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*)*os_context_pc_addr(context)) +=4; }
  91
  92 unsigned char *
  93 arch_internal_error_arguments(os_context_t *context)
  94 {
  95     return (unsigned char *)(*os_context_pc_addr(context)+4);
  96 }
  97
  98 boolean
  99 arch_pseudo_atomic_atomic(os_context_t *context)
 100 {
 101     /* FIXME: this foreign_function_call_active test is dubious at
 102      * best. If a foreign call is made in a pseudo atomic section
 103      * (?) or more likely a pseudo atomic section is in a foreign
 104      * call then an interrupt is executed immediately. Maybe it
 105      * has to do with C code not maintaining pseudo atomic
 106      * properly. MG - 2005-08-10
 107      *
 108      * The foreign_function_call_active used to live at each call-site
 109      * to arch_pseudo_atomic_atomic, but this seems clearer.
 110      * --NS 2007-05-15 */
 111     return (!foreign_function_call_active)
 112         && ((*os_context_register_addr(context,reg_ALLOC)) & 1);
 113 }
 114
 115 void arch_set_pseudo_atomic_interrupted(os_context_t *context)
 116 {
 117     /* On coming out of an atomic section, we subtract 1 from
 118      * reg_Alloc, then try to store something at that address.  So,
 119      * to signal that it was interrupted and a signal should be handled,
 120      * we set bit 63 of reg_ALLOC here so that the end-of-atomic code
 121      * will raise SIGSEGV (no ram mapped there).  We catch the signal
 122      * (see the appropriate *-os.c) and call interrupt_handle_pending()
 123      * for the saved signal instead */
 124
 125     *os_context_register_addr(context,reg_ALLOC) |=  (1L<<63);
 126 }
 127
 128 void arch_clear_pseudo_atomic_interrupted(os_context_t *context)
 129 {
 130     *os_context_register_addr(context, reg_ALLOC) &= ~(1L<<63);
 131 }
 132
 133 unsigned int arch_install_breakpoint(void *pc)
 134 {
 135     unsigned int *ptr = (unsigned int *)pc;
 136     unsigned int result = *ptr;
 137     *ptr = BREAKPOINT_INST;
 138
 139     os_flush_icache((os_vm_address_t)ptr, sizeof(unsigned int));
 140
 141     return result;
 142 }
 143
 144 void arch_remove_breakpoint(void *pc, unsigned int orig_inst)
 145 {
 146     unsigned int *ptr = (unsigned int *)pc;
 147     *ptr = orig_inst;
 148     os_flush_icache((os_vm_address_t)pc, sizeof(unsigned int));
 149 }
 150
 151 static unsigned int *skipped_break_addr, displaced_after_inst,
 152      after_breakpoint;
 153
 154
 155 /* This returns a PC value.  Lisp code is all in the 32-bit-addressable
 156  * space, so we should be ok with an unsigned int. */
 157 unsigned int
 158 emulate_branch(os_context_t *context, unsigned int orig_inst)
 159 {
 160     int op = orig_inst >> 26;
 161     int reg_a = (orig_inst >> 21) & 0x1f;
 162     int reg_b = (orig_inst >> 16) & 0x1f;
 163     int disp =
 164         (orig_inst&(1<<20)) ?
 165         orig_inst | (-1 << 21) :
 166         orig_inst&0x1fffff;
 167     int next_pc = *os_context_pc_addr(context);
 168     int branch = 0; /* was NULL;               */
 169
 170     switch(op) {
 171     case 0x1a: /* jmp, jsr, jsr_coroutine, ret */
 172         *os_context_register_addr(context,reg_a) =
 173             *os_context_pc_addr(context);
 174         *os_context_pc_addr(context) =
 175             *os_context_register_addr(context,reg_b)& ~3;
 176         break;
 177     case 0x30: /* br */
 178         *os_context_register_addr(context,reg_a)=*os_context_pc_addr(context);
 179         branch = 1;
 180         break;
 181     case 0x31: /* fbeq */
 182         if (*(os_context_float_register_addr(context,reg_a))==0) branch = 1;
 183         break;
 184     case 0x32: /* fblt */
 185         if (*os_context_float_register_addr(context,reg_a)<0) branch = 1;
 186         break;
 187     case 0x33: /* fble */
 188         if (*os_context_float_register_addr(context,reg_a)<=0) branch = 1;
 189         break;
 190     case 0x34: /* bsr */
 191         *os_context_register_addr(context,reg_a)=*os_context_pc_addr(context);
 192         branch = 1;
 193         break;
 194     case 0x35: /* fbne */
 195         if (*os_context_register_addr(context,reg_a)!=0) branch = 1;
 196         break;
 197     case 0x36: /* fbge */
 198         if (*os_context_float_register_addr(context,reg_a)>=0) branch = 1;
 199         break;
 200     case 0x37: /* fbgt */
 201         if (*os_context_float_register_addr(context,reg_a)>0) branch = 1;
 202         break;
 203     case 0x38: /* blbc */
 204         if ((*os_context_register_addr(context,reg_a)&1) == 0) branch = 1;
 205         break;
 206     case 0x39: /* beq */
 207         if (*os_context_register_addr(context,reg_a)==0) branch = 1;
 208         break;
 209     case 0x3a: /* blt */
 210         if (*os_context_register_addr(context,reg_a)<0) branch = 1;
 211         break;
 212     case 0x3b: /* ble */
 213         if (*os_context_register_addr(context,reg_a)<=0) branch = 1;
 214         break;
 215     case 0x3c: /* blbs */
 216         if ((*os_context_register_addr(context,reg_a)&1)!=0) branch = 1;
 217         break;
 218     case 0x3d: /* bne */
 219         if (*os_context_register_addr(context,reg_a)!=0) branch = 1;
 220         break;
 221     case 0x3e: /* bge */
 222         if (*os_context_register_addr(context,reg_a)>=0) branch = 1;
 223         break;
 224     case 0x3f: /* bgt */
 225         if (*os_context_register_addr(context,reg_a)>0) branch = 1;
 226         break;
 227     }
 228     if (branch)
 229         next_pc += disp*4;
 230     return next_pc;
 231 }
 232
 233 static sigset_t orig_sigmask;
 234
 235 /* Perform the instruction that we overwrote with a breakpoint.  As we
 236  * don't have a single-step facility, this means we have to:
 237  * - put the instruction back
 238  * - put a second breakpoint at the following instruction,
 239  *   set after_breakpoint and continue execution.
