1 /* Remote target system call callback support. 2 Copyright (C) 1997-2021 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 SIM_CALLBACK_H 46 #define SIM_CALLBACK_H 47 48 #include <ansidecl.h> 49 #include <stdarg.h> 50 #include <stdint.h> 51 /* Needed for enum bfd_endian. */ 52 #include "bfd.h" 53 54 /* Mapping of host/target values. */ 55 /* ??? For debugging purposes, one might want to add a string of the 56 name of the symbol. */ 57 58 typedef struct { 59 const char *name; 60 int host_val; 61 int target_val; 62 } CB_TARGET_DEFS_MAP; 63 64 #define MAX_CALLBACK_FDS 10 65 66 /* Forward decl for stat/fstat. */ 67 struct stat; 68 69 typedef struct host_callback_struct host_callback; 70 71 struct host_callback_struct 72 { 73 int (*close) (host_callback *,int); 74 int (*get_errno) (host_callback *); 75 int (*isatty) (host_callback *, int); 76 int64_t (*lseek) (host_callback *, int, int64_t, int); 77 int (*open) (host_callback *, const char*, int mode); 78 int (*read) (host_callback *,int, char *, int); 79 int (*read_stdin) ( host_callback *, char *, int); 80 int (*rename) (host_callback *, const char *, const char *); 81 int (*system) (host_callback *, const char *); 82 int64_t (*time) (host_callback *); 83 int (*unlink) (host_callback *, const char *); 84 int (*write) (host_callback *,int, const char *, int); 85 int (*write_stdout) (host_callback *, const char *, int); 86 void (*flush_stdout) (host_callback *); 87 int (*write_stderr) (host_callback *, const char *, int); 88 void (*flush_stderr) (host_callback *); 89 int (*to_stat) (host_callback *, const char *, struct stat *); 90 int (*to_fstat) (host_callback *, int, struct stat *); 91 int (*to_lstat) (host_callback *, const char *, struct stat *); 92 int (*ftruncate) (host_callback *, int, int64_t); 93 int (*truncate) (host_callback *, const char *, int64_t); 94 int (*getpid) (host_callback *); 95 int (*kill) (host_callback *, int, int); 96 int (*pipe) (host_callback *, int *); 97 98 /* Called by the framework when a read call has emptied a pipe buffer. */ 99 void (*pipe_empty) (host_callback *, int read_fd, int write_fd); 100 101 /* Called by the framework when a write call makes a pipe buffer 102 non-empty. */ 103 void (*pipe_nonempty) (host_callback *, int read_fd, int write_fd); 104 105 /* When present, call to the client to give it the oportunity to 106 poll any io devices for a request to quit (indicated by a nonzero 107 return value). */ 108 int (*poll_quit) (host_callback *); 109 110 /* Used when the target has gone away, so we can close open 111 handles and free memory etc etc. */ 112 int (*shutdown) (host_callback *); 113 int (*init) (host_callback *); 114 115 /* depreciated, use vprintf_filtered - Talk to the user on a console. */ 116 void (*printf_filtered) (host_callback *, const char *, ...) 117 ATTRIBUTE_PRINTF_2; 118 119 /* Talk to the user on a console. */ 120 void (*vprintf_filtered) (host_callback *, const char *, va_list) 121 ATTRIBUTE_PRINTF (2, 0); 122 123 /* Same as vprintf_filtered but to stderr. */ 124 void (*evprintf_filtered) (host_callback *, const char *, va_list) 125 ATTRIBUTE_PRINTF (2, 0); 126 127 /* Print an error message and "exit". 128 In the case of gdb "exiting" means doing a longjmp back to the main 129 command loop. */ 130 void (*error) (host_callback *, const char *, ...) 131 ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF_2; 132 133 int last_errno; /* host format */ 134 135 int fdmap[MAX_CALLBACK_FDS]; 136 /* fd_buddy is used to contruct circular lists of target fds that point to 137 the same host fd. A uniquely mapped fd points to itself; for a closed 138 one, fd_buddy has the value -1. The host file descriptors for stdin / 139 stdout / stderr are never closed by the simulators, so they are put 140 in a special fd_buddy circular list which also has MAX_CALLBACK_FDS 141 as a member. */ 142 /* ??? We don't have a callback entry for dup, although it is trival to 143 implement now. */ 144 short fd_buddy[MAX_CALLBACK_FDS+1]; 145 146 /* 0 = none, >0 = reader (index of writer), 147 <0 = writer (negative index of reader). 