Commit 2bf2bf23da exposed a bug on targets that create common sections
other than the standard ELF SHN_COMMON. If these are output by ld -r,
then their type becomes SHT_PROGBITS unless the target handles them
specially (eg. by elf_backend_special_sections), and if they are
merged into .bss/.sbss by ld -r then that section becomes SHT_PROGBITS.
Worse, if they are output by ld -r, then their size is increased by
bfd_generic_define_common_symbol during final link, which leads to
bogus file contents being copied to output.
For mips, it seems to me that the .scommon section should not be
output for ld -r, but I haven't made that change in this patch.
PR 24015
* elf.c (bfd_elf_get_default_section_type): Make common sections
SHT_NOBITS.
* linker.c (bfd_generic_define_common_symbol): Clear
SEC_HAS_CONTENTS.
PR 23994
* aoutx.h: Include limits.h.
(get_reloc_upper_bound): Detect long overflow and return a file
too big error if it occurs.
* elf.c: Include limits.h.
(_bfd_elf_get_symtab_upper_bound): Detect long overflow and return
a file too big error if it occurs.
(_bfd_elf_get_dynamic_symtab_upper_bound): Likewise.
(_bfd_elf_get_dynamic_reloc_upper_bound): Likewise.
Linkers group input note sections with the same name into one output
note section with the same name. One output note section is placed in
one PT_NOTE segment. New linkers merge all input .note.gnu.property
sections into one output .note.gnu.property section with a single
NT_GNU_PROPERTY_TYPE_0 note in a single PT_NOTE segment. Since older
linkers treat input .note.gnu.property section as a generic note section
and just concatenate all input .note.gnu.property sections into one
output .note.gnu.property section without merging them, we may
see one or more NT_GNU_PROPERTY_TYPE_0 notes in PT_NOTE segment, which
are invalid.
GNU_PROPERTY_X86_UINT32_VALID was defined to address this issue such
that linker sets the bit for non-relocatable outputs. But it isn't
sufficient:
1. It doesn't cover generic properties.
2. When -mx86-used-note=yes is passed to x86 assembler, the
GNU_PROPERTY_X86_UINT32_VALID bit is set in GNU_PROPERTY_X86_ISA_1_USED
property in object file and older linkers generate invalid
NT_GNU_PROPERTY_TYPE_0 notes with the GNU_PROPERTY_X86_UINT32_VALID bit
set.
I am proposing the following changes:
1. Add PT_GNU_PROPERTY segment type:
# define PT_GNU_PROPERTY (PT_LOOS + 0x474e553)
which covers .note.gnu.property section.
2. Remove GNU_PROPERTY_X86_UINT32_VALID.
bfd/
PR ld/23900
* elf.c (get_program_header_size): Add a PT_GNU_PROPERTY
segment for NOTE_GNU_PROPERTY_SECTION_NAME.
(_bfd_elf_map_sections_to_segments): Create a PT_GNU_PROPERTY
segment for NOTE_GNU_PROPERTY_SECTION_NAME.
* elfxx-x86.c (_bfd_elf_link_setup_gnu_properties): Don't set
GNU_PROPERTY_X86_UINT32_VALID.
binutils/
PR ld/23900
* readelf.c (get_segment_type): Support PT_GNU_PROPERTY.
(decode_x86_isa): Don't check GNU_PROPERTY_X86_UINT32_VALID.
(decode_x86_feature_1): Likewise.
(decode_x86_feature_2): Likewise.
(print_gnu_property_note): Remove GNU_PROPERTY_X86_UINT32_VALID
check.
* testsuite/binutils-all/i386/empty.d: Updated.
* testsuite/binutils-all/x86-64/empty-x32.d: Likewise.
* testsuite/binutils-all/x86-64/empty.d: Likewise.
* testsuite/binutils-all/i386/pr21231b.s: Change
GNU_PROPERTY_X86_ISA_1_USED bits to 0x7fffffff.
