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 "thread.h"
  27
  28 #include "genesis/static-symbols.h"
  29 #include "genesis/symbol.h"
  30
  31 #define BREAKPOINT_INST 0xcc    /* INT3 */
  32
  33 unsigned long fast_random_state = 1;
  34
  35 void arch_init(void)
  36 {}
  37
  38 #ifndef LISP_FEATURE_WIN32
  39 os_vm_address_t
  40 arch_get_bad_addr(int sig, siginfo_t *code, os_context_t *context)
  41 {
  42     return (os_vm_address_t)code->si_addr;
  43 }
  44 #endif
  45
  46 \f
  47 /*
  48  * hacking signal contexts
  49  *
  50  * (This depends both on architecture, which determines what we might
  51  * want to get to, and on OS, which determines how we get to it.)
  52  */
  53
  54 int *
  55 context_eflags_addr(os_context_t *context)
  56 {
  57 #if defined __linux__ || defined __sun
  58     /* KLUDGE: As of kernel 2.2.14 on Red Hat 6.2, there's code in the
  59      * <sys/ucontext.h> file to define symbolic names for offsets into
  60      * gregs[], but it's conditional on __USE_GNU and not defined, so
  61      * we need to do this nasty absolute index magic number thing
  62      * instead. */
  63     return &context->uc_mcontext.gregs[16];
  64 #elif defined __FreeBSD__
  65     return &context->uc_mcontext.mc_eflags;
  66 #elif defined __OpenBSD__
  67     return &context->sc_eflags;
  68 #elif defined LISP_FEATURE_DARWIN
  69     return (int *)(&context->uc_mcontext->SS.EFLAGS);
  70 #elif defined __NetBSD__
  71     return &(context->uc_mcontext.__gregs[_REG_EFL]);
  72 #elif defined LISP_FEATURE_WIN32
  73     return (int *)&context->EFlags;
  74 #else
  75 #error unsupported OS
  76 #endif
  77 }
  78 \f
  79 void arch_skip_instruction(os_context_t *context)
  80 {
  81     /* Assuming we get here via an INT3 xxx instruction, the PC now
  82      * points to the interrupt code (a Lisp value) so we just move
  83      * past it. Skip the code; after that, if the code is an
  84      * error-trap or cerror-trap then skip the data bytes that follow. */
  85
  86     int vlen;
  87     int code;
  88
  89
  90     /* Get and skip the Lisp interrupt code. */
  91     code = *(char*)(*os_context_pc_addr(context))++;
  92     switch (code)
  93         {
  94         case trap_Error:
  95         case trap_Cerror:
  96             /* Lisp error arg vector length */
  97             vlen = *(char*)(*os_context_pc_addr(context))++;
  98             /* Skip Lisp error arg data bytes. */
  99             while (vlen-- > 0) {
 100                 ++*os_context_pc_addr(context);
 101             }
 102             break;
 103
 104         case trap_Breakpoint:           /* not tested */
 105         case trap_FunEndBreakpoint: /* not tested */
 106             break;
 107
 108         case trap_PendingInterrupt:
 109         case trap_Halt:
 110         case trap_SingleStepAround:
 111         case trap_SingleStepBefore:
 112             /* only needed to skip the Code */
 113             break;
 114
 115         default:
 116             fprintf(stderr,"[arch_skip_inst invalid code %d\n]\n",code);
 117             break;
 118         }
 119
 120     FSHOW((stderr,
 121            "/[arch_skip_inst resuming at %x]\n",
 122            *os_context_pc_addr(context)));
 123 }
 124
 125 unsigned char *
 126 arch_internal_error_arguments(os_context_t *context)
 127 {
 128     return 1 + (unsigned char *)(*os_context_pc_addr(context));
 129 }
 130
 131 boolean
 132 arch_pseudo_atomic_atomic(os_context_t *context)
 133 {
 134     return get_pseudo_atomic_atomic(arch_os_get_current_thread());
 135 }
 136
 137 void
 138 arch_set_pseudo_atomic_interrupted(os_context_t *context)
 139 {
 140     struct thread *thread = arch_os_get_current_thread();
 141     set_pseudo_atomic_interrupted(thread);
 142 }
 143
 144 void
 145 arch_clear_pseudo_atomic_interrupted(os_context_t *context)
 146 {
 147     struct thread *thread = arch_os_get_current_thread();
 148     clear_pseudo_atomic_interrupted(thread);
 149 }
 150 \f
 151 /*
 152  * This stuff seems to get called for TRACE and debug activity.
