Summary:
With D43396, no clients use the Path parameter anymore.
Depends on D43396.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43400
llvm-svn: 325619
Summary:
This will avoid the race condition described in the review for D37993.
I believe that the Path parameter to AddBufferFn is no longer utilized.
I would prefer to remove that as a follow up clean up patch to reduce
the diffs in this patch.
Reviewers: pcc
Reviewed By: pcc
Subscribers: inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43396
llvm-svn: 325618
This patch contains logic for handling DW_TAG_label that's present in
darwin's dsymutil implementation, but not yet upstream.
Differential revision: https://reviews.llvm.org/D43438
llvm-svn: 325600
This is the second part of recommit of r325224. The previous part was
committed in r325426, which deals with C++ memory allocation. Solution
for C memory allocation involved functions `llvm::malloc` and similar.
This was a fragile solution because it caused ambiguity errors in some
cases. In this commit the new functions have names like `llvm::safe_malloc`.
The relevant part of original comment is below, updated for new function
names.
Analysis of fails in the case of out of memory errors can be tricky on
Windows. Such error emerges at the point where memory allocation function
fails, but manifests itself when null pointer is used. These two points
may be distant from each other. Besides, next runs may not exhibit
allocation error.
In some cases memory is allocated by a call to some of C allocation
functions, malloc, calloc and realloc. They are used for interoperability
with C code, when allocated object has variable size and when it is
necessary to avoid call of constructors. In many calls the result is not
checked for null pointer. To simplify checks, new functions are defined
in the namespace 'llvm': `safe_malloc`, `safe_calloc` and `safe_realloc`.
They behave as corresponding standard functions but produce fatal error if
allocation fails. This change replaces the standard functions like 'malloc'
in the cases when the result of the allocation function is not checked
for null pointer.
Finally, there are plain C code, that uses malloc and similar functions. If
the result is not checked, assert statement is added.
Differential Revision: https://reviews.llvm.org/D43010
llvm-svn: 325551
Summary:
The current implementation was writing the file name without the extension
whereas GNU objcopy writes the full filename. With this change GDB will now
load the .debug file instead of silently ignoring it.
Reviewers: jakehehrlich, jhenderson
Reviewed By: jakehehrlich
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43474
llvm-svn: 325528
Summary:
This commit separates the abstract accelerator table data structure
from the code for writing out an on-disk representation of a specific
accelerator table format. The idea is that former (now called
AccelTable<T>) can be reused for the DWARF v5 accelerator tables
as-is, without any further customizations.
Some bits of the emission code (now living in the EmissionContext class)
can be reused for DWARF v5 as well, but the subtle differences in the
layout of various subtables mean the sharing is not always possible.
(Also, the individual emit*** functions are fairly simple so there's a
tradeoff between making a bigger general-purpose function, and two
smaller targeted functions.)
Another advantage of this setup is that more of the serialization logic
can be hidden in the .cpp file -- I have moved declarations of the
header and all the emission functions there.
Reviewers: JDevlieghere, aprantl, probinson, dblaikie
Subscribers: echristo, clayborg, vleschuk, llvm-commits
Differential Revision: https://reviews.llvm.org/D43285
llvm-svn: 325516
Summary:
Gold plugin does not add pass to ThinLTO modules without useful symbols.
In this case ThinLTO can't create corresponding index file and some features, like CFI,
cannot be processes by backed correctly without index.
Given that we don't need the backed output we can request it to avoid
processing the module. This is implemented by this patch using new
"SkipModuleByDistributedBackend" flag.
Reviewers: pcc, tejohnson
Subscribers: mehdi_amini, inglorion, eraman, cfe-commits
Differential Revision: https://reviews.llvm.org/D42995
llvm-svn: 325411
This was originally reported as a bug with the symptom being "cvdump
crashes when printing an LLD-linked PDB that has an S_FILESTATIC record
in it". After some additional investigation, I determined that this was
a symptom of a larger problem, and in fact the real problem was in the
way we emitted the global PDB string table. As evidence of this, you can
take any lld-generated PDB, run cvdump -stringtable on it, and it would
return no results.
My hypothesis was that cvdump could not *find* the string table to begin
with. Normally it would do this by looking in the "named stream map",
finding the string /names, and using its value as the stream index. If
this lookup fails, then cvdump would fail to load the string table.
To test this hypothesis, I looked at the name stream map generated by a
link.exe PDB, and I emitted exactly those bytes into an LLD-generated
PDB. Suddenly, cvdump could read our string table!
This code has always been hacky and we knew there was something we
didn't understand. After all, there were some comments to the effect of
"we have to emit strings in a specific order, otherwise things don't
work". The key to fixing this was finally understanding this.
The way it works is that it makes use of a generic serializable hash map
that maps integers to other integers. In this case, the "key" is the
offset into a buffer, and the value is the stream number. If you index
into the buffer at the offset specified by a given key, you find the
name. The underlying cause of all these problems is that we were using
the identity function for the hash. i.e. if a string's offset in the
buffer was 12, the hash value was 12. Instead, we need to hash the
string *at that offset*. There is an additional catch, in that we have
to compute the hash as a uint32 and then truncate it to uint16.
Making this work is a little bit annoying, because we use the same hash
table in other places as well, and normally just using the identity
function for the hash function is actually what's desired. I'm not
totally happy with the template goo I came up with, but it works in any
case.
