Summary:
If an executable needs text relocations, it should be marked as such so
that the loader can prepare for text relocations. We currently create a
dummy segment with DT_TEXTREL for that purpose.
Generic ABI as of 2000 [1] mentioned that "Its [DT_TEXTREL's] use
has been superseded by the DF_TEXTREL flag". However, it's actually not
superseded even after 18 years. OpenBSD and musl recognize only DT_TEXTREL.
So we still need to set both.
[1] http://www.sco.com/developers/gabi/2000-07-17/ch5.dynamic.html
Reviewers: rafael
Subscribers: emaste, llvm-commits, arichardson
Differential Revision: https://reviews.llvm.org/D43920
llvm-svn: 326503
This should resolve the issue that lld build fails in some hosts
that uses case-insensitive file system.
Differential Revision: https://reviews.llvm.org/D43788
llvm-svn: 326339
We sometimes need to iterate over input sections for a given
output section. It is not very convinent because we have to iterate
over section descriptions.
Patch introduces getInputSections helper, it simplifies things.
Differential revision: https://reviews.llvm.org/D43574
llvm-svn: 325763
Summary:
Before the name of the function sounded like it was just a getter for the
private class member Addend. However, it actually calculates the final
value for the r_addend field in Elf_Rela that is used when writing the
.rela.dyn section. I also added a comment to the UseSymVA member to
explain how it interacts with computeAddend().
Differential Revision: https://reviews.llvm.org/D43161
llvm-svn: 325485
Now that we have R_ADDEND, UseSymVA was redundant. We only want to
write the symbol virtual address when using an expression other than
R_ADDEND.
llvm-svn: 325360
Summary:
This follows up on r321889 where writing of Elf_Rel addends was partially
moved to RelocationBaseSection. This patch ensures that the addends are
always written to the output section when a input section uses RELA but the
output is REL.
Differential Revision: https://reviews.llvm.org/D42843
llvm-svn: 325328
When resolving dynamic RELA relocations the addend is taken from the
relocation and not the place being relocated. Accordingly lld does not
write the addend field to the place like it would for a REL relocation.
Unfortunately there is some system software, in particlar dynamic loaders
such as Bionic's linker64 that use the value of the place prior to
relocation to find the offset that they have been loaded at. Both gold
and bfd control this behavior with the --[no-]apply-dynamic-relocs option.
This change implements the option and defaults it to true for compatibility
with gold and bfd.
Differential Revision: https://reviews.llvm.org/D42797
llvm-svn: 324221
Compiler doesn't know the fact that Config->WordSize * 8 is always a
power of two, so it had to use the div instruction to divide some
number with C.
llvm-svn: 323014
I created https://reviews.llvm.org/D42202 to see how large the bloom
filter should be. With that patch, I tested various bloom filter sizes
with the following commands:
$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DLLVM_ENABLE_LLD=true \
-DLLVM_ENABLE_PROJECTS='clang;lld' -DBUILD_SHARED_LIBS=ON \
-DCMAKE_SHARED_LINKER_FLAGS=-Wl,-bloom-filter-bits=<some integer> \
../llvm-project/llvm
$ rm -f $(find . -name \*.so.7.0.0svn)
$ ninja lld
$ LD_BIND_NOW=1 perf stat bin/ld.lld
Here is the result:
-bloom-filter-bits=8 0.220351609 seconds
-bloom-filter-bits=10 0.217146597 seconds
-bloom-filter-bits=12 0.206870826 seconds
-bloom-filter-bits=16 0.209456312 seconds
-bloom-filter-bits=32 0.195092075 seconds
Currently we allocate 8 bits for a symbol, but according to the above
result, that number is not optimal. Even though the numbers follow the
diminishing return rule, the point where a marginal improvement becomes
too small is not -bloom-filter-bits=8 but 12. So this patch sets it to 12.
Differential Revision: https://reviews.llvm.org/D42204
llvm-svn: 323010
Previously we checked (HeaderSize == 0) to find out if
PltSection section is IPLT or PLT. Some targets does not set
HeaderSize though. For example PPC64 has no lazy binding implemented
and does not set PltHeaderSize constant.
