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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Created by: Jason Wessel <[email protected]>
4 *
5 * Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
6 *
7 * This file is licensed under the terms of the GNU General Public
8 * License version 2. This program is licensed "as is" without any
9 * warranty of any kind, whether express or implied.
10 */
11
12#include <linux/kgdb.h>
13#include <linux/kdb.h>
14#include <linux/kdebug.h>
15#include <linux/export.h>
16#include <linux/hardirq.h>
17#include "kdb_private.h"
18#include "../debug_core.h"
19
20/*
21 * KDB interface to KGDB internals
22 */
23get_char_func kdb_poll_funcs[] = {
24 dbg_io_get_char,
25 NULL,
26 NULL,
27 NULL,
28 NULL,
29 NULL,
30};
31EXPORT_SYMBOL_GPL(kdb_poll_funcs);
32
33int kdb_poll_idx = 1;
34EXPORT_SYMBOL_GPL(kdb_poll_idx);
35
36static struct kgdb_state *kdb_ks;
37
38int kdb_common_init_state(struct kgdb_state *ks)
39{
40 kdb_initial_cpu = atomic_read(&kgdb_active);
41 kdb_current_task = kgdb_info[ks->cpu].task;
42 kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
43 return 0;
44}
45
46int kdb_common_deinit_state(void)
47{
48 kdb_initial_cpu = -1;
49 kdb_current_task = NULL;
50 kdb_current_regs = NULL;
51 return 0;
52}
53
54int kdb_stub(struct kgdb_state *ks)
55{
56 int error = 0;
57 kdb_bp_t *bp;
58 unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
59 kdb_reason_t reason = KDB_REASON_OOPS;
60 kdb_dbtrap_t db_result = KDB_DB_NOBPT;
61 int i;
62
63 kdb_ks = ks;
64 if (KDB_STATE(REENTRY)) {
65 reason = KDB_REASON_SWITCH;
66 KDB_STATE_CLEAR(REENTRY);
67 addr = instruction_pointer(ks->linux_regs);
68 }
69 ks->pass_exception = 0;
70 if (atomic_read(&kgdb_setting_breakpoint))
71 reason = KDB_REASON_KEYBOARD;
72
73 if (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP)
74 reason = KDB_REASON_SYSTEM_NMI;
75
76 else if (in_nmi())
77 reason = KDB_REASON_NMI;
78
79 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
80 if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
81 reason = KDB_REASON_BREAK;
82 db_result = KDB_DB_BPT;
83 if (addr != instruction_pointer(ks->linux_regs))
84 kgdb_arch_set_pc(ks->linux_regs, addr);
85 break;
86 }
87 }
88 if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
89 for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
90 if (bp->bp_free)
91 continue;
92 if (bp->bp_addr == addr) {
93 bp->bp_delay = 1;
94 bp->bp_delayed = 1;
95 /*
96 * SSBPT is set when the kernel debugger must single step a
97 * task in order to re-establish an instruction breakpoint
98 * which uses the instruction replacement mechanism. It is
99 * cleared by any action that removes the need to single-step
100 * the breakpoint.
101 */
102 reason = KDB_REASON_BREAK;
103 db_result = KDB_DB_BPT;
104 KDB_STATE_SET(SSBPT);
105 break;
106 }
107 }
108 }
109
110 if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
111 ks->signo == SIGTRAP) {
112 reason = KDB_REASON_SSTEP;
113 db_result = KDB_DB_BPT;
114 }
115 /* Set initial kdb state variables */
116 KDB_STATE_CLEAR(KGDB_TRANS);
117 kdb_common_init_state(ks);
118 /* Remove any breakpoints as needed by kdb and clear single step */
119 kdb_bp_remove();
120 KDB_STATE_CLEAR(DOING_SS);
121 KDB_STATE_SET(PAGER);
122 if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
123 ks->pass_exception = 1;
124 KDB_FLAG_SET(CATASTROPHIC);
125 }
126 /* set CATASTROPHIC if the system contains unresponsive processors */
127 for_each_online_cpu(i)
128 if (!kgdb_info[i].enter_kgdb)
129 KDB_FLAG_SET(CATASTROPHIC);
130 if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
131 KDB_STATE_CLEAR(SSBPT);
132 KDB_STATE_CLEAR(DOING_SS);
133 } else {
134 /* Start kdb main loop */
135 error = kdb_main_loop(KDB_REASON_ENTER, reason,
136 ks->err_code, db_result, ks->linux_regs);
137 }
138 /*
139 * Upon exit from the kdb main loop setup break points and restart
140 * the system based on the requested continue state
141 */
142 kdb_common_deinit_state();
143 KDB_STATE_CLEAR(PAGER);
144 if (error == KDB_CMD_KGDB) {
145 if (KDB_STATE(DOING_KGDB))
146 KDB_STATE_CLEAR(DOING_KGDB);
147 return DBG_PASS_EVENT;
148 }
149 kdb_bp_install(ks->linux_regs);
150 /* Set the exit state to a single step or a continue */
151 if (KDB_STATE(DOING_SS))
152 gdbstub_state(ks, "s");
153 else
154 gdbstub_state(ks, "c");
155
156 KDB_FLAG_CLEAR(CATASTROPHIC);
157
158 /* Invoke arch specific exception handling prior to system resume */
159 kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
160 if (ks->pass_exception)
161 kgdb_info[ks->cpu].ret_state = 1;
162 if (error == KDB_CMD_CPU) {
163 KDB_STATE_SET(REENTRY);
164 /*
165 * Force clear the single step bit because kdb emulates this
166 * differently vs the gdbstub
167 */
168 kgdb_single_step = 0;
169 return DBG_SWITCH_CPU_EVENT;
170 }
171 return kgdb_info[ks->cpu].ret_state;
172}
173
174void kdb_gdb_state_pass(char *buf)
175{
176 gdbstub_state(kdb_ks, buf);
177}