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 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) { 122 ks->pass_exception = 1; 123 KDB_FLAG_SET(CATASTROPHIC); 124 } 125 /* set CATASTROPHIC if the system contains unresponsive processors */ 126 for_each_online_cpu(i) 127 if (!kgdb_info[i].enter_kgdb) 128 KDB_FLAG_SET(CATASTROPHIC); 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 } 180