* testsuite/binutils-all/x86-64/pr21231b.s: Likewise.
gas/
PR ld/23900
* config/tc-i386.c (x86_cleanup): Don't set
GNU_PROPERTY_X86_UINT32_VALID.
* testsuite/gas/i386/property-1.s: Change
GNU_PROPERTY_X86_ISA_1_USED bits to 0.
include/
PR ld/23900
* elf/common.h (PT_GNU_PROPERTY): New.
(GNU_PROPERTY_X86_UINT32_VALID): Removed.
ld/
PR ld/23900
* testsuite/ld-elf/elf.exp: Run PR ld/23900 test.
* testsuite/ld-elf/pr23900-1-32.rd: New file.
* testsuite/ld-elf/pr23900-1-64.rd: Likewise.
* testsuite/ld-elf/pr23900-1.d: Likewise.
* testsuite/ld-elf/pr23900-1.s: Likewise.
* testsuite/ld-elf/pr23900-2.s: Likewise.
* testsuite/ld-elf/pr23900-2a.d: Likewise.
* testsuite/ld-elf/pr23900-2b.d: Likewise.
* testsuite/ld-i386/ibt-plt-1.d: Adjusted.
* testsuite/ld-i386/ibt-plt-2c.d: Likewise.
* testsuite/ld-i386/ibt-plt-2d.d: Likewise.
* testsuite/ld-i386/ibt-plt-3d.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-1-x32.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-1.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-2c-x32.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-2c.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-2d-x32.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-2c.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-3c-x32.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-3c.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-3d-x32.d: Likewise.
* testsuite/ld-x86-64/ibt-plt-3d.d: Likewise.
* testsuite/ld-i386/pr23372c.d: Expect <None>
for GNU_PROPERTY_X86_ISA_1_USED.
* testsuite/ld-x86-64/pr23372c-x32.d: Likewise.
* testsuite/ld-x86-64/pr23372c.d: Likewise.
* testsuite/ld-x86-64/pr23372d-x32.d: Likewise.
* testsuite/ld-x86-64/pr23372d.d: Likewise.
* testsuite/ld-x86-64/property-x86-5a.s: Change
GNU_PROPERTY_X86_ISA_1_USED bits to 0.
* testsuite/ld-x86-64/property-x86-5b.s: Likewise.
PR 23932
* elf.c (IS_CONTAINED_BY_LMA): Add a check for a negative section
size.
(rewrite_elf_program_header): If no sections are mapped into a
segment return an error.
PR binutils/23919
binutils* readelf.c (dump_sections_as_strings): Remove bogus addralign check.
(dump_sections_as_bytes): Likewise.
(load_specific_debug_sections): Likewise.
* testsuite/binutils-all/dw2-3.rS: Adjust alignment.
* testsuite/binutils-all/dw2-3.rt: Likewise.
bfd * bfd.c (bfd_update_compression_header): Explicitly set alignment.
(bfd_check_compression_header): Add uncompressed_alignment_power
argument. Check ch_addralign is a power of 2.
* bfd-in2.h: Regenerated.
* compress.c (bfd_compress_section_contents): Get and set
orig_uncompressed_alignment_pow if section is decompressed.
(bfd_is_section_compressed_with_header): Add and get
uncompressed_align_pow_p argument.
(bfd_is_section_compressed): Add uncompressed_align_power argument
to bfd_is_section_compressed_with_header call.
(bfd_init_section_decompress_status): Get and set
uncompressed_alignment_power.
* elf.c (_bfd_elf_make_section_from_shdr): Add
uncompressed_align_power argument to
bfd_is_section_compressed_with_header call.
strip/objcopy can't deal with alloc reloc sections, not .rela.dyn or
.rela.plt in a dynamic executable, or .rela.plt/.rela.iplt in a static
executable. So, don't have BFD treat them as side-channel data
associated with the section they are relocating.
PR 23850
* elf.c (bfd_section_from_shdr): Treat SHF_ALLOC SHT_REL* sections
in an executable or shared library as normal sections.
