The allocateHeaders() function is called at the end of assignAddresses(), it
decides whether the ELF header and program header table can be allocated to
a PT_LOAD program header. As the function alters state, it prevents
assignAddresses() from being called multiple times.
This change splits out the call to allocateHeaders() from assignAddresses()
this will permit assignAddresses() to be called while processing range
extension thunks without trying to allocateHeaders().
Differential Revision: https://reviews.llvm.org/D34344
llvm-svn: 307131
This patch makes changes to allow sections without the SHF_ALLOC bit to be
assigned to segments in a linker script.
The assignment of output sections to segments is performed in
LinkerScript::createPhdrs. Previously, this function would bail as soon as it
encountered an output section which did not have the SHF_ALLOC bit set, thus
preventing any output section without SHF_ALLOC from being assigned to a
segment.
This restriction has now been removed from LinkerScript::createPhdrs and instead
a check for SHF_ALLOC has been added to LinkerScript::adjustSectionsAfterSorting
to not propagate program headers to sections without SHF_ALLOC which matches the
behaviour of bfd linker scripts.
Differential Revision: https://reviews.llvm.org/D34204
llvm-svn: 307013
I found this while trying to build u-boot. It uses -Ttext in
combination with linker scripts.
My first reaction was to change the linker scripts to have the correct
value, but I found that it is actually quite convenient to have -Ttext
take precedence.
By having just
.text : { *(.text) }
In the script, they can define the text address in a single Makefile
and pass it to ld with -Ttext and for the C code with
-DFoo=value. Doing the same with linker scripts would require them to
be generated during the build.
llvm-svn: 305766
This patch adds support for segment NONE in linker scripts which enables the
specification that a section should not be assigned to any segment.
Note that GNU ld does not disallow the definition of a segment named NONE, which
if defined, effectively overrides the behaviour described above. This feature
has been copied.
Differential Revision: https://reviews.llvm.org/D34203
llvm-svn: 305700
This is probably the main patch left in unifying our intermediary
representation.
It moves the creation of default commands before section sorting. This
has the nice effect that we now have one location where we decide
where an orphan section should be placed.
Before this patch sortSections would decide the relative location of
orphan sections to other sections, but it was up to placeOrphanSection
to decide on the exact location.
We now only sort sections we created since the linker script is
already in the correct order.
llvm-svn: 305512
Currently we do layout as if non alloc sections had an actual address
and then set it to zero. This produces a few odd results where a
symbol has an address that is inconsistent with the section address.
The simplest way to fix it is probably to just set the address earlier.
The behavior of bfd seems to be similar, but it only sets the non
alloc section address is missing from the linker script or if the
script has an explicit " : 0" setting the address of the output
section (which the default script does).
llvm-svn: 305323
Thunks are now generated per InputSectionDescription instead of per
OutputSection. This allows created ThunkSections to be inserted directly
into InputSectionDescription.
Changes in this patch:
- Loop over InputSectionDescriptions to find relocations to Thunks
- Generate a ThunkSection per InputSectionDescription
- Remove synchronize() as we no longer need it
- Move fabricateDefaultCommands() before createThunks
Differential Revision: https://reviews.llvm.org/D33835
llvm-svn: 304887
When linking linux kernel LLD currently reports next errors:
ld: error: unable to evaluate expression: input section .head.text has no output section assigned
ld: error: At least one side of the expression must be absolute
ld: error: At least one side of the expression must be absolute
That does not provide file/line information and overall looks unclear.
Patch adds location information to ExprValue and that allows
to provide more clear error messages.
Differential revision: https://reviews.llvm.org/D33943
llvm-svn: 304881
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.
Differential Revision: https://reviews.llvm.org/D33843
llvm-svn: 304864
We were looking up sections by name during expression evaluation. By
keeping track of forward declarations we can do the lookup during
script parsing.
Doing the lookup earlier will be more efficient when assignAddresses
is run twice and removes two uses of OutputSections.
llvm-svn: 304381
Before InputSectionBase had an OutputSection pointer, but that was not
always valid. For example, if it was a merge section one actually had
to look at MergeSec->OutSec.
This was brittle and caused bugs like the one fixed by r304260.
We now have a single Parent pointer that points to an OutputSection
for InputSection, but to a SyntheticSection for merge sections and
.eh_frame. This makes it impossible to accidentally access an invalid
OutSec.
llvm-svn: 304338
I found that during visual inspection of code while wrote different patch.
Script in testcase probably have nothing common with real life, but
we segfault currently using it.