The reason we never found this bug through our own testing is because we
were building a /parallel/ hash table (in the form of an
llvm::StringMap<>) and doing all of our lookups and "real" hash table
work against that. I deleted all of that code and now everything goes
through the real hash table. Then, to test it, I added a unit test which
adds 7 strings and queries the associated values. I test every possible
insertion order permutation of these 7 strings, to verify that it really
does work as expected.
Differential Revision: https://reviews.llvm.org/D43326
llvm-svn: 325386
Analysis of fails in the case of out of memory errors can be tricky on
Windows. Such error emerges at the point where memory allocation function
fails, but manifests itself when null pointer is used. These two points
may be distant from each other. Besides, next runs may not exhibit
allocation error.
Usual programming practice does not require checking result of 'operator
new' because it throws 'std::bad_alloc' in the case of allocation error.
However, LLVM is usually built with exceptions turned off, so 'new' can
return null pointer. This change installs custom new handler, which causes
fatal error in the case of out of memory. The handler is installed
automatically prior to call to 'main' during construction of a static
object defined in 'lib/Support/ErrorHandling.cpp'. If the application does
not use this file, the handler may be installed manually by a call to
'llvm::install_out_of_memory_new_handler', declared in
'include/llvm/Support/ErrorHandling.h".
There are calls to C allocation functions, malloc, calloc and realloc.
They are used for interoperability with C code, when allocated object has
variable size and when it is necessary to avoid call of constructors. In
many calls the result is not checked against null pointer. To simplify
checks, new functions are defined in the namespace 'llvm' with the
same names as these C function. These functions produce fatal error if
allocation fails. User should use 'llvm::malloc' instead of 'std::malloc'
in order to use the safe variant. This change replaces 'std::malloc'
in the cases when the result of allocation function is not checked against
null pointer.
Finally, there are plain C code, that uses malloc and similar functions. If
the result is not checked, assert statements are added.
Differential Revision: https://reviews.llvm.org/D43010
llvm-svn: 325224
Some ELF files produced by lld may have zero-size segment placeholders as shown
below. Since GNU_STACK Offset is 0, the current code makes it the lowest used
offset, and relocates all the segments over the ELF header. The resulting
binary is total garbage.
This change fixes how llvm-objcopy handles PT_PHDR properlly by treating ELF
headers and the program header table as segments to allow the layout algorithm
decide where those should go.
Author: vit9696
Differential Revision: https://reviews.llvm.org/D42872
llvm-svn: 325189
Summary:
TypeID summaries are used by CFI and need to be serialized by ThinLTO
indexing for later use by LTO Backend.
Reviewers: tejohnson, pcc
Subscribers: mehdi_amini, inglorion, eraman, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D42611
llvm-svn: 325182
While there, change a bunch of helper functions to take references to
avoid adding calls to get().
This should conclude the bugpoint yak shaving.
llvm-svn: 325177
The change implements constructor of DisassembleInfo to avoid duplication
of initialization code and gets rid of malloc/free where possible.
Differential Revision: https://reviews.llvm.org/D43003
llvm-svn: 325098
Summary:
This protects calls to longjmp from transferring control to arbitrary
program points. Instead, longjmp calls are limited to the set of
registered setjmp return addresses.
This also implements /guard:nolongjmp to allow users to link in object
files that call setjmp that weren't compiled with /guard:cf. In this
case, the linker will approximate the set of address taken functions,
but it will leave longjmp unprotected.
I used the following program to test, compiling it with different -guard
flags:
$ cl -c t.c -guard:cf
$ lld-link t.obj -guard:cf
#include <setjmp.h>
#include <stdio.h>
jmp_buf buf;
void g() {
printf("before longjmp\n");
fflush(stdout);
longjmp(buf, 1);
}
void f() {
if (setjmp(buf)) {
printf("setjmp returned non-zero\n");
return;
}
g();
}
int main() {
f();
printf("hello world\n");
}
In particular, the program aborts when the code is compiled *without*
-guard:cf and linked with -guard:cf. That indicates that longjmps are
protected.
Reviewers: ruiu, inglorion, amccarth
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43217
llvm-svn: 325047
If a function doesn't have an exact definition, don't apply debugify
metadata as it triggers a DIVerifier failure.
The issue is that it's invalid to have DILocations inside a DISubprogram
which isn't a definition ("scope points into the type hierarchy!").
llvm-svn: 325036
If the output file is not specified make the modifications in-place
(like binutils objcopy does). In particular, this fixes
the behavior of Clang -gsplit-dwarf (if Clang is configured to use llvm-objcopy),
previously it was creating .dwo files, but still leaving *dwo* sections in
the original binary.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D42873
llvm-svn: 324783
from the value stored in swift_version bits in the flags field in the
objc_image_info struct. ABI version 3 thru 6 were previously added but this
code was not updated to print the Swift version.
rdar://35624067
llvm-svn: 324767
Bugpoint will keep going even if the opt binary it's given doesn't
exist. It should at least alert the user, so it's clear why reductions
are failing.
llvm-svn: 324713
Handles were returned by addModule and used as keys for removeModule,
findSymbolIn, and emitAndFinalize. Their job is now subsumed by VModuleKeys,
which simplify resource management by providing a consistent handle across all
layers.
llvm-svn: 324700
Fix the comments, use early exits, use unique_ptr, and use ranged for
loops.
