src/runtime/alpha-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 /* Note that although superficially it appears that we use
  13  * os_context_t like we ought to, we actually just assume its a
  14  * ucontext in places.  Naughty */
  15
  16 #include <stdio.h>
  17 #include <string.h>
  18
  19 #include "sbcl.h"
  20 #include "runtime.h"
  21 #include "globals.h"
  22 #include "validate.h"
  23 #include "os.h"
  24 #include "arch.h"
  25 #include "lispregs.h"
  26 #include "signal.h"
  27 #include "alloc.h"
  28 #include "interrupt.h"
  29 #include "interr.h"
  30 #include "breakpoint.h"
  31
  32 extern char call_into_lisp_LRA[], call_into_lisp_end[];
  33
  34 extern size_t os_vm_page_size;
  35 #define BREAKPOINT_INST 0x80
  36
  37
  38 void
  39 arch_init(void)
  40 {
  41     /* This must be called _after_ os_init(), so that we know what the
  42      * page size is. */
  43
  44     if (mmap((os_vm_address_t) call_into_lisp_LRA_page,os_vm_page_size,
  45              OS_VM_PROT_ALL,MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,-1,0)
  46         == (os_vm_address_t) -1)
  47         perror("mmap");
  48
  49     /* call_into_lisp_LRA is a collection of trampolines written in asm -
  50      * see alpha-assem.S.  We copy it to call_into_lisp_LRA_page where
  51      * VOPs and things can find it. (I don't know why they can't find it
  52      * where it was to start with.) */
  53     bcopy(call_into_lisp_LRA,(void *)call_into_lisp_LRA_page,os_vm_page_size);
  54
  55     os_flush_icache((os_vm_address_t)call_into_lisp_LRA_page,
  56                     os_vm_page_size);
  57     return;
  58 }
  59
  60 os_vm_address_t
  61 arch_get_bad_addr (int sig, siginfo_t *code, os_context_t *context)
  62 {
  63     unsigned int badinst;
  64
  65     /* Instructions are 32 bit quantities. */
  66     unsigned int *pc ;
  67     /*  fprintf(stderr,"arch_get_bad_addr %d %p %p\n",
  68         sig, code, context); */
  69     pc= (unsigned int *)(*os_context_pc_addr(context));
  70
  71     if (((unsigned long)pc) & 3) {
  72         return NULL;            /* In what case would pc be unaligned?? */
  73     }
  74
  75     if ( (pc < READ_ONLY_SPACE_START ||
  76           pc >= READ_ONLY_SPACE_START+READ_ONLY_SPACE_SIZE) &&
  77          (pc < current_dynamic_space ||
  78           pc >= current_dynamic_space + dynamic_space_size))
  79         return NULL;
  80
  81     return context->uc_mcontext.sc_traparg_a0;
  82 }
  83
  84 void
  85 arch_skip_instruction(os_context_t *context)
  86 {
  87     /* This may be complete rubbish, as (at least for traps) pc points
  88      * _after_ the instruction that caused us to be here anyway.
  89      */
  90     char **pcptr;
  91     pcptr = (char **) os_context_pc_addr(context);
  92     *pcptr += 4;
  93 }
  94
  95 unsigned char *
  96 arch_internal_error_arguments(os_context_t *context)
  97 {
  98     return (unsigned char *)(*os_context_pc_addr(context)+4);
  99 }
 100
 101 boolean
 102 arch_pseudo_atomic_atomic(os_context_t *context)
 103 {
 104     /* FIXME: this foreign_function_call_active test is dubious at
 105      * best. If a foreign call is made in a pseudo atomic section
 106      * (?) or more likely a pseudo atomic section is in a foreign
 107      * call then an interrupt is executed immediately. Maybe it
 108      * has to do with C code not maintaining pseudo atomic
 109      * properly. MG - 2005-08-10
 110      *
 111      * The foreign_function_call_active used to live at each call-site
 112      * to arch_pseudo_atomic_atomic, but this seems clearer.
