Commit Graph

631 Commits

Author SHA1 Message Date
Petr Hosek b93c5b9f7e [ELF] Don't output headers into a segment if there's no space for them
Currently, LLD checks whether there's enough space for headers by
checking if headers fit below the address of the first allocated
section. However, that's always thue if the binary doesn't start
at zero which means that LLD always emits a segment for headers,
even if no other sections belong to that segment.

This is a problem in cases when linker script is being used with a
non-zero start address when we don't want to make the headers visible
by not leaving enough space for them. This pattern is common in
embedded programming but doesn't work in LLD.

This patch changes the behavior of LLD in case when linker script
is being to match the behavior of BFD ld and gold, which is to only
place headers into a segment when they're covered by some output
section.

Differential Revision: https://reviews.llvm.org/D36256

llvm-svn: 311586
2017-08-23 18:44:34 +00:00
George Rimar 5d0ea70ad5 [ELF] - Do not segfault when doing logical and/or operations on symbols that have no output sections.
Previously we would crash on samples from testcase,
because were trying to access zero pointer to output section.

Differential revision: https://reviews.llvm.org/D36145

llvm-svn: 311311
2017-08-21 07:57:12 +00:00
George Rimar 7e5b0a5978 [ELF] - Don't segfault when accessing location counter inside MEMORY command.
We would previously crash on next script:
MEMORY { name : ORIGIN = .; }

Patch fixes that.

Differential revision: https://reviews.llvm.org/D36138

llvm-svn: 311073
2017-08-17 08:47:21 +00:00
George Rimar 945cd31c4b [ELF] - Linkerscript: disallow discarding COMMON.
This patch restricts following construction:

/DISCARD/ : { *(COMMON) }

Previously LLD would crash.

Differential revision: https://reviews.llvm.org/D36468

llvm-svn: 310554
2017-08-10 08:07:05 +00:00
Rafael Espindola 6e93d0546a Move File from SymbolBody to Symbol.
With this Symbol has the same size as before, but DefinedRegular goes
from 72 to 64 bytes.

I also find this a bit easier to read. There are fewer places
initializing File for example.

This has a small but measurable speed improvement on all tests (1%
max).

llvm-svn: 310142
2017-08-04 22:31:42 +00:00
George Rimar d6bcde389a [ELF] - Fix "--symbol-ordering-file doesn't work with linker scripts"
This is PR33889,

Patch adds support of combination of linkerscript and
-symbol-ordering-file option.

If no sorting commands are present in script inside section declaration
and no --sort-section option specified, code uses sorting from ordering 
file if any exist.

Differential revision: https://reviews.llvm.org/D35843

llvm-svn: 310045
2017-08-04 10:25:29 +00:00
Rafael Espindola a2df2f09f4 Avoid warnings when asserts are disabled.
llvm-svn: 309326
2017-07-27 21:42:42 +00:00
Rafael Espindola 8c022ca783 Merge OutputSectionCommand and OutputSection.
This is a bit of a hack, but it is *so* convenient.

Now that we create synthetic linker scripts when none is provided, we
always have to handle paired OutputSection and OutputsectionCommand and
keep a mapping from one to the other.

This patch simplifies things by merging them and creating what used to
be OutputSectionCommands really early.

llvm-svn: 309311
2017-07-27 19:22:43 +00:00
George Rimar aa3541875e [ELF] - Store PhdrEntry values by pointers instead of storing by value.
That is slightly more convinent as allows to store pointer on
program header entry in a more safe way.
 
Change was used in 2 patches currently on review.

Differential revision: https://reviews.llvm.org/D35832

llvm-svn: 309253
2017-07-27 07:46:50 +00:00
Rui Ueyama 709fb2bb10 Rename ObjectFile -> ObjFile.
Rename it because it was too easy to conflict with llvm::object::ObjectFile
which broke buildbots several times.

llvm-svn: 309199
2017-07-26 22:13:32 +00:00
Rafael Espindola a5e8dd35b0 Simplify. NFC.
llvm-svn: 309153
2017-07-26 18:47:49 +00:00
Rafael Espindola 244ef98161 Detemplate SymbolTable.
NFC, just makes it easier to access from non templated code.

llvm-svn: 309152
2017-07-26 18:42:48 +00:00
George Rimar f694d33f4c [ELF] - Fix calculation of memory region offset.
This is PR33714.

Previously for each input section offset of memory region
was incremented on a size of output section.

