include/sim/callback.h

   1 /* Remote target system call callback support.
   2    Copyright (C) 1997-2024 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 <stdarg.h>
  49 #include <stdint.h>
  50
  51 #include <ansidecl.h>
  52 /* Needed for enum bfd_endian.  */
  53 #include <bfd.h>
  54 \f
  55 /* Mapping of host/target values.  */
  56 /* ??? For debugging purposes, one might want to add a string of the
  57    name of the symbol.  */
  58
  59 typedef struct {
  60   const char *name;
  61   int host_val;
  62   int target_val;
  63 } CB_TARGET_DEFS_MAP;
  64
  65 #define MAX_CALLBACK_FDS 10
  66
  67 /* Forward decl for stat/fstat.  */
  68 struct stat;
  69
  70 typedef struct host_callback_struct host_callback;
  71
  72 struct host_callback_struct
  73 {
  74   int (*close) (host_callback *,int);
  75   int (*get_errno) (host_callback *);
  76   int (*isatty) (host_callback *, int);
  77   int64_t (*lseek) (host_callback *, int, int64_t, int);
  78   int (*open) (host_callback *, const char*, int mode);
  79   int (*read) (host_callback *,int,  char *, int);
  80   int (*read_stdin) ( host_callback *, char *, int);
  81   int (*rename) (host_callback *, const char *, const char *);
  82   int (*system) (host_callback *, const char *);
  83   int64_t (*time) (host_callback *);
  84   int (*unlink) (host_callback *, const char *);
  85   int (*write) (host_callback *,int, const char *, int);
  86   int (*write_stdout) (host_callback *, const char *, int);
  87   void (*flush_stdout) (host_callback *);
  88   int (*write_stderr) (host_callback *, const char *, int);
  89   void (*flush_stderr) (host_callback *);
  90   int (*to_stat) (host_callback *, const char *, struct stat *);
  91   int (*to_fstat) (host_callback *, int, struct stat *);
  92   int (*to_lstat) (host_callback *, const char *, struct stat *);
  93   int (*ftruncate) (host_callback *, int, int64_t);
  94   int (*truncate) (host_callback *, const char *, int64_t);
  95   int (*getpid) (host_callback *);
  96   int (*kill) (host_callback *, int, int);
  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     ATTRIBUTE_PRINTF_2;
 119
 120   /* Talk to the user on a console.  */
 121   void (*vprintf_filtered) (host_callback *, const char *, va_list)
 122     ATTRIBUTE_PRINTF (2, 0);
 123
 124   /* Same as vprintf_filtered but to stderr.  */
 125   void (*evprintf_filtered) (host_callback *, const char *, va_list)
 126     ATTRIBUTE_PRINTF (2, 0);
 127
 128   /* Print an error message and "exit".
 129      In the case of gdb "exiting" means doing a longjmp back to the main
 130      command loop.  */
 131   void (*error) (host_callback *, const char *, ...)
 132     ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF_2;
 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   /* Program command line options.  */
 183   char **argv;
 184
 185   /* Program environment.  */
 186   char **envp;
 187
 188   /* Size of an "int" on the target (for syscalls whose ABI uses "int").
 189      This must include padding, and only padding-at-higher-address is
 190      supported.  For example, a 64-bit target with 32-bit int:s which
 191      are padded to 64 bits when in an array, should supposedly set this
 192      to 8.  The default is 4 which matches ILP32 targets and 64-bit
 193      targets with 32-bit ints and no padding.  */
 194   int target_sizeof_int;
 195
 196   /* Marker for those wanting to do sanity checks.
 197      This should remain the last member of this struct to help catch
 198      miscompilation errors. */
 199 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */
 200   int magic;
 201 };
 202
 203 extern host_callback default_callback;
 204 \f
 205 /* Canonical versions of system call numbers.
 206    It's not intended to willy-nilly throw every system call ever heard
 207    of in here.  Only include those that have an important use.
