FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_run.c

     /* 
      * Mach Operating System
      * Copyright (c) 1993-1990 Carnegie Mellon University
      * All Rights Reserved.
      * 
      * Permission to use, copy, modify and distribute this software and its
      * documentation is hereby granted, provided that both the copyright
      * notice and this permission notice appear in all copies of the
      * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     * 
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     * 
     * Carnegie Mellon requests users of this software to return to
     * 
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     * 
     * any improvements or extensions that they make and grant Carnegie Mellon
     * the rights to redistribute these changes.
     */
    /*
     * HISTORY
     * $Log:        db_run.c,v $
     * Revision 2.14  93/01/19  09:00:47  danner
     *      64bit cleanup. software single step code revision.
     *      comment correction (jfriedl).
     *      [92/12/10  16:20:16  af]
     * 
     * Revision 2.13  93/01/14  17:25:38  danner
     *      added use of db_branch_is_delayed in db_restart_at_pc. 
     *      [92/11/28            jfriedl]
     *      64bit cleanup.
     *      [92/12/10  16:20:16  af]
     * 
     * Revision 2.12  92/08/03  17:31:57  jfriedl
     *      removed silly prototypes
     *      [92/08/02            jfriedl]
     * 
     * Revision 2.11  92/05/21  17:07:41  jfriedl
     *      Removed unused variable 'bkpt' from db_clear_task_single_step().
     *      [92/05/16            jfriedl]
     * 
     * Revision 2.10  92/04/01  10:54:05  rpd
     *      Added missing newline print in n/p command.
     *      [92/03/20            danner]
     * 
     * Revision 2.9  91/10/09  16:02:08  af
     *      Added task parameter for user space break point, and changed
     *       db_find_breakpoint_here to db_find_thread_breakpoint_here
     *       to support thread based break point.
     *      Changed db_{set,clear}_single_step to db_{set,clear}_task_single
     *       _step to add task paramter and to maintain compatibility.
     *      [91/08/29            tak]
     * 
     * Revision 2.8  91/07/09  23:16:01  danner
     *      Added logic to db_set_single_step not to set a breakpoint at the
     *       next sequential instruction if the current instruction is an
     *       unconditional transfer of flow of control instruction. This
     *       avoids problems with the debugger overwriting data or clobbering
     *       routines that the debugger itself might need. This is determined
     *       by calling the predicate inst_unconditional_flow_transfer. This
     *       predicate now needs to be defined for all architectures using
     *       the software single step. 
     * 
     *           Added include of ddb/db_run.h, where all the STEP defines have been
     *            moved.
     *       
     *      [91/07/08            danner]
     * 
     * Revision 2.7  91/06/06  17:03:51  jsb
     *      Removed redundant newlines and tabs.
     *      Added delta to instruction count printf.
     *      [91/05/25  10:55:01  jsb]
     * 
     * Revision 2.6  91/05/14  15:35:39  mrt
     *      Correcting copyright
     * 
     * Revision 2.5  91/02/05  17:06:58  mrt
     *      Changed to new Mach copyright
     *      [91/01/31  16:19:05  mrt]
     * 
     * Revision 2.4  91/01/08  15:09:10  rpd
     *      Fixed bug in db_restart_at_pc.
     *      [90/12/07            rpd]
     *      Added STEP_COUNT and count option to db_continue_cmd.
     *      Changed db_stop_at_pc to return (modified) is_breakpoint.
     *      Fixed db_stop_at_pc to print newlines in the right places.
     *      [90/11/27            rpd]
     * 
     * Revision 2.3  90/10/25  14:43:59  rwd
     *      Changed db_find_breakpoint to db_find_breakpoint_here.
     *      [90/10/18            rpd]
     * 
     *      Fixed db_set_single_step to pass regs to branch_taken.
    *      Added watchpoint argument to db_restart_at_pc.
    *      [90/10/17            rpd]
    *      Generalized the watchpoint support.
    *      [90/10/16            rwd]
    *      Added watchpoint support.
    *      [90/10/16            rpd]
    * 
    * Revision 2.2  90/08/27  21:51:59  dbg
    *      Fixed names for single-step functions.
    *      [90/08/20            af]
    *      Reduce lint.
    *      [90/08/07            dbg]
    *      Created.
    *      [90/07/25            dbg]
    * 
    */
   /*
    *      Author: David B. Golub, Carnegie Mellon University
    *      Date:   7/90
    */
   
