
39 dis_lookup_f dh_lookup;
40 dis_read_f dh_read;
41 int dh_mode;
42 dis86_t dh_dis;
43 uint64_t dh_addr;
44 uint64_t dh_end;
45 };
46
47 /*
48 * Returns true if we are near the end of a function. This is a cheap hack at
49 * detecting NULL padding between functions. If we're within a few bytes of the
50 * next function, or past the start, then return true.
51 */
52 static int
53 check_func(void *data)
54 {
55 dis_handle_t *dhp = data;
56 uint64_t start;
57 size_t len;
58
59 if (dhp->dh_lookup(dhp->dh_data, dhp->dh_addr, NULL, 0, &start, &len)
60 != 0)
61 return (0);
62
63 if (start < dhp->dh_addr)
64 return (dhp->dh_addr > start + len - 0x10);
65
66 return (1);
67 }
68
69 static int
70 get_byte(void *data)
71 {
72 uchar_t byte;
73 dis_handle_t *dhp = data;
74
75 if (dhp->dh_read(dhp->dh_data, dhp->dh_addr, &byte, sizeof (byte)) !=
76 sizeof (byte))
77 return (-1);
78
79 dhp->dh_addr++;
80
81 return ((int)byte);
82 }
83
84 static int
85 do_lookup(void *data, uint64_t addr, char *buf, size_t buflen)
86 {
87 dis_handle_t *dhp = data;
88
89 return (dhp->dh_lookup(dhp->dh_data, addr, buf, buflen, NULL, NULL));
90 }
91
92 dis_handle_t *
93 dis_handle_create(int flags, void *data, dis_lookup_f lookup_func,
94 dis_read_f read_func)
95 {
96 dis_handle_t *dhp;
97
98 /*
99 * Validate architecture flags
100 */
101 if (flags & ~(DIS_X86_SIZE16 | DIS_X86_SIZE32 | DIS_X86_SIZE64 |
102 DIS_OCTAL | DIS_NOIMMSYM)) {
103 (void) dis_seterrno(E_DIS_INVALFLAG);
104 return (NULL);
105 }
106
107 /*
108 * Create and initialize the internal structure
109 */
110 if ((dhp = dis_zalloc(sizeof (struct dis_handle))) == NULL) {
111 (void) dis_seterrno(E_DIS_NOMEM);
112 return (NULL);
113 }
114
115 dhp->dh_lookup = lookup_func;
116 dhp->dh_read = read_func;
117 dhp->dh_flags = flags;
118 dhp->dh_data = data;
119
120 /*
121 * Initialize x86-specific architecture structure
122 */
123 if (flags & DIS_X86_SIZE16)
124 dhp->dh_mode = SIZE16;
125 else if (flags & DIS_X86_SIZE64)
126 dhp->dh_mode = SIZE64;
127 else
128 dhp->dh_mode = SIZE32;
129
130 if (flags & DIS_OCTAL)
131 dhp->dh_dis.d86_flags = DIS_F_OCTAL;
132
133 dhp->dh_dis.d86_sprintf_func = snprintf;
134 dhp->dh_dis.d86_get_byte = get_byte;
135 dhp->dh_dis.d86_sym_lookup = do_lookup;
136 dhp->dh_dis.d86_check_func = check_func;
137
138 dhp->dh_dis.d86_data = dhp;
139
140 return (dhp);
141 }
142
143 int
144 dis_disassemble(dis_handle_t *dhp, uint64_t addr, char *buf, size_t buflen)
145 {
146 dhp->dh_addr = addr;
147
148 /* DIS_NOIMMSYM might not be set until now, so update */
149 if (dhp->dh_flags & DIS_NOIMMSYM)
150 dhp->dh_dis.d86_flags |= DIS_F_NOIMMSYM;
151 else
152 dhp->dh_dis.d86_flags &= ~DIS_F_NOIMMSYM;
153
154 if (dtrace_disx86(&dhp->dh_dis, dhp->dh_mode) != 0)
155 return (-1);
156
157 if (buf != NULL)
158 dtrace_disx86_str(&dhp->dh_dis, dhp->dh_mode, addr, buf,
159 buflen);
160
161 return (0);
162 }
163
164 void
165 dis_handle_destroy(dis_handle_t *dhp)
166 {
167 dis_free(dhp, sizeof (dis_handle_t));
168 }
169
170 void
171 dis_set_data(dis_handle_t *dhp, void *data)
172 {
173 dhp->dh_data = data;
174 }
175
176 void
177 dis_flags_set(dis_handle_t *dhp, int f)
178 {
179 dhp->dh_flags |= f;
180 }
181
182 void
183 dis_flags_clear(dis_handle_t *dhp, int f)
184 {
185 dhp->dh_flags &= ~f;
186 }
187
188
189 /* ARGSUSED */
190 int
191 dis_max_instrlen(dis_handle_t *dhp)
192 {
193 return (15);
194 }
195
196 #define MIN(a, b) ((a) < (b) ? (a) : (b))
197
198 /*
199 * Return the previous instruction. On x86, we have no choice except to
200 * disassemble everything from the start of the symbol, and stop when we have
201 * reached our instruction address. If we're not in the middle of a known
202 * symbol, then we return the same address to indicate failure.
203 */
204 uint64_t
205 dis_previnstr(dis_handle_t *dhp, uint64_t pc, int n)
206 {
207 uint64_t *hist, addr, start;
208 int cur, nseen;
209 uint64_t res = pc;
210
211 if (n <= 0)
212 return (pc);
213
214 if (dhp->dh_lookup(dhp->dh_data, pc, NULL, 0, &start, NULL) != 0 ||
215 start == pc)
216 return (res);
217
218 hist = dis_zalloc(sizeof (uint64_t) * n);
219
220 for (cur = 0, nseen = 0, addr = start; addr < pc; addr = dhp->dh_addr) {
221 hist[cur] = addr;
222 cur = (cur + 1) % n;
223 nseen++;
224
225 /* if we cannot make forward progress, give up */
226 if (dis_disassemble(dhp, addr, NULL, 0) != 0)
227 goto done;
228 }
229
230 if (addr != pc) {
231 /*
232 * We scanned past %pc, but didn't find an instruction that
233 * started at %pc. This means that either the caller specified
234 * an invalid address, or we ran into something other than code
235 * during our scan. Virtually any combination of bytes can be
236 * construed as a valid Intel instruction, so any non-code bytes
237 * we encounter will have thrown off the scan.
238 */
239 goto done;
240 }
241
242 res = hist[(cur + n - MIN(n, nseen)) % n];
243
244 done:
245 dis_free(hist, sizeof (uint64_t) * n);
246 return (res);
247 }