If output section is known NOBITS, there is no need to create
writers threads for doing nothing or proccess any filler logic that
is useless here. We can just early return, that is what this patch do.
DIfferential revision: https://reviews.llvm.org/D33646
llvm-svn: 304192
InputSections may contain MergeInputSection members which trigger
a segmentation fault when trying to cast them to InputSection.
Differential Revision: https://reviews.llvm.org/D33628
llvm-svn: 304189
While the following expression is handled fine:
PROVIDE_HIDDEN(newsym = oldsym + address);
The following expression triggers an error because the expression
is evaluated as absolute:
PROVIDE_HIDDEN(newsym = ALIGN(oldsym, CONSTANT(MAXPAGESIZE)) + address);
To avoid this error, we use late evaluation for ALIGN by making the
alignment an attribute of the expression itself.
Differential Revision: https://reviews.llvm.org/D33629
llvm-svn: 304185
This reduces how many times we have to map from OutputSection to
OutputSectionCommand. It is a required step to moving
clearOutputSections earlier.
In order to always use writeTo in OutputSectionCommand we have to call
fabricateDefaultCommands for -r links and move section compression
after it.
llvm-svn: 303784
By the time we get to linker scripts, all special InputSectionBase
should have been combined into synthetic sections, which are a type of
InputSection. The net result is that we can use InputSection in a few
places that were using InputSectionBase.
llvm-svn: 303702
This converts the last (chronologically) user of OutputSections to use
the linker script commands instead.
The idea is to convert all uses after fabricateDefaultCommands, so
that we have a single representation.
llvm-svn: 303384
This is PR32664.
Issue was revealed by linux kernel script which was:
SECTIONS {
. = (0xffffffff80000000 + ALIGN(0x1000000, 0x200000));
phys_startup_64 = ABSOLUTE(startup_64 - 0xffffffff80000000);
.text : AT(ADDR(.text) - 0xffffffff80000000) {
.....
*(.head.text)
Where startup_64 is in .head.text.
At the place of assignment to phys_startup_64 we can not calculate absolute value for startup_64
because .text section has no VA assigned. Two patches were prepared earlier to address this: D32173 and D32174.
And in comments for D32173 was suggested not try to support this case, but error out.
Differential revision: https://reviews.llvm.org/D32793
llvm-svn: 302668
Previously it was impossible to use linkerscript with --compress-debug-sections
because of assert failture:
Assertion failed: isFinalized(), file C:\llvm\lib\MC\StringTableBuilder.cpp, line 64
Patch fixes the issue
llvm-svn: 302413
We can set SectionIndex tentatively as we process the linker script
instead of looking it repeatedly.
In general we should try to have as few name lookups as possible.
llvm-svn: 302299
In the non linker script case we would try very early to find out if
we could allocate the headers. Failing to do that would add extra
alignment to the first ro section, since we would set PageAlign
thinking it was the first section in the PT_LOAD.
In the linker script case the header allocation must be done in the
end, causing some duplication.
We now tentatively add the headers to the first PT_LOAD and if it
turns out they don't fit, remove them. With this we only need to
allocate the headers in one place in the code.
llvm-svn: 302186
We were correctly computing the size contribution of a .tbss input
section (it is none), but we were incorrectly considering the
alignment of the output section: it was advancing Dot instead of
ThreadBssOffset.
As far as I can tell this was always wrong in our linkerscript
implementation, but that became more visible now that the code is
shared with the non linker script case.
llvm-svn: 302107
The --section-start <name>=<address> needs to be translated into equivalent
linker script commands. There are a couple of problems with the existing
implementation:
- The --section-start with the lowest address is assumed to be at the start
of the map. This assumption is incorrect, we have to iterate through the
SectionStartMap to find the lowest address.
- The addresses in --section-start were being over-aligned when the
sections were marked as PageAlign. This is inconsistent with the use of
SectionStartMap in fixHeaders(), and can cause problems when the PageAlign
causes an "unable to move location counter backward" error when the
--section-start with PageAlign is aligned to an address higher than the next
--section-start. The ld.bfd and ld.gold seem to be more consistent with this
approach but this is not a well specified area.
This change fixes the problems above and also corrects a typo in which
fabricateDefaultCommands() is called with the wrong parameter, it should be
called with AllocateHeader not Config->MaxPageSize.
