-q, --emit-relocs - Generate relocations in output
Simplest implementation:
* no GC case,
* no "/DISCARD/" linkerscript command support.
This patch is extracted from D28612 / D29636,
Relative to PR31579.
Differential revision: https://reviews.llvm.org/D29663
llvm-svn: 294464
With a synthetic merge section we can have, for example, a single
.rodata section with stings, fixed sized constants and non merge
constants.
I can be simplified further by not setting Entsize, but that is
probably better done is a followup patch.
This should allow some cleanup in the linker script code now that
every output section command maps to just one output section.
llvm-svn: 294005
Instead of creating multiple PHDRs in a single loop, this patch
runs one for loop for each PHDR type. I think this improves code
readability.
llvm-svn: 293832
There could be multiple discontiguous output .note sections in which
case we need to put these into separate PT_NOTE segments rather then
placing them into a single segment. Where possible, we could reorder
the input sections to make sure that all .note are layed out next to
each other to avoid creation multiple PT_NOTE segments, but even in
that case, it's still possible to construct a discontiguous case e.g.
by using a linker script.
Differential Revision: https://reviews.llvm.org/D29364
llvm-svn: 293811
Thunks are now implemented by redirecting the relocation to the
symbol S, to a symbol TS in a Thunk. The Thunk will transfer control
to S. This has the following implications:
- All the side-effects of Thunks happen within createThunks()
- Thunks are no longer stored in InputSections and Symbols no longer
need to hold a pointer to a Thunk
- The synthetic Thunk sections need to be merged into OutputSections
This implementation is almost a direct conversion of the existing
Thunks with the following exceptions:
- Mips LA25 Thunks are placed before the InputSection that defines
the symbol that needs a Thunk.
- All ARM Thunks are placed at the end of the OutputSection of the
first caller to the Thunk.
Range extension Thunks are not supported yet so it is optimistically
assumed that all Thunks can be reused.
This is a recommit of r293283 with a fixed comparison predicate as
std::merge requires a strict weak ordering.
Differential revision: https://reviews.llvm.org/D29327
llvm-svn: 293757
If no bss sections appear after the relro segment, the loader will round
the r/w segment size to the target's page size. Align the relro size in the
same way to ensure that it does not extend past the end of the program's
own memory region.
Differential Revision: https://reviews.llvm.org/D29242
llvm-svn: 293519
The symbols _end, end, _etext, etext, _edata, edata and __ehdr_start
refer to positions in the file and are therefore not absolute. Making
them absolute was on unfortunate cargo cult of what bfd was doing.
Changing the symbols allows for pc relocations to them to be resolved,
which should fix the wine build.
llvm-svn: 293385
[ELF] Fixed formatting. NFC
and
[ELF] Bypass section type check
Differential revision: https://reviews.llvm.org/D28761
They do the opposite of what was asked for in the code review.
llvm-svn: 293320
Thunks are now implemented by redirecting the relocation to the
symbol S, to a symbol TS in a Thunk. The Thunk will transfer control
to S. This has the following implications:
- All the side-effects of Thunks happen within createThunks()
- Thunks are no longer stored in InputSections and Symbols no longer
need to hold a pointer to a Thunk
- The synthetic Thunk sections need to be merged into OutputSections
This implementation is almost a direct conversion of the existing
Thunks with the following exceptions:
- Mips LA25 Thunks are placed before the InputSection that defines
the symbol that needs a Thunk.
- All ARM Thunks are placed at the end of the OutputSection of the
first caller to the Thunk.
Range extension Thunks are not supported yet so it is optimistically
assumed that all Thunks can be reused.
Differential Revision: https://reviews.llvm.org/D29129
llvm-svn: 293283
It now uses the same infrastructure as symbol versions. This fixes us
creating a dynamic relocation without a corresponding dynamic symbol.
This also means that unlike gold and bfd we keep a STB_LOCAL in the
static symbol table. It seems an odd feature to offer precise control
over what is in a symbol table that is not used by the dynamic
linker. We can bring this back if needed, but it would probably be
better to just have --discard option that tells the linker to keep in
the static symbol table only what is in the dynamic one.
Should fix the eog build.
llvm-svn: 293093
Mapping symbols allow a mapping symbol aware disassembler to
correctly disassemble the PLT when the code immediately prior to the
PLT is Thumb.
To implement this we add a function to add symbols with local
binding to be defined in SyntheticSymbols.
Differential Revision: https://reviews.llvm.org/D28956
llvm-svn: 293044
Previously we stored kept locals in a KeptLocalSyms arrays,
belonged to files.
Patch makes SymbolTableSection to store locals in Symbols member,
that already present and was used for globals.
SymbolTableSection already had NumLocals counter member, so change
itself is trivial.
That allows to simplify handling of -r,
Body::DynsymIndex is no more used as "symbol table index" for relocatable
output.
Change was suggested during review of D28773 and opens road for D28612.
Differential revision: https://reviews.llvm.org/D29021
llvm-svn: 292789
A necessary first step towards range extension thunks is to delay
the creation of thunks until the layout of InputSections within
OutputSections has been done.
The change scans the relocations directly from InputSections rather
than looking in the ELF File the InputSection came from. This will
allow a future change to redirect the relocations to symbols defined
by Thunks rather than indirect when resolving relocations.
