Aaron Plattner
ab84cf9191
These offsets can be useful to decode stack traces through modules that don't
have symbol names. For example, with a simple test that crashes after calling
through several static functions, systemd-coredump reports this:
Oct 17 : Process 640333 (a.out) of user 1000 dumped core.
Stack trace of thread 640333:
#0 0x00005562c2b9f11d n/a (/tmp/a.out)
#1 0x00005562c2b9f12d n/a (/tmp/a.out)
#2 0x00005562c2b9f139 n/a (/tmp/a.out)
#3 0x00005562c2b9f145 n/a (/tmp/a.out)
#4 0x00007fc768b39153 __libc_start_main (libc.so.6)
#5 0x00005562c2b9f04e n/a (/tmp/a.out)
With this change:
Stack trace of thread 666897:
#0 0x0000555668fbe11d n/a (/tmp/a.out + 0x111d)
#1 0x0000555668fbe12d n/a (/tmp/a.out + 0x112d)
#2 0x0000555668fbe139 n/a (/tmp/a.out + 0x1139)
#3 0x0000555668fbe145 n/a (/tmp/a.out + 0x1145)
#4 0x00007f7b5c828153 __libc_start_main (libc.so.6 + 0x27153)
#5 0x0000555668fbe04e n/a (/tmp/a.out + 0x104e)
Disassembling the test binary shows that these offsets line up:
0000000000001119 <crash>:
1119: 55 push %rbp
111a: 48 89 e5 mov %rsp,%rbp
111d: 0f 0b ud2 <---- #0
000000000000111f <b>:
111f: 55 push %rbp
1120: 48 89 e5 mov %rsp,%rbp
1123: b8 00 00 00 00 mov $0x0,%eax
1128: e8 ec ff ff ff callq 1119 <crash>
112d: 90 nop <---- #1
112e: 5d pop %rbp
112f: c3 retq
0000000000001130 <a>:
1130: 55 push %rbp
1131: 48 89 e5 mov %rsp,%rbp
1134: e8 e6 ff ff ff callq 111f <b>
1139: 90 nop <---- #2
113a: 5d pop %rbp
113b: c3 retq
000000000000113c <main>:
113c: 55 push %rbp
113d: 48 89 e5 mov %rsp,%rbp
1140: e8 eb ff ff ff callq 1130 <a>
1145: b8 00 00 00 00 mov $0x0,%eax <---- #3
114a: 5d pop %rbp
114b: c3 retq
114c: 0f 1f 40 00 nopl 0x0(%rax)
(from libc.so.6)
0000000000027060 <__libc_start_main>:
27060: f3 0f 1e fa endbr64
27064: 41 56 push %r14
27066: 31 c0 xor %eax,%eax
[...]
2714c: 48 8b 44 24 18 mov 0x18(%rsp),%rax
27151: ff d0 callq *%rax
27153: 89 c7 mov %eax,%edi <---- #4
27155: e8 e6 76 01 00 callq 3e840 <exit>
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