Turning on .eh_frame processing for ld -r resulted in systemtap
tickling a ld bug. Triggered by the zero terminator not being added
to .eh_frame in a separate file as it usually is (crtend.o), but
instead being present in the last .eh_frame section along with CIEs
and FDEs. The 4-byte terminator makes the section size check fail
on 64-bit targets.
* elf-eh-frame (_bfd_elf_write_section_eh_frame): Adjust section
size check to account for possible zero terminator.
The idea here is to drop .eh_frame FDEs corresponding to dropped
comdat group sections or linkonce sections, but not perform changes in
encoding.
bfd/
PR 17467
* elf-eh-frame.c (ENSURE_NO_RELOCS): Don't stop at first NONE reloc.
(_bfd_elf_parse_eh_frame): When relocatable output, don't set
flags enabling conversion of CIEs and FDEs to use relative encoding.
(find_merged_cie): Similarly.
(_bfd_elf_write_section_eh_frame): Don't edit FDEs when
relocatable, except for CIE pointer.
* elflink.c (bfd_elf_reloc_symbol_deleted_p): Return true for
relocs against symbols in dropped comdat group sections.
(bfd_elf_discard_info): Do some eh_frame optimisation when
relocatable.
ld/
* ldlang.c (lang_add_section): Set up map_head.s and map_tail.s when
relocatable.
These are useless because they can't match any address. In fact,
worse than useless because the .eh_frame_hdr lookup table matching
addresses to FDEs does not contain information about the FDE range.
The table is sorted by address; Range is inferred by the address
delta from one entry to the next. So if a zero address range FDE is
followed by a normal non-zero range FDE for the same address,
everything is good. However, the qsort could just as easily sort the
FDEs in the other order, in which case the normal FDE would
effectively be seen to have a zero range.
bfd/
PR 17447
* elf-bfd.h (struct eh_cie_fde): Comment re NULL u.fde.cie_inf.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): Mark zero address
range FDEs for discarding.
(vma_compare): Sort on range after address.
(_bfd_elf_gc_mark_fdes): Test for NULL u.fde.cie_inf.
(_bfd_elf_discard_section_eh_frame): Likewise. Write "FDE" in
error message rather than "fde".
(_bfd_elf_write_section_eh_frame_hdr): Write "PC" and "FDE" in
error message.
ld/testsuite/
* ld-elf/eh1.s: Don't create FDEs with zero address ranges.
* ld-elf/eh3.s: Likewise.
* ld-elf/eh1.d, * ld-elf/eh2.d, * ld-elf/eh3.d: Adjust.
* ld-mips-elf/eh-frame1-n32.d: Warning match update.
* ld-mips-elf/eh-frame1-n64.d: Likewise.
* ld-mips-elf/eh-frame2-n32.d: Likewise.
* ld-mips-elf/eh-frame2-n64.d: Likewise.
With larger binaries on 64-bit systems, or indeed just binaries that
have a large gap between text and data, it is possible for the
.eh_frame_hdr lookup table entry values to overflow a signed 32-bit
relative offset. It is also a requirement for the glibc FDE lookup
code that only one FDE claim to cover any given address.
* elf-bfd.h (struct eh_frame_array_ent): Add "range".
* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): Stash address
range of FDEs to hdr_info->array.
(_bfd_elf_write_section_eh_frame_hdr): Report overflow in
.eh_frame_hdr entries, and overlapping FDEs.
cie->output_sec is used to when merging CIEs to ensure that only CIEs
from the same output section are merged. I noticed an assignment to
this field in _bfd_elf_parse_eh_frame, and thought "That's wrong,
output_section isn't set properly when _bfd_elf_parse_eh_frame is
called from gc-sections code". It turns out that this assignment is
premature, and in fact a dead store. find_merged_cie overwrites with
the correct value before the field is ever used. On looking a little
more it becomes apparent that cie->cie_inf.u.cie.u.sec->output_section
holds the same value, so cie->output_sec is redundant.
* elf-eh-frame.c (struct cie): Delete "output_sec" field.
(cie_eq, cie_compute_hash): Use output_section from cie_inf instead.
I noticed recently that .eh_frame FDEs generated by the linker for
call stubs and .glink weren't being indexed in .eh_frame_hdr, due to
bfd_elf_discard_info being run before the linker generated .eh_frame
sections were available for parsing. This patch moves code around in
elf64-ppc.c and ppc64elf.em to avoid that problem.
