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 (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP)
  73                 reason = KDB_REASON_SYSTEM_NMI;
  74
  75         else if (in_nmi())
  76                 reason = KDB_REASON_NMI;
  77
  78         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  79                 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
  80                         reason = KDB_REASON_BREAK;
  81                         db_result = KDB_DB_BPT;
  82                         if (addr != instruction_pointer(ks->linux_regs))
  83                                 kgdb_arch_set_pc(ks->linux_regs, addr);
  84                         break;
  85                 }
  86         }
  87         if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
  88                 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  89                         if (bp->bp_free)
  90                                 continue;
  91                         if (bp->bp_addr == addr) {
  92                                 bp->bp_delay = 1;
  93                                 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                                 KDB_STATE_SET(SSBPT);
 104                                 break;
 105                         }
 106                 }
 107         }
 108
 109         if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
 110                 ks->signo == SIGTRAP) {
 111                 reason = KDB_REASON_SSTEP;
 112                 db_result = KDB_DB_BPT;
 113         }
 114         /* Set initial kdb state variables */
 115         KDB_STATE_CLEAR(KGDB_TRANS);
 116         kdb_common_init_state(ks);
 117         /* Remove any breakpoints as needed by kdb and clear single step */
 118         kdb_bp_remove();
 119         KDB_STATE_CLEAR(DOING_SS);
 120         KDB_STATE_SET(PAGER);
 121         /* zero out any offline cpu data */
 122         for_each_present_cpu(i) {
 123                 if (!cpu_online(i)) {
 124                         kgdb_info[i].debuggerinfo = NULL;
 125                         kgdb_info[i].task = NULL;
 126                 }
 127         }
 128         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
 129                 ks->pass_exception = 1;
 130                 KDB_FLAG_SET(CATASTROPHIC);
 131         }
 132         /* set CATASTROPHIC if the system contains unresponsive processors */
 133         for_each_online_cpu(i)
 134                 if (!kgdb_info[i].enter_kgdb)
 135                         KDB_FLAG_SET(CATASTROPHIC);
 136         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 137                 KDB_STATE_CLEAR(SSBPT);
 138                 KDB_STATE_CLEAR(DOING_SS);
 139         } else {
 140                 /* Start kdb main loop */
 141                 error = kdb_main_loop(KDB_REASON_ENTER, reason,
 142                                       ks->err_code, db_result, ks->linux_regs);
 143         }
 144         /*
 145          * Upon exit from the kdb main loop setup break points and restart
 146          * the system based on the requested continue state
 147          */
 148         kdb_common_deinit_state();
 149         KDB_STATE_CLEAR(PAGER);
 150         kdbnearsym_cleanup();
 151         if (error == KDB_CMD_KGDB) {
 152                 if (KDB_STATE(DOING_KGDB))
 153                         KDB_STATE_CLEAR(DOING_KGDB);
 154                 return DBG_PASS_EVENT;
 155         }
 156         kdb_bp_install(ks->linux_regs);
 157         dbg_activate_sw_breakpoints();
 158         /* Set the exit state to a single step or a continue */
 159         if (KDB_STATE(DOING_SS))
 160                 gdbstub_state(ks, "s");
 161         else
 162                 gdbstub_state(ks, "c");
 163
 164         KDB_FLAG_CLEAR(CATASTROPHIC);
 165
 166         /* Invoke arch specific exception handling prior to system resume */
 167         kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
 168         if (ks->pass_exception)
 169                 kgdb_info[ks->cpu].ret_state = 1;
 170         if (error == KDB_CMD_CPU) {
 171                 KDB_STATE_SET(REENTRY);
 172                 /*
 173                  * Force clear the single step bit because kdb emulates this
 174                  * differently vs the gdbstub
 175                  */
 176                 kgdb_single_step = 0;
 177                 dbg_deactivate_sw_breakpoints();
 178                 return DBG_SWITCH_CPU_EVENT;
 179         }
 180         return kgdb_info[ks->cpu].ret_state;
 181 }
 182
 183 void kdb_gdb_state_pass(char *buf)
 184 {
 185         gdbstub_state(kdb_ks, buf);
 186 }