A side-effect of moving ThunkCreation is that the OutSecOff of
InputSections may change in an OutputSection that contains Thunks.
In well behaved programs thunks are not in OutputSections with
dynamic relocations.
Differential Revision: https://reviews.llvm.org/D28811
llvm-svn: 292359
This patch adds a test for an invalid output path for -Map option,
though that test is not for verifying that we are using error()
instead of fatal() in writeMapFile.
llvm-svn: 292336
Patch changes behavior to not try open the output
file if we already know about error.
That is not just cleaner, but also fixes nasty behavior of linker that
could create huge temporarily files under certain conditions.
Differential revision: https://reviews.llvm.org/D28107
llvm-svn: 292219
On MIPS .got section cannot be included into the PT_GNU_RELRO segment.
Sometimes it might work, but in general it is unsupported. One of the
problem is that all sections marked by SHF_MIPS_GPREL should be grouped
together because data in these sections is addressable with a gp
relative address, but such sections might be writable.
This patch exclude mips .got from PT_GNU_RELRO segment and group
SHF_MIPS_GPREL sections.
llvm-svn: 292161
These were 3 last synthetics that were added in addPredefinedSections() instead
of createSyntheticSections(). Now it is possible to move addition to correct common place.
Also patch fixes testcase which discards .shstrtab, by restricting doing that.
Differential revision: https://reviews.llvm.org/D28561
llvm-svn: 291908
When reserving copy relocation space for a shared symbol, scan the DSO's
program headers to see if the symbol is in a read-only segment. If so,
reserve space for that symbol in a new synthetic section named .bss.rel.ro
which will be covered by the relro program header.
This fixes the security issue disclosed on the binutils mailing list at:
https://sourceware.org/ml/libc-alpha/2016-12/msg00914.html
Differential Revision: https://reviews.llvm.org/D28272
llvm-svn: 291524
This is in preparation for my next change, which will introduce a relro
nobits section. That requires that relro sections appear at the end of the
progbits part of the r/w segment so that the relro nobits section can appear
contiguously.
Because of the amount of churn required in the test suite, I'm making this
change separately.
llvm-svn: 291523
This patch enables something like "-o /dev/null".
Previouly, it failed because such files cannot be renamed.
Differential Revision: https://reviews.llvm.org/D28010
llvm-svn: 291496
The glibc dynamic loader rounds the size down, so without this the loader
will fail to change the memory protection for the last page.
Differential Revision: https://reviews.llvm.org/D28267
llvm-svn: 290986
DefinedSynthetic is not created for a real ELF object, so it doesn't
have to be a template function. It has a virtual st_value, which is
either 32 bit or 64 bit, but we can simply use 64 bit.
llvm-svn: 290241
That was requested by Mark Kettenis in llvm-dev:
"It is the intention that .openbsd.randomdata sections are made
read-only after initialization. The native (ld.bfd based) OpenBSD
toolchain accomplishes this by including .openbsd.randomdata into the
PT_GNU_RELRO segment."
He suggested code change, I added testcase.
Differential revision: https://reviews.llvm.org/D27974
llvm-svn: 290174
That variable was of type DenseMap<StringRef, unsigned>, but the
unsigned numbers needed to be monotonicly increasing numbers because
the implementation that used the variable depended on that fact.
That was an implementation detail and shouldn't have leaked into Config.
This patch simplifies its type to std::vector<StringRef>.
llvm-svn: 290151
This handles all the corner cases if setting a section address:
- If the address is too low, we cannot allocate the program headers.
- If the load address is lowered, we have to do that before finalize
This also shares some code with the linker script since it was already
hitting similar cases.
This is used by the freebsd boot loader. It is not clear if we need to
support this with a non binary output, but it is not as bad as I was
expecting.
llvm-svn: 290136
--retain-symbols-file=filename
Retain only the symbols listed in the file filename, discarding all others.
filename is simply a flat file, with one symbol name per line. This option
is especially useful in environments (such as VxWorks) where a large global
symbol table is accumulated gradually, to conserve run-time memory.
Note: though documentation says "--retain-symbols-file does not discard
undefined symbols, or symbols needed for relocations.", both bfd and gold
do that, and this patch too, like testcase show.
Differential revision: https://reviews.llvm.org/D27716
llvm-svn: 290122
Use of CachedHashStringRef makes sense only when we reuse hash values.
Sprinkling it to all DenseMap has no benefits and just complicates data types.
Basically we shouldn't use CachedHashStringRef unless there is a strong
reason to to do so.
llvm-svn: 290076
I thought for a while about how to remove it, but it looks like we
can just copy the file for now. Of course I'm not happy about that,
but it's just less than 50 lines of code, and we already have
duplicate code in Error.h and some other places. I want to solve
them all at once later.
Differential Revision: https://reviews.llvm.org/D27819
llvm-svn: 290062
This change introduces new synthetic sections IpltSection, IgotPltSection
that represent the ifunc entries that would previously have been put in
the PltSection and the GotPltSection. The separation makes sure that
the R_*_IRELATIVE relocations are placed after the non R_*_IRELATIVE
relocations, which permits ifunc resolvers to know that the .got.plt
slots will be initialized prior to the resolver being called.
