1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <skiboot.h>
#include <processor.h>
#include <cpu.h>
#include <stack.h>
#include <mem_region.h>
#include <unistd.h>
#include <lock.h>
#define STACK_BUF_ENTRIES 60
static struct bt_entry bt_buf[STACK_BUF_ENTRIES];
extern uint32_t _stext, _etext;
/* Dumps backtrace to buffer */
void __nomcount ___backtrace(struct bt_entry *entries, unsigned int *count,
unsigned long r1,
unsigned long *token, unsigned long *r1_caller)
{
unsigned int room = *count;
unsigned long *fp = (unsigned long *)r1;
unsigned long top_adj = top_of_ram;
struct stack_frame *eframe = (struct stack_frame *)fp;
/* Assume one stack for early backtraces */
if (top_of_ram == SKIBOOT_BASE + SKIBOOT_SIZE)
top_adj = top_of_ram + STACK_SIZE;
*count = 0;
while(room) {
fp = (unsigned long *)fp[0];
if (!fp || (unsigned long)fp > top_adj)
break;
eframe = (struct stack_frame *)fp;
entries->sp = (unsigned long)fp;
entries->pc = fp[2];
entries++;
*count = (*count) + 1;
room--;
}
*r1_caller = eframe->gpr[1];
if (fp)
*token = eframe->gpr[0];
else
*token = -1UL;
}
void ___print_backtrace(unsigned int pir, struct bt_entry *entries,
unsigned int count, unsigned long token,
unsigned long r1_caller, char *out_buf,
unsigned int *len, bool symbols)
{
static char bt_text_buf[4096];
int i, l = 0, max;
char *buf = out_buf;
unsigned long bottom, top, normal_top, tbot, ttop;
char mark;
if (!out_buf) {
buf = bt_text_buf;
max = sizeof(bt_text_buf) - 16;
} else
max = *len - 1;
bottom = cpu_stack_bottom(pir);
normal_top = cpu_stack_top(pir);
top = cpu_emergency_stack_top(pir);
tbot = SKIBOOT_BASE;
ttop = (unsigned long)&_etext;
l += snprintf(buf, max, "CPU %04x Backtrace:\n", pir);
for (i = 0; i < count && l < max; i++) {
if (entries->sp < bottom || entries->sp > top)
mark = '!';
else if (entries->sp > normal_top)
mark = 'E';
else if (entries->pc < tbot || entries->pc > ttop)
mark = '*';
else
mark = ' ';
l += snprintf(buf + l, max - l,
" S: %016lx R: %016lx %c ",
entries->sp, entries->pc, mark);
if (symbols)
l += snprintf_symbol(buf + l, max - l, entries->pc);
l += snprintf(buf + l, max - l, "\n");
entries++;
}
if (token <= OPAL_LAST)
l += snprintf(buf + l, max - l, " --- OPAL call token: 0x%lx caller R1: 0x%016lx ---\n", token, r1_caller);
else if (token == -1UL)
l += snprintf(buf + l, max - l, " --- OPAL boot ---\n");
if (!out_buf)
write(stdout->fd, bt_text_buf, l);
buf[l++] = 0;
if (len)
*len = l;
}
/*
* To ensure that we always get backtrace output we bypass the usual console
* locking paths. The downside is that when multiple threads need to print
* a backtrace they garble each other. To prevent this we use a seperate
* lock to serialise printing of the dumps.
*/
struct lock bt_lock = LOCK_UNLOCKED;
void backtrace(void)
{
unsigned int ents = STACK_BUF_ENTRIES;
unsigned long token, r1_caller;
lock(&bt_lock);
___backtrace(bt_buf, &ents, (unsigned long)__builtin_frame_address(0),
&token, &r1_caller);
___print_backtrace(mfspr(SPR_PIR), bt_buf, ents, token, r1_caller,
NULL, NULL, true);
unlock(&bt_lock);
}
void __nomcount __stack_chk_fail(void);
void __nomcount __stack_chk_fail(void)
{
static bool failed_once;
if (failed_once)
return;
failed_once = true;
prlog(PR_EMERG, "Stack corruption detected !\n");
abort();
}
#ifdef STACK_CHECK_ENABLED
static int64_t lowest_stack_mark = LONG_MAX;
static struct lock stack_check_lock = LOCK_UNLOCKED;
void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr);
void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr)
{
struct cpu_thread *c = this_cpu();
uint64_t base = (uint64_t)c;
uint64_t bot = base + sizeof(struct cpu_thread);
int64_t mark = sp - bot;
uint64_t top = base + NORMAL_STACK_SIZE;
/*
* Don't check the emergency stack just yet.
*/
if (c->in_opal_call > 1)
return;
/*
* Don't re-enter on this CPU or don't enter at all if somebody
* has spotted an overflow
*/
if (c->in_mcount)
return;
c->in_mcount = true;
/* Capture lowest stack for this thread */
if (mark < c->stack_bot_mark) {
unsigned int count = CPU_BACKTRACE_SIZE;
lock(&stack_check_lock);
c->stack_bot_mark = mark;
c->stack_bot_pc = lr;
c->stack_bot_tok = c->current_token;
__backtrace(c->stack_bot_bt, &count);
c->stack_bot_bt_count = count;
unlock(&stack_check_lock);
}
/* Stack is within bounds ? check for warning and bail */
if (sp >= (bot + STACK_SAFETY_GAP) && sp < top) {
if (mark < STACK_WARNING_GAP) {
prlog(PR_EMERG, "CPU %04x Stack usage danger !"
" pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
c->pir, lr, sp, mark, c->current_token);
backtrace();
}
c->in_mcount = false;
return;
}
prlog(PR_EMERG, "CPU %04x Stack overflow detected !"
" pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
c->pir, lr, sp, mark, c->current_token);
abort();
}
void check_stacks(void)
{
struct cpu_thread *c, *lowest = NULL;
/* We should never call that from mcount */
assert(!this_cpu()->in_mcount);
/* Mark ourselves "in_mcount" to avoid deadlock on stack
* check lock
*/
this_cpu()->in_mcount = true;
for_each_cpu(c) {
if (!c->stack_bot_mark ||
c->stack_bot_mark >= lowest_stack_mark)
continue;
lock(&stack_check_lock);
if (c->stack_bot_mark < lowest_stack_mark) {
lowest = c;
lowest_stack_mark = c->stack_bot_mark;
}
unlock(&stack_check_lock);
}
if (lowest) {
lock(&stack_check_lock);
prlog(PR_NOTICE, "CPU %04x lowest stack mark %lld bytes left"
" pc=%08llx token=%lld\n",
lowest->pir, lowest->stack_bot_mark, lowest->stack_bot_pc,
lowest->stack_bot_tok);
__print_backtrace(lowest->pir, lowest->stack_bot_bt,
lowest->stack_bot_bt_count, NULL, NULL, true);
unlock(&stack_check_lock);
}
this_cpu()->in_mcount = false;
}
#endif /* STACK_CHECK_ENABLED */
|