Symbol tables can change when a number of objcopy options are used.
I figure string tables are similarly changeable.
PR 23788
* elf.c (section_match): Don't require a size match for SHT_SYMTAB
or SHT_STRTAB.
This patch, along with previous patches in the series, supports
putting the ELF file header and program headers in a PT_LOAD without
sections.
Logic governing whether headers a loaded has changed a little: The
primary reason to include headers is now the presence of
SIZEOF_HEADERS in a linker script. However, to support scripts that
may have reserved space for headers by hand, we continue to add
headers whenever the first section address is past the end of headers
modulo page size.
include/
* bfdlink.h (struct bfd_link_info): Add load_phdrs field.
bfd/
* elf-nacl.c (nacl_modify_segment_map): Cope with header PT_LOAD
lacking sections.
* elf.c (_bfd_elf_map_sections_to_segments): Assume file and
program headers are required when info->load_phdrs. Reorganize
code handling program headers. Generate a mapping without
sections just for file and program headers when -z separate-code
would indicate they should be on a different page to the first
section.
ld/
* ldexp.c (fold_name <SIZEOF_HEADERS>): Set link_info.load_phdrs.
* testsuite/ld-elf/loadaddr1.d: Pass -z noseparate-code.
* testsuite/ld-elf/loadaddr2.d: Likewise.
* testsuite/ld-i386/vxworks2.sd: Adjust expected output.
* testsuite/ld-powerpc/vxworks2.sd: Likewise.
* testsuite/ld-elf/overlay.d: Remove spu xfail.
* testsuite/ld-spu/ovl.lnk: Don't use SIZEOF_HEADERS.
* testsuite/ld-tic6x/dsbt-be.ld: Likewise.
* testsuite/ld-tic6x/dsbt-inrange.ld: Likewise.
* testsuite/ld-tic6x/dsbt-overflow.ld: Likewise.
* testsuite/ld-tic6x/dsbt.ld: Likewise.
p_vaddr is currently set from the first section vma if a segment has
sections, and to zero if a segment has no sections. This means we
lose p_vaddr when objcopy'ing executables if a segment without
sections has a non-zero p_vaddr.
This patch saves p_vaddr to p_vaddr_offset, and to make the use of
p_vaddr_offset consistent, inverts the sign. (It's now added to
section vma to get segment vaddr, and added to zero when there are no
sections.)
* elf.c (assign_file_positions_for_load_sections): Set p_vaddr
from m->p_vaddr_offset for segments without sections. Invert
sign of p_vaddr_offset.
(rewrite_elf_program_header, copy_elf_program_header): Save
old segment p_vaddr to p_vaddr_offset. Invert sign of
p_vaddr_offset.
Some targets don't set a default interpreter, resulting in an empty
.interp section unless --dynamic-linker is passed to ld. A PT_INTERP
without a path is rather useless.
The testsuite change fixes a failure on microblaze-linux.
bfd/
* elf.c (get_program_header_size): Don't count PT_INTERP if
.interp is empty.
(_bfd_elf_map_sections_to_segments): Don't create PT_INTERP if
.interp is empty.
ld/
* testsuite/ld-elf/pr22423.d: Pass --dynamic-linker to ld.
This cleans up elf_segment_map allocation when the section array is
empty. "amt += (to - from - 1) * sizeof (asection *)", when "to" and
"from" are unsigned int results in an unsigned value inside the
parentheses. When "to" and "from" are equal on a 64-bit host,
0xffffffff * 8 is added to "amt", not -8 as desired.
The patch also renames a variable for consistency with other functions
using a similar index.
* elf.c (make_mapping): Cope with zero size array at end of
struct elf_segment_map.
(_bfd_elf_map_sections_to_segments): Likewise.
(rewrite_elf_program_header, copy_elf_program_header): Likewise.
(_bfd_elf_map_sections_to_segments): Rename phdr_index to hdr_index.
