xref: /freebsd/sys/gdb/gdb_packet.c (revision 87c1627502a5dde91e5284118eec8682b60f27a2)
1 /*-
2  * Copyright (c) 2004 Marcel Moolenaar
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/ctype.h>
33 #include <sys/kdb.h>
34 #include <sys/ttydefaults.h>
35 
36 #include <machine/gdb_machdep.h>
37 #include <machine/kdb.h>
38 
39 #include <gdb/gdb.h>
40 #include <gdb/gdb_int.h>
41 
42 static char gdb_rxbuf[GDB_BUFSZ];
43 char *gdb_rxp = NULL;
44 size_t gdb_rxsz = 0;
45 static char gdb_txbuf[GDB_BUFSZ];
46 char *gdb_txp = NULL;			/* Used in inline functions. */
47 
48 #define	C2N(c)	(((c) < 'A') ? (c) - '0' : \
49 	    10 + (((c) < 'a') ? (c) - 'A' : (c) - 'a'))
50 #define	N2C(n)	(((n) < 10) ? (n) + '0' : (n) + 'a' - 10)
51 
52 /*
53  * Get a single character
54  */
55 
56 static int
57 gdb_getc(void)
58 {
59 	int c;
60 
61 	do
62 		c = gdb_cur->gdb_getc();
63 	while (c == -1);
64 
65 	if (c == CTRL('C')) {
66 		printf("Received ^C; trying to switch back to ddb.\n");
67 
68 		if (kdb_dbbe_select("ddb") != 0)
69 			printf("The ddb backend could not be selected.\n");
70 		else {
71 			printf("using longjmp, hope it works!\n");
72 			kdb_reenter();
73 		}
74 	}
75 	return (c);
76 }
77 
78 /*
79  * Functions to receive and extract from a packet.
80  */
81 
82 int
83 gdb_rx_begin(void)
84 {
85 	int c, cksum;
86 
87 	gdb_rxp = NULL;
88 	do {
89 		/*
90 		 * Wait for the start character, ignore all others.
91 		 * XXX needs a timeout.
92 		 */
93 		while ((c = gdb_getc()) != '$')
94 			;
95 
96 		/* Read until a # or end of buffer is found. */
97 		cksum = 0;
98 		gdb_rxsz = 0;
99 		while (gdb_rxsz < sizeof(gdb_rxbuf) - 1) {
100 			c = gdb_getc();
101 			if (c == '#')
102 				break;
103 			gdb_rxbuf[gdb_rxsz++] = c;
104 			cksum += c;
105 		}
106 		gdb_rxbuf[gdb_rxsz] = 0;
107 		cksum &= 0xff;
108 
109 		/* Bail out on a buffer overflow. */
110 		if (c != '#') {
111 			gdb_cur->gdb_putc('-');
112 			return (ENOSPC);
113 		}
114 
115 		c = gdb_getc();
116 		cksum -= (C2N(c) << 4) & 0xf0;
117 		c = gdb_getc();
118 		cksum -= C2N(c) & 0x0f;
119 		gdb_cur->gdb_putc((cksum == 0) ? '+' : '-');
120 		if (cksum != 0)
121 			printf("GDB: packet `%s' has invalid checksum\n",
122 			    gdb_rxbuf);
123 	} while (cksum != 0);
124 
125 	gdb_rxp = gdb_rxbuf;
126 	return (0);
127 }
128 
129 int
130 gdb_rx_equal(const char *str)
131 {
132 	int len;
133 
134 	len = strlen(str);
135 	if (len > gdb_rxsz || strncmp(str, gdb_rxp, len) != 0)
136 		return (0);
137 	gdb_rxp += len;
138 	gdb_rxsz -= len;
139 	return (1);
140 }
141 
142 int
143 gdb_rx_mem(unsigned char *addr, size_t size)
144 {
145 	unsigned char *p;
146 	void *prev;
147 	jmp_buf jb;
148 	size_t cnt;
149 	int ret;
150 	unsigned char c;
151 
152 	if (size * 2 != gdb_rxsz)
153 		return (-1);
154 
155 	prev = kdb_jmpbuf(jb);
156 	ret = setjmp(jb);
157 	if (ret == 0) {
158 		p = addr;
159 		cnt = size;
160 		while (cnt-- > 0) {
161 			c = (C2N(gdb_rxp[0]) << 4) & 0xf0;
162 			c |= C2N(gdb_rxp[1]) & 0x0f;
163 			*p++ = c;
164 			gdb_rxsz -= 2;
165 			gdb_rxp += 2;
166 		}
167 		kdb_cpu_sync_icache(addr, size);
168 	}
169 	(void)kdb_jmpbuf(prev);
170 	return ((ret == 0) ? 1 : 0);
171 }
172 
173 int
174 gdb_rx_varhex(uintmax_t *vp)
175 {
176 	uintmax_t v;
177 	int c, neg;
178 
179 	c = gdb_rx_char();
180 	neg = (c == '-') ? 1 : 0;
181 	if (neg == 1)
182 		c = gdb_rx_char();
183 	if (!isxdigit(c)) {
184 		gdb_rxp -= ((c == -1) ? 0 : 1) + neg;
185 		gdb_rxsz += ((c == -1) ? 0 : 1) + neg;
186 		return (-1);
187 	}
188 	v = 0;
189 	do {
190 		v <<= 4;
191 		v += C2N(c);
192 		c = gdb_rx_char();
193 	} while (isxdigit(c));
194 	if (c != -1) {
195 		gdb_rxp--;
196 		gdb_rxsz++;
197 	}
198 	*vp = (neg) ? -v : v;
199 	return (0);
200 }
201 
202 /*
203  * Function to build and send a package.