 208    ??? One can certainly start a discussion over the ones that are currently
 209    here, but that will always be true.  */
 210
 211 /* These are used by the ANSI C support of libc.  */
 212 #define CB_SYS_exit     1
 213 #define CB_SYS_open     2
 214 #define CB_SYS_close    3
 215 #define CB_SYS_read     4
 216 #define CB_SYS_write    5
 217 #define CB_SYS_lseek    6
 218 #define CB_SYS_unlink   7
 219 #define CB_SYS_getpid   8
 220 #define CB_SYS_kill     9
 221 #define CB_SYS_fstat    10
 222 /*#define CB_SYS_sbrk   11 - not currently a system call, but reserved.  */
 223
 224 /* ARGV support.  */
 225 #define CB_SYS_argvlen  12
 226 #define CB_SYS_argv     13
 227
 228 /* These are extras added for one reason or another.  */
 229 #define CB_SYS_chdir    14
 230 #define CB_SYS_stat     15
 231 #define CB_SYS_chmod    16
 232 #define CB_SYS_utime    17
 233 #define CB_SYS_time     18
 234
 235 /* More standard syscalls.  */
 236 #define CB_SYS_lstat    19
 237 #define CB_SYS_rename   20
 238 #define CB_SYS_truncate 21
 239 #define CB_SYS_ftruncate 22
 240 #define CB_SYS_pipe     23
 241
 242 /* New ARGV support.  */
 243 #define CB_SYS_argc     24
 244 #define CB_SYS_argnlen  25
 245 #define CB_SYS_argn     26
 246 \f
 247 /* Struct use to pass and return information necessary to perform a
 248    system call.  */
 249 /* FIXME: Need to consider target word size.  */
 250
 251 typedef struct cb_syscall {
 252   /* The target's value of what system call to perform.  */
 253   int func;
 254   /* The arguments to the syscall.  */
 255   long arg1, arg2, arg3, arg4, arg5, arg6, arg7;
 256
 257   /* The result.  */
 258   long result;
 259   /* Some system calls have two results.  */
 260   long result2;
 261   /* The target's errno value, or 0 if success.
 262      This is converted to the target's value with host_to_target_errno.  */
 263   int errcode;
 264
 265   /* Working space to be used by memory read/write callbacks.  */
 266   void *p1;
 267   void *p2;
 268   long x1,x2;
 269
 270   /* Callbacks for reading/writing memory (e.g. for read/write syscalls).
 271      ??? long or unsigned long might be better to use for the `count'
 272      argument here.  We mimic sim_{read,write} for now.  Be careful to
 273      test any changes with -Wall -Werror, mixed signed comparisons
 274      will get you.  */
 275   int (*read_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 276                    unsigned long /*taddr*/, char * /*buf*/,
 277                    int /*bytes*/);
 278   int (*write_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 279                     unsigned long /*taddr*/, const char * /*buf*/,
 280                     int /*bytes*/);
 281
 282   /* For sanity checking, should be last entry.  */
 283   int magic;
 284 } CB_SYSCALL;
 285
 286 /* Magic number sanity checker.  */
 287 #define CB_SYSCALL_MAGIC 0x12344321
 288
 289 /* Macro to initialize CB_SYSCALL.  Called first, before filling in
 290    any fields.  */
 291 #define CB_SYSCALL_INIT(sc) \
 292 do { \
 293   memset ((sc), 0, sizeof (*(sc))); \
 294   (sc)->magic = CB_SYSCALL_MAGIC; \
 295 } while (0)
 296 \f
 297 /* Return codes for various interface routines.  */
 298
 299 typedef enum {
 300   CB_RC_OK = 0,
 301   /* generic error */
 302   CB_RC_ERR,
 303   /* either file not found or no read access */
 304   CB_RC_ACCESS,
 305   CB_RC_NO_MEM
 306 } CB_RC;
 307
 308 /* Read in target values for system call numbers, errno values, signals.  */
 309 CB_RC cb_read_target_syscall_maps (host_callback *, const char *);
 310
 311 /* Translate target to host syscall function numbers.  */
 312 int cb_target_to_host_syscall (host_callback *, int);
 313
 314 /* Translate host to target errno value.  */
 315 int cb_host_to_target_errno (host_callback *, int);
 316
 317 /* Translate target to host open flags.  */
 318 int cb_target_to_host_open (host_callback *, int);
 319
 320 /* Translate target signal number to host.  */
 321 int cb_target_to_host_signal (host_callback *, int);
 322
 323 /* Translate host signal number to target.  */
 324 int cb_host_to_gdb_signal (host_callback *, int);
 325
 326 /* Translate symbols into human readable strings.  */
 327 const char *cb_host_str_syscall (host_callback *, int);
 328 const char *cb_host_str_errno (host_callback *, int);
 329 const char *cb_host_str_signal (host_callback *, int);
 330 const char *cb_target_str_syscall (host_callback *, int);
 331 const char *cb_target_str_errno (host_callback *, int);
 332 const char *cb_target_str_signal (host_callback *, int);
 333
 334 /* Translate host stat struct to target.
 335    If stat struct ptr is NULL, just compute target stat struct size.
 336    Result is size of target stat struct or 0 if error.  */
 337 int cb_host_to_target_stat (host_callback *, const struct stat *, void *);
 338
 339 /* Translate a value to target endian.  */
 340 void cb_store_target_endian (host_callback *, char *, int, long);
 341
 342 /* Tests for special fds.  */
 343 int cb_is_stdin (host_callback *, int);
 344 int cb_is_stdout (host_callback *, int);
 345 int cb_is_stderr (host_callback *, int);
 346
 347 /* Read a string out of the target.  */
 348 int cb_get_string (host_callback *, CB_SYSCALL *, char *, int, unsigned long);
 349
 350 /* Perform a system call.  */
 351 CB_RC cb_syscall (host_callback *, CB_SYSCALL *);
 352
 353 #endif