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