204  */
205 
206 void
207 gdb_tx_begin(char tp)
208 {
209 
210 	gdb_txp = gdb_txbuf;
211 	if (tp != '\0')
212 		gdb_tx_char(tp);
213 }
214 
215 int
216 gdb_tx_end(void)
217 {
218 	const char *p;
219 	int runlen;
220 	unsigned char c, cksum;
221 
222 	do {
223 		gdb_cur->gdb_putc('$');
224 
225 		cksum = 0;
226 		p = gdb_txbuf;
227 		while (p < gdb_txp) {
228 			/* Send a character and start run-length encoding. */
229 			c = *p++;
230 			gdb_cur->gdb_putc(c);
231 			cksum += c;
232 			runlen = 0;
233 			/* Determine run-length and update checksum. */
234 			while (p < gdb_txp && *p == c) {
235 				runlen++;
236 				p++;
237 			}
238 			/* Emit the run-length encoded string. */
239 			while (runlen >= 97) {
240 				gdb_cur->gdb_putc('*');
241 				cksum += '*';
242 				gdb_cur->gdb_putc(97+29);
243 				cksum += 97+29;
244 				runlen -= 97;
245 				if (runlen > 0) {
246 					gdb_cur->gdb_putc(c);
247 					cksum += c;
248 					runlen--;
249 				}
250 			}
251 			if (runlen == 1) {
252 				gdb_cur->gdb_putc(c);
253 				cksum += c;
254 				runlen--;
255 			}
256 			if (runlen == 0)
257 				continue;
258 			/* Don't emit '$', '#', '+' or '-'. */
259 			if (runlen == 7) {
260 				gdb_cur->gdb_putc(c);
261 				cksum += c;
262 				runlen--;
263 			}
264 			if (runlen == 6 || runlen == 14 || runlen == 16) {
265 				gdb_cur->gdb_putc(c);
266 				cksum += c;
267 				runlen--;
268 			}
269 			gdb_cur->gdb_putc('*');
270 			cksum += '*';
271 			gdb_cur->gdb_putc(runlen+29);
272 			cksum += runlen+29;
273 		}
274 
275 		gdb_cur->gdb_putc('#');
276 		c = cksum >> 4;
277 		gdb_cur->gdb_putc(N2C(c));
278 		c = cksum & 0x0f;
279 		gdb_cur->gdb_putc(N2C(c));
280 
281 		c = gdb_getc();
282 	} while (c != '+');
283 
284 	return (0);
285 }
286 
287 int
288 gdb_tx_mem(const unsigned char *addr, size_t size)
289 {
290 	void *prev;
291 	jmp_buf jb;
292 	int ret;
293 
294 	prev = kdb_jmpbuf(jb);
295 	ret = setjmp(jb);
296 	if (ret == 0) {
297 		while (size-- > 0) {
298 			*gdb_txp++ = N2C(*addr >> 4);
299 			*gdb_txp++ = N2C(*addr & 0x0f);
300 			addr++;
301 		}
302 	}
303 	(void)kdb_jmpbuf(prev);
304 	return ((ret == 0) ? 1 : 0);
305 }
306 
307 void
308 gdb_tx_reg(int regnum)
309 {
310 	unsigned char *regp;
311 	size_t regsz;
312 
313 	regp = gdb_cpu_getreg(regnum, &regsz);
314 	if (regp == NULL) {
315 		/* Register unavailable. */
316 		while (regsz--) {
317 			gdb_tx_char('x');
318 			gdb_tx_char('x');
319 		}
320 	} else
321 		gdb_tx_mem(regp, regsz);
322 }
323