This is in preparation for a global *variable* reducer, which, with any
luck will help us clean up test cases.
Differential Revision: https://reviews.llvm.org/D43084
llvm-svn: 324649
When processing a dSYM bundle, use llvm::sys::path to join the different
path components instead of using a string with hard coded forward
slashes as separators.
llvm-svn: 324622
Before this patch, llvm-dwarfdump would reject `bundel.dSYM/` as input,
while `bundel.dSYM` was accepted. The reason is that `path::extension()`
returns an empty string for the former, leading to the argument not
being recognized as a dSYM bundle.
llvm-svn: 324621
This commit attempts to re-land the r324480 which was reverted in
r324493 because it broke the Windows bots. For now I disabled the two
update tests on Windows until I'm able to debug this.
Differential revision: https://reviews.llvm.org/D42880
llvm-svn: 324592
The LTO opt level should not affect the codegen opt level, and indeed
it does not affect it in lld. Ideally the codegen opt level should
be controlled by an IR-level attribute based on the compile-time opt
level, but that hasn't been implemented yet.
Differential Revision: https://reviews.llvm.org/D43040
llvm-svn: 324557
Now that dsymutil can generate accelerator tables, we can upstream the
update logic that, as the name implies, updates the accelerator tables
in an existing dSYM bundle. In combination with `-minimize` this can be
used to remove redundant .debug_(inlines|pubtypes|pubnames).
Differential revision: https://reviews.llvm.org/D42880
llvm-svn: 324480
Summary:
A recent fix to drop dead symbols (r323633) did not work for ThinLTO
distributed backends because we lose the WithGlobalValueDeadStripping
set on the index during the thin link. This patch adds a new flags
record to the bitcode format for the index, and serializes this flag
for the combined index (it would always be 0 for the per-module index
generated by the compile step, so no need to serialize the new flags
record there until/unless we add another flag that applies to the
per-module indexes).
Generally this flag should always be set for the distributed backends,
which are necessarily performed after the thin link. However, if we were
to simply set this flag on the index applied to the distributed backends
(invoked via clang), we would lose the ability to disable dead stripping
via -compute-dead=false for debugging purposes.
Reviewers: grimar, pcc
Subscribers: mehdi_amini, inglorion, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D42799
llvm-svn: 324444
In particular this patch switches RTDyldObjectLinkingLayer to use
orc::SymbolResolver and threads the requried changse (ExecutionSession
references and VModuleKeys) through the existing layer APIs.
The purpose of the new resolver interface is to improve query performance and
better support parallelism, both in JIT'd code and within the compiler itself.
The most visibile change is switch of the <Layer>::addModule signatures from:
Expected<Handle> addModule(std::shared_ptr<ModuleType> Mod,
std::shared_ptr<JITSymbolResolver> Resolver)
to:
Expected<Handle> addModule(VModuleKey K, std::shared_ptr<ModuleType> Mod);
Typical usage of addModule will now look like:
auto K = ES.allocateVModuleKey();
Resolvers[K] = createSymbolResolver(...);
Layer.addModule(K, std::move(Mod));
See the BuildingAJIT tutorial code for example usage.
llvm-svn: 324405
Summary:
This update now allows users to specify `--blame-context` and `--blame-context-all` to print source file blame information for the source of the blame.
Also updates the inline printing to correctly identify the top of the inlining stack for blame information.
Patch by Mitch Phillips!
Reviewers: vlad.tsyrklevich
Subscribers: llvm-commits, kcc, pcc
Differential Revision: https://reviews.llvm.org/D40111
llvm-svn: 324035
Summary: Existing version doesn't work on Windows as it always prints 0.00.
Reviewers: Dor1s
Reviewed By: Dor1s
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42767
llvm-svn: 323923
For now, we are not using wasm globals, except for modeling of
the stack points.
Alos, factor out common struct WasmGlobalType, which matches the
name for that tuple in the Wasm spec and rename methods
to "isBindingGlobal", "isTypeGlobal" to avoid ambiguity.
Patch by Nicholas Wilson!
Differential Revision: https://reviews.llvm.org/D42750
llvm-svn: 323901
When a the Apple link editor builds a kext bundle file type and the
value of the -miphoneos-version-min argument is significantly current
(like 11.0) then the (__TEXT,__text) section is changed to the
(__TEXT_EXEC,__text) section. So it would be nice for llvm-nm to
show symbols in that section with a type of T instead of the generic
type of S for some section other than text, data, etc.
rdar://36262205
llvm-svn: 323836
Sometimes users do not specify data layout in LLVM assembly and let llc set the
data layout by target triple after loading the LLVM assembly.
Currently the parser checks alloca address space no matter whether the LLVM
assembly contains data layout definition, which causes false alarm since the
default data layout does not contain the correct alloca address space.
The parser also calls verifier to check debug info and updating invalid debug
info. Currently there is no way to let the verifier to check debug info only.
If the verifier finds non-debug-info issues the parser will fail.
For llc, the fix is to remove the check of alloca addr space in the parser and
disable updating debug info, and defer the updating of debug info and
verification to be after setting data layout of the IR by target.
For other llvm tools, since they do not override data layout by target but
instead can override data layout by a command line option, an argument for
overriding data layout is added to the parser. In cases where data layout
overriding is necessary for the parser, the data layout can be provided by
command line.