   /*
    * Commands to run process.
    */
   #include <mach/boolean.h>
   #include <machine/db_machdep.h>
   
   #include <ddb/db_lex.h>
   #include <ddb/db_break.h>
   #include <ddb/db_access.h>
   #include <ddb/db_run.h>
   #include <ddb/db_task_thread.h>
   
   int     db_run_mode;
   
   boolean_t       db_sstep_print;
   int             db_loop_count;
   int             db_call_depth;
   
   int             db_inst_count;
   int             db_last_inst_count;
   int             db_load_count;
   int             db_store_count;
   
   #ifndef db_set_single_step
   void            db_set_task_single_step(/* db_regs_t *, task_t */);/* forward */
   #else
   #define db_set_task_single_step(regs,task)      db_set_single_step(regs)
   #endif
   #ifndef db_clear_single_step
   void            db_clear_task_single_step(/* db_regs_t *, task_t */);
   #else
   #define db_clear_task_single_step(regs,task)    db_clear_single_step(regs)
   #endif
   
   boolean_t
   db_stop_at_pc(is_breakpoint, task)
           boolean_t       *is_breakpoint;
           task_t          task;
   {
           register  db_addr_t     pc;
           register  db_thread_breakpoint_t bkpt;
           boolean_t db_cond_check();
   
           db_clear_task_single_step(DDB_REGS, task);
           db_clear_breakpoints();
           db_clear_watchpoints();
           pc = PC_REGS(DDB_REGS);
   
   #ifdef  FIXUP_PC_AFTER_BREAK
           if (*is_breakpoint) {
               /*
                * Breakpoint trap.  Fix up the PC if the
                * machine requires it.
                */
               FIXUP_PC_AFTER_BREAK
               pc = PC_REGS(DDB_REGS);
           }
   #endif
   
           /*
            * Now check for a breakpoint at this address.
            */
           bkpt = db_find_thread_breakpoint_here(task, pc);
           if (bkpt) {
               if (db_cond_check(bkpt)) {
                   *is_breakpoint = TRUE;
                   return (TRUE);  /* stop here */
               }
           }
           *is_breakpoint = FALSE;
   
           if (db_run_mode == STEP_INVISIBLE) {
               db_run_mode = STEP_CONTINUE;
               return (FALSE);     /* continue */
           }
           if (db_run_mode == STEP_COUNT) {
               return (FALSE); /* continue */
           }
           if (db_run_mode == STEP_ONCE) {
               if (--db_loop_count > 0) {
                   if (db_sstep_print) {
                       db_print_loc_and_inst(pc, task);
                   }
                   return (FALSE); /* continue */
               }
           }
           if (db_run_mode == STEP_RETURN) {
               /* WARNING: the following assumes an instruction fits an int */
               db_expr_t ins = db_get_task_value(pc, sizeof(int), FALSE, task);
   
               /* continue until matching return */
   
               if (!inst_trap_return(ins) &&
                   (!inst_return(ins) || --db_call_depth != 0)) {
                   if (db_sstep_print) {
                       if (inst_call(ins) || inst_return(ins)) {
                           register int i;
   
                           db_printf("[after %6d /%4d] ",
                                     db_inst_count,
                                     db_inst_count - db_last_inst_count);
                           db_last_inst_count = db_inst_count;
                           for (i = db_call_depth; --i > 0; )
                               db_printf("  ");
                           db_print_loc_and_inst(pc, task);
                           db_printf("\n");
                       }
                   }
                   if (inst_call(ins))
                       db_call_depth++;
                   return (FALSE); /* continue */
               }
           }
           if (db_run_mode == STEP_CALLT) {
               /* WARNING: the following assumes an instruction fits an int */
               db_expr_t ins = db_get_task_value(pc, sizeof(int), FALSE, task);
   