148 If abs (ispipe[N]) == N, then N is an end of a pipe whose other 149 end is closed. */ 150 short ispipe[MAX_CALLBACK_FDS]; 151 152 /* A writer stores the buffer at its index. Consecutive writes 153 realloc the buffer and add to the size. The reader indicates the 154 read part in its .size, until it has consumed it all, at which 155 point it deallocates the buffer and zeroes out both sizes. */ 156 struct pipe_write_buffer 157 { 158 int size; 159 char *buffer; 160 } pipe_buffer[MAX_CALLBACK_FDS]; 161 162 /* System call numbers. */ 163 CB_TARGET_DEFS_MAP *syscall_map; 164 /* Errno values. */ 165 CB_TARGET_DEFS_MAP *errno_map; 166 /* Flags to the open system call. */ 167 CB_TARGET_DEFS_MAP *open_map; 168 /* Signal numbers. */ 169 CB_TARGET_DEFS_MAP *signal_map; 170 /* Layout of `stat' struct. 171 The format is a series of "name,length" pairs separated by colons. 172 Empty space is indicated with a `name' of "space". 173 All padding must be explicitly mentioned. 174 Lengths are in bytes. If this needs to be extended to bits, 175 use "name.bits". 176 Example: "st_dev,4:st_ino,4:st_mode,4:..." */ 177 const char *stat_map; 178 179 enum bfd_endian target_endian; 180 181 /* Size of an "int" on the target (for syscalls whose ABI uses "int"). 182 This must include padding, and only padding-at-higher-address is 183 supported. For example, a 64-bit target with 32-bit int:s which 184 are padded to 64 bits when in an array, should supposedly set this 185 to 8. The default is 4 which matches ILP32 targets and 64-bit 186 targets with 32-bit ints and no padding. */ 187 int target_sizeof_int; 188 189 /* Marker for those wanting to do sanity checks. 190 This should remain the last member of this struct to help catch 191 miscompilation errors. */ 192 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */ 193 int magic; 194 }; 195 196 extern host_callback default_callback; 197 198 /* Canonical versions of system call numbers. 199 It's not intended to willy-nilly throw every system call ever heard 200 of in here. Only include those that have an important use. 201 ??? One can certainly start a discussion over the ones that are currently 202 here, but that will always be true. */ 203 204 /* These are used by the ANSI C support of libc. */ 205 #define CB_SYS_exit 1 206 #define CB_SYS_open 2 207 #define CB_SYS_close 3 208 #define CB_SYS_read 4 209 #define CB_SYS_write 5 210 #define CB_SYS_lseek 6 211 #define CB_SYS_unlink 7 212 #define CB_SYS_getpid 8 213 #define CB_SYS_kill 9 214 #define CB_SYS_fstat 10 215 /*#define CB_SYS_sbrk 11 - not currently a system call, but reserved. */ 216 217 /* ARGV support. */ 218 #define CB_SYS_argvlen 12 219 #define CB_SYS_argv 13 220 221 /* These are extras added for one reason or another. */ 222 #define CB_SYS_chdir 14 223 #define CB_SYS_stat 15 224 #define CB_SYS_chmod 16 225 #define CB_SYS_utime 17 226 #define CB_SYS_time 18 227 228 /* More standard syscalls. */ 229 #define CB_SYS_lstat 19 230 #define CB_SYS_rename 20 231 #define CB_SYS_truncate 21 232 #define CB_SYS_ftruncate 22 233 #define CB_SYS_pipe 23 234 235 /* New ARGV support. */ 236 #define CB_SYS_argc 24 237 #define CB_SYS_argnlen 25 238 #define CB_SYS_argn 26 239 240 /* Struct use to pass and return information necessary to perform a 241 system call. */ 242 /* FIXME: Need to consider target word size. */ 243 244 typedef struct cb_syscall { 245 /* The target's value of what system call to perform. */ 246 int func; 247 /* The arguments to the syscall. */ 248 long arg1, arg2, arg3, arg4, arg5, arg6, arg7; 249 250 /* The result. */ 251 long result; 252 /* Some system calls have two results. */ 253 long result2; 254 /* The target's errno value, or 0 if success. 