You can force input section alignment within an output section by using SUBALIGN. The
value specified overrides any alignment given by input sections, whether larger or smaller.
SUBALIGN is used in many projects in the wild.
Differential revision: https://reviews.llvm.org/D23063
llvm-svn: 279256
Spec says "A hidden symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object".
But we previously converted symbols to STB_LOCAL even when -r was specified.
Broken binary was produced, this is PR28967, patch fixes the issue.
Differential revision: https://reviews.llvm.org/D23514
llvm-svn: 279220
We should always include symbol name when reporting relocations
error to simplify debugging of these issues. Without symbol names
users have to manually investigate which of the libraries contain
invalid relocations which can be cumbersome when linking multiple
libraries.
Differential Revision: https://reviews.llvm.org/D23690
llvm-svn: 279162
We only support assignments inside SECTIONS, but this does not match
the behavior of GNU linker which also allows them outside SECTIONS.
The only restriction on assignments outside SECTIONS is that they
cannot reference . (they have to be absolute expressions).
Differential Revision: https://reviews.llvm.org/D23598
llvm-svn: 279033
The linker will normally set the LMA equal to the VMA.
You can change that by using the AT keyword.
The expression lma that follows the AT keyword specifies
the load address of the section.
Patch implements this keyword.
Differential revision: https://reviews.llvm.org/D19272
llvm-svn: 278911
This add support for HIDDEN command which can be used to define
a symbol that will be hidden and won't be exported.
Differential Revision: https://reviews.llvm.org/D23534
llvm-svn: 278770
Previously we searched output section by name to assign VA. That did not
work in the case when multiple output sections with different constraints were defined in script.
Testcase shows the possible issue scenario, patch fixes the issue.
Differential revision: https://reviews.llvm.org/D23451
llvm-svn: 278561
After latest changes we combine input sections with
different attributes into single output section.
Problem here is that regular output sections does not
support adding mergeable input sections (and vise versa).
Patch just temporarily disables merging for now at
the same way we do for -O0 for example.
This change helps for linking FreeBSD kernel.
Differential revision: https://reviews.llvm.org/D23447
llvm-svn: 278555
After 278461 "Create only one section for a name in LinkerScript."
this loop is excessive.
Patch also reorders code slightly to use early return.
Differential revision: https://reviews.llvm.org/D23442
llvm-svn: 278554
We found that GNU assembler 2.17.50 [FreeBSD] 2007-07-03
could generate broken objects. STT_SECTION symbols can be
associated with SHT_REL[A]/SHT_SYMTAB/SHT_STRTAB sections.
This is PR28868, patch fixes handling of such files.
Differential revision: https://reviews.llvm.org/D23201
llvm-svn: 278550
Previously filtering that was used worked incorrectly.
For example for next script it would just remove both sections completely:
SECTIONS {
. = 0x1000;
.aaa : ONLY_IF_RW { *(.aaa.*) }
. = 0x2000;
.aaa : ONLY_IF_RO { *(.aaa.*) }
}
Patch fixes above issues and adds testcase showing the issue. Testcase is a subset of
FreeBSD script which has:
.eh_frame : ONLY_IF_RO { KEEP (*(.eh_frame)) }
...
.eh_frame : ONLY_IF_RW { KEEP (*(.eh_frame)) }
Differential revision: https://reviews.llvm.org/D23326
llvm-svn: 278486
This section supersedes .reginfo and .MIPS.options sections. But for now
we have to support all three sections for ABI transition period.
llvm-svn: 278482
Previously, we were setting LayoutInputSection's OutputSection member
in createSections. Because when we create LayoutInputSectinos, we
don't know the output section for them, so we backfilled the member
in the function. This patch moves the code to backfill it to assignOffsets.
llvm-svn: 278464
Previously, we created two or more output sections if there are
input sections with the same name but with different attributes.
That is a wrong behavior. This patch fixes the issue.
One thing we need to do is to merge output section attributes.
Currently, we create an output section based on the first input
section's attributes. This may make a wrong output section
attributes. What we need to do is to bitwise-OR attributes.
