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