The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/db_trace.c

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    1 /*-
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  *
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  *
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  *
   16  * Carnegie Mellon requests users of this software to return to
   17  *
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  *
   23  * any improvements or extensions that they make and grant Carnegie the
   24  * rights to redistribute these changes.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/kdb.h>
   33 #include <sys/proc.h>
   34 #include <sys/sysent.h>
   35 
   36 #include <machine/cpu.h>
   37 #include <machine/frame.h>
   38 #include <machine/md_var.h>
   39 #include <machine/pcb.h>
   40 #include <machine/reg.h>
   41 #include <machine/stack.h>
   42 
   43 #include <vm/vm.h>
   44 #include <vm/vm_param.h>
   45 #include <vm/pmap.h>
   46 
   47 #include <ddb/ddb.h>
   48 #include <ddb/db_access.h>
   49 #include <ddb/db_sym.h>
   50 #include <ddb/db_variables.h>
   51 
   52 static db_varfcn_t db_esp;
   53 static db_varfcn_t db_frame;
   54 static db_varfcn_t db_frame_seg;
   55 static db_varfcn_t db_gs;
   56 static db_varfcn_t db_ss;
   57 
   58 /*
   59  * Machine register set.
   60  */
   61 #define DB_OFFSET(x)    (db_expr_t *)offsetof(struct trapframe, x)
   62 struct db_variable db_regs[] = {
   63         { "cs",         DB_OFFSET(tf_cs),       db_frame_seg },
   64         { "ds",         DB_OFFSET(tf_ds),       db_frame_seg },
   65         { "es",         DB_OFFSET(tf_es),       db_frame_seg },
   66         { "fs",         DB_OFFSET(tf_fs),       db_frame_seg },
   67         { "gs",         NULL,                   db_gs },
   68         { "ss",         NULL,                   db_ss },
   69         { "eax",        DB_OFFSET(tf_eax),      db_frame },
   70         { "ecx",        DB_OFFSET(tf_ecx),      db_frame },
   71         { "edx",        DB_OFFSET(tf_edx),      db_frame },
   72         { "ebx",        DB_OFFSET(tf_ebx),      db_frame },
   73         { "esp",        NULL,                   db_esp },
   74         { "ebp",        DB_OFFSET(tf_ebp),      db_frame },
   75         { "esi",        DB_OFFSET(tf_esi),      db_frame },
   76         { "edi",        DB_OFFSET(tf_edi),      db_frame },
   77         { "eip",        DB_OFFSET(tf_eip),      db_frame },
   78         { "efl",        DB_OFFSET(tf_eflags),   db_frame },
   79 };
   80 struct db_variable *db_eregs = db_regs + nitems(db_regs);
   81 
   82 static __inline int
   83 get_esp(struct trapframe *tf)
   84 {
   85         return (TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp);
   86 }
   87 
   88 static int
   89 db_frame(struct db_variable *vp, db_expr_t *valuep, int op)
   90 {
   91         int *reg;
   92 
   93         if (kdb_frame == NULL)
   94                 return (0);
   95 
   96         reg = (int *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep);
   97         if (op == DB_VAR_GET)
   98                 *valuep = *reg;
   99         else
  100                 *reg = *valuep;
  101         return (1);
  102 }
  103 
  104 static int
  105 db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op)
  106 {
  107         struct trapframe_vm86 *tfp;
  108         int off;
  109         uint16_t *reg;
  110 
  111         if (kdb_frame == NULL)
  112                 return (0);
  113 
  114         off = (intptr_t)vp->valuep;
  115         if (kdb_frame->tf_eflags & PSL_VM) {
  116                 tfp = (void *)kdb_frame;
  117                 switch ((intptr_t)vp->valuep) {