Another problem fixed here is that --gc-sections parses .eh_frame
early, and the existing machinery allows only one go at parsing the
.eh_frame sections. That resulted in the linker generated .eh_frame
CIEs not being merged and no .eh_frame_hdr index entries for those
FDEs. It turns out that all the info from parsing .eh_frame is
attached to the section, so order of parsing isn't important, and
after parsing sec_info_type being set will prevent a section being
parsed again. At least, when parsing doesn't hit an error. So there
isn't really any need for "parsed_eh_frame". "merge_cies" is also
redundant, which means _bfd_elf_{begin,end}_eh_frame_parsing can also
disappear.
bfd/
* elf-bfd.h (struct eh_frame_hdr_info): Delete merge_cies and
parsed_eh_frames.
(_bfd_elf_begin_eh_frame_parsing): Delete.
(_bfd_elf_end_eh_frame_parsing): Delete.
* elf-eh-frame.c (_bfd_elf_begin_eh_frame_parsing): Delete.
(_bfd_elf_end_eh_frame_parsing): Delete.
(_bfd_elf_parse_eh_frame): Don't test parsed_eh_frame. Test
!info->relocatable in place of merge_cies.
* elflink.c (bfd_elf_gc_sections, bfd_elf_discard_info): Adjust.
* elf64-ppc.c (glink_eh_frame_cie): Pad to multiple of 8.
(ppc64_elf_size_stubs): Likewise pad stub FDE.
(ppc64_elf_build_stubs): Move code setting glink .eh_frame to..
(ppc64_elf_size_stubs): ..here and..
(ppc64_elf_finish_dynamic_sections): ..here.
ld/
* emultempl/ppc64elf.em (gld${EMULATION_NAME}_after_allocation): Call
bfd_elf_discard_info after generating glink .eh_frame. Delete
redundant test on ppc64_elf_setup_section_lists status.
This is all we should need to be able to run the eh_frame parts of
bfd_elf_discard_info before bfd_elf_size_dynamic_sections
* elf-eh-frame.c (struct cie.personality): Replace val with sym.
(find_merged_cie): Identify personality functions by (bfd_id,index)
pair when a local sym is used.
Don't attempt to merge CIEs with a larger number of insns than will
fit in the buffer.
* elf-eh-frame.c (cie_eq): Return false when initial_insn_length
is too large.
(cie_compute_hash): Don't exceed bounds of initial_instructions.
(_bfd_elf_parse_eh_frame): Always set initial_insn_length, and
save as much of insns to initial_instructions[] as will fit.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): Handle CIE version 4
provided that it has the expected address size and zero segment
length.
binutils/
* dwarf.c (struct Frame_Chunk): Add ptr_size and segment_size
fields.
(display_debug_frames): Handle CIE version 4.
* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): Extend previous
patch to handle the new personality relaxation.
ld/testsuite/
* ld-mips-elf/eh-frame5.d: Expect PC-relative encodings
to include DW_EH_PE_sdata4.
* elf-eh-frame.c (make_pc_relative): New function.
(_bfd_elf_write_section_eh_frame): Use it.
ld/testsuite/
* ld-mips-elf/eh-frame1-n32.d: Expect PC-relative encodings
to include DW_EH_PE_sdata4.
* ld-mips-elf/eh-frame2-n32.d: Likewise.
* ld-mips-elf/eh-frame1-n64.d: Expect PC-relative encodings
to include DW_EH_PE_sdata8.
* ld-mips-elf/eh-frame2-n64.d: Likewise.
* elf-bfd.h (eh_cie_fde): Add personality_offset and
make_per_encoding_relative to the CIE structure. Add a padding field.
* elf-eh-frame.c (_bfd_elf_eh_frame_section_offset): Use 0x70
rather than 0xf0 when masking out the base address encoding
Record the offset of personality data from the start of the CIE.
Remove a repeated elf_backend_can_make_relative_eh_frame check.
(find_merged_cie): Take an info argument. If the personality
binds locally, try converting an absolute personality into
a local one.
(_bfd_elf_discard_section_eh_frame): Use 0x70 rather than 0xf0
when masking out the base address encoding. Update the call to
find_merged_cie.
