Some early revisions of the Cortex-A53 have an erratum (843419). The
details of the erratum are quite complex and involve dynamic
conditions. For the purposes of the workaround we have simplified the
static conditions to an ADRP in the last two instructions of a 4KByte
page, followed within four instructions by a load/store dependent on
the ADRP.
This patch adds support to conservatively scan for and workaround
Cortex A53 erratum 843419. There are two different workaround
strategies used. The first is to rewrite ADRP instructions which form
part of an erratum sequence with an ADR instruction. In situations
where the ADR provides insufficient offset the dependent load or store
instruction from the sequence is moved to a stub section and branches
are inserted from the original sequence to the relocated instruction
and back again.
Stub section sizes are rounded up to a multiple of 4096 in order to
ensure that the act of inserting work around stubs does not create
more errata sequences.
Workaround stubs are always inserted into the stub section associated
with the input section containing the erratum sequence. This ensures
that the fully relocated form of the veneered load store instruction
is available at the point in time when the stub section is written.
Since .rela.plt/rel.plt section may contain relocations against .got.plt
section, we set sh_info for .rela.plt/rel.plt section to .got.plt section
index if target has .got.plt section.
bfd/
PR ld/18169
* elf-bfd.h (elf_backend_data): Add get_reloc_section.
(_bfd_elf_get_reloc_section): New.
* elf.c (_bfd_elf_get_reloc_section): Likewise.
(assign_section_numbers): Call get_reloc_section to look up the
section the relocs apply.
* elfxx-target.h (elf_backend_get_reloc_section): Likewise.
(elfNN_bed): Initialize get_reloc_section with
elf_backend_get_reloc_section.
ld/testsuite/
PR ld/18169
* ld-elf/linkinfo1a.d: Updated.
* ld-elf/linkinfo1b.d: Likewise.
Allows .dynbss copy of shared library protected visibility variables
if they are read-only.
To recap: Copying a variable from a shared library into an executable's
.dynbss is an old hack invented for non-PIC executables, to avoid the
text relocations you'd otherwise need to access a shared library
variable. This works with ELF shared libraries because global
symbols can be overridden. The trouble is that protected visibility
symbols can't be overridden. A shared library will continue to access
it's own protected visibility variable while the executable accesses a
copy. If either the shared library or the executable updates the
value then the copy diverges from the original. This is wrong since
there is only one definition of the variable in the application.
So I made the linker report an error on attempting to copy protected
visibility variables into .dynbss. However, you'll notice the above
paragraph contains an "If". An application that does not modify the
variable value remains correct even though two copies of the variable
exist. The linker can detect this situation if the variable was
defined in a read-only section.
PR ld/15228
PR ld/18167
* elflink.c (elf_merge_st_other): Add "sec" parameter. Don't set
protected_def when symbol section is read-only. Adjust all calls.
* elf-bfd.h (struct elf_link_hash_entry): Update protected_def comment.
Ensure that injection of a stub section does not break a link where
there is an xpectation that flow of control can pass from one input
section to another simply by linking the input sections in series.
The solution here is to allow stub sections to be inserted after any
input section (existing behaviour), but inject an additional branch at
the start of each stub section such that control flow falling into the
stub section will branch over the stub section.
I noticed that _bfd_elf_gc_mark_extra_sections attempts to unmark
related debug sections when it finds an unmarked code section.
When it finds .text.foo is unmarked, for example, it removes
.debug_line.text.foo as well (using the section name as a suffix
match check.
However, it bails out after finding one such section.
bfd/
* elflink.c (_bfd_elf_gc_mark_extra_sections): Don't break on
first matching debug section.
ld/testsuite/
* ld-gc/all-debug-sections.d: New file.
* ld-gc/all-debug-sections.s: Likewise.
* ld-gc/gc.exp: Execute new testcase.
No need to write the zlib header if compression didn't make the section
smaller.
PR binutils/18087
* compress.c (bfd_compress_section_contents): Don't write the
zlib header and set contents as well as compress_status if
compression didn't make the section smaller.
(bfd_init_section_compress_status): Don't check compression
size here.
Change the behaviour of section_group[] such that .stub_sec points to
the stub section attached to the indexed section rather than the stub
section attached to the link_section pointed to be the index section.
This provides a mechanism to get to the stub section following any
input section. While still allowing the section grouping mechanism to
find the section group stub section associated with an input section
by first following the link_sec pointer.
This patch recognizes that we only need to perform one scan for the
835769 errata and that this scan can take place before we insert
branch stubs. The erratum scan code is relocated and adjusted to
create stub entries directly rather than populating an intermediate
representation. Since stub entries are created immediately we can
drop the adhoc stub size adjustment code and allow the generic stub
sizing code to deal with 835769 stub entries.
This patch restructures the code but does not change the workaround
used to deal with erratum 83679, the exact placement of workaround
stubs in the final image may change slightly after this patch due to
stubs being created in a different order.
* elf64-ppc.c (ppc64_elf_relocate_section): Report overflow to
stubs, even those for undefined weak symbols. Otherwise, don't
report relocation overflow on branches to undefined strong
symbols. Fix memory leak.
* elf32-ppc.c (ppc_elf_relocate_section): Don't report relocation
overflow on branches to undefined strong symbols.
inc * rl78.h (E_FLAG_RL78_G10): Redefine.
(E_FLAG_RL78_CPU_MASK, E_FLAG_RL78_ANY_CPU, E_FLAG_RL78_G13
E_FLAG_RL78_G14): New flags.
bin * readelf.c (get_machine_flags): Decode RL78's G13 and G14 flags.
gas * config/tc-rl78.c (enum options): Add G13 and G14.
(md_longopts): Add -mg13 and -mg14.
(md_parse_option): Handle -mg13 and -mg14.
(md_show_usage): List -mg13 and -mg14.
* doc/c-rl78.texi: Add description of -mg13 and -mg14 options.
bfd * elf32-rl78.c (rl78_cpu_name): New function. Prints the name of
the RL78 core based upon the flags.
(rl78_elf_merge_private_bfd_data): Handle merging of G13 and G14
flags.
(rl78_elf_print_private_bfd_data): Use rl78_cpu_name.
(elf32_rl78_machine): Always return bfd_mach_rl78.
PR gas/18087
gas/test * gas/i386/dw2-compress-1.d: Allow the test to pass regardless of
whether the .debug_info section was compressed on not.
bfd * compress.c (bfd_compress_section_contents): Do not define this
function if it is not used.
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