Commit Graph

1738 Commits

Author SHA1 Message Date
Rui Ueyama f405b11224 Simplify error handling.
I don't think we have to aim for precise bug compatibility.
We can return a nullptr if a section is consumed by the linker, and
the rest should naturally work.

llvm-svn: 316817
2017-10-28 00:05:12 +00:00
Rui Ueyama 8f6e8ed9dd Remove trailing whitespace.
llvm-svn: 316787
2017-10-27 19:23:12 +00:00
Rafael Espindola bc2b1650d7 Handle all symbol types in --trace.
One case I was not sure was lazy symbols. bfd skips them completely,
but that is probably an artifact of how they implement archives.

llvm-svn: 316782
2017-10-27 18:30:11 +00:00
Peter Collingbourne 5c54f15c55 ELF: Add support for emitting dynamic relocations in the Android relocation packing format.
The Android relocation packing format is a more compact
format for dynamic relocations in executables and DSOs
that is based on delta encoding and SLEBs. An overview
of the format can be found in the Android source code:
https://android.googlesource.com/platform/bionic/+/refs/heads/master/tools/relocation_packer/src/delta_encoder.h

This patch implements relocation packing using that format.

This implementation uses a more intelligent algorithm for compressing
relative relocations than Android's own relocation packer. As a
result it can generally create smaller relocation sections than
that packer. If I link Chromium for Android targeting ARM32 I get a
.rel.dyn of size 174693 bytes, as compared to 371832 bytes with gold
and the Android packer.

Differential Revision: https://reviews.llvm.org/D39152

llvm-svn: 316775
2017-10-27 17:49:40 +00:00
George Rimar 90dacc256f [ELF] - Ignore non-absolute R_386_GOTPC relocation in debug sections.
This is for PR34852.

GCC 8.0 or earlier have a bug that it emits R_386_GOTPC relocations
against _GLOBAL_OFFSET_TABLE for .debug_info. The bug seems to have
been fixed in 2017: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82630,
but we do not want LLD to report errors for such inputs.
In this patch we ignore such relocations.

Differential revision: https://reviews.llvm.org/D38625

llvm-svn: 316761
2017-10-27 11:49:24 +00:00
George Rimar 3396bf07a2 [ELF] - Stop naming relocation sections with first input section name.
It was reported (https://reviews.llvm.org/D38724#902841) that when we use 
-ffunction-sections --emit-relocs build, REL[A] output section receives the name of first
input section, like .rela.text.first_function_in_text rather than .rela.text.

It is probably not really an issue as sh_info still points to correct target section, but
it does not look clean in output and allows internal section name to leak there,
what at least looks confusing and is not consistent with ld.bfd.

Patch changes this behavior so that target output section name is used as a base.

Differential revision: https://reviews.llvm.org/D39242

llvm-svn: 316760
2017-10-27 11:38:31 +00:00
Peter Smith 7f92294e9b [ELF][ARM] Add missing REQUIRES: arm to tests
My apologies I missed REQUIRES: arm from a couple of Arm specific tests.

llvm-svn: 316755
2017-10-27 09:16:46 +00:00
Peter Smith 6c9df3fce5 [ELF] Add support for multiple passes to createThunks()
This change allows Thunks to be added on multiple passes. To do this we must
merge only the thunks added in each pass, and deal with thunks that have
drifted out of range of their callers.

A thunk may end out of range of its caller if enough thunks are added in
between the caller and the thunk. To handle this we create another thunk.

Differential Revision: https://reviews.llvm.org/D34692

llvm-svn: 316754
2017-10-27 09:07:10 +00:00
Peter Smith 75030b6d56 [ELF] Introduce range extension thunks for ARM
This change adds initial support for range extension thunks. All thunks must
be created within the first pass so some corner cases are not supported. A
follow up patch will add support for multiple passes.

With this change the existing tests arm-branch-error.s and
arm-thumb-branch-error.s now no longer fail with an out of range branch.
These have been renamed and tests added for the range extension thunk.