Differential Revision: https://reviews.llvm.org/D32749
llvm-svn: 302007
When using linkerscripts we were trying to sort SHF_LINK_ORDER
sections too early. Instead of always doing two runs of
assignAddresses, record the section order in processCommands.
llvm-svn: 301830
This version uses a set to speed up the synchronize method.
Original message:
Remove LinkerScript::flush.
This patch replaces flush with a last ditch attempt at synchronizing
the section list with the linker script "AST".
The synchronization is a bit of a hack and should in time be avoided
by creating the AST earlier so that modifications can be made directly
to it instead of modifying the section list and synchronizing it back.
This is the main step for fixing
https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
think the only missing thing would be to have processCommands assign
section indexes as dummy offsets so that the sort in
OutputSection::finalize works.
With this LinkerScript::assignAddresses becomes much simpler, which
should help with the thunk work.
llvm-svn: 301745
This reverts commit r301678 since that change significantly slowed
down the linker. Before this patch, LLD could link clang in 8 seconds,
but with this patch it took 40 seconds.
llvm-svn: 301709
This patch replaces flush with a last ditch attempt at synchronizing
the section list with the linker script "AST".
The synchronization is a bit of a hack and should in time be avoided
by creating the AST earlier so that modifications can be made directly
to it instead of modifying the section list and synchronizing it back.
This is the main step for fixing
https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
think the only missing thing would be to have processCommands assign
section indexes as dummy offsets so that the sort in
OutputSection::finalize works.
With this LinkerScript::assignAddresses becomes much simpler, which
should help with the thunk work.
llvm-svn: 301678
We were already pretty close, the one exception was when a name was
reused in another SECTIONS directive:
SECTIONS {
.text : { *(.text) }
.data : { *(.data) }
}
SECTIONS {
.data : { *(other) }
}
In this case we would create a single .data and magically output
"other" while looking at the first OutputSectionCommand.
We now create two .data sections. This matches what gold does. If we
really want to create a single one, we should change the parser so that
the above is parsed as if the user had written
SECTIONS {
.text : { *(.text) }
.data : { *(.data) *(other)}
}
That is, there should be only one OutputSectionCommand for .data and
it would have two InputSectionDescriptions.
By itself this patch makes the code a bit more complicated, but is an
important step in allowing assignAddresses to operate just on the
linker script.
llvm-svn: 301484
This change fabricates linker script commands for the case where there is
no linker script SECTIONS to control address assignment. This permits us
to have a single Script->assignAddresses() function.
There is a small change in user-visible-behavior with respect to the
handling of .tbss SHT_NOBITS, SHF_TLS as the Script->assignAddresses()
requires setDot() to be called with monotically increasing addresses.
The tls-offset.s test has been updated so that the script and non-script
results match.
This change should make the non-script behavior of lld closer to an
equivalent linker script.
Differential Revision: https://reviews.llvm.org/D31888
llvm-svn: 300687
Imagine next script:
SECTIONS { BYTE(0x11); }
Section content written to disk will be 0x11. Previous LLD behavior was to make this
section SHT_NOBITS. What is not correct because section has content.
ld.bfd makes such sections SHT_PROGBITS, this patch do the same.
This fixes PR32537
Differential revision: https://reviews.llvm.org/D32016
llvm-svn: 300317
This fixes an assertion `Align != 0u && "Align can't be 0."'
in llvm::alignTo() when a linker script references a globally
defined variable in an ALIGN() context.
Patch by Alexander Richardson !
Differential revision: https://reviews.llvm.org/D31984
llvm-svn: 300315
Executable sections should not be padded with zero by default. On some
architectures, 0x00 is the start of a valid instruction sequence, so can confuse
disassembly between InputSections (and indeed the start of the next InputSection
in some situations). Further, in the case of misjumps into padding, padding may
start to be executed silently.
On x86, the "0xcc" byte represents the int3 trap instruction. It is a single
byte long so can serve well as padding. This change switches x86 (and x86_64) to
use this value for padding in executable sections, if no linker script directive
overrides it. It also puts the behaviour into place making it easy to change the
behaviour of other targets when desired. I do not know the relevant instruction
sequences for trap instructions on other targets however, so somebody should add
this separately.
Because the old behaviour simply wrote padding in the whole section before
overwriting most of it, this change also modifies the padding algorithm to write
padding only where needed. This in turn has caused a small behaviour change with
regards to what values are written via Fill commands in linker scripts, bringing
it into line with ld.bfd. The fill value is now written starting from the end of
the previous block, which means that it always starts from the first byte of the
fill, whereas the old behaviour meant that the padding sometimes started mid-way
through the fill value. See the test changes for more details.