That resulted in a wrong error message saying about
overflow. Patch fixes that.

Differential revision: https://reviews.llvm.org/D35803

llvm-svn: 308955
2017-07-25 08:29:29 +00:00
Rafael Espindola ca5740d95a Don't crash on an empty section with an ALIGN.
llvm-svn: 308809
2017-07-22 00:00:51 +00:00
Petr Hosek 8b591f592b [ELF] Remove processNonSectionCommands
This method is no longer being used anywhere.

Differential Revision: https://reviews.llvm.org/D35706

llvm-svn: 308706
2017-07-21 01:02:30 +00:00
George Rimar 67c60727ce [ELF] - Apply clang-format. NFC.
llvm-svn: 308297
2017-07-18 11:55:35 +00:00
Shoaib Meenai e1d7776c53 [ELF] Use stable_sort for compareByFilePosition
The comment at the top of compareByFilePosition indicates that it relies
on stable_sort to preserve the order of synthetic sections. We were
using sort instead of stable_sort, however, leading to incorrect
synthetic section ordering.

Differential Revision: https://reviews.llvm.org/D35473

llvm-svn: 308207
2017-07-17 19:42:19 +00:00
Rui Ueyama 1e77ad1456 Move feature-specific functions out of Strings.cpp.
Functions declared in Strings.h should provide generic string operations
for the linker, but some of them are too specific to some features. This
patch moves them to the location where they are used.

llvm-svn: 307949
2017-07-13 20:30:35 +00:00
George Rimar 8c804d9746 [ELF] - Allow moving location counter backward in some cases.
Patch removes restriction about moving location counter
backwards outside of output sections declarations.

That may be useful for some apps relying on such scripts, 
known example is linux kernel.

Differential revision: https://reviews.llvm.org/D34977

llvm-svn: 307794
2017-07-12 14:50:25 +00:00
Peter Smith c1ace40bf9 [ELF] Add comment to explain LinkerScript::CurAddressState [NFC]
r307367 via D34345 split out the temporary address state used within
processCommands() and assignAddresses(). Due to the way that getSymbolValue
is used by the ScriptParser there is no way of giving the current
OutputSection to getSymbolValue() without somehow accessing the created
addressState. The suggestion was that by making a pointer that would go out
of scope we would find out by ASAN/MSAN or a crash if someone had misused
currentAddressState.

Differential Revision: https://reviews.llvm.org/D34345

llvm-svn: 307637
2017-07-11 09:28:27 +00:00
Peter Smith 906e9a1898 [ELF] Extract temporary state used in assignAddresses()
The assignAddresses() function accumulates state in the LinkerScript that
prevents it from being called multiple times. This change moves the state
into a separate structure AddressState that is created at the start of the
function and disposed of at the end.

CurAddressState is used rather than passing a reference to the state as a
parameter to the functions used by assignAddresses(). This is because the
getSymbolValue function needs to be executed in the context of AddressState
but it is stored in ScriptParser when AddressState is not available.

The AddressState is also used in a limited context by processCommands()

Differential Revision: https://reviews.llvm.org/D34345

llvm-svn: 307367
2017-07-07 09:11:27 +00:00
Rafael Espindola 2126334e08 Move fabricateDefaultCommands earlier.
It is now just after the OutputSections are created, which is as early
as it can possibly go.

llvm-svn: 307225
2017-07-05 23:36:24 +00:00
Rafael Espindola 9f9e99be20 Simplify. NFC.
llvm-svn: 307217
2017-07-05 22:30:04 +00:00
Rafael Espindola cf7347379f Remove a function that is now trivial.
llvm-svn: 307214
2017-07-05 22:25:38 +00:00
Rafael Espindola d7faa9165f Merge createOrphanCommands into addOrphanSections.
This is a bit simpler and avoids a walk over OutputSections.

llvm-svn: 307178
2017-07-05 17:50:43 +00:00
Peter Smith 5aedebff38 [ELF] Extract allocateHeaders() from assignAddresses()
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
2017-07-05 09:12:54 +00:00
George Rimar a951d5c40b [ELF] - Use llvm::find_if instead std::find_if where possible. NFC.
Two more places.