Differential Revision: https://reviews.llvm.org/D34691

llvm-svn: 316752
2017-10-27 09:04:11 +00:00
Peter Smith f0c70f8d34 [ELF] Pre-create ThunkSections at Target specific intervals
When an OutputSection is larger than the branch range for a Target we
need to place thunks such that they are always in range of their caller,
and sufficiently spaced to maximise the number of callers that can use
the thunk. We use the simple heuristic of placing the
ThunkSection at intervals corresponding to a target specific branch range.
If the OutputSection is small we put the thunks at the end of the executable
sections.

Differential Revision: https://reviews.llvm.org/D34689

llvm-svn: 316751
2017-10-27 08:58:28 +00:00
George Rimar d605f414db [ELF] - Dedupliсate FDEs when sections are ICFed.
When LLD do ICF for 2 identical sections it leaves 2 duplicate entries in .eh_frame
pointing to the same address. After that it fixes .eh_frame_header's header,
so that it says it contains single FDE, though section itself contains 2 
(it contains garbage data at tail).

As a result excessive entries in .eh_frame and excessive dummy data in .eh_frame_header
emited to output. Patch fixes that. This is PR34518.

Differential revision: https://reviews.llvm.org/D38998

llvm-svn: 316648
2017-10-26 09:13:19 +00:00
George Rimar 9814d15136 [ELF] - Implement --orphan-handling option.
It is PR34946.

Spec (http://man7.org/linux/man-pages/man1/ld.1.html) tells about
--orphan-handling=MODE, option where MODE can be one of four:
"place", "discard", "warn", "error".
Currently we already report orphans when -verbose given,
what becomes excessive with option implemented.

Patch stops reporting orphans when -versbose is given,
and support "place", "warn" and "error" modes.
It is not yet clear that "discard" mode is useful so it is not supported.

Differential revision: https://reviews.llvm.org/D39000

llvm-svn: 316583
2017-10-25 15:20:30 +00:00
George Rimar f22ec9ddf6 [ELF] - Linkerscript: fix issue with SUBALIGN.
This is PR34886.

SUBALIGN command currently triggers failture if result expression
is zero. Patch fixes the issue, treating zero as 1, what is consistent with
other places and ELF spec it seems.

Patch also adds "is power of 2" check for this and other expressions
returning alignment.

Differential revision: https://reviews.llvm.org/D38846

llvm-svn: 316580
2017-10-25 14:50:51 +00:00
Konstantin Zhuravlyov b71d1b8a54 LLD/ELF/AMDGPU: Process AMDGPU-specific e_flags
Differential Revision: https://reviews.llvm.org/D39140

llvm-svn: 316483
2017-10-24 19:05:32 +00:00
George Rimar f4ca4a6fa1 [ELF] - Do not collect SHT_REL[A] sections unconditionally when --gc-sections and --emit-relocs used together.
This is "Bug 34836 - --gc-sections remove relocations from --emit-relocs",

When --emit-relocs is used, LLD currently always drops SHT_REL[A] sections from
output if --gc-sections is present. Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D38724

llvm-svn: 316418
2017-10-24 08:26:32 +00:00
Rafael Espindola 615a064e33 Document a change of behavior in r315552.
We used to reject this, but we now accept. The output seems
reasonable, so this is probably an OK extension over bfd/gold.

llvm-svn: 316376
2017-10-23 21:00:15 +00:00
Petr Hosek 2fd533db9f [ELF] When placing orphans, handle case when last section is dead
r315292 introduced a change that's supposed to consistently ignore
"dead" output sections when placing orphans. Unfortunately, that
change doesn't handle the special case when the orphan section is
second to last section and the last section is dead (e.g. because
it's being discarded) introducing a regression in some cases.

This change handles this case by using the same predicate when
checking the last section.

Differential Revision: https://reviews.llvm.org/D39172

llvm-svn: 316307
2017-10-23 00:51:08 +00:00
Rui Ueyama 8faafa4fb1 Add R_PPC_ADDR16_HI relocation support
The support of R_PPC_ADDR16_HI improves ld compatibility and makes
things on par with RuntimeDyldELF that already implements this
relocation.