Alignments of SHT_NOTE sections can be 8 bytes for 64-bit ELF files. We
should put all adjacent SHT_NOTE sections with the same section alignment
into a single PT_NOTE segment even when the section alignment != 4 bytes.
Also check SHT_NOTE section type instead of section name.
PR ld/23658
* elf.c (get_program_header_size): Put all adjacent SHT_NOTE
sections with the same section alignment into a single PT_NOTE
segment. Check SHT_NOTE section type instead of section name.
(_bfd_elf_map_sections_to_segments): Likewise.
When opening a BFD for update, as gdb --write does, modifications to
anything but the contents of sections is restricted.
Do not try to write back any ELF headers in this case.
bfd/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* elf.c (_bfd_elf_write_object_contents): Return from function
early if abfd->direction == both_direction.
gdb/testsuite/ChangeLog
2018-09-24 Jozef Lawrynowicz <jozef.l@mittosystems.com>
PR gdb/20948
* gdb.base/write_mem.exp: New test.
* gdb.base/write_mem.c: Likewise.
VMA of the first section in the segment containing the ELF file header
(and possibly section headers too) can't be used to reliably find the
size of the headers plus padding. What's really needed is sh_offset
of the first section assuming it has contents (vma does have a
relationship to sh_offset, but is only guaranteed in demand paged
executables).
If the first section is SHT_NOBITS and it hasn't been converted to
have file contents by the existence of a following SHT_PROGBITS
section in the same segment, the sh_offset value also isn't reliable.
PR 23595
elf.c (copy_elf_program_header): When first segment contains
only the headers and SHT_NOBITS sections, use segment p_filesz
to calculate header and padding size. Use filepos of the first
section otherwise.
The BFD linker with PR ld/23499 may generate shared libraries with
corrupt symbol version info which leads to linker error when the
corrupt shared library is used:
/usr/bin/ld: bin/libKF5Service.so.5.49.0: _edata: invalid version 21 (max 0)
/usr/bin/ld: bin/libKF5Service.so.5.49.0: error adding symbols: bad value
Add check for corrupt symbol version info to objdump:
00000000000af005 g D .data 0000000000000000 <corrupt> _edata
and readelf:
728: 00000000000af005 0 NOTYPE GLOBAL DEFAULT 25 _edata@<corrupt> (5)
bfd/
PR ld/23499
* elf.c (_bfd_elf_get_symbol_version_string): Return
_("<corrupt>") for corrupt symbol version info.
binutils/
PR ld/23499
* readelf.c (get_symbol_version_string): Return _("<corrupt>")
for corrupt symbol version info.
I built gdb with ubsan and ran the test suite.
One complaint was due to bfd_get_elf_phdrs passing NULL to memcpy.
This patch avoids the complaint.
bfd/ChangeLog
2018-07-23 Tom Tromey <tom@tromey.com>
* elf.c (bfd_get_elf_phdrs): Don't call memcpy with size 0.
The NT_ARM_SVE section is documented here:
https://github.com/torvalds/linux/blob/master/Documentation/arm64/sve.txt
* A NT_ARM_SVE note will be added to each coredump for each thread of the
dumped process. The contents will be equivalent to the data that would have
been read if a PTRACE_GETREGSET of NT_ARM_SVE were executed for each thread
when the coredump was generated.
* elf.c (elfcore_grok_aarch_sve): New function.
(elfcore_grok_note): Check for Aarch64 SVE.
(elfcore_write_aarch_sve): New function.
(elfcore_write_register_note): Check for Aarch64 SVE.
* elf-bfd.h(elfcore_grok_aarch_sve): New declaration.
Check VER_FLG_BASE instead of assuming that the first symbol version is
base version.
bfd/
PR binutils/23267
* elf.c (_bfd_elf_get_symbol_version_string): Check if the first
symbol version is base version.
binutils/
PR binutils/23267
* readelf.c (get_symbol_version_string): Check if the first
symbol version is base version.
All sections in a section group should be marked with SHF_GROUP. But
some tools generate broken objects without SHF_GROUP. This patch fixes
them up for objcopy and strip.
