I'd be interested in "objdump -d libabc.so | grep -B20 474b2:" for whatever library that came from, and if necessary, "readelf -WwF" output for the corresponding FDE.
start ip=7ffff766a4b2
which belongs to libc in the "mapper" process:
7ffff7600000-7ffff7768000 r-xp 00000000 08:02 2557 /lib/
libc-2.9.so
Disassembly:
0x00007ffff766a4ae <puts+286>: add $0x28,%rsp
0x00007ffff766a4b2 <puts+290>: retq
0x00007ffff766a4b3 <puts+291>: nopl 0x0(%rax,%rax,1)
0x00007ffff766a4b8 <puts+296>: add $0x1,%eax
readelf -Wwf
00006310 00000024 000015e4 FDE cie=00004d30 pc=0006a390..0006a552
Augmentation data: 15 86 01 00
DW_CFA_advance_loc: 10 to 0006a39a
DW_CFA_offset: r6 (rbp) at cfa-32
DW_CFA_offset: r3 (rbx) at cfa-40
DW_CFA_advance_loc: 17 to 0006a3ab
DW_CFA_def_cfa_offset: 48
DW_CFA_offset: r13 (r13) at cfa-16
DW_CFA_offset: r12 (r12) at cfa-24
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
So the change to %rsp at 0006a4b2 is missing unwind information. Probably fixed in the Ubuntu release you're testing with. I'm going to ignore this issue and push your first patchset to git hopefully soon.