llvm-svn: 307076
2017-07-04 13:10:37 +00:00
George Rimar d971e7030e [ELF] - Simplify allocateHeaders(). NFC.
* Return type changed to void, because it was unused.
* std::find_if -> llvm::find_if

llvm-svn: 307039
2017-07-03 16:05:51 +00:00
Andrew Ng a020d3487e [LLD][LinkerScript] Allow non-alloc sections to be assigned to segments.
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
2017-07-03 10:11:25 +00:00
Rui Ueyama 82143d3fbb Move `assert` upwards so that it fails early if it fails.
llvm-svn: 306308
2017-06-26 17:11:36 +00:00
Rafael Espindola 9c0395e39e Prefer -Ttext over linker script values.
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
2017-06-20 01:51:50 +00:00
Andrew Ng 6e9f98c198 [LLD][LinkerScript] Add support for segment NONE.
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
2017-06-19 15:28:58 +00:00
Rafael Espindola 4f1fca270a Error when discarding .dynstr.
We would crash before.

llvm-svn: 305615
2017-06-16 23:53:36 +00:00
Rafael Espindola 656cc20f5b Error when discarding .dynsym.
We would crash instead before.

llvm-svn: 305614
2017-06-16 23:50:09 +00:00
Rafael Espindola 2af64b0bf8 Error on trying to discard .dynamic.
We would crash instead before.

llvm-svn: 305613
2017-06-16 23:45:35 +00:00
Rui Ueyama e6d8c1cb38 Update a comment.
llvm-svn: 305601
2017-06-16 22:45:13 +00:00
Rafael Espindola 383971d2a7 Move clearOutputSections before sortSections.
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
2017-06-15 21:51:01 +00:00
Rafael Espindola e86fddd651 Simplify. NFC.
llvm-svn: 305341
2017-06-13 23:54:34 +00:00
Rafael Espindola f51c80559c Make OutputSections and OutputSectionCommands globals.
This is similar to what we do for InputSections and makes them easier
to access.

llvm-svn: 305337
2017-06-13 23:26:31 +00:00
Rafael Espindola dece28087e Set non alloc section address to 0 earlier.
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
2017-06-13 20:57:43 +00:00
Rafael Espindola 7ff9329b7c Move clearOutputSections before createPhdrs. NFC.
llvm-svn: 305156
2017-06-10 22:12:32 +00:00
Rafael Espindola e76231b647 Move fabricateDefaultCommands earlier.
This then requires delaying a call to getHeaderSize.

llvm-svn: 304961
2017-06-08 04:17:04 +00:00
George Rimar fbb0463f39 [ELF] - Linkerscript: implement NOLOAD section type.
This is PR32351

Each output section may have a type. The type is a keyword in parentheses.
(https://sourceware.org/binutils/docs/ld/Output-Section-Type.html#Output-Section-Type)
This patch support only one type, it is NOLOAD.
If output section has such type, we force it to be SHT_NOBITS. 

More details are available on a review page.

Differential revision: https://reviews.llvm.org/D33647

llvm-svn: 304925
2017-06-07 16:31:08 +00:00
Peter Smith 8e791463ef [ELF] Convert Thunks to use InputSectionDescriptions
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
2017-06-07 09:35:14 +00:00
George Rimar 41c7ab4a3d [ELF] - Linkerscript: improved error reporting.
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
2017-06-07 08:54:43 +00:00
Zachary Turner 264b5d9e88 Move Object format code to lib/BinaryFormat.
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
2017-06-07 03:48:56 +00:00
Rafael Espindola 658a0c74ec Avoid using OutputSection::Sections. NFC.
We now used the InputSectionDescriptions in
OutputSectionCommand::finalize. This will allow moving
clearOutputSections earlier.

llvm-svn: 304827
2017-06-06 20:13:19 +00:00
Rafael Espindola 8c284acf14 Move finalize to OutputSectionCommands. NFC.
This removes a mapping from OutputSection to OutputSectionCommand and
is another step in moving clearOutputSections earlier.

llvm-svn: 304821
2017-06-06 19:40:01 +00:00
George Rimar 1124001c68 [ELF] - Early return from writeTo() if section is SHT_NOBITS. NFCi.
That addresses port commit comments for https://reviews.llvm.org/D33646

llvm-svn: 304777
2017-06-06 07:46:28 +00:00
Rafael Espindola 0f7dc0e2d0 Run fabricateDefaultCommands before fixSectionAlignments.
This allows us to remove the PageAlign field. It will also allow
moving fabricateDefaultCommands earlier.

llvm-svn: 304513
2017-06-02 01:37:58 +00:00