gdb_packet.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2004 Marcel Moolenaar
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  *
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/ctype.h>
   35 #include <sys/kdb.h>
   36 #include <sys/libkern.h>
   37 #include <sys/ttydefaults.h>
   38 
   39 #include <machine/gdb_machdep.h>
   40 #include <machine/kdb.h>
   41 
   42 #include <gdb/gdb.h>
   43 #include <gdb/gdb_int.h>
   44 
   45 static char gdb_rxbuf[GDB_BUFSZ];
   46 char *gdb_rxp = NULL;
   47 size_t gdb_rxsz = 0;
   48 
   49 /*
   50  * The goal here is to allow in-place framing without making the math around
   51  * 'gdb_txbuf' more complicated.  A generous reading of union special rule for
   52  * "common initial sequence" suggests this may be valid in standard C99 and
   53  * later.
   54  */
   55 static union {
   56         struct _midbuf {
   57                 char mb_pad1;
   58                 char mb_buf[GDB_BUFSZ];
   59                 char mb_pad2[4];
   60         } __packed txu_midbuf;
   61         /* sizeof includes trailing nul byte and this is intentional. */
   62         char txu_fullbuf[GDB_BUFSZ + sizeof("$#..")];
   63 } gdb_tx_u;
   64 #define gdb_txbuf       gdb_tx_u.txu_midbuf.mb_buf
   65 #define gdb_tx_fullbuf  gdb_tx_u.txu_fullbuf
   66 _Static_assert(sizeof(gdb_tx_u.txu_midbuf) == sizeof(gdb_tx_u.txu_fullbuf) &&
   67     offsetof(struct _midbuf, mb_buf) == 1,
   68     "assertions necessary for correctness");
   69 char *gdb_txp = NULL;                   /* Used in inline functions. */
   70 
   71 #define C2N(c)  (((c) < 'A') ? (c) - '' : \
   72             10 + (((c) < 'a') ? (c) - 'A' : (c) - 'a'))
   73 #define N2C(n)  (((n) < 10) ? (n) + '' : (n) + 'a' - 10)
   74 
   75 /*
   76  * Get a single character
   77  */
   78 
   79 static int
   80 gdb_getc(void)
   81 {
   82         int c;
   83 
   84         do
   85                 c = gdb_cur->gdb_getc();
   86         while (c == -1);
   87 
   88         if (c == CTRL('C')) {
   89                 printf("Received ^C; trying to switch back to ddb.\n");
   90 
   91                 if (gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_WANTTERM)
   92                         gdb_cur->gdb_term();
   93 
   94                 if (kdb_dbbe_select("ddb") != 0)
   95                         printf("The ddb backend could not be selected.\n");
   96                 else {
   97                         printf("using longjmp, hope it works!\n");
   98                         kdb_reenter();
   99                 }
  100         }
  101         return (c);
  102 }
  103 
  104 /*
  105  * Functions to receive and extract from a packet.
  106  */
  107 
  108 int
  109 gdb_rx_begin(void)
  110 {
  111         int c, cksum;
  112 
  113         gdb_rxp = NULL;
  114         do {
  115                 /*
  116                  * Wait for the start character, ignore all others.
  117                  * XXX needs a timeout.
  118                  */
  119                 while ((c = gdb_getc()) != '$')
  120                         ;
  121 
  122                 /* Read until a # or end of buffer is found. */
  123                 cksum = 0;
  124                 gdb_rxsz = 0;
  125                 while (gdb_rxsz < sizeof(gdb_rxbuf) - 1) {
  126                         c = gdb_getc();
  127                         if (c == '#')
  128                                 break;
  129                         gdb_rxbuf[gdb_rxsz++] = c;
  130                         cksum += c;
  131                 }
  132                 gdb_rxbuf[gdb_rxsz] = 0;
  133                 cksum &= 0xff;
  134 
  135                 /* Bail out on a buffer overflow. */
  136                 if (c != '#') {
  137                         gdb_nack();
  138                         return (ENOSPC);
  139                 }
  140 
  141                 /*
  142                  * In Not-AckMode, we can assume reliable transport and neither
  143                  * need to verify checksums nor send Ack/Nack.