A secondary benefit is that for ARM we can move the IgotPltSection and its
dynamic relocations to the .got and .rel.dyn as the ARM glibc expects all
the R_*_IRELATIVE relocations to be in the .rel.dyn
Differential revision: https://reviews.llvm.org/D27406
llvm-svn: 289045
These MIPS specific symbols should be global because in general they can
have an arbitrary value. By default this value is a fixed offset from .got
section.
This patch adds more checks to the mips-gp-local.s test case but marks
it as XFAIL because LLD does not allow redefinition of absolute symbols
value by a linker script. This should be fixed by D27276.
Differential revision: https://reviews.llvm.org/D27524
llvm-svn: 289025
Shared libraries should have entry set following the same rules as for
regular binaries. The only difference is that in case the default entry
point (_start or __start) isn't found (unless it was set explicitly), we
shouldn't give a warning as in case of regular binaries.
Differential Revision: https://reviews.llvm.org/D27497
llvm-svn: 288878
If we do, the freebsd dynamic linker tries to call mmap with a size 0,
which fails.
It is hard to avoid creating them when linker scripts are used, so we
just delete empty PT_LOADs at the end.
llvm-svn: 288808
On Linux (and probably on other Unix-like systems), unlink(2) is
noticeably slow. It takes 250 milliseconds to remove a 1 GB file
on ext4 filesystem on my machine, whether the file is on SSD or
on a spinning disk.
To create a new result file, we remove existing file first. So, if
you repeatedly link a 1 GB program in a regular compile-link-debug
cycle, every cycle wastes 250 milliseconds only to remove a file.
Since LLD can link a 1 GB in about 5 seconds, that waste actually
matters.
This patch defines `unlinkAsync` function. The function spawns a
background thread to call unlink. The calling thread returns
almost immediately.
Differential Revision: https://reviews.llvm.org/D27295
llvm-svn: 288680
Binary output feature is a bit confuzing. bfd and gold output differs a lot sometimes,
though it is important for FreeBSD mbr loaders.
Patch change the way how we compute file offsets for binary output.
This fixes PR31196.
Previously offsets were calculated basing on offsets and addresses of sections
from the same loads:
if (Sec == First)
return alignTo(Off, Target->MaxPageSize, Sec->Addr);
return First->Offset + Sec->Addr - First->Addr;
bfd assigns offsets for each section to VA - MinVA:
https://github.com/redox-os/binutils-gdb/blob/master/bfd/binary.c#L27https://github.com/redox-os/binutils-gdb/blob/master/bfd/binary.c#L255
(LMA == VA usually)
This patch for now just stops creating phdrs for binary output.
An effect from this that no any additional calculation for offset is performed:
uintX_t getFileAlignment(uintX_t Off, OutputSectionBase *Sec) {
OutputSectionBase *First = Sec->FirstInPtLoad;
// If the section is not in a PT_LOAD, we have no other constraint.
if (!First)
return Off; //**First is always null, condition always happens**
That is enough now with combination of another patch to generate output
that is similar to what bfd produce for mbr loader.
Differential revision: https://reviews.llvm.org/D27341
llvm-svn: 288580
This change continues what was started by D27040
Now all allocatable synthetics should be available from script side.
Differential revision: https://reviews.llvm.org/D27131
llvm-svn: 288150
-N (-omagic)
Set the text and data sections to be readable and writable.
Also, do not page-align the data segment.
Differential revision: https://reviews.llvm.org/D26888
llvm-svn: 288123
That unifies handling cases when we have SECTIONS and when
-no-rosegment is given in compareSectionsNonScript()
Now Config->SingleRoRx is used for check, testcase is provided.
llvm-svn: 288022
--no-rosegment: Do not put read-only non-executable sections in their own segment
Differential revision: https://reviews.llvm.org/D26889
llvm-svn: 288020
Unfortunatelly PT_ARM_EXIDX is special. There is no way to create it
from linker scripts, so we have to create it even if PHDRS is used.
This matches bfd and is required for the lld output to survive bfd's strip.
llvm-svn: 288012
This is important for cases like:
.sdata : {
*(.got.plt .got)
...
}
That was not supported before as there was no way to get access to
synthetic sections from script.
More details on review page.
Differential revision: https://reviews.llvm.org/D27040
llvm-svn: 287913
The .ARM.exidx table has an entry for each function with the first entry
giving the start address of the function, the table is sorted in ascending
order of function address. Given a PC value, the unwinder will search the
table for the entry that contains the PC value.
If the table entry happens to be the last, the range of the addresses that
the final unwinding table describes will extend to the end of the address
space. To prevent an incorrect address outside the address range of the
program matching the last entry we follow ld.bfd's example and add a
sentinel EXIDX_CANTUNWIND entry at the end of the table. This gives the
final real table entry an upper bound.
In addition the llvm libunwind unwinder currently depends on the presence
of a sentinel entry (PR31091).
Differential revision: https://reviews.llvm.org/D26977
llvm-svn: 287869
Previously, if a symbol specified by -e or ENTRY() is not found,
we didn't set entry point address. That is incompatible with GNU
because GNU linkers set the first address of .text to entry.
