How do I translate the rsp: 2b6d2ea40450 kernel trap splitting error back to its original location?
A customer reported a division by zero error in one of our programs. We only have this VLM line:
kernel: myprog[16122] trap divide error rip:79dd99 rsp:2b6d2ea40450 error:0
I don't believe there is a core file for this.
I have searched the web to see how I can point to the line of program that caused this division by zero, but so far I am failing.
I understand that 16122 is the pid of the program, so it won't help me.
I suspect rsp: 2b6d2ea40450 has something to do with the address of the line that caused the error (0x2b6d2ea40450), but is it true?
If so, then how can I translate it to a physical approximate location in the source, assuming I can load the debug version of myprog into gdb and then ask to show the context around that address ...
Any, any help would be greatly appreciated!
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rip is the instruction pointer, rsp is the stack pointer. The stack pointer is not very useful if you don't have a kernel image or a running process.
You can use the command addr2line
or disassemble
in gdb
to see the line getting the error based on ip.
$ cat divtest.c
main ()
{
int a, b;
a = 1; b = a / 0;
}
$ ./divtest
Floating point exception (core dumped)
$ dmesg | tail -1
[6827.463256] traps: divtest [3255] trap divide error ip: 400504 sp: 7fff54e81330
error: 0 in divtest [400000 + 1000]
$ addr2line -e divtest 400504
./divtest.c:5
$ gdb divtest
(gdb) disass / m 0x400504
Dump of assembler code for function main:
2 {
0x00000000004004f0: push% rbp
0x00000000004004f1: mov% rsp,% rbp
3 int a, b;
4
5 a = 1; b = a / 0;
0x00000000004004f4: movl $ 0x1, -0x4 (% rbp)
0x00000000004004fb: mov -0x4 (% rbp),% eax
0x00000000004004fe: mov $ 0x0,% ecx
0x0000000000400503: cltd
0x0000000000400504: idiv% ecx
0x0000000000400506: mov% eax, -0x8 (% rbp)
6}
0x0000000000400509: pop% rbp
0x000000000040050a: retq
End of assembler dump.
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