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 * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
27 */
28
29 #include <libdisasm.h>
30
31 #include "dis_tables.h"
32 #include "libdisasm_impl.h"
33
34 typedef struct dis_handle_i386 {
35 int dhx_mode;
36 dis86_t dhx_dis;
37 uint64_t dhx_end;
38 } dis_handle_i386_t;
39
40 /*
41 * Returns true if we are near the end of a function. This is a cheap hack at
42 * detecting NULL padding between functions. If we're within a few bytes of the
43 * next function, or past the start, then return true.
44 */
45 static int
46 check_func(void *data)
47 {
48 dis_handle_t *dhp = data;
49 uint64_t start;
50 size_t len;
51
52 if (dhp->dh_lookup(dhp->dh_data, dhp->dh_addr, NULL, 0, &start, &len)
53 != 0)
54 return (0);
55
56 if (start < dhp->dh_addr)
57 return (dhp->dh_addr > start + len - 0x10);
58
59 return (1);
60 }
61
62 static int
63 get_byte(void *data)
64 {
65 uchar_t byte;
66 dis_handle_t *dhp = data;
67
68 if (dhp->dh_read(dhp->dh_data, dhp->dh_addr, &byte, sizeof (byte)) !=
69 sizeof (byte))
70 return (-1);
71
72 dhp->dh_addr++;
73
74 return ((int)byte);
75 }
76
77 static int
78 do_lookup(void *data, uint64_t addr, char *buf, size_t buflen)
79 {
80 dis_handle_t *dhp = data;
81
82 return (dhp->dh_lookup(dhp->dh_data, addr, buf, buflen, NULL, NULL));
83 }
84
85 static void
86 dis_i386_handle_detach(dis_handle_t *dhp)
87 {
88 dis_free(dhp->dh_arch_private, sizeof (dis_handle_i386_t));
89 dhp->dh_arch_private = NULL;
90 }
91
92 static int
93 dis_i386_handle_attach(dis_handle_t *dhp)
94 {
95 dis_handle_i386_t *dhx;
96
97 /*
98 * Validate architecture flags
99 */
100 if (dhp->dh_flags & ~(DIS_X86_SIZE16 | DIS_X86_SIZE32 | DIS_X86_SIZE64 |
101 DIS_OCTAL | DIS_NOIMMSYM)) {
102 (void) dis_seterrno(E_DIS_INVALFLAG);
103 return (-1);
104 }
105
106 /*
107 * Create and initialize the internal structure
108 */
109 if ((dhx = dis_zalloc(sizeof (dis_handle_i386_t))) == NULL) {
110 (void) dis_seterrno(E_DIS_NOMEM);
111 return (-1);
112 }
113 dhp->dh_arch_private = dhx;
114
115 /*
116 * Initialize x86-specific architecture structure
117 */
118 if (dhp->dh_flags & DIS_X86_SIZE16)
119 dhx->dhx_mode = SIZE16;
120 else if (dhp->dh_flags & DIS_X86_SIZE64)
121 dhx->dhx_mode = SIZE64;
122 else
123 dhx->dhx_mode = SIZE32;
124
125 if (dhp->dh_flags & DIS_OCTAL)
126 dhx->dhx_dis.d86_flags = DIS_F_OCTAL;
127
128 dhx->dhx_dis.d86_sprintf_func = dis_snprintf;
129 dhx->dhx_dis.d86_get_byte = get_byte;
130 dhx->dhx_dis.d86_sym_lookup = do_lookup;
131 dhx->dhx_dis.d86_check_func = check_func;
132
133 dhx->dhx_dis.d86_data = dhp;
134
135 return (0);
136 }
137
138 static int
139 dis_i386_disassemble(dis_handle_t *dhp, uint64_t addr, char *buf,
140 size_t buflen)
141 {
142 dis_handle_i386_t *dhx = dhp->dh_arch_private;
143 dhp->dh_addr = addr;
144
145 /* DIS_NOIMMSYM might not be set until now, so update */
146 if (dhp->dh_flags & DIS_NOIMMSYM)