We'll do it in a follow-up patch.
llvm-svn: 278461
One reason why we are (ab)using OutputSectionFactory class is
because it owns output sections. Technically there's no need
to have it own sections. So, this patch transfers the ownership
to Out<ELFT>.
llvm-svn: 278452
The reason why we had to assign offsets only to sections that
don't contain layout sections were unclear. It turned out that
we can live without it.
llvm-svn: 278449
MIPS ISA encoded using two ELF flags: general architecture flag like
EF_MIPS_ARCH_32, EF_MIPS_ARCH_64R6 etc and optional machine variant flag
like EF_MIPS_MACH_4111, EF_MIPS_MACH_OCTEON3 etc. When we check
compatibility between two input files and deduce ELF flags for generated
output we need to take into account both of these flags.
llvm-svn: 278230
SIZEOF_HEADERS - Return the size in bytes of the output file’s headers.
It is is a feature used in FreeBsd script, for example.
There is a discussion on PR28688 page about it.
Differential revision: https://reviews.llvm.org/D23165
llvm-svn: 278204
Even if an output is not a dynamic object, the output may have
.{preinit,init,fini} sections. Therefore, managing these sections
as Out<ELFT>::Dynamic's members is not correct.
llvm-svn: 278093
The Factory class is too object-oriented-ish and easy to be abused.
This patch reduces dependency to that class. Eventually we want to
remove the dependency to that class from LinkerScript.
llvm-svn: 278084
Previously, we incrementally updated the reuslting flag as we check
file flags, so it was not very clear who is updating what flags.
This patch makes them pure functions -- that has no side effect and
don't update arguments to improve readability.
Now each function construct a patial result, and all resutls are then
bitwise-OR'ed to construct the final result.
This patch also creates a new file, Mips.cpp, to move all these
MIPS functions to a separate file.
Differential Revision: https://reviews.llvm.org/D23249
llvm-svn: 278042
I faced that when tried to link FreeBSD kernel.
It was "duplicate symbol: _edata in (internal) and (internal)" error.
_data was a shared symbol that came from hack.so. At first it was replaced with DefinedRegular by the code
disabled in this patch and later when script tried to define the same symbol - the error was shown.
In the same situation (as given in testcase) ld defines them as UND. gold defines as ABS with zero value.
Patch just disables any operations of creating these symbols if script do layout.
Differential revision: https://reviews.llvm.org/D23206
llvm-svn: 277986
The patch extends the `getMipsEFlags` function. Now in that function
we iterate over all object files, parse ELF header flags and merge them.
If a file is incompatible with previously analyzed ones we show an error
or warning. That can happen if, for example, we try to link files with
incompatible ABI, ISA, NAN encoding etc.
There is an alternative solution. We can check and merge flags and
reject incompatible input modules in the `isCompatible` function which
is called from the `SymbolTable::addFile` method. But in that case we
have to save and keep somewhere a merged ELF flags combination to use it
later in the writer.
Differential Revision: http://reviews.llvm.org/D23161
llvm-svn: 277911
Summary:
The comparator function to compare input sections as instructed by
SORT command was a bit too complicated because it needed to handle
four different cases. This patch split it into two function calls.
This patch also simplifies the parser.
Reviewers: grimar
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23140
llvm-svn: 277780
ASSERT(exp, message)
Ensure that exp is non-zero. If it is zero, then exit the linker with an error
code, and print message.
ASSERT is useful and was seen in few projects in the wild.
Differential revision: https://reviews.llvm.org/D22912
llvm-svn: 277710
According to spec:
"SORT_BY_ALIGNMENT will sort sections into descending order by
alignment before placing them in the output file"
Previously they were sorted into ascending order.
llvm-svn: 277706
With the previous change, it is now obvious that readProvide in
this context appended new commands to a wrong command list.
It was mistakenly adding new commands to the top level.
Thus, all commands inside output section descriptions were
interpreted as they were written on top level.
PROVIDE command naturally requires symbol assignment support
in the output section description. We don't have that one yet.
I removed the implementation because there's no way to fix it now.