Differential Revision: https://reviews.llvm.org/D41832
llvm-svn: 323826
Summary: ThinLTO may skip object for other reasons, e.g. if there is no summary.
Reviewers: pcc, eugenis
Subscribers: mehdi_amini, inglorion, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D42514
llvm-svn: 323818
Passing -minimize to dsymutil prevents the emission of .debug_inlines,
.debug_pubnames, and .debug_pubtypes in favor of the Apple accelerator
tables.
The actual check in the DWARF linker was added in r323655. This patch
simply enables it.
Differential revision: https://reviews.llvm.org/D42688
llvm-svn: 323812
Summary:
It was a copy-paste typo, sorting only to the 90th percentile twice.
Now, it only sorts the array prefix once, and extracts what we need.
Reviewers: dberris, kpw, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42690
llvm-svn: 323800
Introduce an extension to support passing linker options to the linker.
These would be ignored by older linkers, but newer linkers which support
this feature would be able to process the linker.
Emit a special discarded section `.linker-option`. The content of this
section is a pair of strings (key, value). The key is a type identifier for
the parameter. This allows for an argument free parameter that will be
processed by the linker with the value being the parameter. As an example,
`lib` identifies a library to be linked against, traditionally the `-l`
argument for Unix-based linkers with the parameter being the library name.
Thanks to James Henderson, Cary Coutant, Rafael Espinolda, Sean Silva
for the valuable discussion on the design of this feature.
llvm-svn: 323783
r323476 added support for DW_FORM_line_strp, and incorrectly made that
depend on having a DWARFUnit available. We shouldn't be tracking
.debug_line_str in DWARFUnit after all. After this patch, I can do an
NFC follow up and undo a bunch of the "plumbing" part of r323476.
Differential Revision: https://reviews.llvm.org/D42609
llvm-svn: 323691
This patch adds support for generating accelerator tables in dsymutil.
This feature was already present in our internal repository but not yet
upstreamed because it requires changes to the Apple accelerator table
implementation.
Differential revision: https://reviews.llvm.org/D42501
llvm-svn: 323655
Summary:
This commit renames DWARFAcceleratorTable to AppleAcceleratorTable to free up
the first name as an interface for the different accelerator tables.
Then I add a DWARFDebugNames class for the dwarf5 table.
Presently, the only common functionality of the two classes is the dump()
method, because this is the only method that was necessary to implement
dwarfdump -debug-names; and because the rest of the
AppleAcceleratorTable interface does not directly transfer to the dwarf5
tables (the main reason for that is that the present interface assumes
the tables are homogeneous, but the dwarf5 tables can have different
keys associated with each entry).
I expect to make the common interface richer as I add more functionality
to the new class (and invent a way to represent it in generic way).
In terms of sharing the implementation, I found the format of the two
tables sufficiently different to frustrate any attempts to have common
parsing or dumping code, so presently the implementations share just low
level code for formatting dwarf constants.
Reviewers: vleschuk, JDevlieghere, clayborg, aprantl, probinson, echristo, dblaikie
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42297
llvm-svn: 323638
Tests were working on my system because the old correct files were left over
and the new bug was that the output files were not being output at all.
Consequently the test work on my system but fail on any other system.
This reverts commit r323484.
llvm-svn: 323486
While writing code for input and output formats in llvm-objcopy it became
apparent that there was a code health problem. This change attempts to solve
that problem by refactoring the code to use Reader and Writer objects that can
read in different objects in different formats, convert them to a single shared
internal representation, and then write them to any other representation.
New classes:
Reader: the base class used to construct instances of the internal
representation
Writer: the base class used to write out instances of the internal
representation
ELFBuilder: a helper class for ELFWriter that takes an ELFFile and converts it
to a Object
SectionVisitor: it became necessary to remove writeSection from SectionBase
because, under the new Reader/Writer scheme, it's possible to convert between
ELF Types such as ELF32LE and ELF32BE. This isn't possible with writeSection
because it (dynamically) depends on the underlying section type *and*
(statically) depends on the ELF type. Bad things would happen if the underlying
sections for ELF32LE were used for writing to ELF64BE. To avoid this code smell
(which would have compiled, run, and output some nonsesnse) I decoupled writing
of sections from a class.
SectionWriter: This is just the ELFT templated implementation of
SectionVisitor. Many classes now have this class as a friend so that the
writing methods in this class can write out private data.
ELFWriter: This is the Writer that outputs to ELF
BinaryWriter: This is the Writer that outputs to Binary
ElfType: Because the ELF Type is not a part of the Object anymore we need a way
to construct the correct default Writer based on properties of the Reader. This
enum just keeps track of the ELF type of the input so it can be used as the
default output type as well.
Object has correspondingly undergone some serious changes as well. It now has
more generic methods for building and manipulating ELF binaries. This interface
makes ELFBuilder easy enough to use and will make the BinaryReader/Builder easy
to create as well. Most changes in this diff are cosmetic and deal with the
fact that a method has been moved from one class to another or a change from a
pointer to a reference. Almost no changes should result in a functional
difference (this is after all a refactor). One minor functional change was made
and the result can be seen in remove-shstrtab-error.test. The fact that it
fails hasn't changed but the error message has changed because that failure is
detected at a later point in the code now (because WriteSectionHeaders is a
property of the ElfWriter *not* a property of the Object). I'd say roughly
80-90% of this code is cosmetically different, 10-19% is different but
functionally the same, and 1-5% is functionally different despite not causing a
change in tests.
