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
kdb_common_init_state(struct kgdb_state * ks)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
kdb_common_deinit_state(void)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
kdb_stub(struct kgdb_state * ks)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 /* zero out any offline cpu data */
122 for_each_present_cpu(i) {
123 if (!cpu_online(i)) {
124 kgdb_info[i].debuggerinfo = NULL;
125 kgdb_info[i].task = NULL;
126 }
127 }
128 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
129 ks->pass_exception = 1;
130 KDB_FLAG_SET(CATASTROPHIC);
131 }
132 /* set CATASTROPHIC if the system contains unresponsive processors */
133 for_each_online_cpu(i)
134 if (!kgdb_info[i].enter_kgdb)
135 KDB_FLAG_SET(CATASTROPHIC);
136 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
137 KDB_STATE_CLEAR(SSBPT);
138 KDB_STATE_CLEAR(DOING_SS);
139 } else {
140 /* Start kdb main loop */
141 error = kdb_main_loop(KDB_REASON_ENTER, reason,
142 ks->err_code, db_result, ks->linux_regs);
143 }
144 /*
145 * Upon exit from the kdb main loop setup break points and restart
146 * the system based on the requested continue state
147 */
148 kdb_common_deinit_state();
149 KDB_STATE_CLEAR(PAGER);
150 kdbnearsym_cleanup();
151 if (error == KDB_CMD_KGDB) {
152 if (KDB_STATE(DOING_KGDB))
153 KDB_STATE_CLEAR(DOING_KGDB);
154 return DBG_PASS_EVENT;
155 }
156 kdb_bp_install(ks->linux_regs);
157 dbg_activate_sw_breakpoints();
158 /* Set the exit state to a single step or a continue */
159 if (KDB_STATE(DOING_SS))
160 gdbstub_state(ks, "s");
161 else
162 gdbstub_state(ks, "c");
163
164 KDB_FLAG_CLEAR(CATASTROPHIC);
165
166 /* Invoke arch specific exception handling prior to system resume */
167 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
168 if (ks->pass_exception)
169 kgdb_info[ks->cpu].ret_state = 1;
170 if (error == KDB_CMD_CPU) {
171 KDB_STATE_SET(REENTRY);
172 /*
173 * Force clear the single step bit because kdb emulates this
174 * differently vs the gdbstub
175 */
176 kgdb_single_step = 0;
177 dbg_deactivate_sw_breakpoints();
178 return DBG_SWITCH_CPU_EVENT;
179 }
180 return kgdb_info[ks->cpu].ret_state;
181 }
182
kdb_gdb_state_pass(char * buf)183 void kdb_gdb_state_pass(char *buf)
184 {
185 gdbstub_state(kdb_ks, buf);
186 }
187
