src/runtime/x86-arch.c

   1 /*
   2  * This software is part of the SBCL system. See the README file for
   3  * more information.
   4  *
   5  * This software is derived from the CMU CL system, which was
   6  * written at Carnegie Mellon University and released into the
   7  * public domain. The software is in the public domain and is
   8  * provided with absolutely no warranty. See the COPYING and CREDITS
   9  * files for more information.
  10  */
  11
  12 #include <stdio.h>
  13
  14 #include "sbcl.h"
  15 #include "runtime.h"
  16 #include "globals.h"
  17 #include "validate.h"
  18 #include "os.h"
  19 #include "arch.h"
  20 #include "lispregs.h"
  21 #include "signal.h"
  22 #include "alloc.h"
  23 #include "interrupt.h"
  24 #include "interr.h"
  25 #include "breakpoint.h"
  26 #include "monitor.h"
  27 #include "thread.h"
  28
  29 #include "genesis/static-symbols.h"
  30 #include "genesis/symbol.h"
  31
  32 #define BREAKPOINT_INST 0xcc    /* INT3 */
  33
  34 unsigned long fast_random_state = 1;
  35
  36 void arch_init(void)
  37 {}
  38 \f
  39 /*
  40  * hacking signal contexts
  41  *
  42  * (This depends both on architecture, which determines what we might
  43  * want to get to, and on OS, which determines how we get to it.)
  44  */
  45
  46 int *
  47 context_eflags_addr(os_context_t *context)
  48 {
  49 #if defined __linux__ || defined __sun
  50     /* KLUDGE: As of kernel 2.2.14 on Red Hat 6.2, there's code in the
  51      * <sys/ucontext.h> file to define symbolic names for offsets into
  52      * gregs[], but it's conditional on __USE_GNU and not defined, so
  53      * we need to do this nasty absolute index magic number thing
  54      * instead. */
  55     return &context->uc_mcontext.gregs[16];
  56 #elif defined __FreeBSD__
  57     return &context->uc_mcontext.mc_eflags;
  58 #elif defined __OpenBSD__
  59     return &context->sc_eflags;
  60 #elif defined __NetBSD__
  61     return &(context->uc_mcontext.__gregs[_REG_EFL]);
  62 #else
  63 #error unsupported OS
  64 #endif
  65 }
  66 \f
  67 void arch_skip_instruction(os_context_t *context)
  68 {
  69     /* Assuming we get here via an INT3 xxx instruction, the PC now
  70      * points to the interrupt code (a Lisp value) so we just move
  71      * past it. Skip the code; after that, if the code is an
  72      * error-trap or cerror-trap then skip the data bytes that follow. */
  73
  74     int vlen;
  75     int code;
  76
  77
  78     /* Get and skip the Lisp interrupt code. */
  79     code = *(char*)(*os_context_pc_addr(context))++;
  80     switch (code)
  81         {
  82         case trap_Error:
  83         case trap_Cerror:
  84             /* Lisp error arg vector length */
  85             vlen = *(char*)(*os_context_pc_addr(context))++;
  86             /* Skip Lisp error arg data bytes. */
  87             while (vlen-- > 0) {
  88                 ++*os_context_pc_addr(context);
  89             }
  90             break;
  91
  92         case trap_Breakpoint:           /* not tested */
  93         case trap_FunEndBreakpoint: /* not tested */
  94             break;
  95
  96         case trap_PendingInterrupt:
  97         case trap_Halt:
  98             /* only needed to skip the Code */
  99             break;
 100
 101         default:
 102             fprintf(stderr,"[arch_skip_inst invalid code %d\n]\n",code);
 103             break;
 104         }
 105
 106     FSHOW((stderr,
 107            "/[arch_skip_inst resuming at %x]\n",
 108            *os_context_pc_addr(context)));
 109 }
 110
 111 unsigned char *
 112 arch_internal_error_arguments(os_context_t *context)
 113 {
 114     return 1 + (unsigned char *)(*os_context_pc_addr(context));
 115 }
 116
 117 boolean
 118 arch_pseudo_atomic_atomic(os_context_t *context)
 119 {
 120     return SymbolValue(PSEUDO_ATOMIC_ATOMIC,arch_os_get_current_thread());
 121 }
 122
 123 void
 124 arch_set_pseudo_atomic_interrupted(os_context_t *context)
 125 {
 126     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED, make_fixnum(1),
 127                    arch_os_get_current_thread());
 128 }
 129 \f
 130 /*
 131  * This stuff seems to get called for TRACE and debug activity.
