Comment 1 for bug 956051

I am running into this issue as well on a 12.04 domU with a AMD Opteron 6272 based box.

[14553.237586] apport[18522] trap invalid opcode ip:7f1d632625fc sp:7ffff8701390 error:0 in libm-2.15.so[7f1d63220000+f9000]

Debugging info

(gdb) exec-file python-dbg
(gdb) run
Starting program: /usr/bin/python-dbg
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Python 2.7.3 (default, Apr 20 2012, 22:01:19)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print test

Program received signal SIGILL, Illegal instruction.
__ieee754_exp_fma4 (x=-0.5) at ../sysdeps/ieee754/dbl-64/e_exp.c:63
63 ../sysdeps/ieee754/dbl-64/e_exp.c: No such file or directory.
(gdb) bt
#0 __ieee754_exp_fma4 (x=-0.5) at ../sysdeps/ieee754/dbl-64/e_exp.c:63
#1 0x000000000058509f in ?? ()
#2 0x00000000009bde80 in ?? ()
#3 0x0000000100c52a10 in ?? ()
#4 0x0000000000417380 in ?? ()
#5 0x00000000009d2970 in ?? ()
#6 0x0000000000000000 in ?? ()
(gdb) info address __ieee754_exp_fma4
Symbol "__ieee754_exp_fma4" is a function at address 0x7ffff6cc35f0.
(gdb) disassemble 0x7ffff6cc35f0,+30
Dump of assembler code from 0x7ffff6cc35f0 to 0x7ffff6cc360e:
   0x00007ffff6cc35f0 <__ieee754_exp_fma4+0>: push %rbp
   0x00007ffff6cc35f1 <__ieee754_exp_fma4+1>: mov %rsp,%rbp
   0x00007ffff6cc35f4 <__ieee754_exp_fma4+4>: and $0xffffffffffffffe0,%rsp
   0x00007ffff6cc35f8 <__ieee754_exp_fma4+8>: add $0x10,%rsp
=> 0x00007ffff6cc35fc <__ieee754_exp_fma4+12>: vmovsd %xmm0,-0x20(%rsp)
   0x00007ffff6cc3602 <__ieee754_exp_fma4+18>: mov -0x20(%rsp),%rax
   0x00007ffff6cc3607 <__ieee754_exp_fma4+23>: mov %rax,%rcx
   0x00007ffff6cc360a <__ieee754_exp_fma4+26>: shr $0x20,%rcx

vmovsd is an avx instruction, but avx isn't supported according to cpu flags.

# grep flags /proc/cpuinfo | head -1
flags : fpu de tsc msr pae cx8 cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm rep_good nopl aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 popcnt aes hypervisor lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch xop fma4 perfctr_core arat cpb

perhaps eglibc is assuming if fma4 is supported, avx must be too.

thanks
jim