--change-section address and its alias --adjust-section-vma allows
modification
of section addresses in a relocatable file. This used to be used, for
example,
in Fiasco microkernel.
On a relocatable file this option behaves the same as GNU objcopy, apart
from
the fact that it does not issue any warnings, for example, when an
argument is
not used.
GNU objcopy does not produce an error when passed an executable file but
the
usecase for this is not clear, and the behaviour is inconsistent. The
idea of
GNU objcopy --change-section-address is that the option should change
both LMA
and VMA in an executable file. Since this patch does not implement
executable
file support, only VMA is changed.
llvm-objcopy did not support change-section-lma argument.
This patch adds support for a use case of change-section-lma, that is
shifting load address of all sections by the same offset. This seems to
be the only practical use case of change-section-lma, found in other
software such as Zephyr RTOS's build system.
This is an option that could possibly be supported in some other than
ELF formats, however this change only implements it for ELF. When used
with other formats an error message is raised.
In comparison, the behavior of GNU objcopy is inconsistent. For some ELF
files it behaves the same as described above. For others, it copies the
file without modifying the p_paddr fields when it would be expected. In
some experiments it modifies arbitrary fields in section or program
headers. It is unclear what exactly determines this.
The executable file generated by yaml2obj in this test is not parsable
by GNU objcopy. With Machine set to EM_AARCH64, the file can be parsed
and the first test in the test file completes with 0 exit code. However,
the result is rather arbitrary. AArch64 GNU objcopy subtracts 0x1000
from p_filesz and p_memsz of the first LOAD section and 0x1000 from
p_offset of the second LOAD section. It does not look meaningful.
--compress-sections is similar to --compress-debug-sections but applies
to arbitrary sections.
* `--compress-sections <section>=none`: decompress sections
* `--compress-sections <section>=[zlib|zstd]`: compress sections with zlib/zstd
Like `--remove-section`, the pattern is by default a glob, but a regex
when --regex is specified.
For `--remove-section` like options, `!` prevents matches and is not
dependent on ordering (see `ELF/wildcard-syntax.test`). Since
`--compress-sections a=zlib --compress-sections a=none` naturally allows
overriding, having an order-independent `!` would be confusing.
Therefore, `!` is disallowed.
Sections within a segment are effectively immutable. Report an error for
an attempt to (de)compress them. `SHF_ALLOC` sections in a relocatable
file can be compressed, but linkers usually reject them.
Note: Before this patch, a compressed relocation section is recognized
as a `RelocationSectionBase` as well and `removeSections` `!ToRemove(*ToRelSec)`
may incorrectly interpret a `CompressedSections` as `RelocationSectionBase`,
leading to ubsan failure for the new test. Fix this by setting
`OriginalFlags` in CompressedSection::CompressedSection.
Link: https://discourse.llvm.org/t/rfc-compress-arbitrary-sections-with-ld-lld-compress-sections/71674
Pull Request: https://github.com/llvm/llvm-project/pull/85036
This reverts commit 9e3b64b9f95aadf57568576712902a272fe66503.
Reason: Broke the UBSan buildbot. See the comments in the pull request
(https://github.com/llvm/llvm-project/pull/85036) for more information.
--compress-sections is similar to --compress-debug-sections but applies
to arbitrary sections.
* `--compress-sections <section>=none`: decompress sections
* `--compress-sections <section>=[zlib|zstd]`: compress sections with zlib/zstd
Like `--remove-section`, the pattern is by default a glob, but a regex
when --regex is specified.
For `--remove-section` like options, `!` prevents matches and is not
dependent on ordering (see `ELF/wildcard-syntax.test`). Since
`--compress-sections a=zlib --compress-sections a=none` naturally allows
overriding, having an order-independent `!` would be confusing.
Therefore, `!` is disallowed.
Sections within a segment are effectively immutable. Report an error for
an attempt to (de)compress them. `SHF_ALLOC` sections in a relocatable
file can be compressed, but linkers usually reject them.
Link: https://discourse.llvm.org/t/rfc-compress-arbitrary-sections-with-ld-lld-compress-sections/71674
Pull Request: https://github.com/llvm/llvm-project/pull/85036
Add --skip-symbol and --skip-symbols options that allow to skip symbols
when executing other options that can change the symbol's name, binding
or visibility, similar to an existing option --keep-symbol that keeps a
symbol from being removed by other options.
Simplify --[de]compress-debug-sections to make it easier to add custom section [de]compression.
Change the following two behaviors to match GNU objcopy.
* --compress-debug-sections compresses SHF_ALLOC sections while GNU
doesn't.
* --decompress-debug-sections decompresses non-debug sections while GNU
doesn't.
Pull Request: https://github.com/llvm/llvm-project/pull/84885
Add options --set-symbol-visibility and --set-symbols-visibility to
manually change the visibility of symbols.
There is already an option to set the visibility of newly added symbols
via --add-symbol and --new-symbol-visibility. This option will allow to
change the visibility of already existing symbols.
This fixes the issue mentioned here:
https://github.com/llvm/llvm-project/issues/57407
It prevents `llvm-objcopy` from removing the `.gnu _debuglink` section
when used with the `--strip-all` flag. Since `--strip-all` is the
default of `llvm-strip` the patch also prevents `llvm-strip` from
removing the `.gnu_debuglink` section.
`--gap-fill <value>` fills the gaps between sections with a specified
8-bit value, instead of zero.
`--pad-to <address>` pads the output binary up to the specified load
address, using the 8-bit value from `--gap-fill` or zero.
These options are only supported for ELF input and binary output.
