1 /* Remote target system call callback support. 2 Copyright (C) 1997-2016 Free Software Foundation, Inc. 3 Contributed by Cygnus Solutions. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 /* This interface isn't intended to be specific to any particular kind 21 of remote (hardware, simulator, whatever). As such, support for it 22 (e.g. sim/common/callback.c) should *not* live in the simulator source 23 tree, nor should it live in the gdb source tree. */ 24 25 /* There are various ways to handle system calls: 26 27 1) Have a simulator intercept the appropriate trap instruction and 28 directly perform the system call on behalf of the target program. 29 This is the typical way of handling system calls for embedded targets. 30 [Handling system calls for embedded targets isn't that much of an 31 oxymoron as running compiler testsuites make use of the capability.] 32 33 This method of system call handling is done when STATE_ENVIRONMENT 34 is ENVIRONMENT_USER. 35 36 2) Have a simulator emulate the hardware as much as possible. 37 If the program running on the real hardware communicates with some sort 38 of target manager, one would want to be able to run this program on the 39 simulator as well. 40 41 This method of system call handling is done when STATE_ENVIRONMENT 42 is ENVIRONMENT_OPERATING. 43 */ 44 45 #ifndef CALLBACK_H 46 #define CALLBACK_H 47 48 /* ??? The reason why we check for va_start here should be documented. */ 49 50 #ifndef va_start 51 #include <ansidecl.h> 52 #include <stdarg.h> 53 #endif 54 /* Needed for enum bfd_endian. */ 55 #include "bfd.h" 56 57 /* Mapping of host/target values. */ 58 /* ??? For debugging purposes, one might want to add a string of the 59 name of the symbol. */ 60 61 typedef struct { 62 const char *name; 63 int host_val; 64 int target_val; 65 } CB_TARGET_DEFS_MAP; 66 67 #define MAX_CALLBACK_FDS 10 68 69 /* Forward decl for stat/fstat. */ 70 struct stat; 71 72 typedef struct host_callback_struct host_callback; 73 74 struct host_callback_struct 75 { 76 int (*close) (host_callback *,int); 77 int (*get_errno) (host_callback *); 78 int (*isatty) (host_callback *, int); 79 int (*lseek) (host_callback *, int, long , int); 80 int (*open) (host_callback *, const char*, int mode); 81 int (*read) (host_callback *,int, char *, int); 82 int (*read_stdin) ( host_callback *, char *, int); 83 int (*rename) (host_callback *, const char *, const char *); 84 int (*system) (host_callback *, const char *); 85 long (*time) (host_callback *, long *); 86 int (*unlink) (host_callback *, const char *); 87 int (*write) (host_callback *,int, const char *, int); 88 int (*write_stdout) (host_callback *, const char *, int); 89 void (*flush_stdout) (host_callback *); 90 int (*write_stderr) (host_callback *, const char *, int); 91 void (*flush_stderr) (host_callback *); 92 int (*to_stat) (host_callback *, const char *, struct stat *); 93 int (*to_fstat) (host_callback *, int, struct stat *); 94 int (*to_lstat) (host_callback *, const char *, struct stat *); 95 int (*ftruncate) (host_callback *, int, long); 96 int (*truncate) (host_callback *, const char *, long); 97 int (*pipe) (host_callback *, int *); 98 99 /* Called by the framework when a read call has emptied a pipe buffer. */ 100 void (*pipe_empty) (host_callback *, int read_fd, int write_fd); 101 102 /* Called by the framework when a write call makes a pipe buffer 103 non-empty. */ 104 void (*pipe_nonempty) (host_callback *, int read_fd, int write_fd); 105 106 /* When present, call to the client to give it the oportunity to 107 poll any io devices for a request to quit (indicated by a nonzero 108 return value). */ 109 int (*poll_quit) (host_callback *); 110 111 /* Used when the target has gone away, so we can close open 112 handles and free memory etc etc. */ 113 int (*shutdown) (host_callback *); 114 int (*init) (host_callback *); 115 116 /* depreciated, use vprintf_filtered - Talk to the user on a console. */ 117 void (*printf_filtered) (host_callback *, const char *, ...); 118 119 /* Talk to the user on a console. */ 120 void (*vprintf_filtered) (host_callback *, const char *, va_list); 121 122 /* Same as vprintf_filtered but to stderr. */ 123 void (*evprintf_filtered) (host_callback *, const char *, va_list); 124 125 /* Print an error message and "exit". 