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