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
Without the fix gcc warned with
../lib/ObjCopy/ELF/ELFObjcopy.cpp: In function 'uint64_t getSectionFlagsPreserveMask(uint64_t, uint64_t, uint16_t)':
../lib/ObjCopy/ELF/ELFObjcopy.cpp:106:31: warning: enumeral and non-enumeral type in conditional expression [-Wextra]
106 | ~(EMachine == EM_X86_64 ? ELF::SHF_X86_64_LARGE : 0UL);
| ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Currently, objcopy cannot set the new flag SHF_X86_64_LARGE. This change introduces the named flag "large" which translates to that section flag.
An "invalid argument" error is produced if a user attempts to set the flag on an architecture other than X86_64.
Reviewed By: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D153262
llvm-objcopy should not insert padding before a section if its
physical addresses is not aligned to section's alignment. This
behavior will match GNU objcopy and is important for embedded images
where the physical address is used to store the initial data image.
The loader typically will copy this image using a start symbol
created by the linker. If llvm-objcopy inserts padding before such a
section, the symbol address will not match the location in the image.
This commit refines the change in https://reviews.llvm.org/D128961
which intended to align sections which type changed from NOBITS and
their offset may not be aligned. However, it affected all sections.
Fix https://github.com/llvm/llvm-project/issues/62636
Reviewed By: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D150276
This reverts commit eb1442d0f73c76cfb5051d133f858fe760d189cf.
The test tools/llvm-objcopy/ELF/binary-paddr.test fails on
ppc64be-clang-test-suite:
https://lab.llvm.org/buildbot#builders/231/builds/13120
Reverting at author's request.
llvm-objcopy should not insert padding before a section if its
physical addresses is not aligned to section's alignment. This
behavior will match GNU objcopy and is important for embedded images
where the physical address is used to store the initial data image.
The loader typically will copy this image using a start symbol
created by the linker. If llvm-objcopy inserts padding before such a
section, the symbol address will not match the location in the image.
This commit refines the change in https://reviews.llvm.org/D128961
which intended to align sections which type changed from NOBITS and
their offset may not be aligned. However, it affected all sections.
Fix https://github.com/llvm/llvm-project/issues/62636
Reviewed By: jhenderson, MaskRay
Differential Revision: https://reviews.llvm.org/D150276
value() has undesired exception checking semantics and calls
__throw_bad_optional_access in libc++. Moreover, the API is unavailable without
_LIBCPP_NO_EXCEPTIONS on older Mach-O platforms (see
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS).
This fixes check-llvm.
For an ELFCLASS32 object, a compressed section due to --compress-debug-sections={zlib,zstd} has a
tail padding of 12 zero bytes. zlib happily allows this while zstd is rigid and
reports `error: '{{.*}}': failed to decompress section '.debug_foo': Src size is incorrect`.
Cole Kissane reported the problem.
Reviewed By: jhenderson, phosek
Differential Revision: https://reviews.llvm.org/D134385
The request is mentioned on D129053. I feel that having this functionality is
mildly useful (not strong).
* Rename .ctors to .init_array and change sh_type to SHT_INIT_ARRAY (GNU objcopy
detects the special name but we don't).
* Craft tests for a new SHT_LLVM_* extension
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D129337
* GNU objcopy supports --set-section-flags src=... --rename-section src=tst and --set-section-flags runs first.
* GNU objcopy processes --update-section before --rename-section.
To match the two behaviors, postpone --rename-section and allow its use together
with --set-section-flags.
As a side effect, --rename-section=.foo1=.foo2 --add-section=.foo1=/dev/null
leads to .foo2 while GNU objcopy surprisingly produces .foo1 (so
--set-section-flags --add-section --rename-section do not form a total order).
I think the deviation is fine as a total order makes more sense.
Rename set-section-flags-and-rename.test to
set-section-attr-and-rename.test and additionally test --set-section-alignment
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D129336
clang 14 removed -gz=zlib-gnu support and ld.lld removed linker input support
for zlib-gnu in D126793. Now let's remove zlib-gnu from llvm-objcopy.
* .zdebug* sections are no longer recognized as debug sections. --strip* don't remove them.
They are copied like other opaque sections
* --decompress-debug-sections does not uncompress .zdebug* sections
* --compress-debug-sections=zlib-gnu is not supported
It is very rare but in case a user has object files using .zdebug . They can use
llvm-objcopy<15 or GNU objcopy for uncompression.
--compress-debug-sections=zlib-gnu is unlikely ever used by anyone, so I do not
add a custom diagnostic.
Differential Revision: https://reviews.llvm.org/D128688
STB_GNU_UNIQUE is like STB_GLOBAL with extra semantics:
* gold and ld.lld: changed to STB_GLOBAL if --no-gnu-unique is specified
* glibc: unique even with dlopen `RTLD_LOCAL`, implies DF_1_NODELETE
Therefore, I think it makes sense for --weaken-symbol/--weaken-symbols/--weaken
to change STB_GNU_UNIQUE symbols.
binutils 2.39 will have the same behavior: https://sourceware.org/bugzilla/show_bug.cgi?id=28926
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D120638
Remove Expected<CompressedSection> factory functions in favor of constructors
now that zlib::compress returns void (D121512).
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D121644
Current objcopy implementation has a possibility to add or update sections.
The incoming section is specified as a pair: section name and name of the file
containing section data. The interface does not allow to specify incoming
section as a memory buffer. This patch adds possibility to specify incoming
section as a memory buffer.
Differential Revision: https://reviews.llvm.org/D120486
libtool uses file names to name members of an static library.
Files, located in different directories and having matching name,
would have the same name inside an archive. This is not a problem
for ld, but may be a problem for ar. This patch renames files
from ObjCopy library to avoid names clashing.
See https://reviews.llvm.org/D88827#3335814
Differential Revision: https://reviews.llvm.org/D120345
