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 "kdb_private.h" 15 #include "../debug_core.h" 16 17 /* 18 * KDB interface to KGDB internals 19 */ 20 get_char_func kdb_poll_funcs[] = { 21 dbg_io_get_char, 22 NULL, 23 NULL, 24 NULL, 25 NULL, 26 NULL, 27 }; 28 EXPORT_SYMBOL_GPL(kdb_poll_funcs); 29 30 int kdb_poll_idx = 1; 31 EXPORT_SYMBOL_GPL(kdb_poll_idx); 32 33 static struct kgdb_state *kdb_ks; 34 35 int kdb_stub(struct kgdb_state *ks) 36 { 37 int error = 0; 38 kdb_bp_t *bp; 39 unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); 40 kdb_reason_t reason = KDB_REASON_OOPS; 41 kdb_dbtrap_t db_result = KDB_DB_NOBPT; 42 int i; 43 44 kdb_ks = ks; 45 if (KDB_STATE(REENTRY)) { 46 reason = KDB_REASON_SWITCH; 47 KDB_STATE_CLEAR(REENTRY); 48 addr = instruction_pointer(ks->linux_regs); 49 } 50 ks->pass_exception = 0; 51 if (atomic_read(&kgdb_setting_breakpoint)) 52 reason = KDB_REASON_KEYBOARD; 53 54 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 55 if ((bp->bp_enabled) && (bp->bp_addr == addr)) { 56 reason = KDB_REASON_BREAK; 57 db_result = KDB_DB_BPT; 58 if (addr != instruction_pointer(ks->linux_regs)) 59 kgdb_arch_set_pc(ks->linux_regs, addr); 60 break; 61 } 62 } 63 if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) { 64 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 65 if (bp->bp_free) 66 continue; 67 if (bp->bp_addr == addr) { 68 bp->bp_delay = 1; 69 bp->bp_delayed = 1; 70 /* 71 * SSBPT is set when the kernel debugger must single step a 72 * task in order to re-establish an instruction breakpoint 73 * which uses the instruction replacement mechanism. It is 74 * cleared by any action that removes the need to single-step 75 * the breakpoint. 76 */ 77 reason = KDB_REASON_BREAK; 78 db_result = KDB_DB_BPT; 79 KDB_STATE_SET(SSBPT); 80 break; 81 } 82 } 83 } 84 85 if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 && 86 ks->signo == SIGTRAP) { 87 reason = KDB_REASON_SSTEP; 88 db_result = KDB_DB_BPT; 89 } 90 /* Set initial kdb state variables */ 91 KDB_STATE_CLEAR(KGDB_TRANS); 92 kdb_initial_cpu = atomic_read(&kgdb_active); 93 kdb_current_task = kgdb_info[ks->cpu].task; 94 kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo; 95 /* Remove any breakpoints as needed by kdb and clear single step */ 96 kdb_bp_remove(); 97 KDB_STATE_CLEAR(DOING_SS); 98 KDB_STATE_CLEAR(DOING_SSB); 99 KDB_STATE_SET(PAGER); 100 /* zero out any offline cpu data */ 101 for_each_present_cpu(i) { 102 if (!cpu_online(i)) { 103 kgdb_info[i].debuggerinfo = NULL; 104 kgdb_info[i].task = NULL; 105 } 106 } 107 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) { 108 ks->pass_exception = 1; 109 KDB_FLAG_SET(CATASTROPHIC); 110 } 111 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) { 112 KDB_STATE_CLEAR(SSBPT); 113 KDB_STATE_CLEAR(DOING_SS); 114 } else { 115 /* Start kdb main loop */ 116 error = kdb_main_loop(KDB_REASON_ENTER, reason, 117 ks->err_code, db_result, ks->linux_regs); 118 } 119 /* 120 * Upon exit from the kdb main loop setup break points and restart 121 * the system based on the requested continue state 122 */ 123 kdb_initial_cpu = -1; 124 kdb_current_task = NULL; 125 kdb_current_regs = NULL; 126 KDB_STATE_CLEAR(PAGER); 127 kdbnearsym_cleanup(); 128 if (error == KDB_CMD_KGDB) { 129 if (KDB_STATE(DOING_KGDB)) 130 KDB_STATE_CLEAR(DOING_KGDB); 131 return DBG_PASS_EVENT; 132 } 133 kdb_bp_install(ks->linux_regs); 134 dbg_activate_sw_breakpoints(); 135 /* Set the exit state to a single step or a continue */ 136 if (KDB_STATE(DOING_SS)) 137 gdbstub_state(ks, "s"); 138 else 139 gdbstub_state(ks, "c"); 140 141 KDB_FLAG_CLEAR(CATASTROPHIC); 142 143 /* Invoke arch specific exception handling prior to system resume */ 144 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e"); 145 if (ks->pass_exception) 146 kgdb_info[ks->cpu].ret_state = 1; 147 if (error == KDB_CMD_CPU) { 148 KDB_STATE_SET(REENTRY); 149 /* 150 * Force clear the single step bit because kdb emulates this 151 * differently vs the gdbstub 152 */ 153 kgdb_single_step = 0; 154 dbg_deactivate_sw_breakpoints(); 155 return DBG_SWITCH_CPU_EVENT; 156 } 157 return kgdb_info[ks->cpu].ret_state; 158 } 159 160 void kdb_gdb_state_pass(char *buf) 161 { 162 gdbstub_state(kdb_ks, buf); 163 } 164