This patch implement that behavior.
llvm-svn: 287836
Offset between beginning of a .got section and _gp symbols used in MIPS
GOT relocations calculations. Usually the expression looks like
VA + Offset - GP, where VA is the .got section address, Offset - offset
of the GOT entry, GP - offset between .got and _gp. Also there two "magic"
symbols _gp_disp and __gnu_local_gp which hold the offset mentioned above.
These symbols might be referenced by MIPS relocations.
Now the linker always defines _gp symbol and uses hardcoded value for
its initialization. So offset between .got and _gp is 0x7ff0. The _gp_disp
and __gnu_local_gp defined if required and initialized by 0x7ff0.
In fact that is not correct because _gp symbol might be defined by a linker
script and holds arbitrary value. In that case we need to use this value
in relocation calculation and initialize _gp_disp and __gnu_local_gp
properly.
The patch fixes the problem and completes fixing the bug #30311.
https://llvm.org/bugs/show_bug.cgi?id=30311
Differential revision: https://reviews.llvm.org/D27036
llvm-svn: 287832
We have different functions to stringize objects to construct
error messages. For InputFile, we have getFilename, and for
InputSection, we have getName. You had to memorize them.
I think this is the case where the function overloading comes in handy.
This patch defines toString() functions that are overloaded for all these
types, so that you just call it in error().
Differential Revision: https://reviews.llvm.org/D27030
llvm-svn: 287787
Previously, we stored offsets in string tables to symbols, so
you needed to pass a string table to get a symbol name. This patch
stores const char pointers instead to eliminate the need to pass
a string table.
llvm-svn: 287737
If the linker script has SECTIONS, the address computation is now
always done in LinkerScript::assignAddresses, like for any other
section.
Before fixHeaders would do a tentative computation that
assignAddresses would sometimes override.
This patch also splits the cases where assignAddresses needs to add
the headers to the first PT_LOAD and the address computation. The net
effect is that we no longer create an empty page for no reason in the
included test case, which matches bfd behavior.
llvm-svn: 287565
MergeOutputSection class was a bit hard to use because it provdes
a series of finalize functions that have to be called in a right way
at a right time. It also intereacted with MergeInputSection, and the
logic was somewhat entangled between the two classes.
This patch simplifies it by providing only one finalize function.
Now, all you have to do is to call MergeOutputSection::finalize
when you have added all sections to the output section. Then, it
internally merges strings and initliazes StringPiece objects.
I think this is much easier to understand.
This patch also adds comments.
llvm-svn: 287314
I hit an internal linker script that was defining _DYNAMIC instead of
letting the linker do it. It turns out that both bfd and gold allow
that.
This is pretty easy to implement, just make the linker defined symbol
weak. This should have no impact in the case where there is no user
defined symbol: The visibility is hidden, which causes the output to
still be local.
llvm-svn: 287260
MIPS GOT handling is very different from other targets so it is better
to keep the code in the separatre section class MipsGotSection. This
patch introduces the new section and moves all MIPS specific code from
GotSection to the new class. I did not rename fields and methods in the
MipsGotSection class to reduce the diff and plan to do that by the
separate commit.
Differential revision: https://reviews.llvm.org/D26733
llvm-svn: 287150
This patch introduces the following changes:
- DynamicSection now inherits InputSection<ELFT> and was moved
to SyntheticSections.h/.cpp.
- Link and Entsize fields of DynamicSection are propagated to
its output section
- In<ELFT>::SyntheticSections was removed.
- Finalization of synthetic sections was removed from
OutputSection<ELFT>::finalize. Now finalizeSyntheticSections is
used instead.
Differential revision: https://reviews.llvm.org/D26603
llvm-svn: 286950
This patch stops creating symbols like __ehdr_start,
_end/_etext_edata,__tls_get_addr when using -r.
This fixes PR30984.
Differential revision: https://reviews.llvm.org/D26600
llvm-svn: 286941
Patch adds a filename to that error message.
I faced next error when debugged one of FreeBSD port:
error: relocation R_X86_64_PLT32 cannot refer to absolute symbol __tls_get_addr
error message was poor and this patch improves it to show the locations
of symbol declaration and using.
Differential revision: https://reviews.llvm.org/D26508
llvm-svn: 286940
Propagate program headers by walking the commands, not the
sections. This allows us to propagate program headers even from
sections that don't end up in the output.
Fixes pr30997.
llvm-svn: 286837
Unlike gold, bfd, gas or MC we were putting exidx sections first since
they are ro.
The spec doesn't explicitly say that they must come after, but it is
definitely more convenient for the consumer, matches other producers
and matches other areas in ELF (like SHT_GROUP) where sections are
ordered in a natural way.
llvm-svn: 286659
We would create a MergeInputSection for the synthetic .comment and
crash trying to add it to a regular output section.
With this we just don't add the synthetic section with -r. That is
consistent with gold that doesn't create .note.gnu.gold-version with
-r.
llvm-svn: 286635
Summary:
This patch adds a ".comment" section to an output. The comment
section contains the linker's version string. You can now
find out whether a binary is created by LLD or not using objdump
command like this.
$ objdump -s -j .comment foo
foo: file format elf64-x86-64
Contents of section .comment:
0000 00474343 3a202855 62756e74 7520342e .GCC: (Ubuntu 4.