 113      * --NS 2007-05-15 */
 114     return (!foreign_function_call_active)
 115         && ((*os_context_register_addr(context,reg_ALLOC)) & 1);
 116 }
 117
 118 void arch_set_pseudo_atomic_interrupted(os_context_t *context)
 119 {
 120     /* On coming out of an atomic section, we subtract 1 from
 121      * reg_Alloc, then try to store something at that address.  So,
 122      * to signal that it was interrupted and a signal should be handled,
 123      * we set bit 63 of reg_ALLOC here so that the end-of-atomic code
 124      * will raise SIGSEGV (no ram mapped there).  We catch the signal
 125      * (see the appropriate *-os.c) and call interrupt_handle_pending()
 126      * for the saved signal instead */
 127
 128     *os_context_register_addr(context,reg_ALLOC) |=  (1L<<63);
 129 }
 130
 131 void arch_clear_pseudo_atomic_interrupted(os_context_t *context)
 132 {
 133     *os_context_register_addr(context, reg_ALLOC) &= ~(1L<<63);
 134 }
 135
 136 unsigned int arch_install_breakpoint(void *pc)
 137 {
 138     unsigned int *ptr = (unsigned int *)pc;
 139     unsigned int result = *ptr;
 140     *ptr = BREAKPOINT_INST;
 141
 142     os_flush_icache((os_vm_address_t)ptr, sizeof(unsigned int));
 143
 144     return result;
 145 }
 146
 147 void arch_remove_breakpoint(void *pc, unsigned int orig_inst)
 148 {
 149     unsigned int *ptr = (unsigned int *)pc;
 150     *ptr = orig_inst;
 151     os_flush_icache((os_vm_address_t)pc, sizeof(unsigned int));
 152 }
 153
 154 static unsigned int *skipped_break_addr, displaced_after_inst,
 155      after_breakpoint;
 156
 157
 158 /* This returns a PC value.  Lisp code is all in the 32-bit-addressable
 159  * space, so we should be ok with an unsigned int. */
 160 unsigned int
 161 emulate_branch(os_context_t *context, unsigned int orig_inst)
 162 {
 163     int op = orig_inst >> 26;
 164     int reg_a = (orig_inst >> 21) & 0x1f;
 165     int reg_b = (orig_inst >> 16) & 0x1f;
 166     int disp =
 167         (orig_inst&(1<<20)) ?
 168         orig_inst | (-1 << 21) :
 169         orig_inst&0x1fffff;
 170     int next_pc = *os_context_pc_addr(context);
 171     int branch = 0; /* was NULL;               */
 172
 173     switch(op) {
 174     case 0x1a: /* jmp, jsr, jsr_coroutine, ret */
 175         *os_context_register_addr(context,reg_a) =
 176             *os_context_pc_addr(context);
 177         *os_context_pc_addr(context) =
 178             *os_context_register_addr(context,reg_b)& ~3;
 179         break;
 180     case 0x30: /* br */
 181         *os_context_register_addr(context,reg_a)=*os_context_pc_addr(context);
 182         branch = 1;
 183         break;
 184     case 0x31: /* fbeq */
 185         if (*(os_context_float_register_addr(context,reg_a))==0) branch = 1;
 186         break;
 187     case 0x32: /* fblt */
 188         if (*os_context_float_register_addr(context,reg_a)<0) branch = 1;
 189         break;
 190     case 0x33: /* fble */
 191         if (*os_context_float_register_addr(context,reg_a)<=0) branch = 1;
 192         break;
 193     case 0x34: /* bsr */
 194         *os_context_register_addr(context,reg_a)=*os_context_pc_addr(context);
 195         branch = 1;
 196         break;
 197     case 0x35: /* fbne */
 198         if (*os_context_register_addr(context,reg_a)!=0) branch = 1;
 199         break;
 200     case 0x36: /* fbge */
 201         if (*os_context_float_register_addr(context,reg_a)>=0) branch = 1;
 202         break;
 203     case 0x37: /* fbgt */
 204         if (*os_context_float_register_addr(context,reg_a)>0) branch = 1;
 205         break;
 206     case 0x38: /* blbc */
 207         if ((*os_context_register_addr(context,reg_a)&1) == 0) branch = 1;
 208         break;
 209     case 0x39: /* beq */
 210         if (*os_context_register_addr(context,reg_a)==0) branch = 1;
 211         break;
 212     case 0x3a: /* blt */
 213         if (*os_context_register_addr(context,reg_a)<0) branch = 1;
 214         break;
 215     case 0x3b: /* ble */
 216         if (*os_context_register_addr(context,reg_a)<=0) branch = 1;
 217         break;
 218     case 0x3c: /* blbs */
 219         if ((*os_context_register_addr(context,reg_a)&1)!=0) branch = 1;
 220         break;
 221     case 0x3d: /* bne */
 222         if (*os_context_register_addr(context,reg_a)!=0) branch = 1;
 223         break;
 224     case 0x3e: /* bge */
 225         if (*os_context_register_addr(context,reg_a)>=0) branch = 1;
 226         break;
 227     case 0x3f: /* bgt */
 228         if (*os_context_register_addr(context,reg_a)>0) branch = 1;
 229         break;
 230     }
 231     if (branch)
 232         next_pc += disp*4;
 233     return next_pc;
 234 }
 235
 236 static sigset_t orig_sigmask;
 237
 238 /* Perform the instruction that we overwrote with a breakpoint.  As we
 239  * don't have a single-step facility, this means we have to:
 240  * - put the instruction back
 241  * - put a second breakpoint at the following instruction,
 242  *   set after_breakpoint and continue execution.
 243  *
 244  * When the second breakpoint is hit (very shortly thereafter, we hope)
 245  * sigtrap_handler gets called again, but follows the AfterBreakpoint
 246  * arm, which
 247  * - puts a bpt back in the first breakpoint place (running across a
 248  *   breakpoint shouldn't cause it to be uninstalled)
 249  * - replaces the second bpt with the instruction it was meant to be
 250  * - carries on
 251  *
 252  * Clear?
