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       1                 :            : /*
       2                 :            :  * Created by: Jason Wessel <jason.wessel@windriver.com>
       3                 :            :  *
       4                 :            :  * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
       5                 :            :  *
       6                 :            :  * This file is licensed under the terms of the GNU General Public
       7                 :            :  * License version 2. This program is licensed "as is" without any
       8                 :            :  * warranty of any kind, whether express or implied.
       9                 :            :  */
      10                 :            : 
      11                 :            : #include <linux/kgdb.h>
      12                 :            : #include <linux/kdb.h>
      13                 :            : #include <linux/kdebug.h>
      14                 :            : #include <linux/export.h>
      15                 :            : #include <linux/hardirq.h>
      16                 :            : #include "kdb_private.h"
      17                 :            : #include "../debug_core.h"
      18                 :            : 
      19                 :            : /*
      20                 :            :  * KDB interface to KGDB internals
      21                 :            :  */
      22                 :            : get_char_func kdb_poll_funcs[] = {
      23                 :            :         dbg_io_get_char,
      24                 :            :         NULL,
      25                 :            :         NULL,
      26                 :            :         NULL,
      27                 :            :         NULL,
      28                 :            :         NULL,
      29                 :            : };
      30                 :            : EXPORT_SYMBOL_GPL(kdb_poll_funcs);
      31                 :            : 
      32                 :            : int kdb_poll_idx = 1;
      33                 :            : EXPORT_SYMBOL_GPL(kdb_poll_idx);
      34                 :            : 
      35                 :            : static struct kgdb_state *kdb_ks;
      36                 :            : 
      37                 :          0 : int kdb_common_init_state(struct kgdb_state *ks)
      38                 :            : {
      39                 :          0 :         kdb_initial_cpu = atomic_read(&kgdb_active);
      40                 :          0 :         kdb_current_task = kgdb_info[ks->cpu].task;
      41                 :          0 :         kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
      42                 :          0 :         return 0;
      43                 :            : }
      44                 :            : 
      45                 :          0 : int kdb_common_deinit_state(void)
      46                 :            : {
      47                 :          0 :         kdb_initial_cpu = -1;
      48                 :          0 :         kdb_current_task = NULL;
      49                 :          0 :         kdb_current_regs = NULL;
      50                 :          0 :         return 0;
      51                 :            : }
      52                 :            : 
      53                 :          0 : int kdb_stub(struct kgdb_state *ks)
      54                 :            : {
      55                 :            :         int error = 0;
      56                 :            :         kdb_bp_t *bp;
      57                 :          0 :         unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
      58                 :            :         kdb_reason_t reason = KDB_REASON_OOPS;
      59                 :            :         kdb_dbtrap_t db_result = KDB_DB_NOBPT;
      60                 :            :         int i;
      61                 :            : 
      62                 :          0 :         kdb_ks = ks;
      63         [ #  # ]:          0 :         if (KDB_STATE(REENTRY)) {
      64                 :            :                 reason = KDB_REASON_SWITCH;
      65                 :          0 :                 KDB_STATE_CLEAR(REENTRY);
      66                 :          0 :                 addr = instruction_pointer(ks->linux_regs);
      67                 :            :         }
      68                 :          0 :         ks->pass_exception = 0;
      69         [ #  # ]:          0 :         if (atomic_read(&kgdb_setting_breakpoint))
      70                 :            :                 reason = KDB_REASON_KEYBOARD;
      71                 :            : 
      72   [ #  #  #  # ]:          0 :         if (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP)
      73                 :            :                 reason = KDB_REASON_SYSTEM_NMI;
      74                 :            : 
      75         [ #  # ]:          0 :         else if (in_nmi())
      76                 :            :                 reason = KDB_REASON_NMI;
      77                 :            : 
      78         [ #  # ]:          0 :         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
      79   [ #  #  #  # ]:          0 :                 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
      80                 :            :                         reason = KDB_REASON_BREAK;
      81                 :            :                         db_result = KDB_DB_BPT;
      82         [ #  # ]:          0 :                         if (addr != instruction_pointer(ks->linux_regs))
      83                 :          0 :                                 kgdb_arch_set_pc(ks->linux_regs, addr);
      84                 :            :                         break;
      85                 :            :                 }
      86                 :            :         }
      87         [ #  # ]:          0 :         if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
      88         [ #  # ]:          0 :                 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
      89         [ #  # ]:          0 :                         if (bp->bp_free)
      90                 :          0 :                                 continue;
      91         [ #  # ]:          0 :                         if (bp->bp_addr == addr) {
      92                 :          0 :                                 bp->bp_delay = 1;
      93                 :          0 :                                 bp->bp_delayed = 1;
      94                 :            :         /*
      95                 :            :          * SSBPT is set when the kernel debugger must single step a
      96                 :            :          * task in order to re-establish an instruction breakpoint
      97                 :            :          * which uses the instruction replacement mechanism.  It is
      98                 :            :          * cleared by any action that removes the need to single-step
      99                 :            :          * the breakpoint.
