/* Remote target communications for serial-line targets in custom GDB protocol Copyright 1988, 1991, 1992 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* Remote communication protocol. All values are encoded in ascii hex digits. Request Packet read registers g reply XX....X Each byte of register data is described by two hex digits. Registers are in the internal order for GDB, and the bytes in a register are in the same order the machine uses. or ENN for an error. write regs GXX..XX Each byte of register data is described by two hex digits. reply OK for success ENN for an error read mem mAA..AA,LLLL AA..AA is address, LLLL is length. reply XX..XX XX..XX is mem contents or ENN NN is errno write mem MAA..AA,LLLL:XX..XX AA..AA is address, LLLL is number of bytes, XX..XX is data reply OK for success ENN for an error cont cAA..AA AA..AA is address to resume If AA..AA is omitted, resume at same address. step sAA..AA AA..AA is address to resume If AA..AA is omitted, resume at same address. last signal ? Reply the current reason for stopping. This is the same reply as is generated for step or cont : SAA where AA is the signal number. There is no immediate reply to step or cont. The reply comes when the machine stops. It is SAA AA is the "signal number" or... TAAPPPPPPPPFFFFFFFF where AA is the signal number, PPPPPPPP is the PC (PC_REGNUM), and FFFFFFFF is the frame ptr (FP_REGNUM). kill req k */ #include "defs.h" #include #include "serial.h" #include "frame.h" #include "inferior.h" #include "target.h" #include "wait.h" #include "terminal.h" #include "gdbcmd.h" #include static int kiodebug = 0; static int timeout = 5; #define PBUFSIZ 1024 /* Maximum number of bytes to read/write at once. The value here is chosen to fill up a packet (the headers account for the 32). */ #define MAXBUFBYTES ((PBUFSIZ-32)/2) /* Round up PBUFSIZ to hold all the registers, at least. */ #if REGISTER_BYTES > MAXBUFBYTES #undef PBUFSIZ #define PBUFSIZ (REGISTER_BYTES * 2 + 32) #endif /* remote_detach() takes a program previously attached to and detaches it. We better not have left any breakpoints in the program or it'll die when it hits one. Close the open connection to the remote debugger. Use this when you want to detach and do something else with your gdb. */ static void remote_detach (args, from_tty) char *args; int from_tty; { if (args) error ("Argument given to \"detach\" when remotely debugging."); pop_target (); if (from_tty) printf ("Ending remote debugging.\n"); } /* Convert hex digit A to a number. */ static int fromhex (a) int a; { if (a >= '0' && a <= '9') return a - '0'; else if (a >= 'a' && a <= 'f') return a - 'a' + 10; else error ("Reply contains invalid hex digit"); return -1; } /* Convert number NIB to a hex digit. */ static int tohex (nib) int nib; { if (nib < 10) return '0'+nib; else return 'a'+nib-10; } /* Tell the remote machine to resume. */ /* Send a packet to the remote machine, with error checking. The data of the packet is in BUF. */ static void putpkt (buf) char *buf; { int i; unsigned char csum = 0; char buf2[PBUFSIZ]; int cnt = strlen (buf); char ch; char *p; /* Copy the packet into buffer BUF2, encapsulating it and giving it a checksum. */ if (cnt > sizeof(buf2) - 5) /* Prosanity check */ abort(); p = buf2; *p++ = '$'; for (i = 0; i < cnt; i++) { csum += buf[i]; *p++ = buf[i]; } *p++ = '#'; *p++ = tohex ((csum >> 4) & 0xf); *p++ = tohex (csum & 0xf); /* Send it over and over until we get a positive ack. */ do { if (kiodebug) { *p = '\0'; printf ("Sending packet: %s...", buf2); fflush(stdout); } serial_write (buf2, p - buf2); /* read until either a timeout occurs (\0) or '+' is read */ do { ch = readchar (); if (kiodebug) { if (ch == '+') printf("Ack\n"); else printf ("%02X%c ", ch&0xFF, ch); } } while ((ch != '+') && (ch != '\0')); } while (ch != '+'); } /* Read a packet from the remote machine, with error checking, and store it in BUF. BUF is expected to be of size PBUFSIZ. */ static void getpkt (buf) char *buf; { char *bp; unsigned char csum; int c; unsigned char c1, c2; while (1) { /* Force csum to be zero here because of possible error retry. */ csum = 0; while ((c = readchar()) != '$'); bp = buf; while (1) { c = readchar (); if (c == '#') break; if (bp >= buf+PBUFSIZ-1) { *bp = '\0'; printf_filtered ("Remote packet too long: %s\n", buf); goto whole; } *bp++ = c; csum += c; } *bp = 0; c1 = fromhex (readchar ()); c2 = fromhex (readchar ()); if ((csum & 0xff) == (c1 << 4) + c2) break; printf_filtered ("Bad checksum, sentsum=0x%x, csum=0x%x, buf=%s\n", (c1 << 4) + c2, csum & 0xff, buf); /* Try the whole thing again. */ whole: serial_write ("-", 1); } #if 0 immediate_quit--; #endif serial_write ("+", 1); if (kiodebug) fprintf (stderr,"Packet received: %s\n", buf); } static void remote_resume (step, siggnal) int step, siggnal; { char buf[PBUFSIZ]; if (siggnal) error ("Can't send signals to a remote system. Try `handle %d ignore'.", siggnal); #if 0 dcache_flush (); #endif strcpy (buf, step ? "s": "c"); putpkt (buf); } /* Send ^C to target to halt it. Target will respond, and send us a packet. */ void remote_interrupt(signo) int signo; { if (kiodebug) printf ("remote_interrupt called\n"); serial_write ("\003", 1); /* Send a ^C */ } /* Wait until the remote machine stops, then return, storing status in STATUS just as `wait' would. Returns "pid" (though it's not clear what, if anything, that means in the case of this target). */ static int remote_wait (status) WAITTYPE *status; { unsigned char buf[PBUFSIZ]; void (*ofunc)(); unsigned char *p; int i; char regs[REGISTER_RAW_SIZE (PC_REGNUM) + REGISTER_RAW_SIZE (FP_REGNUM)]; WSETEXIT ((*status), 0); ofunc = (void (*)()) signal (SIGINT, remote_interrupt); getpkt ((char *) buf); signal (SIGINT, ofunc); if (buf[0] == 'E') error ("Remote failure reply: %s", buf); if (buf[0] == 'T') { /* Expedited reply, containing Signal, PC, and FP. */ p = &buf[3]; /* after Txx */ for (i = 0; i < sizeof (regs); i++) { if (p[0] == 0 || p[1] == 0) error ("Remote reply is too short: %s", buf); regs[i] = fromhex (p[0]) * 16 + fromhex (p[1]); p += 2; } supply_register (PC_REGNUM, ®s[0]); supply_register (FP_REGNUM, ®s[REGISTER_RAW_SIZE (PC_REGNUM)]); } else if (buf[0] != 'S') error ("Invalid remote reply: %s", buf); WSETSTOP ((*status), (((fromhex (buf[1])) << 4) + (fromhex (buf[2])))); return 0; } /* Send the command in BUF to the remote machine, and read the reply into BUF. Report an error if we get an error reply. */ static void remote_send (buf) char *buf; { putpkt (buf); getpkt (buf); if (buf[0] == 'E') error ("Remote failure reply: %s", buf); } /* Read the remote registers into the block REGS. */ /* Currently we just read all the registers, so we don't use regno. */ /* ARGSUSED */ static void remote_fetch_registers (regno) int regno; { char buf[PBUFSIZ]; int i; char *p; char regs[REGISTER_BYTES]; sprintf (buf, "g"); remote_send (buf); /* Reply describes registers byte by byte, each byte encoded as two hex characters. Suck them all up, then supply them to the register cacheing/storage mechanism. */ p = buf; for (i = 0; i < REGISTER_BYTES; i++) { if (p[0] == 0 || p[1] == 0) error ("Remote reply is too short: %s", buf); regs[i] = fromhex (p[0]) * 16 + fromhex (p[1]); p += 2; } for (i = 0; i < NUM_REGS; i++) supply_register (i, ®s[REGISTER_BYTE(i)]); } /* Prepare to store