include/sim/callback.h

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