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 "kdb_private.h"
  16 #include "../debug_core.h"
  17
  18 /*
  19  * KDB interface to KGDB internals
  20  */
  21 get_char_func kdb_poll_funcs[] = {
  22         dbg_io_get_char,
  23         NULL,
  24         NULL,
  25         NULL,
  26         NULL,
  27         NULL,
  28 };
  29 EXPORT_SYMBOL_GPL(kdb_poll_funcs);
  30
  31 int kdb_poll_idx = 1;
  32 EXPORT_SYMBOL_GPL(kdb_poll_idx);
  33
  34 int kdb_stub(struct kgdb_state *ks)
  35 {
  36         int error = 0;
  37         kdb_bp_t *bp;
  38         unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
  39         kdb_reason_t reason = KDB_REASON_OOPS;
  40         kdb_dbtrap_t db_result = KDB_DB_NOBPT;
  41         int i;
  42
  43         if (KDB_STATE(REENTRY)) {
  44                 reason = KDB_REASON_SWITCH;
  45                 KDB_STATE_CLEAR(REENTRY);
  46                 addr = instruction_pointer(ks->linux_regs);
  47         }
  48         ks->pass_exception = 0;
  49         if (atomic_read(&kgdb_setting_breakpoint))
  50                 reason = KDB_REASON_KEYBOARD;
  51
  52         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  53                 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
  54                         reason = KDB_REASON_BREAK;
  55                         db_result = KDB_DB_BPT;
  56                         if (addr != instruction_pointer(ks->linux_regs))
  57                                 kgdb_arch_set_pc(ks->linux_regs, addr);
  58                         break;
  59                 }
  60         }
  61         if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
  62                 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
  63                         if (bp->bp_free)
  64                                 continue;
  65                         if (bp->bp_addr == addr) {
  66                                 bp->bp_delay = 1;
  67                                 bp->bp_delayed = 1;
  68         /*
  69          * SSBPT is set when the kernel debugger must single step a
  70          * task in order to re-establish an instruction breakpoint
  71          * which uses the instruction replacement mechanism.  It is
  72          * cleared by any action that removes the need to single-step
  73          * the breakpoint.
  74          */
  75                                 reason = KDB_REASON_BREAK;
  76                                 db_result = KDB_DB_BPT;
  77                                 KDB_STATE_SET(SSBPT);
  78                                 break;
  79                         }
  80                 }
  81         }
  82
  83         if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
  84                 ks->signo == SIGTRAP) {
  85                 reason = KDB_REASON_SSTEP;
  86                 db_result = KDB_DB_BPT;
  87         }
  88         /* Set initial kdb state variables */
  89         KDB_STATE_CLEAR(KGDB_TRANS);
  90         kdb_initial_cpu = atomic_read(&kgdb_active);
  91         kdb_current_task = kgdb_info[ks->cpu].task;
  92         kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
  93         /* Remove any breakpoints as needed by kdb and clear single step */
  94         kdb_bp_remove();
  95         KDB_STATE_CLEAR(DOING_SS);
  96         KDB_STATE_CLEAR(DOING_SSB);
  97         KDB_STATE_SET(PAGER);
  98         /* zero out any offline cpu data */
  99         for_each_present_cpu(i) {
 100                 if (!cpu_online(i)) {
 101                         kgdb_info[i].debuggerinfo = NULL;
 102                         kgdb_info[i].task = NULL;
 103                 }
 104         }
 105         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
 106                 ks->pass_exception = 1;
 107                 KDB_FLAG_SET(CATASTROPHIC);
 108         }
 109         if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 110                 KDB_STATE_CLEAR(SSBPT);
 111                 KDB_STATE_CLEAR(DOING_SS);
 112         } else {
 113                 /* Start kdb main loop */
 114                 error = kdb_main_loop(KDB_REASON_ENTER, reason,
 115                                       ks->err_code, db_result, ks->linux_regs);
 116         }
 117         /*
 118          * Upon exit from the kdb main loop setup break points and restart
 119          * the system based on the requested continue state
 120          */
 121         kdb_initial_cpu = -1;
 122         kdb_current_task = NULL;
 123         kdb_current_regs = NULL;
 124         KDB_STATE_CLEAR(PAGER);
 125         kdbnearsym_cleanup();
 126         if (error == KDB_CMD_KGDB) {
 127                 if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) {
 128         /*
 129          * This inteface glue which allows kdb to transition in into
 130          * the gdb stub.  In order to do this the '?' or '' gdb serial
 131          * packet response is processed here.  And then control is
 132          * passed to the gdbstub.
 133          */
 134                         if (KDB_STATE(DOING_KGDB))
 135                                 gdbstub_state(ks, "?");
 136                         else
 137                                 gdbstub_state(ks, "");
 138                         KDB_STATE_CLEAR(DOING_KGDB);
 139                         KDB_STATE_CLEAR(DOING_KGDB2);
 140                 }
 141                 return DBG_PASS_EVENT;
 142         }
 143         kdb_bp_install(ks->linux_regs);
 144         dbg_activate_sw_breakpoints();
 145         /* Set the exit state to a single step or a continue */
 146         if (KDB_STATE(DOING_SS))
 147                 gdbstub_state(ks, "s");
 148         else
 149                 gdbstub_state(ks, "c");
 150
 151         KDB_FLAG_CLEAR(CATASTROPHIC);
 152
 153         /* Invoke arch specific exception handling prior to system resume */
 154         kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
 155         if (ks->pass_exception)
 156                 kgdb_info[ks->cpu].ret_state = 1;
 157         if (error == KDB_CMD_CPU) {
 158                 KDB_STATE_SET(REENTRY);
 159                 /*
 160                  * Force clear the single step bit because kdb emulates this
 161                  * differently vs the gdbstub
 162                  */
 163                 kgdb_single_step = 0;
 164                 dbg_deactivate_sw_breakpoints();
 165                 return DBG_SWITCH_CPU_EVENT;
 166         }
 167         return kgdb_info[ks->cpu].ret_state;
 168 }
 169