PR binutils/23199
* elf.c (setup_group): Mark section in a section group with
SHF_GROUP.
This patch prevents elf_next_in_group list pointer confusion when
SHT_GROUP sections specify other SHT_GROUP sections in their list of
group sections.
PR 23199
* elf.c (setup_group): Formatting. Check that SHT_GROUP entries
don't point at other SHT_GROUP sections. Set shdr corresponding
to invalid entry, to NULL rather than section 0. Identify
SHT_GROUP section index when reporting an error. Cope with NULL
shdr pointer.
Sections may well belong in multiple segments. The testcase in the PR
saw an allocated section being assigned to an ABIFLAGS segment, then
not being assigned to a LOAD segment because it had already been
handled. To fix that particular problem this patch sets and tests
segment_mark only for LOAD segments. I kept the segment_mark test for
LOAD segments because I think there may otherwise be a problem with
zero size sections.
A few other problems showed up with the testcase. Some targets align
.dynamic, resulting in the test failing with "section .dynamic lma
0x800000c0 adjusted to 0x800000cc" and similar messages. I've tried
to handle that with some more hacks to the segment lma, which do the
right thing for the testcase, but may well fail in other situations.
I've also removed the tests of segment lma (p_paddr) and code involved
in deciding that an adjusted segment no longer covers the file or
program headers. Those test can't be correct in the face of objcopy
--change-section-lma. It may be necessary to reinstate the tests but
do them modulo page size, but we'll see how this goes.
PR 20659
bfd/
* elf.c (rewrite_elf_program_header): Use segment_mark only for
PT_LOAD headers. Delete first_matching_lma and first_suggested_lma.
Instead make matching_lma and suggested_lma pointers to the
sections. Align section vma and lma calculated from segment.
Don't clear includes_phdrs or includes_filehdr based on p_paddr
test. Try to handle alignment padding before first section by
adjusting new segment lma down. Adjust PT_PHDR map p_paddr.
ld/
* testsuite/ld-elf/changelma.d,
* testsuite/ld-elf/changelma.lnk,
* testsuite/ld-elf/changelma.s: New test.
PR 22809
* elf.c (bfd_elf_get_str_section): Check for an excessively large
string section.
* elf-attrs.c (_bfd_elf_parse_attributes): Issue an error if the
attribute section is larger than the size of the file.
This patch is aimed at silencing gcc8 -Wstringop-truncation warnings.
Unfortunately adding __attribute__ ((__nonstring)) doesn't work in a
number of the places patched here, (see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85643) so if you have
recent glibc headers installed you'll need to configure binutils with
--disable-werror to compile using gcc8 or gcc9.
include/
* ansidecl.h: Import from gcc.
* coff/internal.h (struct internal_scnhdr): Add ATTRIBUTE_NONSTRING
to s_name.
(struct internal_syment): Add ATTRIBUTE_NONSTRING to _n_name.
bfd/
* elf-linux-core.h (struct elf_external_linux_prpsinfo32_ugid32),
(struct elf_external_linux_prpsinfo32_ugid16),
(struct elf_external_linux_prpsinfo64_ugid32),
(struct elf_external_linux_prpsinfo64_ugid16): Add ATTRIBUTE_NONSTRING
to pr_fname and pr_psargs fields. Remove GCC diagnostic pragmas.
Move comment to..
* elf.c (elfcore_write_prpsinfo): ..here. Indent nested preprocessor
directives.
* elf32-arm.c (elf32_arm_nabi_write_core_note): Add ATTRIBUTE_NONSTRING
to data.
* elf32-ppc.c (ppc_elf_write_core_note): Likewise.
* elf32-s390.c (elf_s390_write_core_note): Likewise.
* elf64-s390.c (elf_s390_write_core_note): Likewise.
* elfxx-aarch64.c (_bfd_aarch64_elf_write_core_note): Likewise.
* elf64-x86-64.c (elf_x86_64_write_core_note): Add GCC diagnostic
pragmas.