Patch by vit9696.

llvm-svn: 316306
2017-10-22 23:33:49 +00:00
Rafael Espindola 06ea0ce1c9 Handle shared symbols in the gnu hash construction.
They are special in that they they need to be in the hash table iff we
are linking an executable that preempts them.

llvm-svn: 316065
2017-10-18 06:49:59 +00:00
NAKAMURA Takumi 8b6b9cbb33 Prune trailing linefeed.
llvm-svn: 316060
2017-10-18 04:45:09 +00:00
Rafael Espindola 3038c6beb5 Revert "Bring back the rest of r315721."
This reverts commit r316051.

It fails on a bot.

llvm-svn: 316058
2017-10-18 03:06:45 +00:00
Rafael Espindola 07412df152 Bring back the rest of r315721.
The original patch was reported to break a libcxx bot. Unfortunately I
could not reproduce the issue and the bot log is not available anymore.

This patch changes the handling of shared symbols. I will watch the
bot and see it breaks.

Original message:
--------------------------------------------------------------
Handle shared and lazy symbol in the gnu hash construction.

We were not considering those symbols undefined and they could end up
in the end of the dynamic symbol table.
--------------------------------------------------------------

llvm-svn: 316051
2017-10-18 01:10:05 +00:00
Rafael Espindola 14381cf5a6 Bring back part of r315721.
The original patch was reported to break a libcxx bot. Unfortunately
I could not reproduce the issue and the bot log is not available anymore.

This patch changes the handling of just lazy symbols. I will watch the
bot and see it breaks.

Original message:
--------------------------------------------------------------
Handle shared and lazy symbol in the gnu hash construction.

We were not considering those symbols undefined and they could end up
in the end of the dynamic symbol table.
--------------------------------------------------------------

llvm-svn: 316004
2017-10-17 15:29:11 +00:00
Tony Tye 394e1dde6e Add base relative relocation record that can be used for the following case (OpenCL example):
static __global int Var = 0; 
__global int* Ptr[] = {&Var};
...

In this case Var is a non premptable symbol and so its address can be used as the value of Ptr, with a base relative relocation that will add the delta between the ELF address and the actual load address. Such relocations do not require a symbol.

This also fixes LLD which was incorrectly generating a PCREL64 for this case.

Differential Revision: https://reviews.llvm.org/D38910

llvm-svn: 315936
2017-10-16 20:46:53 +00:00
NAKAMURA Takumi 09c234f857 Revert rL315721, "Handle shared and lazy symbol in the gnu hash construction."
It broke check-libcxx with stage1-clang and stage1-lld.

llvm-svn: 315803
2017-10-14 12:21:49 +00:00
Rafael Espindola ea413cbacf Give shared symbols priority over lazy ones.
This matches the behavior of gold and bfd. It also matches lld's own
behavior when the shared symbol is seen first

llvm-svn: 315766
2017-10-13 21:52:33 +00:00
Rafael Espindola a7e3132d03 Handle shared symbols in --gc-sections.
We don't want to gc a section if it is used via __start_*, but we were
doing that if the same symbol was visible in a shared library.

llvm-svn: 315727
2017-10-13 18:32:16 +00:00
Rafael Espindola 8bf95e4678 Handle shared and lazy symbol in the gnu hash construction.
We were not considering those symbols undefined and they could end up
in the end of the dynamic symbol table.

llvm-svn: 315721
2017-10-13 18:07:11 +00:00
Rafael Espindola a2516bef9f Relax test.
These value are irrelevant for the test.

llvm-svn: 315720
2017-10-13 18:03:11 +00:00
Rafael Espindola af6c9edc4b Correctly handle shared and lazy symbols.
I will try to make this API a bit less error prone, but for now just
get another test passing.

llvm-svn: 315645
2017-10-13 00:06:38 +00:00
Rafael Espindola 62222d04cd Update comment.
The number 131076 didn't show up anywhere in the test.

llvm-svn: 315588
2017-10-12 15:54:14 +00:00
Rafael Espindola d7d752ad33 Relax test.
The address of the .got section is not relevant for the test.

llvm-svn: 315585
2017-10-12 15:12:55 +00:00
Rafael Espindola 49419bb303 Use 0 as sh_link when we don't have a dynamic symbol table.
It doesn't make sense to link from an alloc section to a non alloc
one as we were doing.