Because of that using of both IPLT and PLT relocations worked
incorrectly there (testcase is provided).
Patch fixes the issue.
Differential revision: https://reviews.llvm.org/D41613
llvm-svn: 322362
Summary:
As reported in bug 35788, rL316280 reintroduces a race between two
members of SectionPiece, which share the same 64 bit memory location.
To fix the race, check the hash before checking the Live member, as
suggested by Rafael.
Reviewers: ruiu, rafael
Reviewed By: ruiu
Subscribers: smeenai, emaste, llvm-commits
Differential Revision: https://reviews.llvm.org/D41884
llvm-svn: 322264
When setting up the chain, we copy over the bucket's previous symbol
index, assuming that this index will be 0 (STN_UNDEF) for an unused
bucket (marking the end of the chain). When linking with --no-rosegment,
however, unused buckets will in fact contain the padding value, and so
the hash table will end up containing invalid chains. Zero out the hash
table section explicitly to avoid this, similar to what's already done
for GNU hash sections.
Differential Revision: https://reviews.llvm.org/D41928
llvm-svn: 322259
This is "Bug 35751 - .dynamic relocation entries omitted if output
contains only IFUNC relocations"
We have InX::RelaPlt and InX::RelaIPlt synthetic sections for PLT relocations.
They are usually live in rela.plt section. Problem appears when InX::RelaPlt
section is empty. In that case we did not produce normal set of dynamic tags
required, because logic was written in the way assuming we always have
non-IRelative relocations in rela.plt.
Patch fixes the issue.
Differential revision: https://reviews.llvm.org/D41592
llvm-svn: 321600
This was raised in comments for D41592.
With current code we always assign parent
section for Rel[a] sections like
InX::RelaPlt or InX::RelaDyn, so checking
their parent for null is excessive.
llvm-svn: 321581
We add dynamic section entries both in the ctor of the class and
DynamicSection::finalizeContents(). Some entries need to be added early
in the ctor because they add strings to .dynstr. Other entries were
intended to be added in finalizeContents(). However, some entries are
added in the ctor even though they don't add strings. This patch
fix the issue.
llvm-svn: 320851
We might crash in 'ARMExidxSentinelSection::writeTo()' because it expected
the sentinel entry to be put in the same 'InputSectionDescription' as
the last real entry. This assumption fails if the last output section command
for .ARM.exidx is anything but an input section description, because in this
case 'OutputSection::addSection()' creates a new 'InputSectionDescription'.
Differential Revision: https://reviews.llvm.org/D41105
llvm-svn: 320668
By using an index instead of a pointer for verdef we can put the index
next to the alignment field. This uses the otherwise wasted area and
reduces the shared symbol size.
By itself the performance change of this is in the noise, but I have a
followup patch to remove another 8 bytes that improves performance
when combined with this.
llvm-svn: 320449
We fill executable sections with trap instructions (0xcc or equivalent).
If a .gnu.hash section was put into an executable segment, we created
corrupted .gnu.hash section. This patch fixes the issue.
llvm-svn: 319863
This change actually makes the linker slightly faster. My observation
is that, with this patch, link time of clang without debug is about 1%
faster.
Differential Revision: https://reviews.llvm.org/D40697
llvm-svn: 319600
This is for "Bug 35474 - --emit-relocs produces wrongly-named reloc sections".
LLD currently for scripts like:
.text.boot : { *(.text.boot) }
emits relocation section with name .rela.text because does not take
redefined name of output section into account and builds section name
using rules for non-scripted case. Patch fixes this oddness.
Differential revision: https://reviews.llvm.org/D40652
llvm-svn: 319526
The MIPS GOT section has a number of local entries based on the number of pages
needed for output sections referenced by GOT page relocations. The number is
recorded in the DT_MIPS_LOCAL_GOTNO dynamic section tag. However, the dynamic tag
is added before assignAddresses has been called, meaning that any section size used
to calculate the value will not include size modifications caused by, for example,
linker scripts and thunks.
This change moves the calculation of DT_MIPS_LOCAL_GOTNO until writeTo, by which
time the output section sizes have been finalized.
Reviewers: ruiu, rafael
Differential Revision: https://reviews.llvm.org/D39493
llvm-svn: 318828
