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 * Copyright 2012 Joshua M. Clulow <josh@sysmgr.org>
26 */
27
28 #include <libdisasm.h>
29 #include <stdlib.h>
30 #include <stdio.h>
31
32 #include "dis_tables.h"
33 #include "libdisasm_impl.h"
34
35 typedef struct dis_handle_i386 {
36 int dhx_mode;
37 dis86_t dhx_dis;
38 uint64_t dhx_end;
39 } dis_handle_i386_t;
40
41 /*
42 * Returns true if we are near the end of a function. This is a cheap hack at
43 * detecting NULL padding between functions. If we're within a few bytes of the
44 * next function, or past the start, then return true.
45 */
46 static int
47 check_func(void *data)
48 {
49 dis_handle_t *dhp = data;
50 uint64_t start;
51 size_t len;
52
53 if (dhp->dh_lookup(dhp->dh_data, dhp->dh_addr, NULL, 0, &start, &len)
54 != 0)
55 return (0);
56
57 if (start < dhp->dh_addr)
58 return (dhp->dh_addr > start + len - 0x10);
59
60 return (1);
61 }
62
63 static int
64 get_byte(void *data)
65 {
66 uchar_t byte;
67 dis_handle_t *dhp = data;
68
69 if (dhp->dh_read(dhp->dh_data, dhp->dh_addr, &byte, sizeof (byte)) !=
70 sizeof (byte))
71 return (-1);
72
73 dhp->dh_addr++;
74
75 return ((int)byte);
76 }
77
78 static int
79 do_lookup(void *data, uint64_t addr, char *buf, size_t buflen)
80 {
81 dis_handle_t *dhp = data;
82
83 return (dhp->dh_lookup(dhp->dh_data, addr, buf, buflen, NULL, NULL));
84 }
85
86 static void
87 dis_i386_handle_detach(dis_handle_t *dhp)
88 {
89 dis_free(dhp->dh_arch_private, sizeof (dis_handle_i386_t));
90 dhp->dh_arch_private = NULL;
91 }
92
93 static int
94 dis_i386_handle_attach(dis_handle_t *dhp)
95 {
96 dis_handle_i386_t *dhx;
97
98 /*
99 * Validate architecture flags
100 */
101 if (dhp->dh_flags & ~(DIS_X86_SIZE16 | DIS_X86_SIZE32 | DIS_X86_SIZE64 |
102 DIS_OCTAL | DIS_NOIMMSYM)) {
103 (void) dis_seterrno(E_DIS_INVALFLAG);
104 return (-1);
105 }
106
107 /*
108 * Create and initialize the internal structure
109 */
110 if ((dhx = dis_zalloc(sizeof (dis_handle_i386_t))) == NULL) {
111 (void) dis_seterrno(E_DIS_NOMEM);
112 return (-1);
113 }
114 dhp->dh_arch_private = dhx;
115
116 /*
117 * Initialize x86-specific architecture structure
118 */
119 if (dhp->dh_flags & DIS_X86_SIZE16)
120 dhx->dhx_mode = SIZE16;
121 else if (dhp->dh_flags & DIS_X86_SIZE64)
122 dhx->dhx_mode = SIZE64;
123 else
124 dhx->dhx_mode = SIZE32;
125
126 if (dhp->dh_flags & DIS_OCTAL)
127 dhx->dhx_dis.d86_flags = DIS_F_OCTAL;
128
129 dhx->dhx_dis.d86_sprintf_func = snprintf;
130 dhx->dhx_dis.d86_get_byte = get_byte;
131 dhx->dhx_dis.d86_sym_lookup = do_lookup;
132 dhx->dhx_dis.d86_check_func = check_func;
133
134 dhx->dhx_dis.d86_data = dhp;
135
136 return (0);
137 }
138
139 static int
140 dis_i386_disassemble(dis_handle_t *dhp, uint64_t addr, char *buf,
141 size_t buflen)
142 {
143 dis_handle_i386_t *dhx = dhp->dh_arch_private;
144 dhp->dh_addr = addr;
145
146 /* DIS_NOIMMSYM might not be set until now, so update */
147 if (dhp->dh_flags & DIS_NOIMMSYM)
148 dhx->dhx_dis.d86_flags |= DIS_F_NOIMMSYM;
149 else
150 dhx->dhx_dis.d86_flags &= ~DIS_F_NOIMMSYM;
151
152 if (dtrace_disx86(&dhx->dhx_dis, dhx->dhx_mode) != 0)
153 return (-1);
154
155 if (buf != NULL)
156 dtrace_disx86_str(&dhx->dhx_dis, dhx->dhx_mode, addr, buf,
157 buflen);
158
159 return (0);
160 }
161
162 /* ARGSUSED */
163 static int
164 dis_i386_max_instrlen(dis_handle_t *dhp)
165 {
166 return (15);
167 }
168
169 /* ARGSUSED */
170 static int
171 dis_i386_min_instrlen(dis_handle_t *dhp)
172 {
173 return (1);
174 }
175
176 #define MIN(a, b) ((a) < (b) ? (a) : (b))
177
178 /*
179 * Return the previous instruction. On x86, we have no choice except to
180 * disassemble everything from the start of the symbol, and stop when we have
181 * reached our instruction address. If we're not in the middle of a known
182 * symbol, then we return the same address to indicate failure.
183 */
184 static uint64_t
185 dis_i386_previnstr(dis_handle_t *dhp, uint64_t pc, int n)
186 {
187 uint64_t *hist, addr, start;
188 int cur, nseen;
189 uint64_t res = pc;
190
191 if (n <= 0)
192 return (pc);
193
194 if (dhp->dh_lookup(dhp->dh_data, pc, NULL, 0, &start, NULL) != 0 ||
195 start == pc)
196 return (res);
197
198 hist = dis_zalloc(sizeof (uint64_t) * n);
199
200 for (cur = 0, nseen = 0, addr = start; addr < pc; addr = dhp->dh_addr) {
201 hist[cur] = addr;
202 cur = (cur + 1) % n;
203 nseen++;
204
205 /* if we cannot make forward progress, give up */
206 if (dis_disassemble(dhp, addr, NULL, 0) != 0)
207 goto done;
208 }
209
210 if (addr != pc) {
211 /*
212 * We scanned past %pc, but didn't find an instruction that
213 * started at %pc. This means that either the caller specified
214 * an invalid address, or we ran into something other than code
215 * during our scan. Virtually any combination of bytes can be
216 * construed as a valid Intel instruction, so any non-code bytes
217 * we encounter will have thrown off the scan.
218 */
219 goto done;
220 }
221
222 res = hist[(cur + n - MIN(n, nseen)) % n];
223
224 done:
225 dis_free(hist, sizeof (uint64_t) * n);
226 return (res);
227 }
228
229 static int
230 dis_i386_supports_flags(int flags)
231 {
232 int archflags = flags & DIS_ARCH_MASK;
233
234 if (archflags == DIS_X86_SIZE16 || archflags == DIS_X86_SIZE32 ||
235 archflags == DIS_X86_SIZE64)
236 return (1);
237
238 return (0);
239 }
240
241 dis_arch_t dis_arch_i386 = {
242 dis_i386_supports_flags,
243 dis_i386_handle_attach,
244 dis_i386_handle_detach,
245 dis_i386_disassemble,
246 dis_i386_previnstr,
247 dis_i386_min_instrlen,
248 dis_i386_max_instrlen
249 };