1 JITDUMP specification version 2
2 Last Revised: 09/15/2016
3 Author: Stephane Eranian <eranian@gmail.com>
4
5 ----------------------------------------------
6 | Revision | Date | Description
7 ----------------------------------------------
8 | 1 | 09/07/2016 | Initial revision
9 ----------------------------------------------
10 | 2 | 09/15/2016 | Add JIT_CODE_UNWIND
11 ----------------------------------------------
12
13
14 I/ Introduction
15
16
17 This document describes the jitdump file forma
18
19 The format is not specific to any particular p
20
21 The format of the file is binary. It is self-d
22
23
24 II/ Overview of the format
25
26
27 The format requires only sequential accesses,
28
29 The header is followed by a series of records,
30
31 Each entry in the file is timestamped. All tim
32
33
34 III/ Jitdump file header format
35
36 Each jitdump file starts with a fixed size hea
37
38
39 * uint32_t magic : a magic number tagging
40 * uint32_t version : a 4-byte value represen
41 * uint32_t total_size: size in bytes of file h
42 * uint32_t elf_mach : ELF architecture encodi
43 * uint32_t pad1 : padding. Reserved for f
44 * uint32_t pid : JIT runtime process ide
45 * uint64_t timestamp : timestamp of when the f
46 * uint64_t flags : a bitmask of flags
47
48 The flags currently defined are as follows:
49 * bit 0: JITDUMP_FLAGS_ARCH_TIMESTAMP : set i
50
51 IV/ Record header
52
53 The file header is immediately followed by rec
54
55 The record header is specified in order as fol
56 * uint32_t id : a value identifying the
57 * uint32_t total_size: the size in bytes of th
58 * uint64_t timestamp : a timestamp of when the
59
60 The following record types are defined:
61 * Value 0 : JIT_CODE_LOAD : record descr
62 * Value 1 : JIT_CODE_MOVE : record descr
63 * Value 2 : JIT_CODE_DEBUG_INFO: record descr
64 * Value 3 : JIT_CODE_CLOSE : record marki
65 * Value 4 : JIT_CODE_UNWINDING_INFO: record d
66
67 The payload of the record must immediately fo
68
69 V/ JIT_CODE_LOAD record
70
71
72 The record has the following fields followin
73 * uint32_t pid: OS process id of the runtime
74 * uint32_t tid: OS thread identification of
75 * uint64_t vma: virtual address of jitted co
76 * uint64_t code_addr: code start address for
77 * uint64_t code_size: size in bytes of the g
78 * uint64_t code_index: unique identifier for
79 * char[n]: function name in ASCII including
80 * native code: raw byte encoding of the jitt
81
82 The record header total_size field is inclus
83 * record header
84 * fixed-sized fields
85 * function name string, including terminatio
86 * native code length
87 * record specific variable data (e.g., array
88
89 The code_index is used to uniquely identify ea
90
91 The format supports empty functions with no na
92
93
94 VI/ JIT_CODE_MOVE record
95
96 The record type is optional.
97
98 The record has the following fields followin
99 * uint32_t pid : OS process id of t
100 * uint32_t tid : OS thread identifi
101 * uint64_t vma : new virtual addres
102 * uint64_t old_code_addr: previous code addr
103 * uint64_t new_code_addr: alternate new code
104 * uint64_t code_size : size in bytes of t
105 * uint64_t code_index : index referring to
106
107
108 The MOVE record can be used in case an already
109
110 The JIT_CODE_MOVE record cannot come before th
111
112 The code size of the function cannot change.
113
114
115 VII/ JIT_DEBUG_INFO record
116
117 The record type is optional.
118
119 The record contains source lines debug informa
120
121 The record has the following fields following
122 * uint64_t code_addr: address of function fo
123 * uint64_t nr_entry : number of debug entrie
124 * debug_entry[n]: array of nr_entry debug en
125
126 The debug_entry describes the source line info
127 * uint64_t code_addr: address of function for
128 * uint32_t line : source file line number
129 * uint32_t discrim : column discriminator, 0
130 * char name[n] : source file name in ASCI
131
132 The debug_entry entries are saved in sequence
133 They need to be walked sequentially. The next
134
135 IMPORTANT:
136 The JIT_CODE_DEBUG for a given function must
137
138
139 VIII/ JIT_CODE_CLOSE record
140
141
142 The record type is optional.
143
144 The record is used as a marker for the end of
145
146 The JIT_CODE_CLOSE record does not have any sp
147
148
149 IX/ JIT_CODE_UNWINDING_INFO
150
151
152 The record type is optional.
153
154 The record is used to describe the unwinding i
155
156 The record has the following fields following
157
158 uint64_t unwind_data_size : the size in byte
159 uint64_t eh_frame_hdr_size : the size in byte
160 uint64_t mapped_size : the size of the
161 const char unwinding_data[n]: an array of unwi
162
163
164 The EH Frame header follows the Linux Standard
165
166
167 The EH Frame follows the LSB specification as
168
169
170 NOTE: The mapped_size is generally either the
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