We can resurrect the test once we support the symbol assignment
(with a modification to detect errors that we failed to find as
described.)
llvm-svn: 277687
Previously, many read* functions created new command objects and
add them directly to the top-level data structure. This is not
work for some commands because some commands, such as the assignment,
can appear inside and outside of the output section description.
This patch is to not append objects to the top-level data structure.
Callers are now responsible to do that.
llvm-svn: 277686
Previously, a decimal filler expression is interpreted as a byte value.
Gold on the other hand use it as a 32-bit big-endian value.
This patch fixes the compatibility issue.
Differential Revision: https://reviews.llvm.org/D23142
llvm-svn: 277680
Previously we supported only sorting by name.
When there are nested section sorting commands in linker script, there can be at most 1
level of nesting for section sorting commands.
SORT_BY_NAME (SORT_BY_ALIGNMENT (wildcard section pattern)). It will sort the input
sections by name first, then by alignment if 2 sections have the same name.
SORT_BY_ALIGNMENT (SORT_BY_NAME (wildcard section pattern)). It will sort the input
sections by alignment first, then by name if 2 sections have the same alignment.
SORT_BY_NAME (SORT_BY_NAME (wildcard section pattern)) is treated the same as SORT_
BY_NAME (wildcard section pattern).
SORT_BY_ALIGNMENT (SORT_BY_ALIGNMENT (wildcard section pattern)) is treated the
same as SORT_BY_ALIGNMENT (wildcard section pattern).
All other nested section sorting commands are invalid.
Patch implements that all above.
Differential revision: https://reviews.llvm.org/D23019
llvm-svn: 277583
Mergeable sections with size zero are useless because they don't
actually contain data, and therefore there's no merit ot merge them.
However, in reality, there are object files in the wild containing
such sections. Currently, LLD can't handle them proerply.
This patch makes LLD to handle such sections as if they are non-
mergeable to fix the issue.
Fixes bug 28822.
llvm-svn: 277568
Previously, Ignore flag is set if we don't want to assign
a value to symbols. It happens if a symbol assingment is in
PROVIDE() and there's already a symbol with the same name.
The previous code had a subtle but that we assume that the
existing symbol is an absolute symbol even if it is not.
This patch fixes the issue by always overwriting an absolute
symbol.
llvm-svn: 277115
According to the specification, CIE code alignment factor is an
arbitrary unsigned LEB128 encoded value.
Differential revision: https://reviews.llvm.org/D22954
llvm-svn: 277105
All other singleton instances are accessible globally.
CommonInputSection shouldn't be an exception.
Differential Revision: https://reviews.llvm.org/D22935
llvm-svn: 277034
This is a bit of an odd feature. It is normally used in
. = SEGMENT_START(seg, val);
In bfd it evaluates to val or to the value of the corresponding
-T<seg>-segment. Note that the -T<seg>-segment in bfd doesn't actually
change the segment address, just the value this evaluates too,
including in the default linker script.
In gold the -T<seg>-segment options do change the segment address and
seeing this expressions in linker scripts disables the options.
For new this just always evaluates the expression to val.
llvm-svn: 277014
Some scripts can contain SORT(CONSTRUCTORS) expression:
https://svnweb.freebsd.org/base/head/sys/conf/ldscript.amd64?revision=284870&view=markup#l152
for ELF it just a nop:
"When linking object file formats which do not support arbitrary sections, such as ECOFF and XCOFF, the linker will automatically recognize C++ global constructors and destructors by name. For these object file formats, the CONSTRUCTORS command tells the linker to place constructor information in the output section where the CONSTRUCTORS command appears. The CONSTRUCTORS command is ignored for other object file formats."
(http://www.sourceware.org/binutils/docs-2.10/ld_3.html)
So patch implements ignoring.
Differential revision: https://reviews.llvm.org/D22848
llvm-svn: 276965
We already have code for ARM in initializeSections, so this
is more consistent.
Differential Revision: https://reviews.llvm.org/D22833
llvm-svn: 276811
In compare with what GNU linkers do (https://sourceware.org/binutils/docs/ld/Builtin-Functions.html),
this implementation simple:
Do not touch DATA_SEGMENT_ALIGN, it do what it do now - just aligns to the page boundary.