  118                 case (intptr_t)DB_OFFSET(tf_cs):
  119                         reg = (uint16_t *)&tfp->tf_cs;
  120                         break;
  121                 case (intptr_t)DB_OFFSET(tf_ds):
  122                         reg = (uint16_t *)&tfp->tf_vm86_ds;
  123                         break;
  124                 case (intptr_t)DB_OFFSET(tf_es):
  125                         reg = (uint16_t *)&tfp->tf_vm86_es;
  126                         break;
  127                 case (intptr_t)DB_OFFSET(tf_fs):
  128                         reg = (uint16_t *)&tfp->tf_vm86_fs;
  129                         break;
  130                 }
  131         } else
  132                 reg = (uint16_t *)((uintptr_t)kdb_frame + off);
  133         if (op == DB_VAR_GET)
  134                 *valuep = *reg;
  135         else
  136                 *reg = *valuep;
  137         return (1);
  138 }
  139 
  140 static int
  141 db_esp(struct db_variable *vp, db_expr_t *valuep, int op)
  142 {
  143 
  144         if (kdb_frame == NULL)
  145                 return (0);
  146 
  147         if (op == DB_VAR_GET)
  148                 *valuep = get_esp(kdb_frame);
  149         else if (TF_HAS_STACKREGS(kdb_frame))
  150                 kdb_frame->tf_esp = *valuep;
  151         return (1);
  152 }
  153 
  154 static int
  155 db_gs(struct db_variable *vp, db_expr_t *valuep, int op)
  156 {
  157         struct trapframe_vm86 *tfp;
  158 
  159         if (kdb_frame != NULL && kdb_frame->tf_eflags & PSL_VM) {
  160                 tfp = (void *)kdb_frame;
  161                 if (op == DB_VAR_GET)
  162                         *valuep = tfp->tf_vm86_gs;
  163                 else
  164                         tfp->tf_vm86_gs = *valuep;
  165                 return (1);
  166         }
  167         if (op == DB_VAR_GET)
  168                 *valuep = rgs();
  169         else
  170                 load_gs(*valuep);
  171         return (1);
  172 }
  173 
  174 static int
  175 db_ss(struct db_variable *vp, db_expr_t *valuep, int op)
  176 {
  177 
  178         if (kdb_frame == NULL)
  179                 return (0);
  180 
  181         if (op == DB_VAR_GET)
  182                 *valuep = TF_HAS_STACKREGS(kdb_frame) ? kdb_frame->tf_ss :
  183                     rss();
  184         else if (TF_HAS_STACKREGS(kdb_frame))
  185                 kdb_frame->tf_ss = *valuep;
  186         return (1);
  187 }
  188 
  189 #define NORMAL          0
  190 #define TRAP            1
  191 #define INTERRUPT       2
  192 #define SYSCALL         3
  193 #define DOUBLE_FAULT    4
  194 
  195 static void db_nextframe(struct i386_frame **, db_addr_t *, struct thread *);
  196 static int db_numargs(struct i386_frame *);
  197 static void db_print_stack_entry(const char *, int, char **, int *, db_addr_t,
  198     void *);
  199 static void decode_syscall(int, struct thread *);
  200 
  201 static const char * watchtype_str(int type);
  202 int  i386_set_watch(int watchnum, unsigned int watchaddr, int size, int access,
  203                     struct dbreg *d);
  204 int  i386_clr_watch(int watchnum, struct dbreg *d);
  205 
  206 /*
  207  * Figure out how many arguments were passed into the frame at "fp".
  208  */
  209 static int
  210 db_numargs(fp)
  211         struct i386_frame *fp;
  212 {
  213         char   *argp;
  214         int     inst;
  215         int     args;
  216 
  217         argp = (char *)db_get_value((int)&fp->f_retaddr, 4, false);
  218         /*
  219          * XXX etext is wrong for LKMs.  We should attempt to interpret
  220          * the instruction at the return address in all cases.  This
  221          * may require better fault handling.
