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 "alloc.h"
  22 #include "interrupt.h"
  23 #include "interr.h"
  24 #include "breakpoint.h"
  25 #include "thread.h"
  26 #include "pseudo-atomic.h"
  27
  28 #include "genesis/static-symbols.h"
  29 #include "genesis/symbol.h"
  30
  31 #define BREAKPOINT_INST 0xcc    /* INT3 */
  32 #define UD2_INST 0x0b0f         /* UD2 */
  33
  34 #ifndef LISP_FEATURE_UD2_BREAKPOINTS
  35 #define BREAKPOINT_WIDTH 1
  36 #else
  37 #define BREAKPOINT_WIDTH 2
  38 #endif
  39
  40 void arch_init(void)
  41 {}
  42
  43 #ifndef LISP_FEATURE_WIN32
  44 os_vm_address_t
  45 arch_get_bad_addr(int sig, siginfo_t *code, os_context_t *context)
  46 {
  47     return (os_vm_address_t)code->si_addr;
  48 }
  49 #endif
  50
  51 \f
  52 /*
  53  * hacking signal contexts
  54  *
  55  * (This depends both on architecture, which determines what we might
  56  * want to get to, and on OS, which determines how we get to it.)
  57  */
  58
  59 int *
  60 context_eflags_addr(os_context_t *context)
  61 {
  62 #if defined __linux__ || defined __sun
  63     /* KLUDGE: As of kernel 2.2.14 on Red Hat 6.2, there's code in the
  64      * <sys/ucontext.h> file to define symbolic names for offsets into
  65      * gregs[], but it's conditional on __USE_GNU and not defined, so
  66      * we need to do this nasty absolute index magic number thing
  67      * instead. */
  68     return &context->uc_mcontext.gregs[16];
  69 #elif defined __FreeBSD__
  70     return &context->uc_mcontext.mc_eflags;
  71 #elif defined __OpenBSD__
  72     return &context->sc_eflags;
  73 #elif defined LISP_FEATURE_DARWIN
  74     return (int *)(&context->uc_mcontext->SS.EFLAGS);
  75 #elif defined __NetBSD__
  76     return &(context->uc_mcontext.__gregs[_REG_EFL]);
  77 #elif defined LISP_FEATURE_WIN32
  78     return (int *)&context->win32_context->EFlags;
  79 #else
  80 #error unsupported OS
  81 #endif
  82 }
  83 \f
  84 void arch_skip_instruction(os_context_t *context)
  85 {
  86     /* Assuming we get here via an INT3 xxx instruction, the PC now
  87      * points to the interrupt code (a Lisp value) so we just move
  88      * past it. Skip the code; after that, if the code is an
  89      * error-trap or cerror-trap then skip the data bytes that follow. */
  90
  91     int vlen;
  92     int code;
  93
  94
  95     /* Get and skip the Lisp interrupt code. */
  96     code = *(char*)(*os_context_pc_addr(context))++;
  97     switch (code)
  98         {
  99         case trap_Error:
 100         case trap_Cerror:
 101             /* Lisp error arg vector length */
 102             vlen = *(char*)(*os_context_pc_addr(context))++;
 103             /* Skip Lisp error arg data bytes. */
 104             while (vlen-- > 0) {
 105                 ++*os_context_pc_addr(context);
 106             }
 107             break;
 108
 109         case trap_Breakpoint:           /* not tested */
 110         case trap_FunEndBreakpoint: /* not tested */
 111             break;
 112
 113 #ifdef LISP_FEATURE_SB_SAFEPOINT
 114         case trap_GlobalSafepoint:
 115         case trap_CspSafepoint:
 116 #endif
 117         case trap_PendingInterrupt:
 118         case trap_Halt:
 119         case trap_SingleStepAround:
 120         case trap_SingleStepBefore:
 121             /* only needed to skip the Code */
 122             break;
 123
 124         default:
 125             fprintf(stderr,"[arch_skip_inst invalid code %d\n]\n",code);
 126             break;
 127         }
 128
 129     FSHOW((stderr,
 130            "/[arch_skip_inst resuming at %x]\n",
 131            *os_context_pc_addr(context)));
 132 }
 133
 134 unsigned char *
 135 arch_internal_error_arguments(os_context_t *context)
 136 {
 137     return 1 + (unsigned char *)(*os_context_pc_addr(context));
 138 }
 139
 140 boolean
 141 arch_pseudo_atomic_atomic(os_context_t *context)
 142 {
 143     return get_pseudo_atomic_atomic(arch_os_get_current_thread());
 144 }
 145
 146 void
 147 arch_set_pseudo_atomic_interrupted(os_context_t *context)
 148 {
 149     struct thread *thread = arch_os_get_current_thread();
 150     set_pseudo_atomic_interrupted(thread);
 151 }
 152
 153 void
 154 arch_clear_pseudo_atomic_interrupted(os_context_t *context)
 155 {
 156     struct thread *thread = arch_os_get_current_thread();
 157     clear_pseudo_atomic_interrupted(thread);
 158 }
 159 \f
 160 /*
 161  * This stuff seems to get called for TRACE and debug activity.