 153  */
 154
 155 unsigned int
 156 arch_install_breakpoint(void *pc)
 157 {
 158     unsigned int result = *(unsigned int*)pc;
 159
 160     *(char*)pc = BREAKPOINT_INST;               /* x86 INT3       */
 161     *((char*)pc+1) = trap_Breakpoint;           /* Lisp trap code */
 162
 163     return result;
 164 }
 165
 166 void
 167 arch_remove_breakpoint(void *pc, unsigned int orig_inst)
 168 {
 169     *((char *)pc) = orig_inst & 0xff;
 170     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 171 }
 172 \f
 173 /* When single stepping, single_stepping holds the original instruction
 174  * PC location. */
 175 unsigned int *single_stepping = NULL;
 176 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 177 unsigned int  single_step_save1;
 178 unsigned int  single_step_save2;
 179 unsigned int  single_step_save3;
 180 #endif
 181
 182 void
 183 arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
 184 {
 185     unsigned int *pc = (unsigned int*)(*os_context_pc_addr(context));
 186
 187     /* Put the original instruction back. */
 188     *((char *)pc) = orig_inst & 0xff;
 189     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 190
 191 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 192     /* Install helper instructions for the single step:
 193      * pushf; or [esp],0x100; popf. */
 194     single_step_save1 = *(pc-3);
 195     single_step_save2 = *(pc-2);
 196     single_step_save3 = *(pc-1);
 197     *(pc-3) = 0x9c909090;
 198     *(pc-2) = 0x00240c81;
 199     *(pc-1) = 0x9d000001;
 200 #else
 201     *context_eflags_addr(context) |= 0x100;
 202 #endif
 203
 204     single_stepping = pc;
 205
 206 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 207     *os_context_pc_addr(context) = (os_context_register_t)((char *)pc - 9);
 208 #endif
 209 }
 210 \f
 211 void
 212 restore_breakpoint_from_single_step(os_context_t * context)
 213 {
 214     /* fprintf(stderr,"* single step trap %x\n", single_stepping); */
 215 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 216     /* Un-install single step helper instructions. */
 217     *(single_stepping-3) = single_step_save1;
 218     *(single_stepping-2) = single_step_save2;
 219     *(single_stepping-1) = single_step_save3;
 220 #else
 221     *context_eflags_addr(context) &= ~0x100;
 222 #endif
 223     /* Re-install the breakpoint if possible. */
 224     if (*os_context_pc_addr(context) == (int)single_stepping + 1) {
 225         fprintf(stderr, "warning: couldn't reinstall breakpoint\n");
 226     } else {
 227         *((char *)single_stepping) = BREAKPOINT_INST;       /* x86 INT3 */
 228         *((char *)single_stepping+1) = trap_Breakpoint;
 229     }
 230
 231     single_stepping = NULL;
 232     return;
 233 }
 234
 235 void
 236 arch_handle_breakpoint(os_context_t *context)
 237 {
 238     --*os_context_pc_addr(context);
 239     handle_breakpoint(context);
 240 }
 241
 242 void
 243 arch_handle_fun_end_breakpoint(os_context_t *context)
 244 {
 245     --*os_context_pc_addr(context);
 246     *os_context_pc_addr(context) =
 247         (int)handle_fun_end_breakpoint(context);
 248 }
 249
 250 void
 251 arch_handle_single_step_trap(os_context_t *context, int trap)
 252 {
 253     arch_skip_instruction(context);
 254     /* On x86 the fdefn / function is always in EAX, so we pass 0
 255      * as the register_offset. */
 256     handle_single_step_trap(context, trap, 0);
 257 }
 258
 259 #ifndef LISP_FEATURE_WIN32
 260 void
 261 sigtrap_handler(int signal, siginfo_t *info, void *void_context)
 262 {
 263     os_context_t *context = (os_context_t*)void_context;
 264     unsigned int trap;
 265
 266     if (single_stepping && (signal==SIGTRAP)) {
 267         restore_breakpoint_from_single_step(context);
 268         return;
 269     }
 270
 271     /* This is just for info in case the monitor wants to print an
 272      * approximation. */
 273     current_control_stack_pointer =
 274         (lispobj *)*os_context_sp_addr(context);
 275
 276     /* FIXME: CMUCL puts the float control restoration code here.