  222          */
  223         if (argp < btext || argp >= etext) {
  224                 args = -1;
  225         } else {
  226 retry:
  227                 inst = db_get_value((int)argp, 4, false);
  228                 if ((inst & 0xff) == 0x59)      /* popl %ecx */
  229                         args = 1;
  230                 else if ((inst & 0xffff) == 0xc483)     /* addl $Ibs, %esp */
  231                         args = ((inst >> 16) & 0xff) / 4;
  232                 else if ((inst & 0xf8ff) == 0xc089) {   /* movl %eax, %Reg */
  233                         argp += 2;
  234                         goto retry;
  235                 } else
  236                         args = -1;
  237         }
  238         return (args);
  239 }
  240 
  241 static void
  242 db_print_stack_entry(name, narg, argnp, argp, callpc, frame)
  243         const char *name;
  244         int narg;
  245         char **argnp;
  246         int *argp;
  247         db_addr_t callpc;
  248         void *frame;
  249 {
  250         int n = narg >= 0 ? narg : 5;
  251 
  252         db_printf("%s(", name);
  253         while (n) {
  254                 if (argnp)
  255                         db_printf("%s=", *argnp++);
  256                 db_printf("%r", db_get_value((int)argp, 4, false));
  257                 argp++;
  258                 if (--n != 0)
  259                         db_printf(",");
  260         }
  261         if (narg < 0)
  262                 db_printf(",...");
  263         db_printf(") at ");
  264         db_printsym(callpc, DB_STGY_PROC);
  265         if (frame != NULL)
  266                 db_printf("/frame 0x%r", (register_t)frame);
  267         db_printf("\n");
  268 }
  269 
  270 static void
  271 decode_syscall(int number, struct thread *td)
  272 {
  273         struct proc *p;
  274         c_db_sym_t sym;
  275         db_expr_t diff;
  276         sy_call_t *f;
  277         const char *symname;
  278 
  279         db_printf(" (%d", number);
  280         p = (td != NULL) ? td->td_proc : NULL;
  281         if (p != NULL && 0 <= number && number < p->p_sysent->sv_size) {
  282                 f = p->p_sysent->sv_table[number].sy_call;
  283                 sym = db_search_symbol((db_addr_t)f, DB_STGY_ANY, &diff);
  284                 if (sym != DB_SYM_NULL && diff == 0) {
  285                         db_symbol_values(sym, &symname, NULL);
  286                         db_printf(", %s, %s", p->p_sysent->sv_name, symname);
  287                 }
  288         }
  289         db_printf(")");
  290 }
  291 
  292 /*
  293  * Figure out the next frame up in the call stack.
  294  */
  295 static void
  296 db_nextframe(struct i386_frame **fp, db_addr_t *ip, struct thread *td)
  297 {
  298         struct trapframe *tf;
  299         int frame_type;
  300         int narg;
  301         int eip, esp, ebp;
  302         db_expr_t offset;
  303         c_db_sym_t sym;
  304         const char *name;
  305 
  306         eip = db_get_value((int) &(*fp)->f_retaddr, 4, false);
  307         ebp = db_get_value((int) &(*fp)->f_frame, 4, false);
  308 
  309         /*
  310          * Figure out frame type.  We look at the address just before
  311          * the saved instruction pointer as the saved EIP is after the
  312          * call function, and if the function being called is marked as
  313          * dead (such as panic() at the end of dblfault_handler()), then
  314          * the instruction at the saved EIP will be part of a different
  315          * function (syscall() in this example) rather than the one that
  316          * actually made the call.
  317          */
  318         frame_type = NORMAL;
  319 
  320         /*
  321          * This is the number of arguments that a syscall / trap / interrupt
  322          * service routine passes to its callee.  This number is used only for
  323          * special frame types.  In most cases there is one argument: the trap
  324          * frame address.
  325          */
  326         narg = 1;
  327 
  328         if (eip >= PMAP_TRM_MIN_ADDRESS) {
  329                 sym = db_search_symbol(eip - 1 - setidt_disp, DB_STGY_ANY,
  330                     &offset);
  331         } else {
  332                 sym = db_search_symbol(eip - 1, DB_STGY_ANY, &offset);
  333         }
  334         db_symbol_values(sym, &name, NULL);
  335         if (name != NULL) {
  336                 if (strcmp(name, "calltrap") == 0 ||
  337                     strcmp(name, "fork_trampoline") == 0)
  338                         frame_type = TRAP;
  339                 else if (strncmp(name, "Xatpic_intr", 11) == 0 ||
  340                     strncmp(name, "Xapic_isr", 9) == 0) {
  341                         /* Additional argument: vector number. */
  342                         narg = 2;
  343                         frame_type = INTERRUPT;
  344                 } else if (strcmp(name, "Xlcall_syscall") == 0 ||
  345                     strcmp(name, "Xint0x80_syscall") == 0)
  346                         frame_type = SYSCALL;
  347                 else if (strcmp(name, "dblfault_handler") == 0)
  348                         frame_type = DOUBLE_FAULT;
  349                 else if (strcmp(name, "Xtimerint") == 0 ||
  350                     strcmp(name, "Xxen_intr_upcall") == 0)
  351                         frame_type = INTERRUPT;
  352                 else if (strcmp(name, "Xcpustop") == 0 ||
  353                     strcmp(name, "Xrendezvous") == 0 ||
  354                     strcmp(name, "Xipi_intr_bitmap_handler") == 0) {
  355                         /* No arguments. */
  356                         narg = 0;
  357                         frame_type = INTERRUPT;
  358                 }
  359         }
  360 
  361         /*
  362          * Normal frames need no special processing.
