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 <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 int kdb_common_init_state(struct kgdb_state *ks)
  38 {
  39         kdb_initial_cpu = atomic_read(&kgdb_active);
  40         kdb_current_task = kgdb_info[ks->cpu].task;
  41         kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
  42         return 0;
  43 }
  44
  45 int kdb_common_deinit_state(void)
  46 {
  47         kdb_initial_cpu = -1;
  48         kdb_current_task = NULL;
  49         kdb_current_regs = NULL;
  50         return 0;
  51 }
  52
  53 int kdb_stub(struct kgdb_state *ks)
  54 {
  55         int error = 0;
  56         kdb_bp_t *bp;
  57         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         kdb_ks = ks;
  63         if (KDB_STATE(REENTRY)) {
  64                 reason = KDB_REASON_SWITCH;
  65                 KDB_STATE_CLEAR(REENTRY);
  66                 addr = instruction_pointer(ks->linux_regs);
  67         }
  68         ks->pass_exception = 0;
  69         if (atomic_read(&kgdb_setting_breakpoint))
  70                 reason = KDB_REASON_KEYBOARD;
  71
  72         if (in_nmi())
  73                 reason = KDB_REASON_NMI;
  74
  75         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  76                 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
  77                         reason = KDB_REASON_BREAK;
  78                         db_result = KDB_DB_BPT;
  79                         if (addr != instruction_pointer(ks->linux_regs))
  80                                 kgdb_arch_set_pc(ks->linux_regs, addr);
  81                         break;
  82                 }
  83         }
  84         if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
  85                 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  86                         if (bp->bp_free)
  87                                 continue;
  88                         if (bp->bp_addr == addr) {
  89                                 bp->bp_delay = 1;
  90                                 bp->bp_delayed = 1;
  91         /*
  92          * SSBPT is set when the kernel debugger must single step a
  93          * task in order to re-establish an instruction breakpoint
  94          * which uses the instruction replacement mechanism.  It is
  95          * cleared by any action that removes the need to single-step
  96          * the breakpoint.
  97          */
  98                                 reason = KDB_REASON_BREAK;
  99                                 db_result = KDB_DB_BPT;
 100                                 KDB_STATE_SET(SSBPT);
 101                                 break;
 102                         }
 103                 }
 104         }
 105
 106         if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
 107                 ks->signo == SIGTRAP) {
 108                 reason = KDB_REASON_SSTEP;
 109                 db_result = KDB_DB_BPT;
 110         }
 111         /* Set initial kdb state variables */
 112         KDB_STATE_CLEAR(KGDB_TRANS);
 113         kdb_common_init_state(ks);
 114         /* Remove any breakpoints as needed by kdb and clear single step */
 115         kdb_bp_remove();
 116         KDB_STATE_CLEAR(DOING_SS);
 117         KDB_STATE_SET(PAGER);
 118         /* zero out any offline cpu data */
 119         for_each_present_cpu(i) {
 120                 if (!cpu_online(i)) {
 121                         kgdb_info[i].debuggerinfo = NULL;
 122                         kgdb_info[i].task = NULL;
 123                 }
 124         }
 125         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
 126                 ks->pass_exception = 1;
 127                 KDB_FLAG_SET(CATASTROPHIC);
 128         }
 129         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 130                 KDB_STATE_CLEAR(SSBPT);
 131                 KDB_STATE_CLEAR(DOING_SS);
 132         } else {
 133                 /* Start kdb main loop */
 134                 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         KDB_STATE_CLEAR(PAGER);
 143         kdbnearsym_cleanup();
 144         if (error == KDB_CMD_KGDB) {
 145                 if (KDB_STATE(DOING_KGDB))
 146                         KDB_STATE_CLEAR(DOING_KGDB);
 147                 return DBG_PASS_EVENT;
 148         }
 149         kdb_bp_install(ks->linux_regs);
 150         dbg_activate_sw_breakpoints();
 151         /* Set the exit state to a single step or a continue */
 152         if (KDB_STATE(DOING_SS))
 153                 gdbstub_state(ks, "s");
 154         else
 155                 gdbstub_state(ks, "c");
 156
 157         KDB_FLAG_CLEAR(CATASTROPHIC);
 158
 159         /* Invoke arch specific exception handling prior to system resume */
 160         kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
 161         if (ks->pass_exception)
 162                 kgdb_info[ks->cpu].ret_state = 1;
 163         if (error == KDB_CMD_CPU) {
 164                 KDB_STATE_SET(REENTRY);
 165                 /*
 166                  * Force clear the single step bit because kdb emulates this
 167                  * differently vs the gdbstub
 168                  */
 169                 kgdb_single_step = 0;
 170                 dbg_deactivate_sw_breakpoints();
 171                 return DBG_SWITCH_CPU_EVENT;
 172         }
 173         return kgdb_info[ks->cpu].ret_state;
 174 }
 175
 176 void kdb_gdb_state_pass(char *buf)
 177 {
 178         gdbstub_state(kdb_ks, buf);
 179 }