     100                 :            :          */
     101                 :            :                                 reason = KDB_REASON_BREAK;
     102                 :            :                                 db_result = KDB_DB_BPT;
     103                 :          0 :                                 KDB_STATE_SET(SSBPT);
     104                 :          0 :                                 break;
     105                 :            :                         }
     106                 :            :                 }
     107                 :            :         }
     108                 :            : 
     109   [ #  #  #  #  :          0 :         if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
                   #  # ]
     110                 :          0 :                 ks->signo == SIGTRAP) {
     111                 :            :                 reason = KDB_REASON_SSTEP;
     112                 :            :                 db_result = KDB_DB_BPT;
     113                 :            :         }
     114                 :            :         /* Set initial kdb state variables */
     115                 :          0 :         KDB_STATE_CLEAR(KGDB_TRANS);
     116                 :            :         kdb_common_init_state(ks);
     117                 :            :         /* Remove any breakpoints as needed by kdb and clear single step */
     118                 :          0 :         kdb_bp_remove();
     119                 :          0 :         KDB_STATE_CLEAR(DOING_SS);
     120                 :          0 :         KDB_STATE_SET(PAGER);
     121   [ #  #  #  # ]:          0 :         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
     122                 :          0 :                 ks->pass_exception = 1;
     123                 :          0 :                 KDB_FLAG_SET(CATASTROPHIC);
     124                 :            :         }
     125                 :            :         /* set CATASTROPHIC if the system contains unresponsive processors */
     126         [ #  # ]:          0 :         for_each_online_cpu(i)
     127         [ #  # ]:          0 :                 if (!kgdb_info[i].enter_kgdb)
     128                 :          0 :                         KDB_FLAG_SET(CATASTROPHIC);
     129   [ #  #  #  # ]:          0 :         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
     130                 :          0 :                 KDB_STATE_CLEAR(SSBPT);
     131                 :          0 :                 KDB_STATE_CLEAR(DOING_SS);
     132                 :            :         } else {
     133                 :            :                 /* Start kdb main loop */
     134                 :          0 :                 error = kdb_main_loop(KDB_REASON_ENTER, reason,
     135                 :            :                                       ks->err_code, db_result, ks->linux_regs);
     136                 :            :         }
     137                 :            :         /*
     138                 :            :          * Upon exit from the kdb main loop setup break points and restart
     139                 :            :          * the system based on the requested continue state
     140                 :            :          */
     141                 :            :         kdb_common_deinit_state();
     142                 :          0 :         KDB_STATE_CLEAR(PAGER);
     143                 :          0 :         kdbnearsym_cleanup();
     144         [ #  # ]:          0 :         if (error == KDB_CMD_KGDB) {
     145         [ #  # ]:          0 :                 if (KDB_STATE(DOING_KGDB))
     146                 :          0 :                         KDB_STATE_CLEAR(DOING_KGDB);
     147                 :            :                 return DBG_PASS_EVENT;
     148                 :            :         }
     149                 :          0 :         kdb_bp_install(ks->linux_regs);
     150                 :          0 :         dbg_activate_sw_breakpoints();
     151                 :            :         /* Set the exit state to a single step or a continue */
     152         [ #  # ]:          0 :         if (KDB_STATE(DOING_SS))
     153                 :          0 :                 gdbstub_state(ks, "s");
     154                 :            :         else
     155                 :          0 :                 gdbstub_state(ks, "c");
     156                 :            : 
     157                 :          0 :         KDB_FLAG_CLEAR(CATASTROPHIC);
     158                 :            : 
     159                 :            :         /* Invoke arch specific exception handling prior to system resume */
     160                 :          0 :         kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
     161         [ #  # ]:          0 :         if (ks->pass_exception)
     162                 :          0 :                 kgdb_info[ks->cpu].ret_state = 1;
     163         [ #  # ]:          0 :         if (error == KDB_CMD_CPU) {
     164                 :          0 :                 KDB_STATE_SET(REENTRY);
     165                 :            :                 /*
     166                 :            :                  * Force clear the single step bit because kdb emulates this
     167                 :            :                  * differently vs the gdbstub
     168                 :            :                  */
     169                 :          0 :                 kgdb_single_step = 0;
     170                 :          0 :                 dbg_deactivate_sw_breakpoints();
     171                 :          0 :                 return DBG_SWITCH_CPU_EVENT;
     172                 :            :         }
     173                 :          0 :         return kgdb_info[ks->cpu].ret_state;
     174                 :            : }
     175                 :            : 
     176                 :          0 : void kdb_gdb_state_pass(char *buf)
     177                 :            : {
     178                 :          0 :         gdbstub_state(kdb_ks, buf);
     179                 :          0 : }