  144                  */
  145                 if (!gdb_ackmode)
  146                         break;
  147 
  148                 c = gdb_getc();
  149                 cksum -= (C2N(c) << 4) & 0xf0;
  150                 c = gdb_getc();
  151                 cksum -= C2N(c) & 0x0f;
  152                 if (cksum == 0) {
  153                         gdb_ack();
  154                 } else {
  155                         gdb_nack();
  156                         printf("GDB: packet `%s' has invalid checksum\n",
  157                             gdb_rxbuf);
  158                 }
  159         } while (cksum != 0);
  160 
  161         gdb_rxp = gdb_rxbuf;
  162         return (0);
  163 }
  164 
  165 int
  166 gdb_rx_equal(const char *str)
  167 {
  168         int len;
  169 
  170         len = strlen(str);
  171         if (len > gdb_rxsz || strncmp(str, gdb_rxp, len) != 0)
  172                 return (0);
  173         gdb_rxp += len;
  174         gdb_rxsz -= len;
  175         return (1);
  176 }
  177 
  178 int
  179 gdb_rx_mem(unsigned char *addr, size_t size)
  180 {
  181         unsigned char *p;
  182         void *prev;
  183         void *wctx;
  184         jmp_buf jb;
  185         size_t cnt;
  186         int ret;
  187         unsigned char c;
  188 
  189         if (size * 2 != gdb_rxsz)
  190                 return (-1);
  191 
  192         wctx = gdb_begin_write();
  193         prev = kdb_jmpbuf(jb);
  194         ret = setjmp(jb);
  195         if (ret == 0) {
  196                 p = addr;
  197                 cnt = size;
  198                 while (cnt-- > 0) {
  199                         c = (C2N(gdb_rxp[0]) << 4) & 0xf0;
  200                         c |= C2N(gdb_rxp[1]) & 0x0f;
  201                         *p++ = c;
  202                         gdb_rxsz -= 2;
  203                         gdb_rxp += 2;
  204                 }
  205                 kdb_cpu_sync_icache(addr, size);
  206         }
  207         (void)kdb_jmpbuf(prev);
  208         gdb_end_write(wctx);
  209         return ((ret == 0) ? 1 : 0);
  210 }
  211 
  212 int
  213 gdb_rx_varhex(uintmax_t *vp)
  214 {
  215         uintmax_t v;
  216         int c, neg;
  217 
  218         c = gdb_rx_char();
  219         neg = (c == '-') ? 1 : 0;
  220         if (neg == 1)
  221                 c = gdb_rx_char();
  222         if (!isxdigit(c)) {
  223                 gdb_rxp -= ((c == -1) ? 0 : 1) + neg;
  224                 gdb_rxsz += ((c == -1) ? 0 : 1) + neg;
  225                 return (-1);
  226         }
  227         v = 0;
  228         do {
  229                 v <<= 4;
  230                 v += C2N(c);
  231                 c = gdb_rx_char();
  232         } while (isxdigit(c));
  233         if (c != EOF) {
  234                 gdb_rxp--;
  235                 gdb_rxsz++;
  236         }
  237         *vp = (neg) ? -v : v;
  238         return (0);
  239 }
  240 
  241 /*
  242  * Function to build and send a package.
  243  */
  244 
  245 void
  246 gdb_tx_begin(char tp)
  247 {
  248 
  249         gdb_txp = gdb_txbuf;
  250         if (tp != '\0')
  251                 gdb_tx_char(tp);
  252 }
  253 
  254 /*
  255  * Take raw packet buffer and perform typical GDB packet framing, but not run-
  256  * length encoding, before forwarding to driver ::gdb_sendpacket() routine.
  257  */
  258 static void
  259 gdb_tx_sendpacket(void)
  260 {
  261         size_t msglen, i;
  262         unsigned char csum;
  263 
  264         msglen = gdb_txp - gdb_txbuf;
  265 
  266         /* Add GDB packet framing */
  267         gdb_tx_fullbuf[0] = '$';
  268 
  269         csum = 0;
  270         for (i = 0; i < msglen; i++)
  271                 csum += (unsigned char)gdb_txbuf[i];
  272         snprintf(&gdb_tx_fullbuf[1 + msglen], 4, "#%02x", (unsigned)csum);
  273 
  274         gdb_cur->gdb_sendpacket(gdb_tx_fullbuf, msglen + 4);
  275 }
  276 
  277 int
  278 gdb_tx_end(void)
  279 {
  280         const char *p;
  281         int runlen;
  282         unsigned char c, cksum;
  283 
  284         do {
  285                 if (gdb_cur->gdb_sendpacket != NULL) {
  286                         gdb_tx_sendpacket();
  287                         goto getack;
  288                 }
  289 
  290                 gdb_cur->gdb_putc('$');
  291 
  292                 cksum = 0;
  293                 p = gdb_txbuf;
  294                 while (p < gdb_txp) {
  295                         /* Send a character and start run-length encoding. */
  296                         c = *p++;
  297                         gdb_cur->gdb_putc(c);
  298                         cksum += c;
  299                         runlen = 0;
  300                         /* Determine run-length and update checksum. */
  301                         while (p < gdb_txp && *p == c) {
  302                                 runlen++;
  303                                 p++;
  304                         }
  305                         /* Emit the run-length encoded string. */