126 In the case of gdb "exiting" means doing a longjmp back to the main 127 command loop. */ 128 void (*error) (host_callback *, const char *, ...) 129 #ifdef __GNUC__ 130 __attribute__ ((__noreturn__)) 131 #endif 132 ; 133 134 int last_errno; /* host format */ 135 136 int fdmap[MAX_CALLBACK_FDS]; 137 /* fd_buddy is used to contruct circular lists of target fds that point to 138 the same host fd. A uniquely mapped fd points to itself; for a closed 139 one, fd_buddy has the value -1. The host file descriptors for stdin / 140 stdout / stderr are never closed by the simulators, so they are put 141 in a special fd_buddy circular list which also has MAX_CALLBACK_FDS 142 as a member. */ 143 /* ??? We don't have a callback entry for dup, although it is trival to 144 implement now. */ 145 short fd_buddy[MAX_CALLBACK_FDS+1]; 146 147 /* 0 = none, >0 = reader (index of writer), 148 <0 = writer (negative index of reader). 149 If abs (ispipe[N]) == N, then N is an end of a pipe whose other 150 end is closed. */ 151 short ispipe[MAX_CALLBACK_FDS]; 152 153 /* A writer stores the buffer at its index. Consecutive writes 154 realloc the buffer and add to the size. The reader indicates the 155 read part in its .size, until it has consumed it all, at which 156 point it deallocates the buffer and zeroes out both sizes. */ 157 struct pipe_write_buffer 158 { 159 int size; 160 char *buffer; 161 } pipe_buffer[MAX_CALLBACK_FDS]; 162 163 /* System call numbers. */ 164 CB_TARGET_DEFS_MAP *syscall_map; 165 /* Errno values. */ 166 CB_TARGET_DEFS_MAP *errno_map; 167 /* Flags to the open system call. */ 168 CB_TARGET_DEFS_MAP *open_map; 169 /* Signal numbers. */ 170 CB_TARGET_DEFS_MAP *signal_map; 171 /* Layout of `stat' struct. 172 The format is a series of "name,length" pairs separated by colons. 173 Empty space is indicated with a `name' of "space". 174 All padding must be explicitly mentioned. 175 Lengths are in bytes. If this needs to be extended to bits, 176 use "name.bits". 177 Example: "st_dev,4:st_ino,4:st_mode,4:..." */ 178 const char *stat_map; 179 180 enum bfd_endian target_endian; 181 182 /* Size of an "int" on the target (for syscalls whose ABI uses "int"). 183 This must include padding, and only padding-at-higher-address is 184 supported. For example, a 64-bit target with 32-bit int:s which 185 are padded to 64 bits when in an array, should supposedly set this 186 to 8. The default is 4 which matches ILP32 targets and 64-bit 187 targets with 32-bit ints and no padding. */ 188 int target_sizeof_int; 189 190 /* Marker for those wanting to do sanity checks. 191 This should remain the last member of this struct to help catch 192 miscompilation errors. */ 193 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */ 194 int magic; 195 }; 196 197 extern host_callback default_callback; 198 199 /* Canonical versions of system call numbers. 200 It's not intended to willy-nilly throw every system call ever heard 201 of in here. Only include those that have an important use. 202 ??? One can certainly start a discussion over the ones that are currently 203 here, but that will always be true. */ 204 205 /* These are used by the ANSI C support of libc. */ 206 #define CB_SYS_exit 1 207 #define CB_SYS_open 2 208 #define CB_SYS_close 3 209 #define CB_SYS_read 4 210 #define CB_SYS_write 5 211 #define CB_SYS_lseek 6 212 #define CB_SYS_unlink 7 213 #define CB_SYS_getpid 8 214 #define CB_SYS_kill 9 215 #define CB_SYS_fstat 10 216 /*#define CB_SYS_sbrk 11 - not currently a system call, but reserved. */ 217 218 /* ARGV support. */ 219 #define CB_SYS_argvlen 12 220 #define CB_SYS_argv 13 221 222 /* These are extras added for one reason or another. */ 223 #define CB_SYS_chdir 14 224 #define CB_SYS_stat 15 225 #define CB_SYS_chmod 16 226 #define CB_SYS_utime 17 227 #define CB_SYS_time 18 228 229 /* More standard syscalls. */ 230 #define