 132  */
 133
 134 unsigned long
 135 arch_install_breakpoint(void *pc)
 136 {
 137     unsigned long result = *(unsigned long*)pc;
 138
 139     *(char*)pc = BREAKPOINT_INST;               /* x86 INT3       */
 140     *((char*)pc+1) = trap_Breakpoint;           /* Lisp trap code */
 141
 142     return result;
 143 }
 144
 145 void
 146 arch_remove_breakpoint(void *pc, unsigned long orig_inst)
 147 {
 148     *((char *)pc) = orig_inst & 0xff;
 149     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 150 }
 151 \f
 152 /* When single stepping, single_stepping holds the original instruction
 153  * PC location. */
 154 unsigned int *single_stepping = NULL;
 155 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 156 unsigned int  single_step_save1;
 157 unsigned int  single_step_save2;
 158 unsigned int  single_step_save3;
 159 #endif
 160
 161 void
 162 arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
 163 {
 164     unsigned int *pc = (unsigned int*)(*os_context_pc_addr(context));
 165
 166     /* Put the original instruction back. */
 167     *((char *)pc) = orig_inst & 0xff;
 168     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 169
 170 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 171     /* Install helper instructions for the single step:
 172      * pushf; or [esp],0x100; popf. */
 173     single_step_save1 = *(pc-3);
 174     single_step_save2 = *(pc-2);
 175     single_step_save3 = *(pc-1);
 176     *(pc-3) = 0x9c909090;
 177     *(pc-2) = 0x00240c81;
 178     *(pc-1) = 0x9d000001;
 179 #else
 180     *context_eflags_addr(context) |= 0x100;
 181 #endif
 182
 183     single_stepping = (unsigned int*)pc;
 184
 185 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 186     *os_context_pc_addr(context) = (char *)pc - 9;
 187 #endif
 188 }
 189 \f
 190 void
 191 sigtrap_handler(int signal, siginfo_t *info, void *void_context)
 192 {
 193     int code = info->si_code;
 194     os_context_t *context = (os_context_t*)void_context;
 195     unsigned int trap;
 196
 197     if (single_stepping && (signal==SIGTRAP))
 198     {
 199         /* fprintf(stderr,"* single step trap %x\n", single_stepping); */
 200
 201 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 202         /* Un-install single step helper instructions. */
 203         *(single_stepping-3) = single_step_save1;
 204         *(single_stepping-2) = single_step_save2;
 205         *(single_stepping-1) = single_step_save3;
 206 #else
 207         *context_eflags_addr(context) ^= 0x100;
 208 #endif
 209         /* Re-install the breakpoint if possible. */
 210         if (*os_context_pc_addr(context) == (int)single_stepping + 1) {
 211             fprintf(stderr, "warning: couldn't reinstall breakpoint\n");
 212         } else {
 213             *((char *)single_stepping) = BREAKPOINT_INST;       /* x86 INT3 */
 214             *((char *)single_stepping+1) = trap_Breakpoint;
 215         }
 216
 217         single_stepping = NULL;
 218         return;
 219     }
 220
 221     /* This is just for info in case the monitor wants to print an
 222      * approximation. */
 223     current_control_stack_pointer =
 224         (lispobj *)*os_context_sp_addr(context);
 225
 226     /* FIXME: CMUCL puts the float control restoration code here.
 227        Thus, it seems to me that single-stepping won't restore the
 228        float control.  Since SBCL currently doesn't support
 229        single-stepping (as far as I can tell) this is somewhat moot,
 230        but it might be worth either moving this code up or deleting
 231        the single-stepping code entirely.  -- CSR, 2002-07-15 */
 232 #ifdef LISP_FEATURE_LINUX
 233     os_restore_fp_control(context);
 234 #endif
 235
 236     /* On entry %eip points just after the INT3 byte and aims at the
 237      * 'kind' value (eg trap_Cerror). For error-trap and Cerror-trap a
 238      * number of bytes will follow, the first is the length of the byte
 239      * arguments to follow. */
 240     trap = *(unsigned char *)(*os_context_pc_addr(context));
 241     switch (trap) {
 242
 243     case trap_PendingInterrupt:
 244         FSHOW((stderr, "/<trap pending interrupt>\n"));
 245         arch_skip_instruction(context);
 246         interrupt_handle_pending(context);
 247         break;
 248
 249     case trap_Halt:
 250         /* Note: the old CMU CL code tried to save FPU state
 251          * here, and restore it after we do our thing, but there
 252          * seems to be no point in doing that, since we're just
 253          * going to lose(..) anyway. */
 254         fake_foreign_function_call(context);