  363          */
  364         if (frame_type == NORMAL) {
  365                 *ip = (db_addr_t) eip;
  366                 *fp = (struct i386_frame *) ebp;
  367                 return;
  368         }
  369 
  370         db_print_stack_entry(name, 0, 0, 0, eip, &(*fp)->f_frame);
  371 
  372         /*
  373          * For a double fault, we have to snag the values from the
  374          * previous TSS since a double fault uses a task gate to
  375          * switch to a known good state.
  376          */
  377         if (frame_type == DOUBLE_FAULT) {
  378                 esp = PCPU_GET(common_tssp)->tss_esp;
  379                 eip = PCPU_GET(common_tssp)->tss_eip;
  380                 ebp = PCPU_GET(common_tssp)->tss_ebp;
  381                 db_printf(
  382                     "--- trap 0x17, eip = %#r, esp = %#r, ebp = %#r ---\n",
  383                     eip, esp, ebp);
  384                 *ip = (db_addr_t) eip;
  385                 *fp = (struct i386_frame *) ebp;
  386                 return;
  387         }
  388 
  389         /*
  390          * Point to base of trapframe which is just above the
  391          * current frame.  Note that struct i386_frame already accounts for one
  392          * argument.
  393          */
  394         tf = (struct trapframe *)((char *)*fp + sizeof(struct i386_frame) +
  395             4 * (narg - 1));
  396 
  397         esp = get_esp(tf);
  398         eip = tf->tf_eip;
  399         ebp = tf->tf_ebp;
  400         switch (frame_type) {
  401         case TRAP:
  402                 db_printf("--- trap %#r", tf->tf_trapno);
  403                 break;
  404         case SYSCALL:
  405                 db_printf("--- syscall");
  406                 decode_syscall(tf->tf_eax, td);
  407                 break;
  408         case INTERRUPT:
  409                 db_printf("--- interrupt");
  410                 break;
  411         default:
  412                 panic("The moon has moved again.");
  413         }
  414         db_printf(", eip = %#r, esp = %#r, ebp = %#r ---\n", eip, esp, ebp);
  415 
  416         switch (frame_type) {
  417         case TRAP:
  418         case INTERRUPT:
  419                 if ((tf->tf_eflags & PSL_VM) != 0 ||
  420                     (tf->tf_cs & SEL_RPL_MASK) != 0)
  421                         ebp = 0;
  422                 break;
  423         case SYSCALL:
  424                 ebp = 0;
  425                 break;
  426         }
  427 
  428         *ip = (db_addr_t) eip;
  429         *fp = (struct i386_frame *) ebp;
  430 }
  431 
  432 static int
  433 db_backtrace(struct thread *td, struct trapframe *tf, struct i386_frame *frame,
  434     db_addr_t pc, register_t sp, int count)
  435 {
  436         struct i386_frame *actframe;
  437 #define MAXNARG 16
  438         char *argnames[MAXNARG], **argnp = NULL;
  439         const char *name;
  440         int *argp;
  441         db_expr_t offset;
  442         c_db_sym_t sym;
  443         int instr, narg;
  444         bool first;
  445 
  446         if (db_segsize(tf) == 16) {
  447                 db_printf(
  448 "--- 16-bit%s, cs:eip = %#x:%#x, ss:esp = %#x:%#x, ebp = %#x, tf = %p ---\n",
  449                     (tf->tf_eflags & PSL_VM) ? " (vm86)" : "",
  450                     tf->tf_cs, tf->tf_eip,
  451                     TF_HAS_STACKREGS(tf) ? tf->tf_ss : rss(),
  452                     TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp,
  453                     tf->tf_ebp, tf);
  454                 return (0);
  455         }
  456 
  457         /* 'frame' can be null initially.  Just print the pc then. */
  458         if (frame == NULL)
  459                 goto out;
  460 
  461         /*
  462          * If an indirect call via an invalid pointer caused a trap,
  463          * %pc contains the invalid address while the return address
  464          * of the unlucky caller has been saved by CPU on the stack
  465          * just before the trap frame.  In this case, try to recover
  466          * the caller's address so that the first frame is assigned
  467          * to the right spot in the right function, for that is where
  468          * the failure actually happened.