CB_SYS_lstat 19 231 #define CB_SYS_rename 20 232 #define CB_SYS_truncate 21 233 #define CB_SYS_ftruncate 22 234 #define CB_SYS_pipe 23 235 236 /* New ARGV support. */ 237 #define CB_SYS_argc 24 238 #define CB_SYS_argnlen 25 239 #define CB_SYS_argn 26 240 241 /* Struct use to pass and return information necessary to perform a 242 system call. */ 243 /* FIXME: Need to consider target word size. */ 244 245 typedef struct cb_syscall { 246 /* The target's value of what system call to perform. */ 247 int func; 248 /* The arguments to the syscall. */ 249 long arg1, arg2, arg3, arg4; 250 251 /* The result. */ 252 long result; 253 /* Some system calls have two results. */ 254 long result2; 255 /* The target's errno value, or 0 if success. 256 This is converted to the target's value with host_to_target_errno. */ 257 int errcode; 258 259 /* Working space to be used by memory read/write callbacks. */ 260 PTR p1; 261 PTR p2; 262 long x1,x2; 263 264 /* Callbacks for reading/writing memory (e.g. for read/write syscalls). 265 ??? long or unsigned long might be better to use for the `count' 266 argument here. We mimic sim_{read,write} for now. Be careful to 267 test any changes with -Wall -Werror, mixed signed comparisons 268 will get you. */ 269 int (*read_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/, 270 unsigned long /*taddr*/, char * /*buf*/, 271 int /*bytes*/); 272 int (*write_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/, 273 unsigned long /*taddr*/, const char * /*buf*/, 274 int /*bytes*/); 275 276 /* For sanity checking, should be last entry. */ 277 int magic; 278 } CB_SYSCALL; 279 280 /* Magic number sanity checker. */ 281 #define CB_SYSCALL_MAGIC 0x12344321 282 283 /* Macro to initialize CB_SYSCALL. Called first, before filling in 284 any fields. */ 285 #define CB_SYSCALL_INIT(sc) \ 286 do { \ 287 memset ((sc), 0, sizeof (*(sc))); \ 288 (sc)->magic = CB_SYSCALL_MAGIC; \ 289 } while (0) 290 291 /* Return codes for various interface routines. */ 292 293 typedef enum { 294 CB_RC_OK = 0, 295 /* generic error */ 296 CB_RC_ERR, 297 /* either file not found or no read access */ 298 CB_RC_ACCESS, 299 CB_RC_NO_MEM 300 } CB_RC; 301 302 /* Read in target values for system call numbers, errno values, signals. */ 303 CB_RC cb_read_target_syscall_maps (host_callback *, const char *); 304 305 /* Translate target to host syscall function numbers. */ 306 int cb_target_to_host_syscall (host_callback *, int); 307 308 /* Translate host to target errno value. */ 309 int cb_host_to_target_errno (host_callback *, int); 310 311 /* Translate target to host open flags. */ 312 int cb_target_to_host_open (host_callback *, int); 313 314 /* Translate target signal number to host. */ 315 int cb_target_to_host_signal (host_callback *, int); 316 317 /* Translate host signal number to target. */ 318 int cb_host_to_gdb_signal (host_callback *, int); 319 320 /* Translate symbols into human readable strings. */ 321 const char *cb_host_str_syscall (host_callback *, int); 322 const char *cb_host_str_errno (host_callback *, int); 323 const char *cb_host_str_signal (host_callback *, int); 324 const char *cb_target_str_syscall (host_callback *, int); 325 const char *cb_target_str_errno (host_callback *, int); 326 const char *cb_target_str_signal (host_callback *, int); 327 328 /* Translate host stat struct to target. 329 If stat struct ptr is NULL, just compute target stat struct size. 330 Result is size of target stat struct or 0 if error. */ 331 int cb_host_to_target_stat (host_callback *, const struct stat *, PTR); 332 333 /* Translate a value to target endian. */ 334 void cb_store_target_endian (host_callback *, char *, int, long); 335 336 /* Tests for special fds. */ 337 int cb_is_stdin (host_callback *, int); 338 int cb_is_stdout (host_callback *, int); 339 int cb_is_stderr (host_callback *, int); 340 341 /* Read a string out of the target. */ 342 int cb_get_string (host_callback *, CB_SYSCALL *, char *, int, unsigned long); 343 344 /* Perform a system call. */ 345 CB_RC cb_syscall (host_callback *, CB_SYSCALL *); 346 347 #endif 348