* peXXigen.c (_bfd_XXi_swap_scnhdr_out): Use strnlen to avoid
false positive gcc-8 warning.
gas/
* config/obj-evax.c (shorten_identifier): Use memcpy in place
of strncpy.
* config/obj-macho.c (obj_mach_o_make_or_get_sect): Ensure
segname and sectname fields are NUL terminated.
This seems to work with gcc-8 and a bunch of prior gcc versions I tested.
* elf-linux-core.h: Disable gcc-8 string truncation warning.
* elf.c (elfcore_write_prpsinfo): Likewise.
The gcc warning has been fixed, and the patch regressed builds with
some older versions of gcc.
* elf-linux-core.h: Revert last change.
* elf.c: Likewise.
All of these warnings were false positives. -Wstringop-truncation is
particularly annoying when it warns about strncpy used quite correctly.
bfd/
* elf-linux-core.h (swap_linux_prpsinfo32_ugid32_out): Disable
gcc-8 string truncation warning.
(swap_linux_prpsinfo32_ugid16_out): Likewise.
(swap_linux_prpsinfo64_ugid32_out): Likewise.
(swap_linux_prpsinfo64_ugid16_out): Likewise.
* elf.c (elfcore_write_prpsinfo): Likewise.
gas/
* stabs.c (generate_asm_file): Use memcpy rather than strncpy.
Remove call to strlen inside loop.
* config/tc-cr16.c (getreg_image): Warning fix.
* config/tc-crx.c (getreg_image): Warning fix.
A number of ARM tests show results like:
ld-new: no address assigned to the veneers output section .gnu.sgstubs
ld-new: can not size stub section: invalid operation
ld-new: warning: cannot find entry symbol _start; defaulting to 0000000000010074
ld-new: tmpdir/cmse-veneers-no-gnu_sgstubs: warning: allocated section `.text' not in segment
Segmentation fault
PASS: Secure gateway veneers: no .gnu.sgstubs section
The PASS despite the segv shows the danger of using "#..." to match
error output. This patch doesn't try to fix the testuite, but does
prevent the segfault.
* elf.c (assign_file_positions_except_relocs): Don't segfault
when actual number of phdrs is less than allocated. Delete
outdated comment. Formatting.
Commit 325ba6fb34 excluded degenerate zero length PT_LOAD segments,
but that only fixed part of the problem, which was that the load
segment limits were not calculated properly.
PR 22845
* elf.c (IS_TBSS): Define.
(_bfd_elf_map_sections_to_segments): Use IS_TBSS.
(assign_file_positions_for_non_load_sections): Revert last change.
Properly calculate load segment limits to compare against relro limits.
Fixes a failure triggered by -z separate-code. p_memsz is tested
rather than p_filesz for objcopy --only-keep-debug where p_filesz is
set to zero.
PR 22845
* elf.c (assign_file_positions_for_non_load_sections): Ignore
degenerate zero size PT_LOAD segments when finding one overlapping
the PT_GNU_RELRO segment.
This fixes the case where all of a group is removed with ld -r, the
situation in the PR, and failures where part of a group is removed
that contain relocs.
bfd/
PR 22836
* elf.c (_bfd_elf_fixup_group_sections): Account for removed
relocation sections. If size reduces to just the flag word,
remove that too and mark with SEC_EXCLUDE.
* elflink.c (bfd_elf_final_link): Strip empty group sections.
binutils/
* testsuite/binutils-all/group-7.s,
* testsuite/binutils-all/group-7a.d,
* testsuite/binutils-all/group-7b.d,
* testsuite/binutils-all/group-7c.d: New tests.
* testsuite/binutils-all/objcopy.exp: Run them.
ld/
* testsuite/ld-elf/pr22836-2.d,
* testsuite/ld-elf/pr22836-2.s: New test.
lld lays out the relro segment differently to GNU ld, not bothering to
include the first few bytes of .got.plt and padding out to a page at
the end of the segment. This patch teaches binutils to recognize the
different (and somewhat inferior) layout as valid.
bfd/
PR 22829
* elf.c (assign_file_positions_for_non_load_sections): Rewrite
PT_GNU_RELRO setup.
ld/
* testsuite/ld-x86-64/pr14207.d: Adjust relro p_filesz.