Parameters of DATA_SEGMENT_RELRO_END is ignored. That should be correct as it is usually just a 24 bytes
shift that allows to protect first 3 entries of got.plt with relro.
(https://svnweb.freebsd.org/base/head/sys/conf/ldscript.amd64?revision=284870&view=markup#l146).
DATA_SEGMENT_RELRO_END just aligns to the page boundary.
That is what expected because all sections that are not affected by relro should be on another memory page.
So at fact the difference with documented behavior is that we do not pad DATA_SEGMENT_ALIGN.
3 entries of got.plt are uncovered by relro, but functionality is simple and equal to lld behavior
for case when script is not given.
Differential revision: https://reviews.llvm.org/D22813
llvm-svn: 276778
We can simplify the evaluation of DATA_SEGMENT_ALIGN
just to simple align(). That way it will work exactly like we have in non-script case.
Change was suggested by Rafael Ávila de Espíndola
Differential revision: https://reviews.llvm.org/D22807
llvm-svn: 276745
We can have Opt.Commands size greater then Sections.size().
For example if we have next script:
SECTIONS {
.aaa : { *(.aaa) }
.bbb : { *(.bbb) }
.ccc : { *(.ccc) }
}
and next code:
.global _start
_start:
nop
.section .aaa,"a"
.quad 0
Then amount of sections is less than amound of Opt.Commands
and if we for example have all commands NoConstraint,
that overflowed the iterator used.
llvm-svn: 276741
This flag is implemented similarly to --reproduce in the ELF linker.
This patch implements /linkrepro by moving the cpio writer and associated
utility functions to lldCore, and using that implementation in both linkers.
One COFF-specific detail is that we store the object file from which the
resource files were created in our reproducer, rather than the resource
files themselves. This allows the reproducer to be used on non-Windows
systems for example.
Differential Revision: https://reviews.llvm.org/D22418
llvm-svn: 276719
createSections function is getting longer, so it is time to split it
into small functions. The reason why the function is long is because
it has deeply nested for-loops. This patch constructs temporary data
to reduce nesting level.
Differential Revision: https://reviews.llvm.org/D22786
llvm-svn: 276706
match() returns true of the first argument, a target string, matches
one of the second argument, a list of glob patterns. Calling the
target string, which is not a glob pattern, "Pattern" was very confusing.
llvm-svn: 276705
This will grow because I have a patch to support more complex
constructs, e.g.:
KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
Let's make this a separate function.
llvm-svn: 276695
PROVIDE request us to define a symbol only if it is referenced and is
not defined by any object included in the link. We created the
symbol in the symbol table no matter what.
Differential Revision: https://reviews.llvm.org/D22739
llvm-svn: 276592
Previously, we handled an expression as a vector of tokens. In other
words, an expression was a vector of uncooked raw StringRefs.
When we need a value of an expression, we used ExprParser to run
the expression.
The separation was needed essentially because parse time is too
early to evaluate an expression. In order to evaluate an expression,
we need to finalize section sizes. Because linker script parsing
is done at very early stage of the linking process, we can't
evaluate expressions while parsing.
The above mechanism worked fairly well, but there were a few
drawbacks.
One thing is that we sometimes have to parse the same expression
more than once in order to find the end of the expression.
In some contexts, linker script expressions have no clear end marker.
So, we needed to recognize balanced expressions and ternary operators.
The other is poor error reporting. Since expressions are parsed
basically twice, and some information that is available at the first
stage is lost in the second stage, it was hard to print out
apprpriate error messages.
This patch fixes the issues with a new approach.
Now the expression parsing is integrated into ScriptParser.
ExprParser class is removed. Expressions are represented as lambdas
instead of vectors of tokens. Lambdas captures information they
need to run themselves when they are created.
In this way, ends of expressions are naturally detected, and
errors are handled in the usual way. This patch also reduces
the amount of code.
Differential Revision: https://reviews.llvm.org/D22728
llvm-svn: 276574
Otherwhise undefined references to symbols defined in linker scripts
are never resolved.
Differential Revision: https://reviews.llvm.org/D22664
llvm-svn: 276536
George Rimar