Differential Revision: https://reviews.llvm.org/D42222
llvm-svn: 323480
It was reverted after buildbot regressions.
Original commit message:
This allows relative block frequency of call edges to be passed
to the thinlink stage where it will be used to compute synthetic
entry counts of functions.
llvm-svn: 323460
Summary:
This allows relative block frequency of call edges to be passed to the
thinlink stage where it will be used to compute synthetic entry counts
of functions.
Reviewers: tejohnson, pcc
Subscribers: mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D42212
llvm-svn: 323349
This is needed in order to use our StringPool entries in the Apple
accelerator tables.
As this is NFC we rely on the existing tests for correctness.
llvm-svn: 323339
Combine expression patterns to form expressions with fewer, simple instructions.
This pass does not modify the CFG.
For example, this pass reduce width of expressions post-dominated by TruncInst
into smaller width when applicable.
It differs from instcombine pass in that it contains pattern optimization that
requires higher complexity than the O(1), thus, it should run fewer times than
instcombine pass.
Differential Revision: https://reviews.llvm.org/D38313
llvm-svn: 323321
Summary:
Currently, there is no way to extract a basic block from a function easily. This patch
extends llvm-extract to extract the specified basic block(s).
Reviewers: loladiro, rafael, bogner
Reviewed By: bogner
Subscribers: hintonda, mgorny, qcolombet, llvm-commits
Differential Revision: https://reviews.llvm.org/D41638
llvm-svn: 323266
Opt's "-enable-debugify" mode adds an instance of Debugify at the
beginning of the pass pipeline, and an instance of CheckDebugify at the
end.
You can enable this mode with lit using: -Dopt="opt -enable-debugify".
Note that running test suites in this mode will result in many failures
due to strict FileCheck commands, etc.
It can be more useful to look for assertion failures which arise only
when Debugify is enabled, e.g to prove that we have (or do not have)
test coverage for some code path with debug info present.
Differential Revision: https://reviews.llvm.org/D41793
llvm-svn: 323256
We were a bit too trusting about the offsets encoded in MachO compact unwind
sections, so this passes every access through a bounds check just in case. It
prevents a few segfaults on malformed object files, if one should ever come
along.
Mostly to silence fuzzers in the vague hope they might be able to produce
something useful without the noise.
llvm-svn: 323198
This applies to most pipelines except the LTO and ThinLTO backend
actions - it is for use at the beginning of the overall pipeline.
This extension point will be used to add the GCOV pass when enabled in
Clang.
llvm-svn: 323166
Summary:
First, we need to explain the core of the vulnerability. Note that this
is a very incomplete description, please see the Project Zero blog post
for details:
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html
The basis for branch target injection is to direct speculative execution
of the processor to some "gadget" of executable code by poisoning the
prediction of indirect branches with the address of that gadget. The
gadget in turn contains an operation that provides a side channel for
reading data. Most commonly, this will look like a load of secret data
followed by a branch on the loaded value and then a load of some
predictable cache line. The attacker then uses timing of the processors
cache to determine which direction the branch took *in the speculative
execution*, and in turn what one bit of the loaded value was. Due to the
nature of these timing side channels and the branch predictor on Intel
processors, this allows an attacker to leak data only accessible to
a privileged domain (like the kernel) back into an unprivileged domain.
The goal is simple: avoid generating code which contains an indirect
branch that could have its prediction poisoned by an attacker. In many
cases, the compiler can simply use directed conditional branches and
a small search tree. LLVM already has support for lowering switches in
this way and the first step of this patch is to disable jump-table
lowering of switches and introduce a pass to rewrite explicit indirectbr
sequences into a switch over integers.
However, there is no fully general alternative to indirect calls. We
introduce a new construct we call a "retpoline" to implement indirect
calls in a non-speculatable way. It can be thought of loosely as
a trampoline for indirect calls which uses the RET instruction on x86.
Further, we arrange for a specific call->ret sequence which ensures the
processor predicts the return to go to a controlled, known location. The
retpoline then "smashes" the return address pushed onto the stack by the
call with the desired target of the original indirect call. The result
is a predicted return to the next instruction after a call (which can be
used to trap speculative execution within an infinite loop) and an
actual indirect branch to an arbitrary address.
On 64-bit x86 ABIs, this is especially easily done in the compiler by
using a guaranteed scratch register to pass the target into this device.
For 32-bit ABIs there isn't a guaranteed scratch register and so several
different retpoline variants are introduced to use a scratch register if
one is available in the calling convention and to otherwise use direct
stack push/pop sequences to pass the target address.
This "retpoline" mitigation is fully described in the following blog
post: https://support.google.com/faqs/answer/7625886
We also support a target feature that disables emission of the retpoline
thunk by the compiler to allow for custom thunks if users want them.
These are particularly useful in environments like kernels that
routinely do hot-patching on boot and want to hot-patch their thunk to
different code sequences. They can write this custom thunk and use
`-mretpoline-external-thunk` *in addition* to `-mretpoline`. In this
case, on x86-64 thu thunk names must be:
```
__llvm_external_retpoline_r11
```
or on 32-bit:
```
__llvm_external_retpoline_eax
__llvm_external_retpoline_ecx
__llvm_external_retpoline_edx
__llvm_external_retpoline_push
```
And the target of the retpoline is passed in the named register, or in
the case of the `push` suffix on the top of the stack via a `pushl`
instruction.