               /* continue until call or return */
   
               if (!inst_call(ins) &&
                   !inst_return(ins) &&
                   !inst_trap_return(ins)) {
                   return (FALSE); /* continue */
               }
           }
           if (db_find_breakpoint_here(task, pc))
                   return(FALSE);
           db_run_mode = STEP_NONE;
           return (TRUE);
   }
   
   void
   db_restart_at_pc(watchpt, task)
           boolean_t watchpt;
           task_t    task;
   {
           register db_addr_t pc = PC_REGS(DDB_REGS), brpc;
   
           if ((db_run_mode == STEP_COUNT) ||
               (db_run_mode == STEP_RETURN) ||
               (db_run_mode == STEP_CALLT)) {
               db_expr_t           ins;
   
               /*
                * We are about to execute this instruction,
                * so count it now.
                */
   
               ins = db_get_task_value(pc, sizeof(int), FALSE, task);
               db_inst_count++;
               db_load_count += inst_load(ins);
               db_store_count += inst_store(ins);
   #ifdef  SOFTWARE_SSTEP
               /* Account for instructions in delay slots */
               brpc = next_instr_address(pc,1,task);
               if ((brpc != pc) && (inst_branch(ins) || inst_call(ins))) {
                   /* Note: this ~assumes an instruction <= sizeof(int) */
                   ins = db_get_task_value(brpc, sizeof(int), FALSE, task);
                   db_inst_count++;
                   db_load_count += inst_load(ins);
                   db_store_count += inst_store(ins);
               }
   #endif  /* SOFTWARE_SSTEP */
           }
   
           if (db_run_mode == STEP_CONTINUE) {
               if (watchpt || db_find_breakpoint_here(task, pc)) {
                   /*
                    * Step over breakpoint/watchpoint.
                    */
                   db_run_mode = STEP_INVISIBLE;
                   db_set_task_single_step(DDB_REGS, task);
               } else {
                   db_set_breakpoints();
                   db_set_watchpoints();
               }
           } else {
               db_set_task_single_step(DDB_REGS, task);
           }
   }
   
   void
   db_single_step(regs, task)
           db_regs_t *regs;
           task_t    task;
   {
           if (db_run_mode == STEP_CONTINUE) {
               db_run_mode = STEP_INVISIBLE;
               db_set_task_single_step(regs, task);
           }
   }
   
   #ifdef  SOFTWARE_SSTEP
   /*
    *      Software implementation of single-stepping.
    *      If your machine does not have a trace mode
    *      similar to the vax or sun ones you can use
    *      this implementation, done for the mips.
    *      Just define the above conditional and provide
    *      the functions/macros defined below.
    *
    * extern boolean_t
    *      inst_branch(),          returns true if the instruction might branch
    * extern unsigned
    *      branch_taken(),         return the address the instruction might
    *                              branch to
    *      db_getreg_val();        return the value of a user register,
    *                              as indicated in the hardware instruction
    *                              encoding, e.g. 8 for r8
    *                      
    * next_instr_address(pc,bd,task) returns the address of the first
    *                              instruction following the one at "pc",
    *                              which is either in the taken path of
    *                              the branch (bd==1) or not.  This is
    *                              for machines (mips) with branch delays.
    *
    *      A single-step may involve at most 2 breakpoints -
    *      one for branch-not-taken and one for branch taken.
    *      If one of these addresses does not already have a breakpoint,
    *      we allocate a breakpoint and save it here.
    *      These breakpoints are deleted on return.
    */                     
   db_breakpoint_t db_not_taken_bkpt = 0;
   db_breakpoint_t db_taken_bkpt = 0;
   
   db_breakpoint_t
   db_find_temp_breakpoint(task, addr)
           task_t             task;
           db_addr_t          addr;
   {
           if (db_taken_bkpt && (db_taken_bkpt->address == addr) &&
               db_taken_bkpt->task == task)
                   return db_taken_bkpt;
           if (db_not_taken_bkpt && (db_not_taken_bkpt->address == addr) &&
               db_not_taken_bkpt->task == task)
                   return db_not_taken_bkpt;
           return 0;
   }
   
   void
   db_set_task_single_step(regs, task)
           register db_regs_t *regs;
           task_t             task;
   {
           db_addr_t pc = PC_REGS(regs), brpc;
           register unsigned int    inst;
           register boolean_t       unconditional;
   
