Previously, we try to promote unresolved weak undefined symbols to
dynamic symbols so that they will get another chance to be resolved at
runtime. This is not always doable. Consider the following two cases:
- There's a relocation that directly refers a weak undefined symbol
- There's a relocation that is in a read-only section
In the former case, we need to create a copy relocation, but we can't
do that against a weak undef becasue a weak undef doesn't have the notion
of the symbol size.
In the latter case, we need to create a dynamic relocation, but such
dynamic relocation would fail at load-time when the runtime linker tries
to mutate the contents of a read-only section.
So, we had a logic to detect the above cases and promote weak undefs
only when they can be promoted. But the logic is not as robust as I
hoped. So, in this patch, I removed the logic and stop promoting weak
undefs.
We shouldn't create TLSDESC dynamic relocations for statically-
linked executables because such executables don't contain the
tranpoline function needed for TLSDESC. Instead, we should
always relax these relocations.
We used to write only global symbols to .dynsym because, in most
use cases, .dynsym are used for resolving inter-module dependencies.
However, we need to put local symbols to .dynsym if they are thread-
local symbols.
Previously, we created dynamic relocations against read-only sections
if the sections contain relocations against weak undefined symbols.
Since such dynamic relocations cannot be applied at load-time, the
generated executables failed with SEGV.
Now, such relocations are resolved to address 0.
Reported at https://github.com/rui314/mold/pull/110
Previously, only /usr/bin/ld, /usr/bin/ld.lld and /usr/bin/ld.gold
were intercepted. Now, mold ignores the directory part when comparing
a command name with `ld`, `ld.lld` or `ld.gold`.
This change is made because ld is often installed other than /usr/bin.
Fixes https://github.com/rui314/mold/issues/101
You can now build mold with the following commands:
$ mkdir -p out/debug
$ cd out/debug
$ cmake -GNinja -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Debug ../..
$ ninja
To run tests, use the following commands:
$ cd out/debug
$ ctest -j$(nproc)
Previously, a GOT relocation (e.g. R_X86_64_REX_GOTPCRELX) and a
R_X86_64_64 relocation referring the same imported symbols were
resolved to different addresses. Here is why:
- When we saw a R_X86_64_64 relocation against an imported symbol,
we created a PLT and resolve the relocation there.
- GOT relocation is resolved to a GOT entry, which has a true
address of an imported function at runtime, which is different
from PLT entries that redirect calls to the real function.
With this patch, we no longer create a PLT entry for R_X86_64_64.
Instead, we emit a dynamic relocation so that it is always resolved
to a real function address.
Fixes GNU MP's `make check` failure, which was reported at
https://github.com/rui314/mold/issues/81
The grammar of the command is this
VERSION { <version-script> }
where <version-script> is a version script you can specify with
the --version-script option.
The default size and offsets of the .dynamic section are not necessarily
same with different builds of clang. For example, some builds can make
clang pass --hash-style=gnu to the linker and some --hash-style=both.
This change updates the test to compute the difference in size of the
.dynamic section before and after using the flag -spare-dynamic-tags,
making it independent of the compiler build.
Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com>
mold: /__w/mold/mold/test/tmp/pie/a.o:(.text): R_X86_64_32 relocation
against symbol `.rodata' can not be used; recompile with -fPIE
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com>