 277        Thus, it seems to me that single-stepping won't restore the
 278        float control.  Since SBCL currently doesn't support
 279        single-stepping (as far as I can tell) this is somewhat moot,
 280        but it might be worth either moving this code up or deleting
 281        the single-stepping code entirely.  -- CSR, 2002-07-15 */
 282 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
 283     os_restore_fp_control(context);
 284 #endif
 285
 286 #ifdef LISP_FEATURE_SUNOS
 287     /* For some reason the breakpoints that :ENCAPSULATE NIL tracing sets up
 288      * cause a trace trap (i.e. processor single-stepping trap) on the following
 289      * instruction on Solaris 10/x86. -- JES, 2006-04-07
 290      */
 291     if (info->si_code == TRAP_TRACE) {
 292         lose("foo");
 293         return;
 294     }
 295 #endif
 296
 297     /* On entry %eip points just after the INT3 byte and aims at the
 298      * 'kind' value (eg trap_Cerror). For error-trap and Cerror-trap a
 299      * number of bytes will follow, the first is the length of the byte
 300      * arguments to follow. */
 301     trap = *(unsigned char *)(*os_context_pc_addr(context));
 302     handle_trap(context, trap);
 303 }
 304
 305 void
 306 sigill_handler(int signal, siginfo_t *siginfo, void *void_context) {
 307     os_context_t *context = (os_context_t*)void_context;
 308
 309     /* Triggering SIGTRAP using int3 is unreliable on OS X/x86, so
 310      * we need to use illegal instructions for traps.
 311      */
 312 #if defined(LISP_FEATURE_DARWIN) && !defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 313     if (*((unsigned short *)*os_context_pc_addr(context)) == 0x0b0f) {
 314         *os_context_pc_addr(context) += 2;
 315         return sigtrap_handler(signal, siginfo, void_context);
 316     }
 317 #endif
 318     fake_foreign_function_call(context);
 319     lose("Unhandled SIGILL");
 320 }
 321 #endif /* not LISP_FEATURE_WIN32 */
 322
 323 void
 324 arch_install_interrupt_handlers()
 325 {
 326     SHOW("entering arch_install_interrupt_handlers()");
 327
 328     /* Note: The old CMU CL code here used sigtrap_handler() to handle
 329      * SIGILL as well as SIGTRAP. I couldn't see any reason to do
 330      * things that way. So, I changed to separate handlers when
 331      * debugging a problem on OpenBSD, where SBCL wasn't catching
 332      * SIGILL properly, but was instead letting the process be
 333      * terminated with an "Illegal instruction" output. If this change
 334      * turns out to break something (maybe breakpoint handling on some
 335      * OS I haven't tested on?) and we have to go back to the old CMU
 336      * CL way, I hope there will at least be a comment to explain
 337      * why.. -- WHN 2001-06-07 */
 338 #if !defined(LISP_FEATURE_WIN32) && !defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 339     undoably_install_low_level_interrupt_handler(SIGILL , sigill_handler);
 340     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 341 #endif
 342     SHOW("returning from arch_install_interrupt_handlers()");
 343 }
 344 \f
 345 #ifdef LISP_FEATURE_LINKAGE_TABLE
 346 /* FIXME: It might be cleaner to generate these from the lisp side of
 347  * things.
 348  */
 349
 350 void
 351 arch_write_linkage_table_jmp(char * reloc, void * fun)
 352 {
 353     /* Make JMP to function entry. JMP offset is calculated from next
 354      * instruction.
 355      */
 356     long offset = (char *)fun - (reloc + 5);
 357     int i;
 358
 359     *reloc++ = 0xe9;            /* opcode for JMP rel32 */
 360     for (i = 0; i < 4; i++) {
 361         *reloc++ = offset & 0xff;
 362         offset >>= 8;
 363     }
 364
 365     /* write a nop for good measure. */
 366     *reloc = 0x90;
 367 }
 368
 369 void
 370 arch_write_linkage_table_ref(void * reloc, void * data)
 371 {
 372     *(unsigned long *)reloc = (unsigned long)data;
 373 }
 374
 375 #endif