  306                         while (runlen >= 97) {
  307                                 gdb_cur->gdb_putc('*');
  308                                 cksum += '*';
  309                                 gdb_cur->gdb_putc(97+29);
  310                                 cksum += 97+29;
  311                                 runlen -= 97;
  312                                 if (runlen > 0) {
  313                                         gdb_cur->gdb_putc(c);
  314                                         cksum += c;
  315                                         runlen--;
  316                                 }
  317                         }
  318                         /* Don't emit '$', '#', '+', '-' or a run length below 3. */
  319                         while (runlen == 1 || runlen == 2 ||
  320                             runlen + 29 == '$' || runlen + 29 == '#' ||
  321                             runlen + 29 == '+' || runlen + 29 == '-') {
  322                                 gdb_cur->gdb_putc(c);
  323                                 cksum += c;
  324                                 runlen--;
  325                         }
  326                         if (runlen == 0)
  327                                 continue;
  328                         gdb_cur->gdb_putc('*');
  329                         cksum += '*';
  330                         gdb_cur->gdb_putc(runlen+29);
  331                         cksum += runlen+29;
  332                 }
  333 
  334                 gdb_cur->gdb_putc('#');
  335                 c = cksum >> 4;
  336                 gdb_cur->gdb_putc(N2C(c));
  337                 c = cksum & 0x0f;
  338                 gdb_cur->gdb_putc(N2C(c));
  339 
  340 getack:
  341                 /*
  342                  * In NoAckMode, it is assumed that the underlying transport is
  343                  * reliable and thus neither conservant sends acknowledgements;
  344                  * there is nothing to wait for here.
  345                  */
  346                 if (!gdb_ackmode)
  347                         break;
  348 
  349                 c = gdb_getc();
  350         } while (c != '+');
  351 
  352         return (0);
  353 }
  354 
  355 int
  356 gdb_tx_mem(const unsigned char *addr, size_t size)
  357 {
  358         void *prev;
  359         jmp_buf jb;
  360         int ret;
  361 
  362         prev = kdb_jmpbuf(jb);
  363         ret = setjmp(jb);
  364         if (ret == 0) {
  365                 while (size-- > 0) {
  366                         *gdb_txp++ = N2C(*addr >> 4);
  367                         *gdb_txp++ = N2C(*addr & 0x0f);
  368                         addr++;
  369                 }
  370         }
  371         (void)kdb_jmpbuf(prev);
  372         return ((ret == 0) ? 1 : 0);
  373 }
  374 
  375 void
  376 gdb_tx_reg(int regnum)
  377 {
  378         unsigned char *regp;
  379         size_t regsz;
  380 
  381         regp = gdb_cpu_getreg(regnum, &regsz);
  382         if (regp == NULL) {
  383                 /* Register unavailable. */
  384                 while (regsz--) {
  385                         gdb_tx_char('x');
  386                         gdb_tx_char('x');
  387                 }
  388         } else
  389                 gdb_tx_mem(regp, regsz);
  390 }
  391 
  392 bool
  393 gdb_txbuf_has_capacity(size_t req)
  394 {
  395         return (((char *)gdb_txbuf + sizeof(gdb_txbuf) - gdb_txp) >= req);
  396 }
  397 
  398 /* Read binary data up until the end of the packet or until we have datalen decoded bytes */
  399 int
  400 gdb_rx_bindata(unsigned char *data, size_t datalen, size_t *amt)
  401 {
  402         int c;
  403 
  404         *amt = 0;
  405 
  406         while (*amt < datalen) {
  407                 c = gdb_rx_char();
  408                 if (c == EOF)
  409                         break;
  410                 /* Escaped character up next */
  411                 if (c == '}') {
  412                         /* Malformed packet. */
  413                         if ((c = gdb_rx_char()) == EOF)
  414                                 return (1);
  415                         c ^= 0x20;
  416                 }
  417                 *(data++) = c & 0xff;
  418                 (*amt)++;
  419         }
  420 
  421         return (0);
  422 }
  423 
  424 int
  425 gdb_search_mem(const unsigned char *addr, size_t size, const unsigned char *pat, size_t patlen, const unsigned char **found)
  426 {
  427         void *prev;
  428         jmp_buf jb;
  429         int ret;
  430 
  431         prev = kdb_jmpbuf(jb);
  432         ret = setjmp(jb);
  433         if (ret == 0)
  434                 *found = memmem(addr, size, pat, patlen);
  435 
  436         (void)kdb_jmpbuf(prev);
  437         return ((ret == 0) ? 1 : 0);
  438 }
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FreeBSD/Linux Kernel Cross Reference sys/gdb/gdb_packet.c

FreeBSD/Linux Kernel Cross Reference
sys/gdb/gdb_packet.c
