libpthread has very strange .eh_frame contents

[Jim Blandy]

I'm looking at libpthread from http://packages.ubuntu.com/lucid/libc6 2.11.1-0ubuntu7.1 amd64, whose sha1sum is:

29b0368a599cdd725078d2d2a932b416a6c81817 lib/libpthread-2.11.1.so

readelf -wf libpthread-2.11.1.so says, among other things:

00001440 0000004c 00001374 FDE cie=000000d0 pc=000095ca..000095e5
  DW_CFA_val_expression: r16 (rip) (DW_OP_breg16: 15)
  DW_CFA_advance_loc: 3 to 000095cd
  DW_CFA_val_expression: r16 (rip) (DW_OP_breg16: 12)
  DW_CFA_advance_loc: 7 to 000095d4
  DW_CFA_def_cfa_offset: 0
  DW_CFA_val_expression: r16 (rip) (DW_OP_breg16: 5)
  DW_CFA_advance_loc: 4 to 000095d8
  DW_CFA_def_cfa_offset: 128
  DW_CFA_val_expression: r16 (rip) (DW_OP_breg16: 6; DW_OP_const4s: -43821; DW_OP_minus; DW_OP_const4s: -44305; DW_OP_plus)
  DW_CFA_advance_loc: 8 to 000095e0
  DW_CFA_def_cfa_offset_sf: -128
  DW_CFA_val_expression: r16 (rip) (DW_OP_breg16: -7)

That first instruction says that the caller's $rip is the callee's $rip + 15. This can't be right. The instruction with the two DW_OP_const4s looks like garbage, too.

[Jim Blandy (jimb)]

Unless I've made a mistake, lucid-updates has the same libpthread.