registers. Since we send them all, we have to read out the ones we don't want to change first. */ static void remote_prepare_to_store () { remote_fetch_registers (-1); } /* Store the remote registers from the contents of the block REGISTERS. FIXME, eventually just store one register if that's all that is needed. */ /* ARGSUSED */ static void remote_store_registers (regno) int regno; { char buf[PBUFSIZ]; int i; char *p; buf[0] = 'G'; /* Command describes registers byte by byte, each byte encoded as two hex characters. */ p = buf + 1; for (i = 0; i < REGISTER_BYTES; i++) { *p++ = tohex ((registers[i] >> 4) & 0xf); *p++ = tohex (registers[i] & 0xf); } *p = '\0'; remote_send (buf); } /* Write memory data directly to the remote machine. This does not inform the data cache; the data cache uses this. MEMADDR is the address in the remote memory space. MYADDR is the address of the buffer in our space. LEN is the number of bytes. */ static void remote_write_bytes (memaddr, myaddr, len) CORE_ADDR memaddr; char *myaddr; int len; { char buf[PBUFSIZ]; int i; char *p; if (len > PBUFSIZ / 2 - 20) abort (); sprintf (buf, "M%x,%x:", memaddr, len); /* We send target system values byte by byte, in increasing byte addresses, each byte encoded as two hex characters. */ p = buf + strlen (buf); for (i = 0; i < len; i++) { *p++ = tohex ((myaddr[i] >> 4) & 0xf); *p++ = tohex (myaddr[i] & 0xf); } *p = '\0'; remote_send (buf); } /* Read memory data directly from the remote machine. This does not use the data cache; the data cache uses this. MEMADDR is the address in the remote memory space. MYADDR is the address of the buffer in our space. LEN is the number of bytes. */ static void remote_read_bytes (memaddr, myaddr, len) CORE_ADDR memaddr; char *myaddr; int len; { char buf[PBUFSIZ]; int i; char *p; if (len > PBUFSIZ / 2 - 1) abort (); sprintf (buf, "m%x,%x", memaddr, len); remote_send (buf); /* Reply describes memory byte by byte, each byte encoded as two hex characters. */ p = buf; for (i = 0; i < len; i++) { if (p[0] == 0 || p[1] == 0) error ("Remote reply is too short: %s", buf); myaddr[i] = fromhex (p[0]) * 16 + fromhex (p[1]); p += 2; } } /* Read or write LEN bytes from inferior memory at MEMADDR, transferring to or from debugger address MYADDR. Write to inferior if SHOULD_WRITE is nonzero. Returns length of data written or read; 0 for error. */ /* ARGSUSED */ static int remote_xfer_memory(memaddr, myaddr, len, should_write, target) CORE_ADDR memaddr; char *myaddr; int len; int should_write; struct target_ops *target; /* ignored */ { int origlen = len; int xfersize; while (len > 0) { if (len > MAXBUFBYTES) xfersize = MAXBUFBYTES; else xfersize = len; if (should_write) remote_write_bytes(memaddr, myaddr, xfersize); else remote_read_bytes (memaddr, myaddr, xfersize); memaddr += xfersize; myaddr += xfersize; len -= xfersize; } return origlen; /* no error possible */ } static void remote_files_info (ignore) struct target_ops *ignore; { printf ("Debugging a target over a serial line.\n"); } /* A debug packet whose contents are is encapsulated for transmission in the form: $ # CSUM1 CSUM2 must be ASCII alphanumeric and cannot include characters '$' or '#' CSUM1 and CSUM2 are ascii hex representation of an 8-bit checksum of , the most significant nibble is sent first. the hex digits 0-9,a-f are used. Receiver responds with: + - if CSUM is correct and ready for next packet - - if CSUM is incorrect */ /* Read a single character from the remote end. (If supported, we actually read many characters and buffer them up.) */ static int readchar () { static int inbuf_index, inbuf_count; #define INBUFSIZE PBUFSIZ static char inbuf[INBUFSIZE]; if (inbuf_index >= inbuf_count) { /* Time to do another read... */ inbuf_index = 0; inbuf_count = 0; inbuf[0] = 0; /* Just in case */ if ((inbuf[inbuf_index] = serial_readchar (timeout)) < 0) inbuf_count = -1; else inbuf_count = 1; } /* Just return the next character from the buffer. */ return inbuf[inbuf_index++] & 0x7f; } /* The data cache leads to incorrect results because it doesn't know about volatile variables, thus making it impossible to debug functions which use hardware registers. Therefore it is #if 0'd out. Effect on performance is some, for backtraces of functions with a few arguments each. For functions with many arguments, the stack frames don't fit in the cache blocks, which makes the cache less helpful. Disabling the cache is a big performance win for fetching large structures, because the cache code fetched data in 16-byte chunks. */ #if 0 /* The data cache records all the data read from the remote machine since the last time it stopped. Each cache block holds 16 bytes of data starting at a multiple-of-16 address. */ #define DCACHE_SIZE 64 /* Number of cache blocks */ struct dcache_block { struct dcache_block *next, *last; unsigned int addr; /* Address for which data is recorded. */ int data[4]; }; struct dcache_block dcache_free, dcache_valid; /* Free all the data cache blocks, thus discarding all cached data. */ static void dcache_flush () { register struct dcache_block *db; while ((db = dcache_valid.next) != &dcache_valid) { remque (db); insque (db, &dcache_free); } } /* * If addr is present in the dcache, return the address of the block * containing it. */ struct dcache_block * dcache_hit (addr) { register struct dcache_block *db; if (addr & 3) abort (); /* Search all cache blocks for one that is at this address. */ db = dcache_valid.next; while (db != &dcache_valid) { if ((addr & 0xfffffff0) == db->addr) return db; db = db->next; } return NULL; } /* Return the int data at address ADDR in dcache block DC. */ int dcache_value (db, addr) struct dcache_block *db; unsigned int addr; { if (addr & 3) abort (); return (db->data[(addr>>2)&3]); } /* Get a free cache block, put it on the valid list, and return its address. The caller should store into the block the address and data that it describes. */ struct dcache_block * dcache_alloc () { register struct dcache_block *db; if ((db = dcache_free.next) == &dcache_free) /* If we can't get one from the free list, take last valid */ db = dcache_valid.last; remque (db); insque (db, &dcache_valid); return (db); } /* Return the contents of the word at address ADDR in the remote machine, using the data cache. */ int dcache_fetch (addr) CORE_ADDR addr; { register struct dcache_block *db; db = dcache_hit (addr); if (db == 0) { db = dcache_alloc (); remote_read_bytes (addr & ~0xf, db->data, 16); db->addr = addr & ~0xf; } return (dcache_value (db, addr)); } /* Write the word at ADDR both in the data cache and in the remote machine. */ dcache_poke (addr, data) CORE_ADDR addr; int data; { register struct dcache_block *db; /* First make sure the word is IN the cache. DB is its cache block. */ db = dcache_hit (addr); if (db == 0) { db = dcache_alloc (); remote_read_bytes (addr & ~0xf, db->data, 16); db->addr = addr & ~0xf; } /* Modify the word in the cache. */ db->data[(addr>>2)&3] = data; /* Send the changed word. */ remote_write_bytes (addr, &data, 4); } /* Initialize the data cache. */ dcache_init () { register i; register struct dcache_block *db; db = (struct dcache_block *) xmalloc (sizeof (struct dcache_block) * DCACHE_SIZE); dcache_free.next = dcache_free.last = &dcache_free; dcache_valid.next = dcache_valid.last = &dcache_valid; for (i=0;i