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 "kdb_private.h"
16 #include "../debug_core.h"
17
18 /*
19 * KDB interface to KGDB internals
20 */
21 get_char_func kdb_poll_funcs[] = {
22 dbg_io_get_char,
23 NULL,
24 NULL,
25 NULL,
26 NULL,
27 NULL,
28 };
29 EXPORT_SYMBOL_GPL(kdb_poll_funcs);
30
31 int kdb_poll_idx = 1;
32 EXPORT_SYMBOL_GPL(kdb_poll_idx);
33
34 static struct kgdb_state *kdb_ks;
35
kdb_stub(struct kgdb_state * ks)36 int kdb_stub(struct kgdb_state *ks)
37 {
38 int error = 0;
39 kdb_bp_t *bp;
40 unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
41 kdb_reason_t reason = KDB_REASON_OOPS;
42 kdb_dbtrap_t db_result = KDB_DB_NOBPT;
43 int i;
44
45 kdb_ks = ks;
46 if (KDB_STATE(REENTRY)) {
47 reason = KDB_REASON_SWITCH;
48 KDB_STATE_CLEAR(REENTRY);
49 addr = instruction_pointer(ks->linux_regs);
50 }
51 ks->pass_exception = 0;
52 if (atomic_read(&kgdb_setting_breakpoint))
53 reason = KDB_REASON_KEYBOARD;
54
55 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
56 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
57 reason = KDB_REASON_BREAK;
58 db_result = KDB_DB_BPT;
59 if (addr != instruction_pointer(ks->linux_regs))
60 kgdb_arch_set_pc(ks->linux_regs, addr);
61 break;
62 }
63 }
64 if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
65 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
66 if (bp->bp_free)
67 continue;
68 if (bp->bp_addr == addr) {
69 bp->bp_delay = 1;
70 bp->bp_delayed = 1;
71 /*
72 * SSBPT is set when the kernel debugger must single step a
73 * task in order to re-establish an instruction breakpoint
74 * which uses the instruction replacement mechanism. It is
75 * cleared by any action that removes the need to single-step
76 * the breakpoint.
77 */
78 reason = KDB_REASON_BREAK;
79 db_result = KDB_DB_BPT;
80 KDB_STATE_SET(SSBPT);
81 break;
82 }
83 }
84 }
85
86 if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
87 ks->signo == SIGTRAP) {
88 reason = KDB_REASON_SSTEP;
89 db_result = KDB_DB_BPT;
90 }
91 /* Set initial kdb state variables */
92 KDB_STATE_CLEAR(KGDB_TRANS);
93 kdb_initial_cpu = atomic_read(&kgdb_active);
94 kdb_current_task = kgdb_info[ks->cpu].task;
95 kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
96 /* Remove any breakpoints as needed by kdb and clear single step */
97 kdb_bp_remove();
98 KDB_STATE_CLEAR(DOING_SS);
99 KDB_STATE_CLEAR(DOING_SSB);
100 KDB_STATE_SET(PAGER);
101 /* zero out any offline cpu data */
102 for_each_present_cpu(i) {
103 if (!cpu_online(i)) {
104 kgdb_info[i].debuggerinfo = NULL;
105 kgdb_info[i].task = NULL;
106 }
107 }
108 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
109 ks->pass_exception = 1;
110 KDB_FLAG_SET(CATASTROPHIC);
111 }
112 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
113 KDB_STATE_CLEAR(SSBPT);
114 KDB_STATE_CLEAR(DOING_SS);
115 } else {
116 /* Start kdb main loop */
117 error = kdb_main_loop(KDB_REASON_ENTER, reason,
118 ks->err_code, db_result, ks->linux_regs);
119 }
120 /*
121 * Upon exit from the kdb main loop setup break points and restart
122 * the system based on the requested continue state
123 */
124 kdb_initial_cpu = -1;
125 kdb_current_task = NULL;
126 kdb_current_regs = NULL;
127 KDB_STATE_CLEAR(PAGER);
128 kdbnearsym_cleanup();
129 if (error == KDB_CMD_KGDB) {
130 if (KDB_STATE(DOING_KGDB))
131 KDB_STATE_CLEAR(DOING_KGDB);
132 return DBG_PASS_EVENT;
133 }
134 kdb_bp_install(ks->linux_regs);
135 dbg_activate_sw_breakpoints();
136 /* Set the exit state to a single step or a continue */
137 if (KDB_STATE(DOING_SS))
138 gdbstub_state(ks, "s");
139 else
140 gdbstub_state(ks, "c");
141
142 KDB_FLAG_CLEAR(CATASTROPHIC);
143
144 /* Invoke arch specific exception handling prior to system resume */
145 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
146 if (ks->pass_exception)
147 kgdb_info[ks->cpu].ret_state = 1;
148 if (error == KDB_CMD_CPU) {
149 KDB_STATE_SET(REENTRY);
150 /*
151 * Force clear the single step bit because kdb emulates this
152 * differently vs the gdbstub
153 */
154 kgdb_single_step = 0;
155 dbg_deactivate_sw_breakpoints();
156 return DBG_SWITCH_CPU_EVENT;
157 }
158 return kgdb_info[ks->cpu].ret_state;
159 }
160
kdb_gdb_state_pass(char * buf)161 void kdb_gdb_state_pass(char *buf)
162 {
163 gdbstub_state(kdb_ks, buf);
164 }
165