 255         lose("%%PRIMITIVE HALT called; the party is over.");
 256
 257     case trap_Error:
 258     case trap_Cerror:
 259         FSHOW((stderr, "<trap error/cerror %d>\n", code));
 260         interrupt_internal_error(signal, info, context, code==trap_Cerror);
 261         break;
 262
 263     case trap_Breakpoint:
 264         --*os_context_pc_addr(context);
 265         handle_breakpoint(signal, info, context);
 266         break;
 267
 268     case trap_FunEndBreakpoint:
 269         --*os_context_pc_addr(context);
 270         *os_context_pc_addr(context) =
 271             (int)handle_fun_end_breakpoint(signal, info, context);
 272         break;
 273
 274     default:
 275         FSHOW((stderr,"/[C--trap default %d %d %x]\n",
 276                signal, code, context));
 277         interrupt_handle_now(signal, info, context);
 278         break;
 279     }
 280 }
 281
 282 static void
 283 sigill_handler(int signal, siginfo_t *siginfo, void *void_context) {
 284     os_context_t *context = (os_context_t*)void_context;
 285     fake_foreign_function_call(context);
 286     monitor_or_something();
 287 }
 288
 289 void
 290 arch_install_interrupt_handlers()
 291 {
 292     SHOW("entering arch_install_interrupt_handlers()");
 293
 294     /* Note: The old CMU CL code here used sigtrap_handler() to handle
 295      * SIGILL as well as SIGTRAP. I couldn't see any reason to do
 296      * things that way. So, I changed to separate handlers when
 297      * debugging a problem on OpenBSD, where SBCL wasn't catching
 298      * SIGILL properly, but was instead letting the process be
 299      * terminated with an "Illegal instruction" output. If this change
 300      * turns out to break something (maybe breakpoint handling on some
 301      * OS I haven't tested on?) and we have to go back to the old CMU
 302      * CL way, I hope there will at least be a comment to explain
 303      * why.. -- WHN 2001-06-07 */
 304     undoably_install_low_level_interrupt_handler(SIGILL , sigill_handler);
 305     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 306
 307     SHOW("returning from arch_install_interrupt_handlers()");
 308 }
 309 \f
 310 /* This is implemented in assembly language and called from C: */
 311 extern lispobj
 312 call_into_lisp(lispobj fun, lispobj *args, int nargs);
 313
 314 /* These functions are an interface to the Lisp call-in facility.
 315  * Since this is C we can know nothing about the calling environment.
 316  * The control stack might be the C stack if called from the monitor
 317  * or the Lisp stack if called as a result of an interrupt or maybe
 318  * even a separate stack. The args are most likely on that stack but
 319  * could be in registers depending on what the compiler likes. So we
 320  * copy the args into a portable vector and let the assembly language
 321  * call-in function figure it out. */
 322
 323 lispobj
 324 funcall0(lispobj function)
 325 {
 326     lispobj *args = NULL;
 327
 328     FSHOW((stderr, "/entering funcall0(0x%lx)\n", (long)function));
 329     return call_into_lisp(function, args, 0);
 330 }
 331 lispobj
 332 funcall1(lispobj function, lispobj arg0)
 333 {
 334     lispobj args[1];
 335     args[0] = arg0;
 336     return call_into_lisp(function, args, 1);
 337 }
 338 lispobj
 339 funcall2(lispobj function, lispobj arg0, lispobj arg1)
 340 {
 341     lispobj args[2];
 342     args[0] = arg0;
 343     args[1] = arg1;
 344     return call_into_lisp(function, args, 2);
 345 }
 346 lispobj
 347 funcall3(lispobj function, lispobj arg0, lispobj arg1, lispobj arg2)
 348 {
 349     lispobj args[3];
 350     args[0] = arg0;
 351     args[1] = arg1;
 352     args[2] = arg2;
 353     return call_into_lisp(function, args, 3);
 354 }
 355
 356 #ifdef LISP_FEATURE_LINKAGE_TABLE
 357 /* FIXME: It might be cleaner to generate these from the lisp side of
 358  * things.
 359  */
 360
 361 void
 362 arch_write_linkage_table_jmp(char * reloc, void * fun)
 363 {
 364     /* Make JMP to function entry. JMP offset is calculated from next
 365      * instruction.
 366      */
 367     long offset = (char *)fun - (reloc + 5);
 368     int i;
 369
 370     *reloc++ = 0xe9;            /* opcode for JMP rel32 */
 371     for (i = 0; i < 4; i++) {
 372         *reloc++ = offset & 0xff;
 373         offset >>= 8;
 374     }
 375
 376     /* write a nop for good measure. */
 377     *reloc = 0x90;
 378 }
 379
 380 void
 381 arch_write_linkage_table_ref(void * reloc, void * data)
 382 {
 383     *(unsigned long *)reloc = (unsigned long)data;
 384 }
 385
 386 #endif