           /*
            *      User was stopped at pc, e.g. the instruction
            *      at pc was not executed.
            */
           inst = db_get_task_value(pc, sizeof(int), FALSE, task);
           if (inst_branch(inst) || inst_call(inst)) {
               extern db_expr_t getreg_val();
   
               brpc = branch_taken(inst, pc, getreg_val, regs);
               if (brpc != pc) {   /* self-branches are hopeless */
                   db_taken_bkpt = db_set_temp_breakpoint(task, brpc);
               } else
                   db_taken_bkpt = 0;
               pc = next_instr_address(pc,1,task);
           }
           
           /* check if this control flow instruction is an unconditional transfer */
           unconditional = inst_unconditional_flow_transfer(inst);
   
           pc = next_instr_address(pc,0,task);
           /* 
             We only set the sequential breakpoint if previous instruction was not
             an unconditional change of flow of control. If the previous instruction
             is an unconditional change of flow of control, setting a breakpoint in the
             next sequential location may set a breakpoint in data or in another routine,
             which could screw up either the program or the debugger. 
             (Consider, for instance, that the next sequential instruction is the 
             start of a routine needed by the debugger.)
           */
           if (!unconditional && db_find_breakpoint_here(task, pc) == 0) {
               db_not_taken_bkpt = db_set_temp_breakpoint(task, pc);
           }
           else
               db_not_taken_bkpt = 0;
   }
   
   void
   db_clear_task_single_step(regs, task)
           db_regs_t *regs;
           task_t    task;
   {
           if (db_taken_bkpt != 0) {
               db_delete_temp_breakpoint(task, db_taken_bkpt);
               db_taken_bkpt = 0;
           }
           if (db_not_taken_bkpt != 0) {
               db_delete_temp_breakpoint(task, db_not_taken_bkpt);
               db_not_taken_bkpt = 0;
           }
   }
   
   #endif  /* SOFTWARE_SSTEP */
   
   
   extern int      db_cmd_loop_done;
   
   /* single-step */
   /*ARGSUSED*/
   void
   db_single_step_cmd(addr, have_addr, count, modif)
           db_expr_t       addr;
           int             have_addr;
           db_expr_t       count;
           char *          modif;
   {
           boolean_t       print = FALSE;
   
           if (count == -1)
               count = 1;
   
           if (modif[0] == 'p')
               print = TRUE;
   
           db_run_mode = STEP_ONCE;
           db_loop_count = count;
           db_sstep_print = print;
           db_inst_count = 0;
           db_last_inst_count = 0;
           db_load_count = 0;
           db_store_count = 0;
   
           db_cmd_loop_done = 1;
   }
   
   /* trace and print until call/return */
   /*ARGSUSED*/
   void
   db_trace_until_call_cmd(addr, have_addr, count, modif)
           db_expr_t       addr;
           int             have_addr;
           db_expr_t       count;
           char *          modif;
   {
           boolean_t       print = FALSE;
   
           if (modif[0] == 'p')
               print = TRUE;
   
           db_run_mode = STEP_CALLT;
           db_sstep_print = print;
           db_inst_count = 0;
           db_last_inst_count = 0;
           db_load_count = 0;
           db_store_count = 0;
   
           db_cmd_loop_done = 1;
   }
   
   /*ARGSUSED*/
   void
   db_trace_until_matching_cmd(addr, have_addr, count, modif)
           db_expr_t       addr;
           int             have_addr;
           db_expr_t       count;
           char *          modif;
   {
           boolean_t       print = FALSE;
   
           if (modif[0] == 'p')
               print = TRUE;
   
           db_run_mode = STEP_RETURN;
           db_call_depth = 1;
           db_sstep_print = print;
           db_inst_count = 0;
           db_last_inst_count = 0;
           db_load_count = 0;
           db_store_count = 0;
   
           db_cmd_loop_done = 1;
   }
   
   /* continue */
   /*ARGSUSED*/
   void
   db_continue_cmd(addr, have_addr, count, modif)
           db_expr_t       addr;
           int             have_addr;
           db_expr_t       count;
           char *          modif;
   {
           if (modif[0] == 'c')
               db_run_mode = STEP_COUNT;
           else
               db_run_mode = STEP_CONTINUE;
           db_inst_count = 0;
           db_last_inst_count = 0;
           db_load_count = 0;
           db_store_count = 0;
   
           db_cmd_loop_done = 1;
   }
   
   boolean_t
   db_in_single_step()
   {
           return(db_run_mode != STEP_NONE && db_run_mode != STEP_CONTINUE);
   }

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