There is one other important source of indirect branches in x86 ELF
binaries: the PLT. These patches also include support for LLD to
generate PLT entries that perform a retpoline-style indirection.
The only other indirect branches remaining that we are aware of are from
precompiled runtimes (such as crt0.o and similar). The ones we have
found are not really attackable, and so we have not focused on them
here, but eventually these runtimes should also be replicated for
retpoline-ed configurations for completeness.
For kernels or other freestanding or fully static executables, the
compiler switch `-mretpoline` is sufficient to fully mitigate this
particular attack. For dynamic executables, you must compile *all*
libraries with `-mretpoline` and additionally link the dynamic
executable and all shared libraries with LLD and pass `-z retpolineplt`
(or use similar functionality from some other linker). We strongly
recommend also using `-z now` as non-lazy binding allows the
retpoline-mitigated PLT to be substantially smaller.
When manually apply similar transformations to `-mretpoline` to the
Linux kernel we observed very small performance hits to applications
running typical workloads, and relatively minor hits (approximately 2%)
even for extremely syscall-heavy applications. This is largely due to
the small number of indirect branches that occur in performance
sensitive paths of the kernel.
When using these patches on statically linked applications, especially
C++ applications, you should expect to see a much more dramatic
performance hit. For microbenchmarks that are switch, indirect-, or
virtual-call heavy we have seen overheads ranging from 10% to 50%.
However, real-world workloads exhibit substantially lower performance
impact. Notably, techniques such as PGO and ThinLTO dramatically reduce
the impact of hot indirect calls (by speculatively promoting them to
direct calls) and allow optimized search trees to be used to lower
switches. If you need to deploy these techniques in C++ applications, we
*strongly* recommend that you ensure all hot call targets are statically
linked (avoiding PLT indirection) and use both PGO and ThinLTO. Well
tuned servers using all of these techniques saw 5% - 10% overhead from
the use of retpoline.
We will add detailed documentation covering these components in
subsequent patches, but wanted to make the core functionality available
as soon as possible. Happy for more code review, but we'd really like to
get these patches landed and backported ASAP for obvious reasons. We're
planning to backport this to both 6.0 and 5.0 release streams and get
a 5.0 release with just this cherry picked ASAP for distros and vendors.
This patch is the work of a number of people over the past month: Eric, Reid,
Rui, and myself. I'm mailing it out as a single commit due to the time
sensitive nature of landing this and the need to backport it. Huge thanks to
everyone who helped out here, and everyone at Intel who helped out in
discussions about how to craft this. Also, credit goes to Paul Turner (at
Google, but not an LLVM contributor) for much of the underlying retpoline
design.
Reviewers: echristo, rnk, ruiu, craig.topper, DavidKreitzer
Subscribers: sanjoy, emaste, mcrosier, mgorny, mehdi_amini, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D41723
llvm-svn: 323155
For sections with different virtual and physical addresses, alignment and
placement in the output binary should be based on the physical address.
Ran into this problem with a bare metal ARM project where llvm-objcopy added a
lot of zero-padding before the .data section that had differing addresses. GNU
objcopy did not add the padding, and after this fix, neither does llvm-objcopy.
Update a test case so a section has different physical and virtual addresses.
Fixes B35708
Authored By: Owen Shaw (owenpshaw)
Differential Revision: https://reviews.llvm.org/D41619
llvm-svn: 323144
This frees up the first name to be used as an base class for the
apple table and the dwarf5 .debug_names accel table. The rename was
split off from D42297 (adding of debug_names support), which is still
under review.
llvm-svn: 323113
Summary:
Rename LLVM_CONFIG_EXE to LLVM_CONFIG_PATH, and avoid building it if
passed in by user. This is the same way CLANG_TABLEGEN and
LLVM_TABLEGEN are handled, e.g., when -DLLVM_OPTIMIZED_TABLEGEN=ON is
passed.
Differential Revision: https://reviews.llvm.org/D41806
llvm-svn: 323053
ExternalSymbolMap now stores the string key (rather than using a StringRef),
as the object file backing the key may be removed at any time.
llvm-svn: 323001
Bulk queries reduce IPC/RPC overhead for cross-process JITing and expose
opportunities for parallel compilation.
The two new query methods are lookupFlags, which finds the flags for each of a
set of symbols; and lookup, which finds the address and flags for each of a
set of symbols. (See doxygen comments for more details.)
The existing JITSymbolResolver class is renamed LegacyJITSymbolResolver, and
modified to extend the new JITSymbolResolver class using the following scheme:
- lookupFlags is implemented by calling findSymbolInLogicalDylib for each of the
symbols, then returning the result of calling getFlags() on each of these
symbols. (Importantly: lookupFlags does NOT call getAddress on the returned
symbols, so lookupFlags will never trigger materialization, and lookupFlags will
never call findSymbol, so only symbols that are part of the logical dylib will
return results.)
- lookup is implemented by calling findSymbolInLogicalDylib for each symbol and
falling back to findSymbol if findSymbolInLogicalDylib returns a null result.
Assuming a symbol is found its getAddress method is called to materialize it and
the result (if getAddress succeeds) is stored in the result map, or the error
(if getAddress fails) is returned immediately from lookup. If any symbol is not
found then lookup returns immediately with an error.
