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 } 169