 162  */
 163
 164 unsigned int
 165 arch_install_breakpoint(void *pc)
 166 {
 167     unsigned int result = *(unsigned int*)pc;
 168
 169 #ifndef LISP_FEATURE_UD2_BREAKPOINTS
 170     *(char*)pc = BREAKPOINT_INST;               /* x86 INT3       */
 171     *((char*)pc+1) = trap_Breakpoint;           /* Lisp trap code */
 172 #else
 173     *(char*)pc = UD2_INST & 0xff;
 174     *((char*)pc+1) = UD2_INST >> 8;
 175     *((char*)pc+2) = trap_Breakpoint;
 176 #endif
 177
 178     return result;
 179 }
 180
 181 void
 182 arch_remove_breakpoint(void *pc, unsigned int orig_inst)
 183 {
 184     *((char *)pc) = orig_inst & 0xff;
 185     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 186 #if BREAKPOINT_WIDTH > 1
 187     *((char *)pc + 2) = (orig_inst & 0xff0000) >> 16;
 188 #endif
 189 }
 190 \f
 191 /* When single stepping, single_stepping holds the original instruction
 192  * PC location. */
 193 unsigned int *single_stepping = NULL;
 194 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 195 unsigned int  single_step_save1;
 196 unsigned int  single_step_save2;
 197 unsigned int  single_step_save3;
 198 #endif
 199
 200 void
 201 arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
 202 {
 203     unsigned int *pc = (unsigned int*)(*os_context_pc_addr(context));
 204
 205     /* Put the original instruction back. */
 206     arch_remove_breakpoint(pc, orig_inst);
 207
 208 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 209     /* Install helper instructions for the single step:
 210      * pushf; or [esp],0x100; popf. */
 211     single_step_save1 = *(pc-3);
 212     single_step_save2 = *(pc-2);
 213     single_step_save3 = *(pc-1);
 214     *(pc-3) = 0x9c909090;
 215     *(pc-2) = 0x00240c81;
 216     *(pc-1) = 0x9d000001;
 217 #else
 218     *context_eflags_addr(context) |= 0x100;
 219 #endif
 220
 221     single_stepping = pc;
 222
 223 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 224     *os_context_pc_addr(context) = (os_context_register_t)((char *)pc - 9);
 225 #endif
 226 }
 227 \f
 228 void
 229 restore_breakpoint_from_single_step(os_context_t * context)
 230 {
 231     /* fprintf(stderr,"* single step trap %x\n", single_stepping); */
 232 #ifdef CANNOT_GET_TO_SINGLE_STEP_FLAG
 233     /* Un-install single step helper instructions. */
 234     *(single_stepping-3) = single_step_save1;
 235     *(single_stepping-2) = single_step_save2;
 236     *(single_stepping-1) = single_step_save3;
 237 #else
 238     *context_eflags_addr(context) &= ~0x100;
 239 #endif
 240     /* Re-install the breakpoint if possible. */
 241     if (((char *)*os_context_pc_addr(context) >
 242          (char *)single_stepping) &&
 243         ((char *)*os_context_pc_addr(context) <=
 244          (char *)single_stepping + BREAKPOINT_WIDTH)) {
 245         fprintf(stderr, "warning: couldn't reinstall breakpoint\n");
 246     } else {
 247         arch_install_breakpoint(single_stepping);
 248     }
 249
 250     single_stepping = NULL;
 251     return;
 252 }
 253
 254 void
 255 arch_handle_breakpoint(os_context_t *context)
 256 {
 257     *os_context_pc_addr(context) -= BREAKPOINT_WIDTH;
 258     handle_breakpoint(context);
 259 }
 260
 261 void
 262 arch_handle_fun_end_breakpoint(os_context_t *context)
 263 {
 264     *os_context_pc_addr(context) -= BREAKPOINT_WIDTH;
 265     *os_context_pc_addr(context) =
 266         (int)handle_fun_end_breakpoint(context);
 267 }
 268
 269 void
 270 arch_handle_single_step_trap(os_context_t *context, int trap)
 271 {
 272     arch_skip_instruction(context);
 273     /* On x86 the fdefn / function is always in EAX, so we pass 0
 274      * as the register_offset. */
 275     handle_single_step_trap(context, trap, 0);
 276 }
 277
 278 #ifndef LISP_FEATURE_WIN32
 279 void
 280 sigtrap_handler(int signal, siginfo_t *info, os_context_t *context)