0010 382e342d 32756275 6e747531 7e31342e 8.4-2ubuntu1~14.
...
00c0 766d2f74 72756e6b 20323835 38343629 vm/trunk 285846)
00d0 004c696e 6b65723a 204c4c44 20342e30 .Linker: LLD 4.0
00e0 2e302028 7472756e 6b203238 36343036 .0 (trunk 286406
00f0 2900 ).
Compilers emits .comment section as well, so the output contains
both compiler and linker information.
Alternative considered:
I first tried to add a SHT_NOTE section because GNU gold does that.
A NOTE section starts with a header which contains content type.
It turned out that ld.gold sets type NT_GNU_GOLD_VERSION to their
NOTE section. So the NOTE type is only for GNU gold (surprise!)
Next, I tried to create ".linker-version" section. However, it seems
that reusing the existing ".comment" section is better because 1)
other tools already know about .comment section and is able to strip
it and 2) the result contans not only linker info but also compiler
info.
Differential Revision: https://reviews.llvm.org/D26487
llvm-svn: 286496
Relocations are the last thing that we wore storing a raw section
pointer to and parsing on demand.
With this patch we parse it only once and store a pointer to the
actual data.
The patch also changes where we store it. It is now in
InputSectionBase. Not all sections have relocations, but most do and
this simplifies the logic. It also means that we now only support one
relocation section per section. Given that that constraint is
maintained even with -r with gold bfd and lld, I think it is OK.
llvm-svn: 286459
Patch allows to pass a symbols file to linker.
LLD will map symbols to sections and sort sections
in output according to symbol ordering file.
That can help to reduce the startup time and/or
amount of pagefaults during startup.
Also, interesting benchmark result was produced by Rafael Espíndola.
After applying the symbols file for clang he timed compiling
X86MCTargetDesc.ii to an object file.
The page faults went from just
56,988 to 56,946 since most faults are not in the binary.
Running time went from 4.403053515 to 4.178112244.
The speedup seems to be because of better cache
locality.
Differential revision: https://reviews.llvm.org/D26130
llvm-svn: 286440
The disadvantage is that we use uint64_t instad of uint32_t for some
value in 32 bit files. The advantage is a substantially simpler code,
faster builds and less code duplication.
llvm-svn: 286414
Previously, we have both input and output section for .MIPS.abiflags.
Now we have only one class for .MIPS.abiflags, which is MipsAbiFlagsSection.
This class is a synthetic input section.
.MIPS.abiflags sections are handled as regular sections until
the control reaches Writer. Writer then aggregates all sections
whose type is SHT_MIPS_ABIFLAGS to create a single synthesized
input section. The synthesized section is then processed normally
as if it came from an input file.
llvm-svn: 286398
Previously, we have both input and output sections for .reginfo and
.MIPS.options. Now for each such sections we have one synthetic input
sections: MipsReginfoSection and MipsOptionsSection respectively.
Both sections are handled as regular sections until the control reaches
Writer. Writer then aggregates all sections whose type is SHT_MIPS_REGINFO
or SHT_MIPS_OPTIONS to create a single synthesized input section. In that
moment Writer also save GP0 value to the MipsGp0 field of the corresponding
ObjectFile. This value required for R_MIPS_GPREL16 and R_MIPS_GPREL32
relocations calculation.
Differential revision: https://reviews.llvm.org/D26444
llvm-svn: 286397
This is similar to what was done for InputSection.
With this the various fields are stored in host order and only
converted to target order when writing.
llvm-svn: 286327
A CommonInputSection is a section containing all common symbols.
That was an input section but was abstracted in a different way
than the synthetic input sections because it was written before
the synthetic input section was invented.
This patch rewrites CommonInputSection as a synthetic input section
so that it behaves better with other sections.
llvm-svn: 286053
Previously, we do this piece of code to iterate over all input sections.
for (elf::ObjectFile<ELFT> *F : Symtab.getObjectFiles())
for (InputSectionBase<ELFT> *S : F->getSections())
It turned out that this mechanisms doesn't work well with synthetic
input sections because synthetic input sections don't belong to any
input file.
This patch defines a vector that contains all input sections including
synthetic ones.
llvm-svn: 286051
Previously, we added strings from DynamicSection::finalize().
It was a bit tricky because finalize() is supposed to fix the final
size of the section, but adding new strings would change the size of
.dynstr section. So there was a dependency between finalize functions
of .dynamic and .dynstr.
However, I noticed that we can elimiante the dependency by simply
add strings early; we don't have to do that in finalize() but can do
from DynamicSection's ctor.
This patch defines a new function, DynamicSection::addEntries, to
add .dynamic entries that doesn't depend on other sections.
llvm-svn: 285784
We are going to have many more classes for linker-synthesized
input sections, so it's worth to be added to a separate file
than to the file for regular input sections.
llvm-svn: 285740
Previously, we have a lot of BumpPtrAllocators, but all these
allocators virtually have the same lifetime because they are
not freed until the linker finishes its job. This patch aggregates
them into a single allocator.
Differential revision: https://reviews.llvm.org/D26042
llvm-svn: 285452
Instead of having 3 section allocators per file, have 3 for all files.
