[Bug libc/15407] Partial frame info in sysdeps/x86_64/start.S

["hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=15407

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> 2013-04-26 21:58:51 UTC ---
--build-id --no-add-needed --hash-style=gnu -m elf_x86_64 -static -fuse-ld=gold
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/crtbeginT.o
-L/usr/lib/gcc/x86_64-redhat-linux/4.7.2
-L/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../.. foo.o
-lstdc++ -lm --start-group -lgcc -lgcc_eh -lc --end-group
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/crtend.o
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/crtn.o

is passed to linker. BFD linker puts the bad eh_frame section at
very beginning:

Contents of the .eh_frame section:

00000000 00000014 00000000 CIE
  Version:               1
  Augmentation:          "zR"
  Code alignment factor: 1
  Data alignment factor: -8
  Return address column: 16
  Augmentation data:     1b

  DW_CFA_def_cfa: r7 (rsp) ofs 8
  DW_CFA_offset: r16 (rip) at cfa-8
  DW_CFA_undefined: r16 (rip)

00000018 00000014 0000001c FDE cie=00000000 pc=00400d8c..00400db6
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop

while gold puts it in the middle:

000099b0 0000004c 000099b4 FDE cie=00000000 pc=004928d0..00492b12
  DW_CFA_advance_loc: 34 to 004928f2
  DW_CFA_def_cfa_offset: 16
  DW_CFA_offset: r14 (r14) at cfa-16
  DW_CFA_advance_loc: 5 to 004928f7
  DW_CFA_def_cfa_offset: 24
  DW_CFA_offset: r13 (r13) at cfa-24
  DW_CFA_advance_loc: 5 to 004928fc
  DW_CFA_def_cfa_offset: 32
  DW_CFA_offset: r12 (r12) at cfa-32
  DW_CFA_advance_loc: 4 to 00492900
  DW_CFA_def_cfa_offset: 40
  DW_CFA_offset: r6 (rbp) at cfa-40
  DW_CFA_advance_loc: 1 to 00492901
  DW_CFA_def_cfa_offset: 48
  DW_CFA_offset: r3 (rbx) at cfa-48
  DW_CFA_advance_loc: 4 to 00492905
  DW_CFA_def_cfa_offset: 128
  DW_CFA_advance_loc2: 382 to 00492a83
  DW_CFA_remember_state
  DW_CFA_def_cfa_offset: 48
  DW_CFA_advance_loc: 1 to 00492a84
  DW_CFA_restore: r3 (rbx)
  DW_CFA_def_cfa_offset: 40
  DW_CFA_advance_loc: 1 to 00492a85
  DW_CFA_restore: r6 (rbp)
  DW_CFA_def_cfa_offset: 32
  DW_CFA_advance_loc: 2 to 00492a87
  DW_CFA_restore: r12 (r12)
  DW_CFA_def_cfa_offset: 24
  DW_CFA_advance_loc: 2 to 00492a89
  DW_CFA_restore: r13 (r13)
  DW_CFA_def_cfa_offset: 16
  DW_CFA_advance_loc: 2 to 00492a8b
  DW_CFA_restore: r14 (r14)
  DW_CFA_def_cfa_offset: 8
  DW_CFA_advance_loc: 5 to 00492a90
  DW_CFA_restore_state
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop

00009a00 00000024 00009a04 FDE cie=00000000 pc=004002e0..004003b0
  DW_CFA_def_cfa_offset: 16
  DW_CFA_advance_loc: 6 to 004002e6
  DW_CFA_def_cfa_offset: 24
  DW_CFA_advance_loc: 10 to 004002f0
  DW_CFA_def_cfa_expression (DW_OP_breg7 (rsp): 8; DW_OP_breg16 (rip): 0;
DW_OP_lit15; DW_OP_and; DW_OP_lit11; DW_OP_ge; DW_OP_lit3; DW_OP_shl;
DW_OP_plus)
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop

00009a28 00000014 00000000 CIE
  Version:               1
  Augmentation:          "zR"
  Code alignment factor: 1
  Data alignment factor: -8
  Return address column: 16
  Augmentation data:     1b

  DW_CFA_def_cfa: r7 (rsp) ofs 8
  DW_CFA_offset: r16 (rip) at cfa-8
  DW_CFA_undefined: r16 (rip)

00009a40 00000014 0000001c FDE cie=00009a28 pc=00400d9c..00400dc6
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop
  DW_CFA_nop

00009a58 00000014 00000000 CIE
  Version:               1
  Augmentation:          "zR"
  Code alignment factor: 1
  Data alignment factor: -8
  Return address column: 16
  Augmentation data:     1b

  DW_CFA_def_cfa: r7 (rsp) ofs 8
  DW_CFA_offset: r16 (rip) at cfa-8
  DW_CFA_def_cfa_offset: 24

00009a70 00000014 0000001c FDE cie=00009a58 pc=00451540..004515a1
  DW_CFA_advance_loc: 4 to 00451544

The extra frame info comes from the first entry in PLT since gold
doesn't skip it in static executable.  I think this combination
leads to the problem.

Dynamic executables are OK since they have GNU_EH_FRAME.

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