Currently, we have a code duplication in llvm-readobj which was introduced in D63266.
The duplication was introduced to allow llvm-readobj to dump the partially
broken object. Methods in ELFFile<ELFT> perform a strict validation of the inputs,
what is itself good, but not for dumper tools, that might want to dump the information,
even if some pieces are broken/unexpected.
This patch introduces a warning handler which can be passed to ELFFile<ELFT> methods
and can allow skipping the non-critical errors when needed/possible.
For demonstration, I removed the duplication from llvm-readobj and implemented a warning using
the new custom warning handler. It also deduplicates the strings printed, making the output less verbose.
Differential revision: https://reviews.llvm.org/D65515
llvm-svn: 368260
readelf -n:
```
// "Data size" is not left justified
Owner Data size Description
GNU 0x00000010 NT_GNU_ABI_TAG (ABI version tag)
```
llvm-readelf -n (before):
```
// "Data size" column shifted by 1
Owner Data size Description
GNU 0x00000010 NT_GNU_ABI_TAG (ABI version tag)
```
llvm-readelf -n (after):
```
Owner Data size Description
GNU 0x00000010 NT_GNU_ABI_TAG (ABI version tag)
```
This change is made to reduce the diff with readelf -n, so that it is
slightly easier to check what features readelf implements but we don't.
Reviewed By: grimar, jhenderson
Differential Revision: https://reviews.llvm.org/D65847
llvm-svn: 368138
When e_shstrndx is broken, it is impossible to get a section name.
In this patch I improved the error message we show and
added tests for Object and for llvm-readelf/llvm-readobj
Message was changed in two places:
1) llvm-readelf/llvm-readobj previously used a code from Object/ELF.h,
now they have a modified version of it (it has less checks and allows
dumping broken things).
2) Code in Object/ELF.h is still used for generic cases.
Differential revision: https://reviews.llvm.org/D64714
llvm-svn: 366203
It does not make sence to stop dumping the object if the broken
dynamic section was found. In this patch I changed the behavior from
"report an error" to "report a warning". This matches GNU.
Differential revision: https://reviews.llvm.org/D64472
llvm-svn: 365762
If dynamic table is missing, output "dynamic strtab not found'. If the index is
out of range, output "Invalid Offset<..>".
https://bugs.llvm.org/show_bug.cgi?id=40807
Reviewed by: jhenderson, grimar, MaskRay
Differential Revision: https://reviews.llvm.org/D63084
Patch by Yuanfang Chen.
llvm-svn: 363374
Summary:
Use llvm::fouts() as the default stream for outputing. No new stream
should be constructed to output at the same time.
https://bugs.llvm.org/show_bug.cgi?id=42140
Reviewers: jhenderson, grimar, MaskRay, phosek, rupprecht
Reviewed By: rupprecht
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63115
Patch by Yuanfang Chen!
llvm-svn: 363198
ELF for the 64-bit Arm Architecture defines two processor-specific dynamic
tags:
DT_AARCH64_BTI_PLT 0x70000001, d_val
DT_AARCH64_PAC_PLT 0x70000003, d_val
These presence of these tags indicate that PLT sequences have been
protected using Branch Target Identification and Pointer Authentication
respectively. The presence of both indicates that the PLT sequences have
been protected with both Branch Target Identification and Pointer
Authentication.
This patch adds the tags and tests for llvm-readobj and yaml2obj.
As some of the processor specific dynamic tags overlap, this patch splits
them up, keeping their original default value if they were not previously
mentioned explicitly in a switch case.
Differential Revision: https://reviews.llvm.org/D62596
llvm-svn: 362493
ELF for the 64-bit Arm Architecture defines a processor specific property
type GNU_PROPERTY_AARCH64_FEATURE_1_AND as GNU_PROPERTY_LOPROC. This
property works in a similar way to the existing X86 processor specific
property GNU_PROPERTY_GNU_X86_FEATURE_1_AND.
Two feature bits are defined for GNU_PROPERTY_AARCH64_FEATURE_1_AND:
- GNU_PROPERTY_AARCH64_FEATURE_1_BTI 0x1
- GNU_PROPERTY_AARCH64_FEATURE_1_PAC 0x2
This patch defines the property, feature bits and implements support for
printing in llvm-readobj.
Differential Revision: https://reviews.llvm.org/D62595
llvm-svn: 362490
BB failed:
http://lab.llvm.org:8011/builders/clang-armv7-linux-build-cache/builds/15062/steps/build%20stage%201/logs/stdio
Error was:
/home/buildslave/buildslave/clang-armv7-linux-build-cache/llvm/tools/llvm-readobj/ELFDumper.cpp:3540:7:
error: non-constant-expression cannot be narrowed from type 'llvm::support::detail::packed_endian_specific_integral<unsigned long long,
llvm::support::endianness::little, 1>::value_type' (aka 'unsigned long long') to 'size_t' (aka 'unsigned int') in initializer list [-Wc++11-narrowing]
StrTabSec->sh_size};
llvm-svn: 362084
It is now possible after D61937 was landed and was discussed
in it's review comments. It is not consistent with GNU, which
does not output .dynamic section content in this case for
no visible reason.