This is a substantial performance improvement for some cases. Linking
chromium without gc speeds up by 1.065x.
This requires using _exit in fatal since we have to avoid destructing
an InputSection if fatal is called from the constructor.
Thanks to Rui for the suggestion.
llvm-svn: 285290
When static linking in ARM (like Mips) __tls_get_addr is defined by
the library so we should not define it as a synthetic.
We also need to add __exidx_start and __exidx_end for the .ARM.exidx
section as the static libc library startup code is expecting them to
be defined by the default linker script for static linking on ARM.
Differential revision: https://reviews.llvm.org/D25978
llvm-svn: 285279
As the state of lld gets more complicated, shutting down gets more
expensive.
In a normal lld run we can just call _exit immediately after renaming
the temporary output file. We still want the ability to run a full
shutdown since that is useful for detecting memory leaks.
This patch adds a --full-shutdown flag and changes lit to use it.
llvm-svn: 285224
Instead of storing a pointer, store the members we need.
The reason for doing this is that it makes it far easier to create
synthetic sections. It also avoids reading data from files multiple
times., which might help with cross endian linking and host
architectures with slow unaligned access.
There are obvious compacting opportunities, but this already has mixed
results even on native x86_64 linking.
There is also the possibility of better refactoring the code for
handling common symbols, but this already shows that a custom class is
not necessary.
llvm-svn: 285148
We were fairly inconsistent as to what information should be accessed
with getSectionHdr and what information (like alignment) was stored
elsewhere.
Now all section info has a dedicated getter. The code is also a bit
more compact.
llvm-svn: 285079
We were previously using the (static) addSynthetic function to create
*_start/*_end symbols. This function was doing almost the same thing as
addOptionalSynthetic, except that it would also create the symbol in the
case where it is unreferenced. Because the symbol has hidden visibility,
creating it in that case would have no effect other than adding another
entry to the static symbol table. Remove addSynthetic and change callers to
use addOptionalSynthetic instead.
Differential Revision: https://reviews.llvm.org/D25545
llvm-svn: 285021
In this patch partial gdb_index section is created.
For costructing the .gdb_index section 6 steps should be performed (details are in
SplitDebugInfo.cpp file header), this patch do first 3:
Creates proper section header.
Fills list of compilation units.
Types CU list area is not supposed to be supported, so it is ignored and therefore
can be treated as implemented either.
Differential revision: https://reviews.llvm.org/D24706
llvm-svn: 284708
Previously, we were checking the existence of an entry symbol
too early. It was done before the linker script processor creates
symbols defined in scripts. Fixes bug 30743.
llvm-svn: 284676
This is 30646.
PT_OPENBSD_RANDOMIZE
The array element specifies the location and size of a part of the memory image of the program that must be filled with random data before any code in the object is executed. The memory region specified by a segment of this type may overlap the region specified by a PT_GNU_RELRO segment, in which case the intersection will be filled with random data before being marked read-only.
Reference links:
http://man.openbsd.org/OpenBSD-current/man5/elf.5c494713c45
Differential revision: https://reviews.llvm.org/D25469
llvm-svn: 284234
-z wxneeded creates a PHDR PT_OPENBSD_WXNEEDED.
PT_OPENBSD_WXNEEDED
The array element specifies that a process executing this file may need to be able to map or protect memory regions as simultaneously executable and writable. If the system is unable or unwilling to permit that for this executable then it may fail immediately. This segment type is meaningful only for executable files and is ignored in other objects.
http://man.openbsd.org/OpenBSD-current/man5/elf.5
Differential revision: https://reviews.llvm.org/D25472
llvm-svn: 284226
Previously we would fail to synthesise a __start_ or __stop_ symbol if
there existed a definition in a DSO. Instead, we would try to link against
the DSO definition. This became possible after D23552 when linking against
lld-produced DSOs but could in principle also occur when linking against
DSOs produced by other linkers.
Not only does it seem more likely that a user would expect the resolved
definition to be local to the executable, but if a __start_ or __stop_
symbol was synthesised by the linker, it is effectively impossible to link
against correctly from a non-PIC executable in a read-only section. Neither
a PLT nor a copy relocation would give us the right semantics here. The only
way the link could succeed is if the executable provided its own synthetic
definition of the symbol.
The fix is to also synthesise the definition if the only definition comes
from a DSO. Since this is what the addOptionalSynthetic function does,
switch to using that function.
Fixes PR30680.
Differential Revision: https://reviews.llvm.org/D25544
llvm-svn: 284168
Previously, we supported only SHF_COMPRESSED sections because it's
new and it's the ELF standard. But there are object files compressed
in the GNU style out there, so we had to support it.
Sections compressed in the GNU style start with ".zdebug_" and
contain different headers than the ELF standard's one. In this
patch, getRawCompressedData is responsible to handle it.
A tricky thing about GNU-style compressed sections is that we have
to rename them when creating output sections. ".zdebug_" prefix
implies the section is compressed. We need to rename ".zdebug_"
".debug" because our output sections are not compressed.
We do that in this patch.
llvm-svn: 284068
This part was splitted from D25016.
When sh_info value was set in the way that non-local symbol was treated as local, lld
was asserting, patch fixes that.