This change will break any out-of-tree derivatives of JITSymbolResolver. This
can be fixed by updating those classes to derive from LegacyJITSymbolResolver
instead.
llvm-svn: 322913
Get rid of DEBUG_FUNCTION_NAME symbols. When we actually debug
data, maybe we'll want somewhere to put it... but having a symbol
that just stores the name of another symbol seems odd.
It means you have multiple Symbols with the same name, one
containing the actual function and another containing the name!
Store the names in a vector on the WasmObjectFile when reading
them in. Also stash them on the WasmFunctions themselves.
The names are //not// "symbol names" or aliases or anything,
they're just the name that a debugger should show against the
function body itself. NB. The WasmObjectFile stores them so that
they can be exported in the YAML losslessly, and hence the tests
can be precise.
Enforce that the CODE section has been read in before reading
the "names" section. Requires minor adjustment to some tests.
Patch by Nicholas Wilson!
Differential Revision: https://reviews.llvm.org/D42075
llvm-svn: 322741
Summary:
- Fix a bug in PrettyBuiltinDumper that returns "void" as the name for
an unspecified builtin type. Since the unspecified param of a variadic
function is considered a builtin of unspecified type in PDBs, we set
"..." for its name.
- Provide a method to determine if a PDBSymbolFunc is variadic in
PrettyFunctionDumper since PDBSymbolFunc::getArgument() doesn't return the
last unspecified-type param.
- Add a pretty-func-dumper.test to test pretty dumping of variadic
functions.
Reviewers: zturner, llvm-commits
Reviewed By: zturner
Differential Revision: https://reviews.llvm.org/D41801
llvm-svn: 322608
Summary:
This speeds up export "summary-only" execution by an order of magnitude or two,
depending on number of threads used for prepareFileReports execution.
Also includes minor refactoring for splitting render of summary and detailed data
in two independent methods.
Reviewers: vsk, morehouse
Reviewed By: vsk
Subscribers: llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D42000
llvm-svn: 322397
There were a few places where outs() was being used
directly rather than the ScopedPrinter object.
Differential Revision: https://reviews.llvm.org/D41370
llvm-svn: 322141
These indexes are useful because they are not always zero based and
functions and globals are referenced elsewhere by their index.
This matches what we already do for the type index space.
Differential Revision: https://reviews.llvm.org/D41877
llvm-svn: 322121
llc, opt, and clang can all autodetect the CPU and supported features. lli cannot as far as I could tell.
This patch uses the getCPUStr() and introduces a new getCPUFeatureList() and uses those in lli in place of MCPU and MAttrs.
Ideally, we would merge getCPUFeatureList and getCPUFeatureStr, but opt and llc need a string and lli wanted a list. Maybe we should just return the SubtargetFeature object and let the caller decide what it needs?
Differential Revision: https://reviews.llvm.org/D41833
llvm-svn: 322100
This change adds support in llvm-objcopy for GNU objcopy's --localize-hidden
option. This option changes every hidden or internal symbol into a local symbol.
llvm-svn: 321884
This is not a record type that clang currently generates,
but it is a record that is encountered in object files generated
by cl. This record is unusual in that it refers directly to
the string table instead of indirectly to the string table via
the FileChecksums table. Because of this, it was previously
overlooked and we weren't remapping the string indices at all.
This would lead to crashes in MSVC when trying to display a
variable whose debug info involved an S_FILESTATIC.
Original bug report by Alexander Ganea
Differential Revision: https://reviews.llvm.org/D41718
llvm-svn: 321883
Summary:
Add a method `OptTable::findNearest`, which allows users of OptTable to
check user input for misspelled options. In addition, have llvm-mt
check for misspelled options. For example, if a user invokes
`llvm-mt /oyt:foo`, the error message will indicate that while an
option named `/oyt:` does not exist, `/out:` does.
The method ports the functionality of the `LookupNearestOption` method
from LLVM CommandLine to libLLVMOption. This allows tools like Clang
and Swift, which do not use CommandLine, to use this functionality to
suggest similarly spelled options.
As room for future improvement, the new method as-is cannot yet properly suggest
nearby "joined" options -- that is, for an option string "-FozBar", where
"-Foo" is the correct option name and "Bar" is the value being passed along
with the misspelled option, this method will calculate an edit distance of 4,
by deleting "Bar" and changing "z" to "o". It should instead calculate an edit
distance of just 1, by changing "z" to "o" and recognizing "Bar" as a
value. This commit includes a disabled test that expresses this limitation.
Test Plan: `check-llvm`
Reviewers: yamaguchi, v.g.vassilev, teemperor, ruiu, jroelofs
Reviewed By: jroelofs
Subscribers: jroelofs, llvm-commits
Differential Revision: https://reviews.llvm.org/D41732
llvm-svn: 321877
Summary:
Local testing has demonstrated a great speed improvement, compare the following:
1) Existing version:
```
$ time llvm-cov show -format=html -output-dir=report -instr-profile=... ...
The tool has been launched: 00:00:00
Loading coverage data: 00:00:00
Get unique source files: 00:00:33
Creating an index out of the source files: 00:00:34
Going into prepareFileReports: 00:00:34
Going to emit summary information for each file: 00:28:55 <-- 28:21 min!