  469          *
  470          * This trick depends on the fault address stashed in tf_err
  471          * by trap_fatal() before entering KDB.
  472          */
  473         if (kdb_frame && pc == kdb_frame->tf_err) {
  474                 /*
  475                  * Find where the trap frame actually ends.
  476                  * It won't contain tf_esp or tf_ss unless crossing rings.
  477                  */
  478                 if (TF_HAS_STACKREGS(kdb_frame))
  479                         instr = (int)(kdb_frame + 1);
  480                 else
  481                         instr = (int)&kdb_frame->tf_esp;
  482                 pc = db_get_value(instr, 4, false);
  483         }
  484 
  485         if (count == -1)
  486                 count = 1024;
  487 
  488         first = true;
  489         while (count-- && !db_pager_quit) {
  490                 sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
  491                 db_symbol_values(sym, &name, NULL);
  492 
  493                 /*
  494                  * Attempt to determine a (possibly fake) frame that gives
  495                  * the caller's pc.  It may differ from `frame' if the
  496                  * current function never sets up a standard frame or hasn't
  497                  * set one up yet or has just discarded one.  The last two
  498                  * cases can be guessed fairly reliably for code generated
  499                  * by gcc.  The first case is too much trouble to handle in
  500                  * general because the amount of junk on the stack depends
  501                  * on the pc (the special handling of "calltrap", etc. in
  502                  * db_nextframe() works because the `next' pc is special).
  503                  */
  504                 actframe = frame;
  505                 if (first) {
  506                         first = false;
  507                         if (sym == C_DB_SYM_NULL && sp != 0) {
  508                                 /*
  509                                  * If a symbol couldn't be found, we've probably
  510                                  * jumped to a bogus location, so try and use
  511                                  * the return address to find our caller.
  512                                  */
  513                                 db_print_stack_entry(name, 0, 0, 0, pc,
  514                                     NULL);
  515                                 pc = db_get_value(sp, 4, false);
  516                                 if (db_search_symbol(pc, DB_STGY_PROC,
  517                                     &offset) == C_DB_SYM_NULL)
  518                                         break;
  519                                 continue;
  520                         } else if (tf != NULL) {
  521                                 instr = db_get_value(pc, 4, false);
  522                                 if ((instr & 0xffffff) == 0x00e58955) {
  523                                         /* pushl %ebp; movl %esp, %ebp */
  524                                         actframe = (void *)(get_esp(tf) - 4);
  525                                 } else if ((instr & 0xffff) == 0x0000e589) {
  526                                         /* movl %esp, %ebp */
  527                                         actframe = (void *)get_esp(tf);
  528                                         if (tf->tf_ebp == 0) {
  529                                                 /* Fake frame better. */
  530                                                 frame = actframe;
  531                                         }
  532                                 } else if ((instr & 0xff) == 0x000000c3) {
  533                                         /* ret */
  534                                         actframe = (void *)(get_esp(tf) - 4);
  535                                 } else if (offset == 0) {
  536                                         /* Probably an assembler symbol. */
  537                                         actframe = (void *)(get_esp(tf) - 4);
  538                                 }
  539                         } else if (strcmp(name, "fork_trampoline") == 0) {
  540                                 /*
  541                                  * Don't try to walk back on a stack for a
  542                                  * process that hasn't actually been run yet.