Differential revision: https://reviews.llvm.org/D62179
llvm-svn: 361943
This is how multi-partition combined output files are going to look. If we
see multiple sections, the tools will just read the first one.
Differential Revision: https://reviews.llvm.org/D62349
llvm-svn: 361869
They were failing on 32-bit Windows. In the cases where I've changed
test expectations, I've checked that they match the output of GNU
readelf.
llvm-svn: 361807
GNU readelf tool prints slightly different dynamic table "header" and
surrounds dynamic tag names by brackets. This patch implements the same
formatting for GNU-style output of the `llvm-readobj`.
LLVM
```
DynamicSection [ (13 entries)
Tag Type Name/Value
0x00000006 SYMTAB 0x168
...
]
```
GNU
```
Dynamic section at offset 0x1d0 contains 13 entries:
Tag Type Name/Value
0x00000006 (SYMTAB) 0x168
...
```
Differential Revision: https://reviews.llvm.org/D62256
llvm-svn: 361633
It is now possible after D61937 was landed and was discussed
in it's review comments. It is not consistent with GNU, which
does not output .dynamic section content in this case for
no visible reason.
Differential revision: https://reviews.llvm.org/D62179
llvm-svn: 361630
This is a result of what I found during my work on https://bugs.llvm.org/show_bug.cgi?id=41679.
Previously LLVM readelf took the information about .dynamic section
from its PT_DYNAMIC segment only. GNU tools have a bit different logic.
They also use the information from the .dynamic section header if it is available.
This patch changes the code to improve the compatibility with the GNU Binutils.
Differential revision: https://reviews.llvm.org/D61937
llvm-svn: 361165
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.
Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.
The design goals were to provide:
- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
environments (MSVC in particular).
Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.
In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:
1. There are no competing defined symbols in a given set of libraries, or
if they exist, the program owner doesn't care which is linked to their
program.
2. There may be circular dependencies between libraries.
The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:
.section ".deplibs","MS",@llvm_dependent_libraries,1
.asciz "foo"
For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.
LLD processes the dependent library specifiers in the following way:
1. Dependent libraries which are found from the specifiers in .deplibs sections
of relocatable object files are added when the linker decides to include that
file (which could itself be in a library) in the link. Dependent libraries
behave as if they were appended to the command line after all other options. As
a consequence the set of dependent libraries are searched last to resolve
symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
strings in a .deplibs section by; first, handling the string as if it was
specified on the command line; second, by looking for the string in each of the
library search paths in turn; third, by looking for a lib<string>.a or
lib<string>.so (depending on the current mode of the linker) in each of the
library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
dependent libraries.
Rationale for the above points:
1. Adding the dependent libraries last makes the process simple to understand
from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
will affect all of the dependent libraries. There is a potential problem of
surprise for developers, who might not realize that these options would apply
to these "invisible" input files; however, despite the potential for surprise,
this is easy for developers to reason about and gives developers the control
that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
find input files. The different search methods are tried by the linker in most
obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
is not necessary: if finer control is required developers can fall back to using
the command line directly.
RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.
Differential Revision: https://reviews.llvm.org/D60274
llvm-svn: 360984
In the r360676 "Apply clang format. NFC" I applied clang-format
for whole ELFDumper.cpp. It caused a little discussion,
one of the points mentioned was that previously nicely lined up
tables are not so nice now.
This patch reverts them.
llvm-svn: 360860
Summary: Currently, `llvm-readobj` do not support GNU style dumper for symbol versioning sections. In this patch, I would like to implement dumper for `.gnu.version` section
Reviewers: jhenderson, rupprecht, grimar
Reviewed By: jhenderson, rupprecht
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59877
llvm-svn: 357578
Summary: Support reading notes that don't have a standard note name.
Reviewers: MaskRay
Reviewed By: MaskRay
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59969
llvm-svn: 357271
The majority of the printRelocation and printDynamicRelocation functions
were identical. This patch factors this all out into a new function.
There are a couple of minor differences to do with printing of symbols
without names, but I think these are harmless, and in some cases a small
improvement.
Reviewed by: grimar, rupprecht, Higuoxing
Differential Revision: https://reviews.llvm.org/D59823
llvm-svn: 357246
Summary: When implementing `GNU style` dumper for `.gnu.version` section, we should find symbol version name by `vs_index`.
Reviewers: jhenderson, rupprecht
Reviewed By: rupprecht
Subscribers: arphaman, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59545
llvm-svn: 357164
Summary:
Currently, llvm-readobj can dump symbol version sections only in LLVM style. In this patch, I would like to separate these dumpers into GNU style and
LLVM style for future implementation.
Reviewers: grimar, jhenderson, mattd, rupprecht
Reviewed By: jhenderson, rupprecht
Subscribers: ormris, dyung, RKSimon, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59186
llvm-svn: 356881