(_bfd_elf_eh_frame_section_offset): Discard relocations against
the personality data if we are converting into PC-relative form.
(_bfd_elf_write_section_eh_frame): Use 0x70 rather than 0xf0
when masking out the base address encoding. Handle
make_per_encoding_relative.
ld/testsuite/
* ld-mips-elf/eh-frame5.s, ld-mips-elf/eh-frame5.ld,
ld-mips-elf/eh-frame5.d: New test.
* ld-mips-elf/mips-elf.exp: Run it.
* elf-eh-frame.c (REQUIRE_CLEARED_RELOCS) Remove.
(_bfd_elf_parse_eh_frame): Do not check relocations for removed FDEs.
ld/testsuite/
* ld-elf/eh-group2.s: New `.cfi_lsda' referencing `.gcc_except_table'.
* ld-elf/eh-group.exp: New test and conditional defininiton of `ELF64'.
PR 6893 - Do not consider FDEs for discarded sections as invalid.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): New REQUIRE_CLEARED_RELOCS.
Consider FDEs with cleared relocations as valid and ignorable.
ld/testsuite/
* ld-elf/eh-group.exp, ld-elf/eh-group1.s, ld-elf/eh-group2.s: New test.
binutils/
Suppress warnings on NONE relocations to discarded sections.
* readelf.c (is_none_reloc): New function.
(debug_apply_relocations): Ignore is_none_reloc() relocations.
PR ld/5526
* elf-bfd.h (eh_cie_fde): Add u.cie.u.full_cie and u.cie.merged
fields. Rename u.cie.u.merged to u.cie.u.merged_with.
(eh_frame_sec_info): Add a cies field.
(eh_frame_hdr_info): Add a merge_cies field.
* elf-eh-frame.c (cie): Add a reloc_index member to the personality
union.
(_bfd_elf_begin_eh_frame_parsing): Set hdr_info->merge_cies instead
of hdr_info->cies.
(_bfd_elf_parse_eh_frame): Remove tmp_cie. Ccreate an array of
cie structures in all cases and use it instead of extended_cies.
If merging, store the cie array in sec_info->cies and point each
CIE's eh_fde_cie at the associated element. Do not try to
calculate the value of the personality routine here; record the
offset of the relocation instead. Do not merge CIEs here.
(_bfd_elf_end_eh_frame_parsing): Do not free hdr_info->cies here...
(_bfd_elf_discard_section_eh_frame_hdr): ...do it here instead.
(_bfd_elf_gc_mark_fdes): Mark the original (unmerged) CIE.
(find_merged_cie): New function.
(_bfd_elf_gc_mark_fdes): Use it. Free sec_info->cies.
ld/testsuite/
PR ld/5526
* ld-elf/eh6.s, ld-elf/eh6.d: New test.
* elf-bfd.h (eh_cie_fde): Replace u.cie.merged with a union of
a merged field and a sec field.
(eh_frame_hdr_info): Remove offsets_adjusted.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): Update accesses to
the CIE merged field.
(_bfd_elf_gc_mark_fdes): Likewise.
(_bfd_elf_discard_section_eh_frame): Likewise. Set u.cie.u.sec
when clearing the removed flag.
(_bfd_elf_eh_frame_section_offset): Remove offsets_adjusted handling.
(_bfd_elf_write_section_eh_frame): Likewise. Apply output_offsets
where appropriate.
* elf-bfd.h (eh_cie_fde): Move add_fde_encoding and
per_encoding_relative to u.cie. Add commentary.
* elf-eh-frame.c (cie): Remove make_relative.
(extra_augmentation_string_bytes): Update use of add_fde_encoding.
(extra_augmentation_data_bytes): Likewise. Use an FDE's own
add_augmentation_size field, rather than referring to the CIE.
(_bfd_elf_parse_eh_frame): Don't set the struct cie
make_relative field; set the eh_cie_fde field directly.
Update setting of add_fde_encoding and per_encoding_relative.
Copy make_relative and add_augmentation_size from the CIE
to the FDE.
(_bfd_elf_discard_section_eh_frame): Use the FDE's own
make_relative field.
(_bfd_elf_eh_frame_section_offset): Likewise.
(_bfd_elf_write_section_eh_frame): Update accesses to
add_fde_encoding and per_encoding_relative. Use the FDE's
own make_relative and add_augmentation_size fields.
