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
|
/* Emulation of eBPF helpers.
Copyright (C) 2020-2021 Free Software Foundation, Inc.
This file is part of GDB, the GNU debugger.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* BPF programs rely on the existence of several helper functions,
which are provided by the kernel. This simulator provides an
implementation of the helpers, which can be customized by the
user. */
/* This must come before any other includes. */
#include "defs.h"
#define WANT_CPU_BPFBF
#define WANT_CPU bpfbf
#include "sim-main.h"
#include "cgen-mem.h"
#include "cgen-ops.h"
#include "cpu.h"
#include "bpf-helpers.h"
/* bpf_trace_printk is a printk-like facility for debugging.
In the kernel, it appends a line to the Linux's tracing debugging
interface.
In this simulator, it uses the simulator's tracing interface
instead.
The format tags recognized by this helper are:
%d, %i, %u, %x, %ld, %li, %lu, %lx, %lld, %lli, %llu, %llx,
%p, %s
A maximum of three tags are supported.
This helper returns the number of bytes written, or a negative
value in case of failure. */
int
bpf_trace_printk (SIM_CPU *current_cpu)
{
va_list ap;
SIM_DESC sd = CPU_STATE (current_cpu);
DI fmt_address;
uint32_t size, tags_processed;
size_t i, bytes_written = 0;
/* The first argument is the format string, which is passed as a
pointer in %r1. */
fmt_address = GET_H_GPR (1);
/* The second argument is the length of the format string, as an
unsigned 32-bit number in %r2. */
size = GET_H_GPR (2);
/* Read the format string from the memory pointed by %r2, printing
out the stuff as we go. There is a maximum of three format tags
supported, which are read from %r3, %r4 and %r5 respectively. */
for (i = 0, tags_processed = 0; i < size;)
{
UDI value;
QI c = GETMEMUQI (current_cpu, CPU_PC_GET (current_cpu),
fmt_address + i);
switch (c)
{
case '%':
/* Check we are not exceeding the limit of three format
tags. */
if (tags_processed > 2)
return -1; /* XXX look for kernel error code. */
/* Depending on the kind of tag, extract the value from the
proper argument. */
if (i++ >= size)
return -1; /* XXX look for kernel error code. */
value = GET_H_GPR (3 + tags_processed);
switch ((GETMEMUQI (current_cpu, CPU_PC_GET (current_cpu),
fmt_address + i)))
{
case 'd':
trace_printf (sd, current_cpu, "%d", (int) value);
break;
case 'i':
trace_printf (sd, current_cpu, "%i", (int) value);
break;
case 'u':
trace_printf (sd, current_cpu, "%u", (unsigned int) value);
break;
case 'x':
trace_printf (sd, current_cpu, "%x", (unsigned int) value);
break;
case 'l':
{
if (i++ >= size)
return -1;
switch (GETMEMUQI (current_cpu, CPU_PC_GET (current_cpu),
fmt_address + i))
{
case 'd':
trace_printf (sd, current_cpu, "%ld", (long) value);
break;
case 'i':
trace_printf (sd, current_cpu, "%li", (long) value);
break;
case 'u':
trace_printf (sd, current_cpu, "%lu", (unsigned long) value);
break;
case 'x':
trace_printf (sd, current_cpu, "%lx", (unsigned long) value);
break;
case 'l':
{
if (i++ >= size)
return -1;
switch (GETMEMUQI (current_cpu, CPU_PC_GET (current_cpu),
fmt_address + i)) {
case 'd':
trace_printf (sd, current_cpu, "%lld", (long long) value);
break;
case 'i':
trace_printf (sd, current_cpu, "%lli", (long long) value);
break;
case 'u':
trace_printf (sd, current_cpu, "%llu", (unsigned long long) value);
break;
case 'x':
trace_printf (sd, current_cpu, "%llx", (unsigned long long) value);
break;
default:
assert (0);
break;
}
break;
}
default:
assert (0);
break;
}
break;
}
default:
/* XXX completeme */
assert (0);
break;
}
tags_processed++;
i++;
break;
case '\0':
i = size;
break;
default:
trace_printf (sd, current_cpu, "%c", c);
bytes_written++;
i++;
break;
}
}
return bytes_written;
}
|