Reviewed by: ruiu
Differential Revision: https://reviews.llvm.org/D30886
Bugzilla: http://bugs.llvm.org/show_bug.cgi?id=32227
llvm-svn: 299635
LinkerScript.cpp contains both the linker script processor and the
linker script parser. I put both into a single file, but the file grown
too large, so it's time to put them into two different files.
llvm-svn: 299515
This requires collectign all symbols referenced in the linker script
and adding them to symbol table as undefined symbol.
Differential Revision: https://reviews.llvm.org/D31147
llvm-svn: 298577
LinkerScript used to be a template class, so we couldn't instantiate
that class in elf::link. We instantiated ScriptConfig class earlier
instead so that the linker script parser can store configurations to
the object.
Now that LinkerScript is not a template, it doesn't make sense to
separate ScriptConfig from LinkerScript. This patch merges them.
llvm-svn: 298457
This fixes pr32031 by representing the expressions results as a
SectionBase and offset. This allows us to use an input section
directly instead of getting lost trying to compute an offset in an
outputsection when not all the information is available yet.
This also creates a struct to represent the *value* of and expression,
allowing the expression itself to be a simple typedef. I think this is
easier to read and will make it easier to extend the expression
computation to handle more complicated cases.
llvm-svn: 298079
This also requires postponing the assignment the assignment of
symbols defined in input linker scripts since those can refer to
output sections and in case we don't have a SECTIONS command, we
need to wait until all output sections have been created and
assigned addresses.
Differential Revision: https://reviews.llvm.org/D30851
llvm-svn: 297802
That moves all members that s possible to move for now (all which
does not depend on ELFT templating).
After that change LinkerScript contains only 8 methods in total,
and I believe it is possible to move them all after tweaking other
parts of linker. And we will be able to have single class for
linkerscript at the end.
llvm-svn: 297735
We can move all not templated functionality to LinkerScriptBase.
Patch do that for hasPhdrsCommands() and shows how it helps to detemplate
things in other places.
Probably we should be able to merge these 2 classes into single one after such steps.
Even if not, it still looks as reasonable cleanup for me.
Differential revision: https://reviews.llvm.org/D30895
llvm-svn: 297714
With this we have a single section hierarchy. It is a bit less code,
but the main advantage will be in a future patch being able to handle
foo = symbol_in_obj;
in a linker script. Currently that fails since we try to find the
output section of symbol_in_obj. With this we should be able to just
return an InputSection from the expression.
llvm-svn: 297313
That function doesn't use any member of SymbolTableSection, so I
couldn't see a reason to make it a member of that class. The function
takes a SymbolBody, so it is more natural to make it a member of
SymbolBody.
llvm-svn: 296433
The list of all input sections was defined in SymbolTable class for a
historical reason. The list itself is not a template. However, because
SymbolTable class is a template, we needed to pass around ELFT to access
the list. This patch moves the list out of the class so that it doesn't
need ELFT.
llvm-svn: 296309
With the current design an InputSection is basically anything that
goes directly in a OutputSection. That includes plain input section
but also synthetic sections, so this should probably not be a
template.
llvm-svn: 295993
This change exposes the symbol table insert method and uses it to
insert the linkerscript defined symbols directly into the symbol
table to avoid unnecessarily pulling the object out of an archive.
Differential Revision: https://reviews.llvm.org/D30224
llvm-svn: 295780
Patch fixes PR32024.
Sections that were not marked as Live has null output section.
Previously we tried to access that field and segfaulted.
Differential revision: https://reviews.llvm.org/D30188
llvm-svn: 295727
Previously we evaluated the values of LMA incorrectly for next cases:
.text : AT(ADDR(.text) - 0xffffffff80000000) { ... }
.data : AT(ADDR(.data) - 0xffffffff80000000) { ... }
.init.begin : AT(ADDR(.init.begin) - 0xffffffff80000000) { ... }
Reason was that we evaluated offset when VA was not assigned. For case above
we ended up with 3 loads that has similar LMA and it was incorrect.
That is critical for linux kernel.
Patch updates the offset after VA calculation. That fixes the issue.
Differential revision: https://reviews.llvm.org/D30163
llvm-svn: 295722
Previously LLD would error out just "ld.lld: error: unable to move location counter backward"
What does not really reveal the place of issue,
Patch adds location to the output.
Differential revision: https://reviews.llvm.org/D30187
llvm-svn: 295720
Peter Smith