* elf-bfd.h (eh_cie_fde): Remove need_lsda_relative.
Move make_lsda_relative to u.cie.
* elf-eh-frame.c (cie): Rename make_lsda_relative to
can_make_lsda_relative.
(_bfd_elf_parse_eh_frame): Don't set the old eh_cie_fde
make_lsda_relative field. Update after cie renaming.
Set u.cie.make_lsda_relative if can_make_lsda_relative
and if we find a relocation against the LSDA.
(_bfd_elf_discard_section_eh_frame): Copy make_lsda_relative when
changing a CIE's group representative.
(_bfd_elf_eh_frame_section_offset): Don't set need_ldsa_relative here.
(_bfd_elf_write_section_eh_frame): Check u.cie.make_lsda_relative
rather than need_lsda_relative.
* elf-bfd.h (eh_cie_fde): Add u.fde.next_for_section and
u.cie.gc_mark.
(bfd_elf_section_data): Add fde_list.
(elf_fde_list): New macro.
(elf_obj_tdata): Add eh_frame_section.
(elf_eh_frame_section): New macro.
(_bfd_elf_gc_mark_reloc): Remove last parameter.
(_bfd_elf_gc_mark_fdes): Declare.
* elf-eh-frame.c (_bfd_elf_get_eh_frame_sec_info): Chain the FDEs
for each input section.
(mark_entry, _bfd_elf_gc_mark_fdes): New functions.
* elflink.c (_bfd_elf_gc_mark_reloc): Remove is_eh parameter.
(_bfd_elf_gc_mark): Update call accordingly. Mark the relocations
againts the section's FDEs. Don't mark the bfd's elf_eh_frame_section.
(bfd_elf_gc_sections): Parse each input bfd's .eh_frame before
marking any input sections. Remove the current EH handling.
* section.c (bfd_section): Remove gc_mark_from_eh.
* ecoff.c (bfd_debug_section): Update initializer accordingly.
* elf-bfd.h (eh_cie_fde): Add u.cie. Document how u.fde.cie_inf
changes when removed == 0.
(eh_frame_hdr_info): Add parsed_eh_frames.
(_bfd_elf_begin_eh_frame_parsing): Declare.
(_bfd_elf_parse_eh_frame): Declare.
(_bfd_elf_end_eh_frame_parsing): Declare.
* elf-eh-frame.c (_bfd_elf_begin_eh_frame_parsing): New function.
(_bfd_elf_parse_eh_frame): New function, split out from
_bfd_elf_discard_section_eh_frame. Make a first pass through the
buffer to calculate the number of entries and CIEs. Allocate memory
for them before the main loop. Replace current extended cie
representation with a pair of pointers, one to the local eh_cie_fde
and one to the full struct cie. Allocate a separate array of struct
cies if not merging. Merge CIEs during the main loop and set up each
u.cie.merged field. Point an FDE's cie_inf field directly at the
local CIE. Initially assume that all entries should be removed.
(_bfd_elf_end_eh_frame_parsing): New function.
(_bfd_elf_discard_section_eh_frame): Assume that the section has
already been parsed. Use a separate pass to mark entries that
need to be kept. Use the u.cie.merged field to track a CIE's
group representative.
* elflink.c (bfd_elf_discard_info): Call _bfd_elf_parse_eh_frame
before _bfd_elf_discard_section_eh_frame. Wrap loop with calls to
_bfd_elf_begin_eh_frame_parsing and _bfd_elf_end_eh_frame_parsing.
* elf-bfd.h (eh_cie_fde): Put cie_inf in a union. Add a reloc_index
field. Use bitfields for fde_encoding, lsda_encoding and lsda_offset.
* elf-eh-frame.c (extra_augmentation_data_bytes): Adjust cie_inf
accesses after the above change.
(_bfd_elf_eh_frame_section_offset): Likewise.
(_bfd_elf_write_section_eh_frame): Likewise.
(_bfd_elf_discard_section_eh_frame): Likewise. Set up reloc_index.
* elf-eh-frame.c (struct cie): Add "local_personality". Make
"personality" a union.
(cie_eq): Compare local_personality too. Adjust personality
comparison.
(_bfd_elf_discard_section_eh_frame): Check binding on personality
reloc sym to allow for bad symtab. Use stashed local syms rather
than reading personality local sym. Handle discarded sections.
