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 int kdb_stub(struct kgdb_state *ks) 34 { 35 int error = 0; 36 kdb_bp_t *bp; 37 unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); 38 kdb_reason_t reason = KDB_REASON_OOPS; 39 kdb_dbtrap_t db_result = KDB_DB_NOBPT; 40 int i; 41 42 if (KDB_STATE(REENTRY)) { 43 reason = KDB_REASON_SWITCH; 44 KDB_STATE_CLEAR(REENTRY); 45 addr = instruction_pointer(ks->linux_regs); 46 } 47 ks->pass_exception = 0; 48 if (atomic_read(&kgdb_setting_breakpoint)) 49 reason = KDB_REASON_KEYBOARD; 50 51 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 52 if ((bp->bp_enabled) && (bp->bp_addr == addr)) { 53 reason = KDB_REASON_BREAK; 54 db_result = KDB_DB_BPT; 55 if (addr != instruction_pointer(ks->linux_regs)) 56 kgdb_arch_set_pc(ks->linux_regs, addr); 57 break; 58 } 59 } 60 if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) { 61 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { 62 if (bp->bp_free) 63 continue; 64 if (bp->bp_addr == addr) { 65 bp->bp_delay = 1; 66 bp->bp_delayed = 1; 67 /* 68 * SSBPT is set when the kernel debugger must single step a 69 * task in order to re-establish an instruction breakpoint 70 * which uses the instruction replacement mechanism. It is 71 * cleared by any action that removes the need to single-step 72 * the breakpoint. 73 */ 74 reason = KDB_REASON_BREAK; 75 db_result = KDB_DB_BPT; 76 KDB_STATE_SET(SSBPT); 77 break; 78 } 79 } 80 } 81 82 if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 && 83 ks->signo == SIGTRAP) { 84 reason = KDB_REASON_SSTEP; 85 db_result = KDB_DB_BPT; 86 } 87 /* Set initial kdb state variables */ 88 KDB_STATE_CLEAR(KGDB_TRANS); 89 kdb_initial_cpu = ks->cpu; 90 kdb_current_task = kgdb_info[ks->cpu].task; 91 kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo; 92 /* Remove any breakpoints as needed by kdb and clear single step */ 93 kdb_bp_remove(); 94 KDB_STATE_CLEAR(DOING_SS); 95 KDB_STATE_CLEAR(DOING_SSB); 96 KDB_STATE_SET(PAGER); 97 /* zero out any offline cpu data */ 98 for_each_present_cpu(i) { 99 if (!cpu_online(i)) { 100 kgdb_info[i].debuggerinfo = NULL; 101 kgdb_info[i].task = NULL; 102 } 103 } 104 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) { 105 ks->pass_exception = 1; 106 KDB_FLAG_SET(CATASTROPHIC); 107 } 108 kdb_initial_cpu = ks->cpu; 109 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) { 110 KDB_STATE_CLEAR(SSBPT); 111 KDB_STATE_CLEAR(DOING_SS); 112 } else { 113 /* Start kdb main loop */ 114 error = kdb_main_loop(KDB_REASON_ENTER, reason, 115 ks->err_code, db_result, ks->linux_regs); 116 } 117 /* 118 * Upon exit from the kdb main loop setup break points and restart 119 * the system based on the requested continue state 120 */ 121 kdb_initial_cpu = -1; 122 kdb_current_task = NULL; 123 kdb_current_regs = NULL; 124 KDB_STATE_CLEAR(PAGER); 125 kdbnearsym_cleanup(); 126 if (error == KDB_CMD_KGDB) { 127 if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) { 128 /* 129 * This inteface glue which allows kdb to transition in into 130 * the gdb stub. In order to do this the '?' or '' gdb serial 131 * packet response is processed here. And then control is 132 * passed to the gdbstub. 133 */ 134 if (KDB_STATE(DOING_KGDB)) 135 gdbstub_state(ks, "?"); 136 else 137 gdbstub_state(ks, ""); 138 KDB_STATE_CLEAR(DOING_KGDB); 139 KDB_STATE_CLEAR(DOING_KGDB2); 140 } 141 return DBG_PASS_EVENT; 142 } 143 kdb_bp_install(ks->linux_regs); 144 dbg_activate_sw_breakpoints(); 145 /* Set the exit state to a single step or a continue */ 146 if (KDB_STATE(DOING_SS)) 147 gdbstub_state(ks, "s"); 148 else 149 gdbstub_state(ks, "c"); 150 151 KDB_FLAG_CLEAR(CATASTROPHIC); 152 153 /* Invoke arch specific exception handling prior to system resume */ 154 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e"); 155 if (ks->pass_exception) 156 kgdb_info[ks->cpu].ret_state = 1; 157 if (error == KDB_CMD_CPU) { 158 KDB_STATE_SET(REENTRY); 159 /* 160 * Force clear the single step bit because kdb emulates this 161 * differently vs the gdbstub 162 */ 163 kgdb_single_step = 0; 164 dbg_deactivate_sw_breakpoints(); 165 return DBG_SWITCH_CPU_EVENT; 166 } 167 return kgdb_info[ks->cpu].ret_state; 168 } 169 170