 240  *
 241  * When the second breakpoint is hit (very shortly thereafter, we hope)
 242  * sigtrap_handler gets called again, but follows the AfterBreakpoint
 243  * arm, which
 244  * - puts a bpt back in the first breakpoint place (running across a
 245  *   breakpoint shouldn't cause it to be uninstalled)
 246  * - replaces the second bpt with the instruction it was meant to be
 247  * - carries on
 248  *
 249  * Clear?
 250  */
 251
 252 void arch_do_displaced_inst(os_context_t *context,unsigned int orig_inst)
 253 {
 254     /* Apparent off-by-one errors ahoy.  If you consult the Alpha ARM,
 255      * it will tell you that after a BPT, the saved PC is the address
 256      * of the instruction _after_ the instruction that caused the trap.
 257      *
 258      * However, we decremented PC by 4 before calling the Lisp-level
 259      * handler that calls this routine (see alpha-arch.c line 322 and
 260      * friends) so when we get to this point PC is actually pointing
 261      * at the BPT instruction itself.  This is good, because this is
 262      * where we want to restart execution when we do that */
 263
 264     unsigned int *pc=(unsigned int *)(*os_context_pc_addr(context));
 265     unsigned int *next_pc;
 266     int op = orig_inst >> 26;;
 267
 268     orig_sigmask = *os_context_sigmask_addr(context);
 269     sigaddset_blockable(os_context_sigmask_addr(context));
 270
 271     /* Put the original instruction back. */
 272     *pc = orig_inst;
 273     os_flush_icache((os_vm_address_t)pc, sizeof(unsigned int));
 274     skipped_break_addr = pc;
 275
 276     /* Figure out where we will end up after running the displaced
 277      * instruction */
 278     if (op == 0x1a || (op&0xf) == 0x30) /* a branch */
 279         /* The cast to long is just to shut gcc up. */
 280         next_pc = (unsigned int *)((long)emulate_branch(context,orig_inst));
 281     else
 282         next_pc = pc+1;
 283
 284     /* Set the after breakpoint. */
 285     displaced_after_inst = *next_pc;
 286     *next_pc = BREAKPOINT_INST;
 287     after_breakpoint=1;
 288     os_flush_icache((os_vm_address_t)next_pc, sizeof(unsigned int));
 289 }
 290
 291 void
 292 arch_handle_breakpoint(os_context_t *context)
 293 {
 294         *os_context_pc_addr(context) -=4;
 295         handle_breakpoint(context);
 296 }
 297
 298 void
 299 arch_handle_fun_end_breakpoint(os_context_t *context)
 300 {
 301     *os_context_pc_addr(context) -=4;
 302     *os_context_pc_addr(context) =
 303         (int)handle_fun_end_breakpoint(context);
 304 }
 305
 306 static void
 307 sigtrap_handler(int signal, siginfo_t *siginfo, os_context_t *context)
 308 {
 309     unsigned int code;
 310 #ifdef LISP_FEATURE_LINUX
 311     os_restore_fp_control(context);
 312 #endif
 313
 314     /* this is different from how CMUCL does it.  CMUCL used "call_pal
 315      * PAL_gentrap", which doesn't do anything on Linux (unless NL0
 316      * contains certain specific values).  We use "bugchk" instead.
 317      * It's (for our purposes) just the same as bpt but has a
 318      * different opcode so we can test whether we're dealing with a
 319      * breakpoint or a "system service" */
 320
 321     if ((*(unsigned int*)(*os_context_pc_addr(context)-4))==BREAKPOINT_INST) {
 322         if (after_breakpoint) {
 323             /* see comments above arch_do_displaced_inst.  This is where
 324              * we reinsert the breakpoint that we removed earlier */
 325
 326             *os_context_pc_addr(context) -=4;
 327             *skipped_break_addr = BREAKPOINT_INST;
 328             os_flush_icache((os_vm_address_t)skipped_break_addr,
 329                             sizeof(unsigned int));
 330             skipped_break_addr = NULL;
 331             *(unsigned int *)*os_context_pc_addr(context) =
 332                 displaced_after_inst;
 333             os_flush_icache((os_vm_address_t)*os_context_pc_addr(context), sizeof(unsigned int));
 334             *os_context_sigmask_addr(context)= orig_sigmask;
 335             after_breakpoint=0; /* false */
 336             return;
 337         } else
 338             code = trap_Breakpoint;
 339     } else
 340         /* a "system service" */
 341     code=*((u32 *)(*os_context_pc_addr(context)));
 342     handle_trap(context, code);
 343 }
 344
 345 unsigned long
 346 arch_get_fp_control()
 347 {
 348     return ieee_get_fp_control();
 349 }
 350
 351 void
 352 arch_set_fp_control(unsigned long fp)
 353 {
 354     ieee_set_fp_control(fp);
 355 }
 356
 357
 358 void arch_install_interrupt_handlers()
 359 {
 360     undoably_install_low_level_interrupt_handler(SIGTRAP, sigtrap_handler);
 361 }