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 /* ??? 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 \f
  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 \f
 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 \f
 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 \f
 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