Going to emit links to files with no function: 00:28:55
Launching 32 threads for generating HTML files: 00:28:55
real 37m43.651s
user 112m5.540s
sys 7m39.872s
```
2) Multi-threaded version with 32 CPUs:
```
$ time llvm-cov show -format=html -output-dir=report -instr-profile=... ...
The tool has been launched: 00:00:00
Loading coverage data: 00:00:00
Get unique source files: 00:00:38
Creating an index out of the source files: 00:00:40
Going into prepareFileReports: 00:00:40
Preparing file reports using 32 threads: 00:00:40
# Creating thread tasks for the following number of files: 16422
Going to emit summary information for each file: 00:01:57 <-- 1:17 min!
Going to emit links to files with no function: 00:01:58
Launching 32 threads for generating HTML files: 00:01:58
real 11m2.044s
user 134m48.124s
sys 7m53.388s
```
Reviewers: vsk, morehouse
Reviewed By: vsk
Subscribers: Dor1s, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D41206
llvm-svn: 321871
Currently it's not possible to access MCSubtargetInfo from a TgtMCAsmBackend.
D20830 threaded an MCSubtargetInfo reference through
MCAsmBackend::relaxInstruction, but this isn't the only function that would
benefit from access. This patch removes the Triple and CPUString arguments
from createMCAsmBackend and replaces them with MCSubtargetInfo.
This patch just changes the interface without making any intentional
functional changes. Once in, several cleanups are possible:
* Get rid of the awkward MCSubtargetInfo handling in ARMAsmBackend
* Support 16-bit instructions when valid in MipsAsmBackend::writeNopData
* Get rid of the CPU string parsing in X86AsmBackend and just use a SubtargetFeature for HasNopl
* Emit 16-bit nops in RISCVAsmBackend::writeNopData if the compressed instruction set extension is enabled (see D41221)
This change initially exposed PR35686, which has since been resolved in r321026.
Differential Revision: https://reviews.llvm.org/D41349
llvm-svn: 321692
I have no clue how this was missed when symbol table support was added. This
change ensures that the visibility of symbols is preserved by default.
llvm-svn: 321681
This patch replaces a block of logic that was implemented using
CoreFoundations calls with functionally equivalent logic that makes use
of LLVM libraries.
llvm-svn: 321522
This change adds `printMipsGOT` and `printMipsPLT` methods to the
`DumpStyle` class and overrides them in the `GNUStyle` and `LLVMStyle`
descendants. To pass information about GOT/PLT layout into these
methods, the `MipsGOTParser` class has been extended to hold all
necessary data.
llvm-svn: 321253
borked by: rL284966 (see: https://reviews.llvm.org/D25730).
Previously, Interval was unsigned (see: CachePruning.h), replacing the type with std::chrono::seconds (which is signed) causes a regression in behaviour because the c-api intends negative values to translate to large positive intervals to *effectively* disable the pruning (see comments on: setCachePruningInterval()).
Differential Revision: https://reviews.llvm.org/D41231
llvm-svn: 321077
Before this patch, dwarfdump's lookup parameter only accepts unsigned.
Given that for many current platforms the load address already exceeds
unsigned (e.g. arm64 w/ 0x100000000), dwarfdump needs an unsigned long
long parameter.
Patch by: Dr. Michael 'Mickey' Lauer <mickey@vanille-media.de>
llvm-svn: 321064
This change adds support for adding progbits sections with contents from a file
Differential Revision: https://reviews.llvm.org/D41212
llvm-svn: 321047
LLVM IR function names which disable mangling start with '\01'
(https://www.llvm.org/docs/LangRef.html#identifiers).
When an identifier like "\01@abc@" gets dumped to MIR, it is quoted, but
only with single quotes.
http://www.yaml.org/spec/1.2/spec.html#id2770814:
"The allowed character range explicitly excludes the C0 control block
allowed), the surrogate block #xD800-#xDFFF, #xFFFE, and #xFFFF."
http://www.yaml.org/spec/1.2/spec.html#id2776092:
"All non-printable characters must be escaped.
[...]
Note that escape sequences are only interpreted in double-quoted scalars."
This patch adds support for printing escaped non-printable characters
between double quotes if needed.
Should also fix PR31743.
Differential Revision: https://reviews.llvm.org/D41290
llvm-svn: 320996
Overtime some non-clang formatted code has creeped into llvm-objcopy. This
patch fixes all of that.
Differential Revision: https://reviews.llvm.org/D41262
llvm-svn: 320856
Summary:
llvm-objdump's Mach-O parser was updated in r306037 to display external
relocations for MH_KEXT_BUNDLE file types. This change extends the Macho-O
parser to display local relocations for MH_PRELOAD files. When used with
the -macho option relocations will be displayed in a historical format.
All tests are passing for llvm, clang, and lld. llvm-objdump builds without
compiler warnings.
rdar://35778019
Reviewers: enderby
Reviewed By: enderby
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D41199
llvm-svn: 320832
This is a special code that indicates that it's a function id.
While I'm still not certain how to interpret these, we definitely
should *not* be using these values as indices into an array directly.
For now, when we encounter one of these, just print the numeric value.
llvm-svn: 320775
This is a Swift feature. The output stream for the index page and the source
HTML page is utf-8 now.
The next patch will add the HTML magic to properly render these characters in
the browser.
llvm-svn: 320725
Teresa Johnson