kernel/debug/kdb/kdb_debugger.c

   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 "kdb_private.h"
  15 #include "../debug_core.h"
  16
  17 /*
  18  * KDB interface to KGDB internals
  19  */
  20 get_char_func kdb_poll_funcs[] = {
  21         dbg_io_get_char,
  22         NULL,
  23         NULL,
  24         NULL,
  25         NULL,
  26         NULL,
  27 };
  28 EXPORT_SYMBOL_GPL(kdb_poll_funcs);
  29
  30 int kdb_poll_idx = 1;
  31 EXPORT_SYMBOL_GPL(kdb_poll_idx);
  32
  33 static struct kgdb_state *kdb_ks;
  34
  35 int kdb_stub(struct kgdb_state *ks)
  36 {
  37         int error = 0;
  38         kdb_bp_t *bp;
  39         unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
  40         kdb_reason_t reason = KDB_REASON_OOPS;
  41         kdb_dbtrap_t db_result = KDB_DB_NOBPT;
  42         int i;
  43
  44         kdb_ks = ks;
  45         if (KDB_STATE(REENTRY)) {
  46                 reason = KDB_REASON_SWITCH;
  47                 KDB_STATE_CLEAR(REENTRY);
  48                 addr = instruction_pointer(ks->linux_regs);
  49         }
  50         ks->pass_exception = 0;
  51         if (atomic_read(&kgdb_setting_breakpoint))
  52                 reason = KDB_REASON_KEYBOARD;
  53
  54         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  55                 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
  56                         reason = KDB_REASON_BREAK;
  57                         db_result = KDB_DB_BPT;
  58                         if (addr != instruction_pointer(ks->linux_regs))
  59                                 kgdb_arch_set_pc(ks->linux_regs, addr);
  60                         break;
  61                 }
  62         }
  63         if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
  64                 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  65                         if (bp->bp_free)
  66                                 continue;
  67                         if (bp->bp_addr == addr) {
  68                                 bp->bp_delay = 1;
  69                                 bp->bp_delayed = 1;
  70         /*
  71          * SSBPT is set when the kernel debugger must single step a
  72          * task in order to re-establish an instruction breakpoint
  73          * which uses the instruction replacement mechanism.  It is
  74          * cleared by any action that removes the need to single-step
  75          * the breakpoint.
  76          */
  77                                 reason = KDB_REASON_BREAK;
  78                                 db_result = KDB_DB_BPT;
  79                                 KDB_STATE_SET(SSBPT);
  80                                 break;
  81                         }
  82                 }
  83         }
  84
  85         if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
  86                 ks->signo == SIGTRAP) {
  87                 reason = KDB_REASON_SSTEP;
  88                 db_result = KDB_DB_BPT;
  89         }
  90         /* Set initial kdb state variables */
  91         KDB_STATE_CLEAR(KGDB_TRANS);
  92         kdb_initial_cpu = atomic_read(&kgdb_active);
  93         kdb_current_task = kgdb_info[ks->cpu].task;
  94         kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
  95         /* Remove any breakpoints as needed by kdb and clear single step */
  96         kdb_bp_remove();
  97         KDB_STATE_CLEAR(DOING_SS);
  98         KDB_STATE_CLEAR(DOING_SSB);
  99         KDB_STATE_SET(PAGER);
 100         /* zero out any offline cpu data */
 101         for_each_present_cpu(i) {
 102                 if (!cpu_online(i)) {
 103                         kgdb_info[i].debuggerinfo = NULL;
 104                         kgdb_info[i].task = NULL;
 105                 }
 106         }
 107         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
 108                 ks->pass_exception = 1;
 109                 KDB_FLAG_SET(CATASTROPHIC);
 110         }
 111         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 112                 KDB_STATE_CLEAR(SSBPT);
 113                 KDB_STATE_CLEAR(DOING_SS);
 114         } else {
 115                 /* Start kdb main loop */
 116                 error = kdb_main_loop(KDB_REASON_ENTER, reason,
 117                                       ks->err_code, db_result, ks->linux_regs);
 118         }
 119         /*
 120          * Upon exit from the kdb main loop setup break points and restart
 121          * the system based on the requested continue state
 122          */
 123         kdb_initial_cpu = -1;
 124         kdb_current_task = NULL;
 125         kdb_current_regs = NULL;
 126         KDB_STATE_CLEAR(PAGER);
 127         kdbnearsym_cleanup();
 128         if (error == KDB_CMD_KGDB) {
 129                 if (KDB_STATE(DOING_KGDB))
 130                         KDB_STATE_CLEAR(DOING_KGDB);
 131                 return DBG_PASS_EVENT;
 132         }
 133         kdb_bp_install(ks->linux_regs);
 134         dbg_activate_sw_breakpoints();
 135         /* Set the exit state to a single step or a continue */
 136         if (KDB_STATE(DOING_SS))
 137                 gdbstub_state(ks, "s");
 138         else
 139                 gdbstub_state(ks, "c");
 140
 141         KDB_FLAG_CLEAR(CATASTROPHIC);
 142
 143         /* Invoke arch specific exception handling prior to system resume */
 144         kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
 145         if (ks->pass_exception)
 146                 kgdb_info[ks->cpu].ret_state = 1;
 147         if (error == KDB_CMD_CPU) {
 148                 KDB_STATE_SET(REENTRY);
 149                 /*
 150                  * Force clear the single step bit because kdb emulates this
 151                  * differently vs the gdbstub
 152                  */
 153                 kgdb_single_step = 0;
 154                 dbg_deactivate_sw_breakpoints();
 155                 return DBG_SWITCH_CPU_EVENT;
 156         }
 157         return kgdb_info[ks->cpu].ret_state;
 158 }
 159
 160 void kdb_gdb_state_pass(char *buf)
 161 {
 162         gdbstub_state(kdb_ks, buf);
 163 }