255 This is converted to the target's value with host_to_target_errno. */ 256 int errcode; 257 258 /* Working space to be used by memory read/write callbacks. */ 259 void *p1; 260 void *p2; 261 long x1,x2; 262 263 /* Callbacks for reading/writing memory (e.g. for read/write syscalls). 264 ??? long or unsigned long might be better to use for the `count' 265 argument here. We mimic sim_{read,write} for now. Be careful to 266 test any changes with -Wall -Werror, mixed signed comparisons 267 will get you. */ 268 int (*read_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/, 269 unsigned long /*taddr*/, char * /*buf*/, 270 int /*bytes*/); 271 int (*write_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/, 272 unsigned long /*taddr*/, const char * /*buf*/, 273 int /*bytes*/); 274 275 /* For sanity checking, should be last entry. */ 276 int magic; 277 } CB_SYSCALL; 278 279 /* Magic number sanity checker. */ 280 #define CB_SYSCALL_MAGIC 0x12344321 281 282 /* Macro to initialize CB_SYSCALL. Called first, before filling in 283 any fields. */ 284 #define CB_SYSCALL_INIT(sc) \ 285 do { \ 286 memset ((sc), 0, sizeof (*(sc))); \ 287 (sc)->magic = CB_SYSCALL_MAGIC; \ 288 } while (0) 289 290 /* Return codes for various interface routines. */ 291 292 typedef enum { 293 CB_RC_OK = 0, 294 /* generic error */ 295 CB_RC_ERR, 296 /* either file not found or no read access */ 297 CB_RC_ACCESS, 298 CB_RC_NO_MEM 299 } CB_RC; 300 301 /* Read in target values for system call numbers, errno values, signals. */ 302 CB_RC cb_read_target_syscall_maps (host_callback *, const char *); 303 304 /* Translate target to host syscall function numbers. */ 305 int cb_target_to_host_syscall (host_callback *, int); 306 307 /* Translate host to target errno value. */ 308 int cb_host_to_target_errno (host_callback *, int); 309 310 /* Translate target to host open flags. */ 311 int cb_target_to_host_open (host_callback *, int); 312 313 /* Translate target signal number to host. */ 314 int cb_target_to_host_signal (host_callback *, int); 315 316 /* Translate host signal number to target. */ 317 int cb_host_to_gdb_signal (host_callback *, int); 318 319 /* Translate symbols into human readable strings. */ 320 const char *cb_host_str_syscall (host_callback *, int); 321 const char *cb_host_str_errno (host_callback *, int); 322 const char *cb_host_str_signal (host_callback *, int); 323 const char *cb_target_str_syscall (host_callback *, int); 324 const char *cb_target_str_errno (host_callback *, int); 325 const char *cb_target_str_signal (host_callback *, int); 326 327 /* Translate host stat struct to target. 328 If stat struct ptr is NULL, just compute target stat struct size. 329 Result is size of target stat struct or 0 if error. */ 330 int cb_host_to_target_stat (host_callback *, const struct stat *, void *); 331 332 /* Translate a value to target endian. */ 333 void cb_store_target_endian (host_callback *, char *, int, long); 334 335 /* Tests for special fds. */ 336 int cb_is_stdin (host_callback *, int); 337 int cb_is_stdout (host_callback *, int); 338 int cb_is_stderr (host_callback *, int); 339 340 /* Read a string out of the target. */ 341 int cb_get_string (host_callback *, CB_SYSCALL *, char *, int, unsigned long); 342 343 /* Perform a system call. */ 344 CB_RC cb_syscall (host_callback *, CB_SYSCALL *); 345 346 #endif 347