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 */
22get_char_func kdb_poll_funcs[] = {
23	dbg_io_get_char,
24	NULL,
25	NULL,
26	NULL,
27	NULL,
28	NULL,
29};
30EXPORT_SYMBOL_GPL(kdb_poll_funcs);
31
32int kdb_poll_idx = 1;
33EXPORT_SYMBOL_GPL(kdb_poll_idx);
34
35static struct kgdb_state *kdb_ks;
36
37int 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
45int 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
53int 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
173void kdb_gdb_state_pass(char *buf)
174{
175	gdbstub_state(kdb_ks, buf);
176}
177