147 dhx->dhx_dis.d86_flags |= DIS_F_NOIMMSYM;
148 else
149 dhx->dhx_dis.d86_flags &= ~DIS_F_NOIMMSYM;
150
151 if (dtrace_disx86(&dhx->dhx_dis, dhx->dhx_mode) != 0)
152 return (-1);
153
154 if (buf != NULL)
155 dtrace_disx86_str(&dhx->dhx_dis, dhx->dhx_mode, addr, buf,
156 buflen);
157
158 return (0);
159 }
160
161 /* ARGSUSED */
162 static int
163 dis_i386_max_instrlen(dis_handle_t *dhp)
164 {
165 return (15);
166 }
167
168 /* ARGSUSED */
169 static int
170 dis_i386_min_instrlen(dis_handle_t *dhp)
171 {
172 return (1);
173 }
174
175 /*
176 * Return the previous instruction. On x86, we have no choice except to
177 * disassemble everything from the start of the symbol, and stop when we have
178 * reached our instruction address. If we're not in the middle of a known
179 * symbol, then we return the same address to indicate failure.
180 */
181 static uint64_t
182 dis_i386_previnstr(dis_handle_t *dhp, uint64_t pc, int n)
183 {
184 uint64_t *hist, addr, start;
185 int cur, nseen;
186 uint64_t res = pc;
187
188 if (n <= 0)
189 return (pc);
190
191 if (dhp->dh_lookup(dhp->dh_data, pc, NULL, 0, &start, NULL) != 0 ||
192 start == pc)
193 return (res);
194
195 hist = dis_zalloc(sizeof (uint64_t) * n);
196
197 for (cur = 0, nseen = 0, addr = start; addr < pc; addr = dhp->dh_addr) {
198 hist[cur] = addr;
199 cur = (cur + 1) % n;
200 nseen++;
201
202 /* if we cannot make forward progress, give up */
203 if (dis_disassemble(dhp, addr, NULL, 0) != 0)
204 goto done;
205 }
206
207 if (addr != pc) {
208 /*
209 * We scanned past %pc, but didn't find an instruction that
210 * started at %pc. This means that either the caller specified
211 * an invalid address, or we ran into something other than code
212 * during our scan. Virtually any combination of bytes can be
213 * construed as a valid Intel instruction, so any non-code bytes
214 * we encounter will have thrown off the scan.
215 */
216 goto done;
217 }
218
219 res = hist[(cur + n - MIN(n, nseen)) % n];
220
221 done:
222 dis_free(hist, sizeof (uint64_t) * n);
223 return (res);
224 }
225
226 static int
227 dis_i386_supports_flags(int flags)
228 {
229 int archflags = flags & DIS_ARCH_MASK;
230
231 if (archflags == DIS_X86_SIZE16 || archflags == DIS_X86_SIZE32 ||
232 archflags == DIS_X86_SIZE64)
233 return (1);
234
235 return (0);
236 }
237
238 static int
239 dis_i386_instrlen(dis_handle_t *dhp, uint64_t pc)
240 {
241 if (dis_disassemble(dhp, pc, NULL, 0) != 0)
242 return (-1);
243
244 return (dhp->dh_addr - pc);
245 }
246
247 dis_arch_t dis_arch_i386 = {
248 .da_supports_flags = dis_i386_supports_flags,
249 .da_handle_attach = dis_i386_handle_attach,
250 .da_handle_detach = dis_i386_handle_detach,
251 .da_disassemble = dis_i386_disassemble,
252 .da_previnstr = dis_i386_previnstr,
253 .da_min_instrlen = dis_i386_min_instrlen,
254 .da_max_instrlen = dis_i386_max_instrlen,
255 .da_instrlen = dis_i386_instrlen,
256 };