 253  */
 254
 255 void arch_do_displaced_inst(os_context_t *context,unsigned int orig_inst)
 256 {
 257     /* Apparent off-by-one errors ahoy.  If you consult the Alpha ARM,
 258      * it will tell you that after a BPT, the saved PC is the address
 259      * of the instruction _after_ the instruction that caused the trap.
 260      *
 261      * However, we decremented PC by 4 before calling the Lisp-level
 262      * handler that calls this routine (see alpha-arch.c line 322 and
 263      * friends) so when we get to this point PC is actually pointing
 264      * at the BPT instruction itself.  This is good, because this is
 265      * where we want to restart execution when we do that */
 266
 267     unsigned int *pc=(unsigned int *)(*os_context_pc_addr(context));
 268     unsigned int *next_pc;
 269     int op = orig_inst >> 26;;
 270
 271     orig_sigmask = *os_context_sigmask_addr(context);
 272     sigaddset_blockable(os_context_sigmask_addr(context));
 273
 274     /* Put the original instruction back. */
 275     *pc = orig_inst;
 276     os_flush_icache((os_vm_address_t)pc, sizeof(unsigned int));
 277     skipped_break_addr = pc;
 278
 279     /* Figure out where we will end up after running the displaced
 280      * instruction */
 281     if (op == 0x1a || (op&0xf) == 0x30) /* a branch */
 282         /* The cast to long is just to shut gcc up. */
 283         next_pc = (unsigned int *)((long)emulate_branch(context,orig_inst));
 284     else
 285         next_pc = pc+1;
 286
 287     /* Set the after breakpoint. */
 288     displaced_after_inst = *next_pc;
 289     *next_pc = BREAKPOINT_INST;
 290     after_breakpoint=1;
 291     os_flush_icache((os_vm_address_t)next_pc, sizeof(unsigned int));
 292 }
 293
 294 void
 295 arch_handle_breakpoint(os_context_t *context)
 296 {
 297         *os_context_pc_addr(context) -=4;
 298         handle_breakpoint(context);
 299 }
 300
 301 void
 302 arch_handle_fun_end_breakpoint(os_context_t *context)
 303 {
 304     *os_context_pc_addr(context) -=4;
 305     *os_context_pc_addr(context) =
 306         (int)handle_fun_end_breakpoint(context);
 307 }
 308
 309 void
 310 arch_handle_single_step_trap(os_context_t *context, int trap)
 311 {
 312     unsigned int code = *((u32 *) (*os_context_pc_addr(context)));
 313     int register_offset = code >> 5 & 0x1f;
 314     handle_single_step_trap(context, trap, register_offset);
 315     arch_skip_instruction(context);
 316 }
 317
 318 static void
 319 sigtrap_handler(int signal, siginfo_t *siginfo, os_context_t *context)
 320 {
 321     unsigned int code;
 322
 323     /* this is different from how CMUCL does it.  CMUCL used "call_pal
 324      * PAL_gentrap", which doesn't do anything on Linux (unless NL0
 325      * contains certain specific values).  We use "bugchk" instead.
 326      * It's (for our purposes) just the same as bpt but has a
 327      * different opcode so we can test whether we're dealing with a
 328      * breakpoint or a "system service" */
 329
 330     if ((*(unsigned int*)(*os_context_pc_addr(context)-4))==BREAKPOINT_INST) {
 331         if (after_breakpoint) {
 332             /* see comments above arch_do_displaced_inst.  This is where
 333              * we reinsert the breakpoint that we removed earlier */
 334
 335             *os_context_pc_addr(context) -=4;
 336             *skipped_break_addr = BREAKPOINT_INST;
 337             os_flush_icache((os_vm_address_t)skipped_break_addr,
 338                             sizeof(unsigned int));
 339             skipped_break_addr = NULL;
 340             *(unsigned int *)*os_context_pc_addr(context) =
 341                 displaced_after_inst;
 342             os_flush_icache((os_vm_address_t)*os_context_pc_addr(context), sizeof(unsigned int));
 343             *os_context_sigmask_addr(context)= orig_sigmask;
 344             after_breakpoint=0; /* false */
 345             return;
 346         } else
 347             code = trap_Breakpoint;
 348     } else
 349         /* a "system service" */
 350     code=*((u32 *)(*os_context_pc_addr(context)));
 351     handle_trap(context, code);
 352 }
 353
 354 unsigned long
 355 arch_get_fp_control()
 356 {
 357     return ieee_get_fp_control();
 358 }
 359
 360 void
 361 arch_set_fp_control(unsigned long fp)
 362 {
 363     ieee_set_fp_control(fp);
 364 }
 365
 366
 367 void arch_install_interrupt_handlers()
 368 {
 369     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 370 }