 281 {
 282     unsigned int trap;
 283
 284     if (single_stepping) {
 285         restore_breakpoint_from_single_step(context);
 286         return;
 287     }
 288
 289     /* This is just for info in case the monitor wants to print an
 290      * approximation. */
 291     access_control_stack_pointer(arch_os_get_current_thread()) =
 292         (lispobj *)*os_context_sp_addr(context);
 293
 294 #ifdef LISP_FEATURE_SUNOS
 295     /* For some reason the breakpoints that :ENCAPSULATE NIL tracing sets up
 296      * cause a trace trap (i.e. processor single-stepping trap) on the following
 297      * instruction on Solaris 10/x86. -- JES, 2006-04-07
 298      */
 299     if (info->si_code == TRAP_TRACE) {
 300         lose("foo");
 301         return;
 302     }
 303 #endif
 304
 305     /* On entry %eip points just after the INT3 byte and aims at the
 306      * 'kind' value (eg trap_Cerror). For error-trap and Cerror-trap a
 307      * number of bytes will follow, the first is the length of the byte
 308      * arguments to follow. */
 309     trap = *(unsigned char *)(*os_context_pc_addr(context));
 310     handle_trap(context, trap);
 311 }
 312
 313 void
 314 sigill_handler(int signal, siginfo_t *siginfo, os_context_t *context) {
 315     /* Triggering SIGTRAP using int3 is unreliable on OS X/x86, so
 316      * we need to use illegal instructions for traps.
 317      */
 318 #if defined(LISP_FEATURE_UD2_BREAKPOINTS) && !defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 319     if (*((unsigned short *)*os_context_pc_addr(context)) == UD2_INST) {
 320         *os_context_pc_addr(context) += 2;
 321         return sigtrap_handler(signal, siginfo, context);
 322     }
 323 #endif
 324     fake_foreign_function_call(context);
 325     lose("Unhandled SIGILL");
 326 }
 327 #endif /* not LISP_FEATURE_WIN32 */
 328
 329 void
 330 arch_install_interrupt_handlers()
 331 {
 332     SHOW("entering arch_install_interrupt_handlers()");
 333
 334     /* Note: The old CMU CL code here used sigtrap_handler() to handle
 335      * SIGILL as well as SIGTRAP. I couldn't see any reason to do
 336      * things that way. So, I changed to separate handlers when
 337      * debugging a problem on OpenBSD, where SBCL wasn't catching
 338      * SIGILL properly, but was instead letting the process be
 339      * terminated with an "Illegal instruction" output. If this change
 340      * turns out to break something (maybe breakpoint handling on some
 341      * OS I haven't tested on?) and we have to go back to the old CMU
 342      * CL way, I hope there will at least be a comment to explain
 343      * why.. -- WHN 2001-06-07 */
 344 #if !defined(LISP_FEATURE_WIN32) && !defined(LISP_FEATURE_MACH_EXCEPTION_HANDLER)
 345     undoably_install_low_level_interrupt_handler(SIGILL , sigill_handler);
 346     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 347 #endif
 348     SHOW("returning from arch_install_interrupt_handlers()");
 349 }
 350 \f
 351 #ifdef LISP_FEATURE_LINKAGE_TABLE
 352 /* FIXME: It might be cleaner to generate these from the lisp side of
 353  * things.
 354  */
 355
 356 void
 357 arch_write_linkage_table_jmp(char * reloc, void * fun)
 358 {
 359     /* Make JMP to function entry. JMP offset is calculated from next
 360      * instruction.
 361      */
 362     long offset = (char *)fun - (reloc + 5);
 363     int i;
 364
 365     *reloc++ = 0xe9;            /* opcode for JMP rel32 */
 366     for (i = 0; i < 4; i++) {
 367         *reloc++ = offset & 0xff;
 368         offset >>= 8;
 369     }
 370
 371     /* write a nop for good measure. */
 372     *reloc = 0x90;
 373 }
 374
 375 void
 376 arch_write_linkage_table_ref(void * reloc, void * data)
 377 {
 378     *(unsigned long *)reloc = (unsigned long)data;
 379 }
 380
 381 #endif