This matches the behavior of both gold and bfd.

llvm-svn: 315584
2017-10-12 15:05:04 +00:00
George Rimar 81eca18df3 [ELF] - Linkerscript: Add `~` as separate math token.
Previously we did not support following:
foo = ~0xFF;
and had to add space before numeric value:
foo = ~ 0xFF

That was constistent with ld.bfd < 2.30, which shows:
script.txt:3: undefined symbol `~2' referenced in expression,
but inconsistent with gold.

It was fixed for ld.bfd 2.30 as well:
https://sourceware.org/bugzilla/show_bug.cgi?id=22267

Differential revision: https://reviews.llvm.org/D36508

llvm-svn: 315569
2017-10-12 08:40:12 +00:00
Rui Ueyama be85529d2b Remove one parameter from Target::getRelExpr.
A section was passed to getRelExpr just to create an error message.
But if there's an invalid relocation, we would eventually report it
in relocateOne. So we don't have to pass a section to getRelExpr.

llvm-svn: 315552
2017-10-12 03:14:06 +00:00
Davide Italiano db710f28e6 [ELF] Try to not emit weird diagnostics on undefined symbols.
Fixes PR34872.

Differential Revision:  https://reviews.llvm.org/D38712

llvm-svn: 315487
2017-10-11 18:37:24 +00:00
George Rimar 26fa916deb [ELF] - Do not set output section flags except SHF_{ALLOC,WRITE,EXECINSTR}.
This is PR34546.

Currently LLD creates output sections even if it has no input sections,
but its command contains an assignment.
Committed code just assigns the same flag that was used in previous
live section.
That does not work sometimes. For example if we have following script:

.ARM.exidx : { *(.ARM.exidx*) }
.foo : { _foo = 0; } }
Then first section has SHF_LINK_ORDER flag. But section foo should not.
That was a reason of crash in OutputSection::finalize(). LLD tried to calculate
Link value, calling front() on empty input sections list.
We should only keep access flags and omit all others when creating such sections.

Patch fixes the crash observed.

Differential revision: https://reviews.llvm.org/D37736

llvm-svn: 315441
2017-10-11 08:13:40 +00:00
Rafael Espindola 97c57b9e7b Don't create a dummy __tls_get_addr.
We just don't need one with the current setup.

We only error on undefined references that are used by some
relocation.

If we managed to relax all uses of __tls_get_addr, no relocation uses
it and we don't produce an error.

This is less code and fixes the case were we fail to relax. Before we
would produce a broken output, but now we produce an error.

llvm-svn: 315334
2017-10-10 17:27:34 +00:00
James Henderson b5ca92ef73 [ELF] Set Dot initially to --image-base value when using linker scripts
When parsing linker scripts, LLD previously started with a '.' value of 0,
regardless of the internal default image base for the target, and regardless of
switches such as --image-base. It seems reasonable to use a different image base
value when using linker scripts and --image-base is specified, since otherwise the
switch has no effect. This change does this, as well as removing unnecessary
initialisation of Dot where it is not used.

The default image base should not be used when processing linker
scripts, because this will change the behaviour for existing linker script users,
and potentially result in invalid output being produced, as a subsequent assignment
to Dot could move the location counter backwards. Instead, we maintain the existing
behaviour of starting from 0 if --image-base is not specified.

Reviewers: ruiu

Differential Revision: https://reviews.llvm.org/D38360

llvm-svn: 315293
2017-10-10 10:09:35 +00:00
Andrew Ng 4d54a4b4f7 [LLD] Fix findOrphanPos to consistently ignore "dead" OutputSection's
When findOrphanPos does the reverse search to find the OutputSection
preceding the orphan's insertion point, look for a live OutputSection
and ignore "dead" OutputSection's. This matches the behaviour of the
forward search performed earlier in this function.

Added test which without the above fix fails as a result of an orphan
executable section being incorrectly placed in a non-executable segment.

Differential Review: https://reviews.llvm.org/D38690

llvm-svn: 315292
2017-10-10 10:05:52 +00:00
George Rimar 7e9c5610c9 [ELF] - Improve "has non-ABS reloc" error.
It did not contain information about relocation type and symbol.

