$ coredumpctl gdb expr                                                                                                                                    
           PID: 2255 (expr)                                                                                                                                                    
           UID: 1000 (benni)                                                                                                                                                   
           GID: 100 (users)                                                                                                                                                    
        Signal: 4 (ILL)                                                                                                                                                        
     Timestamp: Mo 2015-12-14 21:07:15 CET (32min ago)                                                                                                                         
  Command Line: expr 4 * 4                                                                                                                                                     
    Executable: /usr/bin/expr                                                                                                                                                  
 Control Group: /user.slice/user-1000.slice/session-c1.scope                                                                                                                   
          Unit: session-c1.scope                                                                                                                                               
         Slice: user-1000.slice                                                                                                                                                
       Session: c1                                                                                                                                                             
     Owner UID: 1000 (benni)
       Boot ID: <removed>
    Machine ID: <removed>
      Hostname: <removed>
      Coredump: /var/lib/systemd/coredump/core.expr.<removed>.lz4
       Message: Process 2255 (expr) of user 1000 dumped core.
                
                Stack trace of thread 2255:
                #0  0x00007f023df0abdb __gmpn_mul_1_coreibwl (libgmp.so.10)

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Reading symbols from /usr/bin/expr...(no debugging symbols found)...done.
[New LWP 2255]

warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
Core was generated by `expr 4 * 4'.
Program terminated with signal SIGILL, Illegal instruction.
#0  0x00007f023df0abdb in __gmpn_mul_1_coreibwl () from /usr/lib/libgmp.so.10
(gdb) disas
Dump of assembler code for function __gmpn_mul_1_coreibwl:
   0x00007f023df0ab40 <+0>:     mov    %rcx,%r10
   0x00007f023df0ab43 <+3>:     mov    %rdx,%rcx
   0x00007f023df0ab46 <+6>:     mov    %edx,%r8d
   0x00007f023df0ab49 <+9>:     shr    $0x3,%rcx
   0x00007f023df0ab4d <+13>:    and    $0x7,%r8d
   0x00007f023df0ab51 <+17>:    mov    %r10,%rdx
   0x00007f023df0ab54 <+20>:    lea    0x25694d(%rip),%r10        # 0x7f023e1614a8
   0x00007f023df0ab5b <+27>:    movslq (%r10,%r8,4),%r8
   0x00007f023df0ab5f <+31>:    lea    (%r8,%r10,1),%r10
   0x00007f023df0ab63 <+35>:    jmpq   *%r10
   0x00007f023df0ab66 <+38>:    mulx   (%rsi),%r10,%r8
   0x00007f023df0ab6b <+43>:    lea    0x38(%rsi),%rsi
   0x00007f023df0ab6f <+47>:    lea    -0x8(%rdi),%rdi
   0x00007f023df0ab73 <+51>:    jmpq   0x7f023df0ac17 <__gmpn_mul_1_coreibwl+215>
   0x00007f023df0ab78 <+56>:    mulx   (%rsi),%r9,%rax
   0x00007f023df0ab7d <+61>:    lea    0x10(%rsi),%rsi
   0x00007f023df0ab81 <+65>:    lea    0x10(%rdi),%rdi
   0x00007f023df0ab85 <+69>:    inc    %rcx
   0x00007f023df0ab88 <+72>:    jmpq   0x7f023df0ac5c <__gmpn_mul_1_coreibwl+284>
   0x00007f023df0ab8d <+77>:    mulx   (%rsi),%r10,%r8
   0x00007f023df0ab92 <+82>:    lea    0x18(%rsi),%rsi
   0x00007f023df0ab96 <+86>:    lea    0x18(%rdi),%rdi
   0x00007f023df0ab9a <+90>:    inc    %rcx
   0x00007f023df0ab9d <+93>:    jmpq   0x7f023df0ac4f <__gmpn_mul_1_coreibwl+271>
   0x00007f023df0aba2 <+98>:    mulx   (%rsi),%r9,%rax
   0x00007f023df0aba7 <+103>:   lea    0x20(%rsi),%rsi
   0x00007f023df0abab <+107>:   lea    0x20(%rdi),%rdi
   0x00007f023df0abaf <+111>:   inc    %rcx
   0x00007f023df0abb2 <+114>:   jmpq   0x7f023df0ac42 <__gmpn_mul_1_coreibwl+258>
   0x00007f023df0abb7 <+119>:   mulx   (%rsi),%r10,%r8
   0x00007f023df0abbc <+124>:   lea    0x28(%rsi),%rsi
   0x00007f023df0abc0 <+128>:   lea    0x28(%rdi),%rdi
   0x00007f023df0abc4 <+132>:   inc    %rcx
   0x00007f023df0abc7 <+135>:   jmp    0x7f023df0ac35 <__gmpn_mul_1_coreibwl+245>
   0x00007f023df0abc9 <+137>:   mulx   (%rsi),%r9,%rax
   0x00007f023df0abce <+142>:   lea    0x30(%rsi),%rsi
   0x00007f023df0abd2 <+146>:   lea    0x30(%rdi),%rdi
   0x00007f023df0abd6 <+150>:   inc    %rcx
   0x00007f023df0abd9 <+153>:   jmp    0x7f023df0ac28 <__gmpn_mul_1_coreibwl+232>
=> 0x00007f023df0abdb <+155>:   mulx   (%rsi),%r9,%rax
   0x00007f023df0abe0 <+160>:   test   %rcx,%rcx
   0x00007f023df0abe3 <+163>:   jne    0x7f023df0ac07 <__gmpn_mul_1_coreibwl+199>
   0x00007f023df0abe5 <+165>:   mov    %r9,(%rdi)
   0x00007f023df0abe8 <+168>:   retq   
   0x00007f023df0abe9 <+169>:   mulx   (%rsi),%r10,%r8
   0x00007f023df0abee <+174>:   lea    0x8(%rsi),%rsi
   0x00007f023df0abf2 <+178>:   lea    0x8(%rdi),%rdi
   0x00007f023df0abf6 <+182>:   mulx   (%rsi),%r9,%rax
   0x00007f023df0abfb <+187>:   test   %rcx,%rcx
   0x00007f023df0abfe <+190>:   je     0x7f023df0ac73 <__gmpn_mul_1_coreibwl+307>
---Type <return> to continue, or q <return> to quit---
   0x00007f023df0ac00 <+192>:   mov    %r10,-0x8(%rdi)
   0x00007f023df0ac04 <+196>:   adc    %r8,%r9
   0x00007f023df0ac07 <+199>:   mulx   0x8(%rsi),%r10,%r8
   0x00007f023df0ac0d <+205>:   adc    %rax,%r10
   0x00007f023df0ac10 <+208>:   lea    0x40(%rsi),%rsi
   0x00007f023df0ac14 <+212>:   mov    %r9,(%rdi)
   0x00007f023df0ac17 <+215>:   mov    %r10,0x8(%rdi)
   0x00007f023df0ac1b <+219>:   mulx   -0x30(%rsi),%r9,%rax
   0x00007f023df0ac21 <+225>:   lea    0x40(%rdi),%rdi
   0x00007f023df0ac25 <+229>:   adc    %r8,%r9
   0x00007f023df0ac28 <+232>:   mulx   -0x28(%rsi),%r10,%r8
   0x00007f023df0ac2e <+238>:   mov    %r9,-0x30(%rdi)
   0x00007f023df0ac32 <+242>:   adc    %rax,%r10
   0x00007f023df0ac35 <+245>:   mov    %r10,-0x28(%rdi)
   0x00007f023df0ac39 <+249>:   mulx   -0x20(%rsi),%r9,%rax
   0x00007f023df0ac3f <+255>:   adc    %r8,%r9
   0x00007f023df0ac42 <+258>:   mulx   -0x18(%rsi),%r10,%r8
   0x00007f023df0ac48 <+264>:   mov    %r9,-0x20(%rdi)
   0x00007f023df0ac4c <+268>:   adc    %rax,%r10
   0x00007f023df0ac4f <+271>:   mulx   -0x10(%rsi),%r9,%rax
   0x00007f023df0ac55 <+277>:   mov    %r10,-0x18(%rdi)
   0x00007f023df0ac59 <+281>:   adc    %r8,%r9
   0x00007f023df0ac5c <+284>:   mulx   -0x8(%rsi),%r10,%r8
   0x00007f023df0ac62 <+290>:   adc    %rax,%r10
   0x00007f023df0ac65 <+293>:   mov    %r9,-0x10(%rdi)
   0x00007f023df0ac69 <+297>:   dec    %rcx
   0x00007f023df0ac6c <+300>:   mulx   (%rsi),%r9,%rax
   0x00007f023df0ac71 <+305>:   jne    0x7f023df0ac00 <__gmpn_mul_1_coreibwl+192>
   0x00007f023df0ac73 <+307>:   mov    %r10,-0x8(%rdi)
   0x00007f023df0ac77 <+311>:   adc    %r8,%r9
   0x00007f023df0ac7a <+314>:   mov    %r9,(%rdi)
   0x00007f023df0ac7d <+317>:   adc    %rcx,%rax
   0x00007f023df0ac80 <+320>:   retq   
End of assembler dump.