  543                                  */
  544                                 db_print_stack_entry(name, 0, 0, 0, pc,
  545                                     actframe);
  546                                 break;
  547                         }
  548                 }
  549 
  550                 argp = &actframe->f_arg0;
  551                 narg = MAXNARG;
  552                 if (sym != NULL && db_sym_numargs(sym, &narg, argnames)) {
  553                         argnp = argnames;
  554                 } else {
  555                         narg = db_numargs(frame);
  556                 }
  557 
  558                 db_print_stack_entry(name, narg, argnp, argp, pc, actframe);
  559 
  560                 if (actframe != frame) {
  561                         /* `frame' belongs to caller. */
  562                         pc = (db_addr_t)
  563                             db_get_value((int)&actframe->f_retaddr, 4, false);
  564                         continue;
  565                 }
  566 
  567                 db_nextframe(&frame, &pc, td);
  568 
  569 out:
  570                 /*
  571                  * 'frame' can be null here, either because it was initially
  572                  * null or because db_nextframe() found no frame.
  573                  * db_nextframe() may also have found a non-kernel frame.
  574                  * !INKERNEL() classifies both.  Stop tracing if either,
  575                  * after printing the pc if it is the kernel.
  576                  */
  577                 if (frame == NULL || frame <= actframe) {
  578                         sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
  579                         db_symbol_values(sym, &name, NULL);
  580                         db_print_stack_entry(name, 0, 0, 0, pc, frame);
  581                         break;
  582                 }
  583         }
  584 
  585         return (0);
  586 }
  587 
  588 void
  589 db_trace_self(void)
  590 {
  591         struct i386_frame *frame;
  592         db_addr_t callpc;
  593         register_t ebp;
  594 
  595         __asm __volatile("movl %%ebp,%0" : "=r" (ebp));
  596         frame = (struct i386_frame *)ebp;
  597         callpc = (db_addr_t)db_get_value((int)&frame->f_retaddr, 4, false);
  598         frame = frame->f_frame;
  599         db_backtrace(curthread, NULL, frame, callpc, 0, -1);
  600 }
  601 
  602 int
  603 db_trace_thread(struct thread *thr, int count)
  604 {
  605         struct pcb *ctx;
  606         struct trapframe *tf;
  607 
  608         ctx = kdb_thr_ctx(thr);
  609         tf = thr == kdb_thread ? kdb_frame : NULL;
  610         return (db_backtrace(thr, tf, (struct i386_frame *)ctx->pcb_ebp,
  611             ctx->pcb_eip, ctx->pcb_esp, count));
  612 }
  613 
  614 int
  615 i386_set_watch(watchnum, watchaddr, size, access, d)
  616         int watchnum;
  617         unsigned int watchaddr;
  618         int size;
  619         int access;
  620         struct dbreg *d;
  621 {
  622         int i, len;
  623 
  624         if (watchnum == -1) {
  625                 for (i = 0; i < 4; i++)
  626                         if (!DBREG_DR7_ENABLED(d->dr[7], i))
  627                                 break;
  628                 if (i < 4)
  629                         watchnum = i;
  630                 else
  631                         return (-1);
  632         }
  633 
  634         switch (access) {
  635         case DBREG_DR7_EXEC:
  636                 size = 1; /* size must be 1 for an execution breakpoint */
  637                 /* fall through */
  638         case DBREG_DR7_WRONLY:
  639         case DBREG_DR7_RDWR:
  640                 break;
  641         default:
  642                 return (-1);
  643         }
  644 
  645         /*
  646          * we can watch a 1, 2, or 4 byte sized location
  647          */
  648         switch (size) {
  649         case 1:
  650                 len = DBREG_DR7_LEN_1;
  651                 break;
  652         case 2:
  653                 len = DBREG_DR7_LEN_2;
  654                 break;
  655         case 4:
  656                 len = DBREG_DR7_LEN_4;
  657                 break;
  658         default:
  659                 return (-1);
  660         }
  661 
  662         /* clear the bits we are about to affect */