Differential revision: https://reviews.llvm.org/D25371
llvm-svn: 283859
Absolute local symbols with name staring from ".L" were reason of crash.
The same could happen when using some broken inputs found by AFL.
Patch fixes that.
Differential revision: https://reviews.llvm.org/D25365
llvm-svn: 283731
The .ARM.exidx sections contain a table. Each entry has two fields:
- PREL31 offset to the function the table entry describes
- Action to take, either cantunwind, inline unwind, or PREL31 offset to
.ARM.extab section
The table entries must be sorted in order of the virtual addresses the
first entry of the table describes. Traditionally this is implemented by
the SHF_LINK_ORDER dependency. Instead of implementing this directly we
sort the table entries post relocation.
The .ARM.exidx OutputSection is described by the PT_ARM_EXIDX program
header
Differential revision: https://reviews.llvm.org/D25127
llvm-svn: 283730
Since they end up going on the same PT_LOAD, there is no reason to
sort them. This matches bfd's behaviour and is user visible in the
placement of orphan sections.
llvm-svn: 282799
If there is not sufficient address space, just give up and don't put
the header in the PT_LOAD.
This matches bfd behaviour and I found at least one script that
depends on having a section at address 0.
llvm-svn: 282750
If we two sections reside in the same PT_LOAD segment,
we compute second section using the following formula:
Off2 = Off1 + VA2 - VA1. This allows OS kernel allocating
sections correctly when loading an image.
Differential revision: https://reviews.llvm.org/D25014
llvm-svn: 282705
This matches the behavior of Binutils linkers. We also change the
default MaxPageSize on x86-64 to 0x1000 to preserver the current
behavior, which is the same as the behavior implemented by gold.
https://llvm.org/bugs/show_bug.cgi?id=30541
Differential Revision: https://reviews.llvm.org/D24987
llvm-svn: 282560
If section contains local symbols ldd crashes, because local
symbols are added to symbol table before section is discarded
by linker script processor. This patch calls copyLocalSymbols()
after createSections, so discarded section symbols are not copied
llvm-svn: 282244
This reverts commit r282021, bringing back r282015.
The problem was that the comparison function was not a strict weak
ordering anymore, which this patch fixes.
Original message:
Only restrict order if both sections are in the script.
This matches gold and bfd behavior and is required to handle some scripts.
The script has to assume where PT_LOADs start in order to align that
spot. If we don't allow section it doesn't know about to move to the
middle, we can need more PT_LOADs and those will not be aligned.
llvm-svn: 282035
Linker scripts are responsible for aliging '.'. Since they are
designed for bfd which has no --rosegment, they don't align the RO to
RX transition.
llvm-svn: 281978
InputSection<ELFT>::Discarded has no name and it's not backed by
a file. Trying to report it as discared will cause a nullptr
dereference, therefore a crash. Skip it.
Differential Revision: https://reviews.llvm.org/D24731
llvm-svn: 281946
The InputSection variables in the Writer were named `C`. This
was because when the ELF linker was ported (from COFF)
the name `Chunks` for input sections was retained.
Luckily we switched to a more ELF-compliant jargon, but these
variables weren't reanamed accordingly during the transition.
llvm-svn: 281917
This matches gold and bfd, and is pretty much required by some linker
scripts. They end with commands like
foo 0 : { *(bar) }
if we put any SHF_ALLOC sections after they can have an address that
is too low.
llvm-svn: 281778
--section-start=sectionname=org
Locate a section in the output file at the absolute address given by org.
You may use this option as many times as necessary to locate multiple sections in the command line.
org must be a single hexadecimal integer; for compatibility with other linkers,
you may omit the leading `0x' usually associated with hexadecimal values.
Note: there should be no white space between sectionname, the equals sign (“<=>”), and org.
-Tbss=org
-Tdata=org
-Ttext=org
Same as --section-start, with .bss, .data or .text as the sectionname.
Differential revision: https://reviews.llvm.org/D24294
llvm-svn: 281458
Previously, all input files were owned by the symbol table.
Files were created at various places, such as the Driver, the lazy
symbols, or the bitcode compiler, and the ownership of new files
was transferred to the symbol table using std::unique_ptr.
All input files were then free'd when the symbol table is freed
which is on program exit.
I think we don't have to transfer ownership just to free all
instance at once on exit.
In this patch, all instances are automatically collected to a
vector and freed on exit. In this way, we no longer have to
use std::unique_ptr.
Differential Revision: https://reviews.llvm.org/D24493
llvm-svn: 281425
Without this flag set, an AArch64 Linux kernel won't try to load the executable
(even if a 32 bit arm kernel will run the binary just fine).
Patch by Martin Storsjö!
Differential revision: https://reviews.llvm.org/D24471
llvm-svn: 281394
This simplifies error handling as there is now only one place in the
code that needs to consider the possibility that the name is
corrupted. Before we would do it in every access.
llvm-svn: 280937
On most architectures the linker is required to optimize away any
references to __tls_get_addr in case of static linking. As usual
a special case is MIPS - libc defines __tls_get_addr itself because
there are no TLS optimizations for this architecture.
llvm-svn: 280664
The primary use of build-id is in debugging, hence omitting debug
sections when computing it significantly reduces its usability as
changes in debug section content wouldn't alter the build-id.
