1 /* 2 * Created by: Jason Wessel <[email protected]> 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 (in_nmi()) 73 reason = KDB_REASON_NMI; 74 75 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 76 if ((bp->bp_enabled) && (bp->bp_addr == addr)) { 77 reason = KDB_REASON_BREAK; 78 db_result = KDB_DB_BPT; 79 if (addr != instruction_pointer(ks->linux_regs)) 80 kgdb_arch_set_pc(ks->linux_regs, addr); 81 break; 82 } 83 } 84 if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) { 85 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 86 if (bp->bp_free) 87 continue; 88 if (bp->bp_addr == addr) { 89 bp->bp_delay = 1; 90 bp->bp_delayed = 1; 91 /* 92 * SSBPT is set when the kernel debugger must single step a 93 * task in order to re-establish an instruction breakpoint 94 * which uses the instruction replacement mechanism. It is 95 * cleared by any action that removes the need to single-step 96 * the breakpoint. 97 */ 98 reason = KDB_REASON_BREAK; 99 db_result = KDB_DB_BPT; 100 KDB_STATE_SET(SSBPT); 101 break; 102 } 103 } 104 } 105 106 if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 && 107 ks->signo == SIGTRAP) { 108 reason = KDB_REASON_SSTEP; 109 db_result = KDB_DB_BPT; 110 } 111 /* Set initial kdb state variables */ 112 KDB_STATE_CLEAR(KGDB_TRANS); 113 kdb_common_init_state(ks); 114 /* Remove any breakpoints as needed by kdb and clear single step */ 115 kdb_bp_remove(); 116 KDB_STATE_CLEAR(DOING_SS); 117 KDB_STATE_CLEAR(DOING_SSB); 118 KDB_STATE_SET(PAGER); 119 /* zero out any offline cpu data */ 120 for_each_present_cpu(i) { 121 if (!cpu_online(i)) { 122 kgdb_info[i].debuggerinfo = NULL; 123 kgdb_info[i].task = NULL; 124 } 125 } 126 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) { 127 ks->pass_exception = 1; 128 KDB_FLAG_SET(CATASTROPHIC); 129 } 130 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) { 131 KDB_STATE_CLEAR(SSBPT); 132 KDB_STATE_CLEAR(DOING_SS); 133 } else { 134 /* Start kdb main loop */ 135 error = kdb_main_loop(KDB_REASON_ENTER, reason, 136 ks->err_code, db_result, ks->linux_regs); 137 } 138 /* 139 * Upon exit from the kdb main loop setup break points and restart 140 * the system based on the requested continue state 141 */ 142 kdb_common_deinit_state(); 143 KDB_STATE_CLEAR(PAGER); 144 kdbnearsym_cleanup(); 145 if (error == KDB_CMD_KGDB) { 146 if (KDB_STATE(DOING_KGDB)) 147 KDB_STATE_CLEAR(DOING_KGDB); 148 return DBG_PASS_EVENT; 149 } 150 kdb_bp_install(ks->linux_regs); 151 dbg_activate_sw_breakpoints(); 152 /* Set the exit state to a single step or a continue */ 153 if (KDB_STATE(DOING_SS)) 154 gdbstub_state(ks, "s"); 155 else 156 gdbstub_state(ks, "c"); 157 158 KDB_FLAG_CLEAR(CATASTROPHIC); 159 160 /* Invoke arch specific exception handling prior to system resume */ 161 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e"); 162 if (ks->pass_exception) 163 kgdb_info[ks->cpu].ret_state = 1; 164 if (error == KDB_CMD_CPU) { 165 KDB_STATE_SET(REENTRY); 166 /* 167 * Force clear the single step bit because kdb emulates this 168 * differently vs the gdbstub 169 */ 170 kgdb_single_step = 0; 171 dbg_deactivate_sw_breakpoints(); 172 return DBG_SWITCH_CPU_EVENT; 173 } 174 return kgdb_info[ks->cpu].ret_state; 175 } 176 177 void kdb_gdb_state_pass(char *buf) 178 { 179 gdbstub_state(kdb_ks, buf); 180 } 181