  663         d->dr[7] &= ~DBREG_DR7_MASK(watchnum);
  664 
  665         /* set drN register to the address, N=watchnum */
  666         DBREG_DRX(d, watchnum) = watchaddr;
  667 
  668         /* enable the watchpoint */
  669         d->dr[7] |= DBREG_DR7_SET(watchnum, len, access,
  670             DBREG_DR7_GLOBAL_ENABLE);
  671 
  672         return (watchnum);
  673 }
  674 
  675 
  676 int
  677 i386_clr_watch(watchnum, d)
  678         int watchnum;
  679         struct dbreg *d;
  680 {
  681 
  682         if (watchnum < 0 || watchnum >= 4)
  683                 return (-1);
  684 
  685         d->dr[7] &= ~DBREG_DR7_MASK(watchnum);
  686         DBREG_DRX(d, watchnum) = 0;
  687 
  688         return (0);
  689 }
  690 
  691 
  692 int
  693 db_md_set_watchpoint(addr, size)
  694         db_expr_t addr;
  695         db_expr_t size;
  696 {
  697         struct dbreg d;
  698         int avail, i, wsize;
  699 
  700         fill_dbregs(NULL, &d);
  701 
  702         avail = 0;
  703         for(i = 0; i < 4; i++) {
  704                 if (!DBREG_DR7_ENABLED(d.dr[7], i))
  705                         avail++;
  706         }
  707 
  708         if (avail * 4 < size)
  709                 return (-1);
  710 
  711         for (i = 0; i < 4 && (size > 0); i++) {
  712                 if (!DBREG_DR7_ENABLED(d.dr[7], i)) {
  713                         if (size > 2)
  714                                 wsize = 4;
  715                         else
  716                                 wsize = size;
  717                         i386_set_watch(i, addr, wsize,
  718                                        DBREG_DR7_WRONLY, &d);
  719                         addr += wsize;
  720                         size -= wsize;
  721                 }
  722         }
  723 
  724         set_dbregs(NULL, &d);
  725 
  726         return(0);
  727 }
  728 
  729 
  730 int
  731 db_md_clr_watchpoint(addr, size)
  732         db_expr_t addr;
  733         db_expr_t size;
  734 {
  735         struct dbreg d;
  736         int i;
  737 
  738         fill_dbregs(NULL, &d);
  739 
  740         for(i = 0; i < 4; i++) {
  741                 if (DBREG_DR7_ENABLED(d.dr[7], i)) {
  742                         if ((DBREG_DRX((&d), i) >= addr) &&
  743                             (DBREG_DRX((&d), i) < addr+size))
  744                                 i386_clr_watch(i, &d);
  745 
  746                 }
  747         }
  748 
  749         set_dbregs(NULL, &d);
  750 
  751         return(0);
  752 }
  753 
  754 
  755 static const char *
  756 watchtype_str(type)
  757         int type;
  758 {
  759         switch (type) {
  760                 case DBREG_DR7_EXEC   : return "execute";    break;
  761                 case DBREG_DR7_RDWR   : return "read/write"; break;
  762                 case DBREG_DR7_WRONLY : return "write";      break;
  763                 default               : return "invalid";    break;
  764         }
  765 }
  766 
  767 
  768 void
  769 db_md_list_watchpoints(void)
  770 {
  771         struct dbreg d;
  772         int i, len, type;
  773 
  774         fill_dbregs(NULL, &d);
  775 
  776         db_printf("\nhardware watchpoints:\n");
  777         db_printf("  watch    status        type  len     address\n");
  778         db_printf("  -----  --------  ----------  ---  ----------\n");
  779         for (i = 0; i < 4; i++) {
  780                 if (DBREG_DR7_ENABLED(d.dr[7], i)) {
  781                         type = DBREG_DR7_ACCESS(d.dr[7], i);
  782                         len = DBREG_DR7_LEN(d.dr[7], i);
  783                         db_printf("  %-5d  %-8s  %10s  %3d  ",
  784                             i, "enabled", watchtype_str(type), len + 1);
  785                         db_printsym((db_addr_t)DBREG_DRX(&d, i), DB_STGY_ANY);
  786                         db_printf("\n");
  787                 } else {
  788                         db_printf("  %-5d  disabled\n", i);
  789                 }
  790         }
  791 
  792         db_printf("\ndebug register values:\n");
  793         for (i = 0; i < 8; i++)
  794                 if (i != 4 && i != 5)
  795                         db_printf("  dr%d 0x%08x\n", i, DBREG_DRX(&d, i));
  796         db_printf("\n");
  797 }

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