Differential Revision: https://reviews.llvm.org/D24120
llvm-svn: 280421
Symbol assignments outside of SECTIONS command need to be created
even when SECTIONS command is not used.
Differential Revision: https://reviews.llvm.org/D23751
llvm-svn: 280252
DiscardPolicy is enum replacing several boolean options.
This approach is not only consistent with what we use for
unresolveds (UnresolvedPolicy), but also should help to solve a problem
of options with opposing meanings, mentioned in PR28843
Differential revision: https://reviews.llvm.org/D23868
llvm-svn: 280209
This approach is not only consistent with UnresolvedPolicy,
but also should help to solve a problem
of options with opposing meanings, mentioned in PR28843
Differential revision: https://reviews.llvm.org/D23869
llvm-svn: 280206
-oformat output-format
`-oformat' option can be used to specify the binary format for the output object file.
Patch implements binary format output type.
Differential revision: https://reviews.llvm.org/D23769
llvm-svn: 279726
The ARM Exception handling ABI requires that all ARM exception index
table sections have a prefix of .ARM.exidx and are combined into a
single contiguous block either in their own output section or as part
of another output section.
In general clang will output a single .ARM.exidx section per object,
but will use .ARM.exidx.<section name> when -ffunction-sections is used.
This change canonicalizes the names of sections with the .ARM.exidx
prefix to just .ARM.exidx, which ensures that there is only a single
output section.
Differential Revision: https://reviews.llvm.org/D23775
llvm-svn: 279617
This patch is opposite to D19024, which made this symbols to be hidden by default.
Unfortunately FreeBSD loader wants to see
start_set_modmetadata_set/stop_set_modmetadata_set in the dynamic symbol table.
They were not placed there because had hidden visibility.
Patch makes them to have default visibility again.
Differential revision: https://reviews.llvm.org/D23552
llvm-svn: 279262
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
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
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
All other singleton instances are accessible globally.
CommonInputSection shouldn't be an exception.
Differential Revision: https://reviews.llvm.org/D22935
llvm-svn: 277034
This adds InputSectionDescription command to represent
the input section declaration.
This leads to next cleanup:
SectionRule removed.
ScriptConfiguration::Sections mamber removed.
LinkerScript<ELFT>::getOutputSection() removed.
Differential revision: https://reviews.llvm.org/D22617
llvm-svn: 276283
This change simplifies interaction between Writer and the linker script
because we can make needsInterpSection() a file-scope function.
llvm-svn: 276261
LLD still does not produce a correct combination of MIPS ELF flags if
input files have different sets of ELF flags (i.e. EF_MIPS_ARCH_32 and
EF_MIPS_ARCH_32R2). But now we do not stick to "R2" ABI version and can
emit EF_MIPS_ARCH_32R6 for example.
llvm-svn: 276172
We will need to do something like this to support range extension
thunks since that process is iterative.
Doing this also has the advantage that when doing the regular
relocation scan the offset in the output section is known and we can
just store that. This reduces the number of times we have to run
getOffset and I think will allow a more specialized .eh_frame
representation.
By itself this is already a performance win.
firefox
master 7.295045737
patch 7.209466989 0.98826892235
chromium
master 4.531254468
patch 4.509221804 0.995137623774
chromium fast
master 1.836928973
patch 1.823805241 0.992855612714
the gold plugin
master 0.379768791
patch 0.380043405 1.00072310839
clang
master 0.642698284
patch 0.642215663 0.999249070657
llvm-as
master 0.036665467
patch 0.036456225 0.994293213284
the gold plugin fsds
master 0.40395817
patch 0.404384555 1.0010555177
clang fsds
master 0.722045545
patch 0.720946135 0.998477367518
llvm-as fsds
master 0.03292646
patch 0.032759965 0.994943428477
scylla
master 3.427376378
patch 3.368316181 0.98276810292
llvm-svn: 276146
This patch simplifies output section management by making
Factory class have ownership of sections that creates.
Differential Revision: https://reviews.llvm.org/D22575
llvm-svn: 276141
In the last patch for --trace-symbol, I introduced a new symbol type
PlaceholderKind and store it to SymVector storage. It made all code
that iterates over SymVector to recognize and skip PlaceholderKind
symbols. I found that that's annoying.
In this patch, I removed PlaceholderKind and stop storing them to SymVector.
Now the information whether a symbol is being watched by --trace-symbol
is stored to the Symtab hash table.
llvm-svn: 275747
Previously, each subclass of SymbolBody had a pointer to a source
file from which it was created. So, there was no single way to get
a source file for a symbol. We had getSourceFile<ELFT>(), but the
function was a bit inconvenient as it's a template.
This patch makes SymbolBody have a pointer to a source file.
If a symbol is not created from a file, the pointer has a nullptr.
llvm-svn: 275701
Previously, it checked for the EC parameter and set HasError
only when there was an error. But in most places we called
error only when error had occurred, so this behavior was confusing.
llvm-svn: 275517
Config members are named after corresponding command line options.
This patch renames VAStart ImageBase so that they are in line with
--image-base.
Differential Revision: http://reviews.llvm.org/D22277
llvm-svn: 275298
George Rimar