Fix the issue of any failure from `->elf_backend_section_processing'
not being propagated by `_bfd_elf_write_object_contents'. The MIPS
`_bfd_mips_elf_section_processing' handler can actually potentially
fail, however the caller currently ignores that.
bfd/
* elf.c (_bfd_elf_write_object_contents): Propagate a failure
status from `->elf_backend_section_processing'.
We can't map different disk pages into the same memory page; The last
page mapped will simply overwrite any previous pages. The
executable/non-executable new_segment test ignored this fact, leading
to a ld.so segfault on hppa when .dynamic is overwritten with zeros.
This patch moves existing tests for demand paging with lma on the same
memory page, to a new test performed before any case where we want a
new segment due to protection or loadable conflicts.
PR 22758
* elf.c (_bfd_elf_map_sections_to_segments): Don't start a new
segment when demand paged with lma on the same page. Test this
before load/non-load, executable/non-executable,
writable/non-writable tests and simplify. Delete bogus relro
condition in writable/non-writable test. Delete outdated
comment. Formatting.
When processing a section that is a member of a group, the group
that contains it is looked up using a linear search. The resulting
O(n^2) complexity causes significant performance issues when
dealing with object files with very many groups.
By remembering the index of the last found group and restarting
the next search from that index, the search instead becomes O(n)
in common cases.
* elf.c (setup_group): Optimize search for group by remembering
last found group and restarting search at that index.
* elf-bfd.h (struct elf_obj_tdata): Add group_search_offset field.
When generating separate code LOAD segment, create a new LOAD segment
if the previous section contains text and the current section doesn't
or vice versa:
Elf file type is DYN (Shared object file)
Entry point 0x200020
There are 7 program headers, starting at offset 52
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x00200 0x00200 R 0x200000
LOAD 0x200000 0x00200000 0x00200000 0x00036 0x00036 R E 0x200000
LOAD 0x400000 0x00400000 0x00400000 0x00064 0x00064 R 0x200000
LOAD 0x400f80 0x00600f80 0x00600f80 0x000a0 0x000a0 RW 0x200000
DYNAMIC 0x400f80 0x00600f80 0x00600f80 0x00080 0x00080 RW 0x4
GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RW 0x10
GNU_RELRO 0x400f80 0x00600f80 0x00600f80 0x00080 0x00080 R 0x1
Section to Segment mapping:
Segment Sections...
00 .hash .gnu.hash .dynsym .dynstr .rela.plt
01 .plt .text
02 .rodata .eh_frame
03 .dynamic .got.plt
04 .dynamic
05
06 .dynamic
to prevent fetching or executing data in code pages as instructions.
Also don't put a writable section in a read-only segment if there is a
RELRO segment.
Since code segment is aligned and padded to the maximum page size on
disk, the minimum file size is bigger than the maximum page size which
is 2MB (0x200000):
-rwxr-xr-x 1 hjl hjl 4201932 Jan 10 10:41 libfoo.so
"-z max-page-size=0x1000" can be used to reduce the maximum page size to
4KB (0x1000):
-rwxr-xr-x 1 hjl hjl 15820 Jan 10 10:44 libfoo.so
PR ld/22393
* elf.c (_bfd_elf_map_sections_to_segments): When generating
separate code and read-only data LOAD segments, create a new
LOAD segment if the previous section contains text and the
current section doesn't or vice versa. Don't put a writable
section in a read-only segment if there is a RELRO segment.
Alan Modra
H.J. Lu
Nick Clifton
Mark Wielaard
Jozef Lawrynowicz
Tom Tromey
Edjunior Barbosa Machado
Alan Hayward
Maciej W. Rozycki
Jens Widell
John Baldwin