Differential revision: https://reviews.llvm.org/D38623

llvm-svn: 315280
2017-10-10 07:55:07 +00:00
Peter Collingbourne d6924d7474 Reland r315114, "ELF: Export preempted symbols even if there is a dynamic list." which was reverted in r315116.
I hadn't synced past the change that changed the default hash style
to --hash-style=both, so my test had the symbols in the wrong order.

llvm-svn: 315119
2017-10-06 22:09:03 +00:00
Peter Collingbourne accab5908d Revert r315114, "ELF: Export preempted symbols even if there is a dynamic list."
For some reason the symbols get emitted in the wrong order on one of the
buildbots: http://bb9.pgr.jp/#builders/15/builds/180

llvm-svn: 315116
2017-10-06 21:48:39 +00:00
Peter Collingbourne 5a8928c605 ELF: Export preempted symbols even if there is a dynamic list.
Dynamic lists in an executable are additive, not restrictive, so we
must continue to export preempted symbols even with a dynamic list.

This fixes sanitizer interception of libc symbols (and should also fix
symbol preemption by users of sanitizers).

Differential Revision: https://reviews.llvm.org/D38647

llvm-svn: 315114
2017-10-06 21:33:59 +00:00
Rafael Espindola 469350810a Refine our --wrap implementation.
Before this patch we would copy foo into real_foo and wrap_foo into
foo. The net result is that __wrap_foo shows up twice in the symbol
table.

With this patch we:

* save a copy of __real_foo before copying foo.
* drop one of the __wrap_foo from the symbol table.
* if __real_foo was not undefined, add a *new* symbol with that content to
  the symbol table.

The net result is that

Anything using foo now uses __wrap_foo
Anything using __real_foo now uses foo.
Anything using __wrap_foo still does.

And the symbol table has foo, __wrap_foo and __real_foo (if defined).

Which I think is the desired behavior.

llvm-svn: 315097
2017-10-06 20:09:34 +00:00
Alexander Richardson f52a3b94e1 [ELF][MIPS] Check for overflow when writing R_MIPS_CALL16 and R_MIPS_TLS_GOTTPREL
Summary:
These are 16 bit relocations and not part of a HI/LO pair so we need to
check that they don't overflow.

Reviewers: atanasyan

Reviewed By: atanasyan

Subscribers: ruiu, llvm-commits, emaste, sdardis

Tags: #lld

Differential Revision: https://reviews.llvm.org/D38614

llvm-svn: 315073
2017-10-06 16:15:59 +00:00
George Rimar 8f3a6c8143 [ELF] - Do not produce broken .dynamic section with --no-rosegment
LLD produces broken .dynamic section when --no-rosegment and at least
one of following options is present:
  1) -z rodynamic is given.
  2) MIPS target.

That happens because code that writes .dynamic assumes target buffer
is zero-filled, what can be not true after LLD fills it with trap
instructions. With one of two options above, .dynamic becomes
SHF_ALLOC section, so can be affected.

Differential revision: https://reviews.llvm.org/D38580

llvm-svn: 315054
2017-10-06 10:06:13 +00:00
George Rimar 2727ce2c1f [ELF] - Do not produce broken .dynsym with --no-rosegment.
We produce broken output currently.
Code that writes .dynsym assumes output buffer is zero-filled,
though that is not always true. When --no-rosegment is given,
buffer can be filled with trap instructions. Patch fixes the issue.

It is relative with PR34705.

Differential revision: https://reviews.llvm.org/D38579

llvm-svn: 315053
2017-10-06 09:56:24 +00:00
George Rimar 148d75d8d5 [ELF] - Fix BB after r315051.
Testcase has "zlib" requirement, which is unsupported on
windows, so that it was not run locally for me.

llvm-svn: 315052
2017-10-06 09:46:04 +00:00
George Rimar d46753e421 [ELF] - Do --hash-style=both by default.
Its PR34712,

GNU linkers recently changed default values to "both" of "sysv".
Patch do the same for all targets except MIPS, where .gnu.hash
section is not yet supported.

Code suggested by Rui Ueyama.

Differential revision: https://reviews.llvm.org/D38407

llvm-svn: 315051
2017-10-06 09:37:44 +00:00