This fixes remaining issues in my previous PR #90959.
Changes:
- Removed dependency on LLVM header in `xray_interface.cpp`
- Fixed XRay patching for some targets due to missing changes in
architecture-specific patching functions
- Addressed some remaining compiler warnings that I missed in the
previous patch
- Formatting
I have tested these changes on `x86_64` (natively), as well as
`ppc64le`, `aarch64` and `arm32` (cross-compiled and emulated using
qemu).
**Original description:**
This PR introduces shared library (DSO) support for XRay based on a
revised version of the implementation outlined in [this
RFC](https://discourse.llvm.org/t/rfc-upstreaming-dso-instrumentation-support-for-xray/73000).
The feature enables the patching and handling of events from DSOs,
supporting both libraries linked at startup or explicitly loaded, e.g.
via `dlopen`.
This patch adds the following:
- The `-fxray-shared` flag to enable the feature (turned off by default)
- A small runtime library that is linked into every instrumented DSO,
providing position-independent trampolines and code to register with the
main XRay runtime
- Changes to the XRay runtime to support management and patching of
multiple objects
These changes are fully backward compatible, i.e. running without
instrumented DSOs will produce identical traces (in terms of recorded
function IDs) to the previous implementation.
Due to my limited ability to test on other architectures, this feature
is only implemented and tested with x86_64. Extending support to other
architectures is fairly straightforward, requiring only a
position-independent implementation of the architecture-specific
trampoline implementation (see
`compiler-rt/lib/xray/xray_trampoline_x86_64.S` for reference).
This patch does not include any functionality to resolve function IDs
from DSOs for the provided logging/tracing modes. These modes still work
and will record calls from DSOs, but symbol resolution for these
functions in not available. Getting this to work properly requires
recording information about the loaded DSOs and should IMO be discussed
in a separate RFC, as there are mulitple feasible approaches.
---------
Co-authored-by: Sebastian Kreutzer <sebastian.kreutzer@tu-darmstadt.de>
Removes a dependency on LLVM in `xray_interface.cpp` by replacing
`llvm_unreachable` with compiler-rt's `UNREACHABLE`.
Applies clang-format to some unformatted changes.
Original PR: #90959
This PR introduces shared library (DSO) support for XRay based on a
revised version of the implementation outlined in [this
RFC](https://discourse.llvm.org/t/rfc-upstreaming-dso-instrumentation-support-for-xray/73000).
The feature enables the patching and handling of events from DSOs,
supporting both libraries linked at startup or explicitly loaded, e.g.
via `dlopen`.
This patch adds the following:
- The `-fxray-shared` flag to enable the feature (turned off by default)
- A small runtime library that is linked into every instrumented DSO,
providing position-independent trampolines and code to register with the
main XRay runtime
- Changes to the XRay runtime to support management and patching of
multiple objects
These changes are fully backward compatible, i.e. running without
instrumented DSOs will produce identical traces (in terms of recorded
function IDs) to the previous implementation.
Due to my limited ability to test on other architectures, this feature
is only implemented and tested with x86_64. Extending support to other
architectures is fairly straightforward, requiring only a
position-independent implementation of the architecture-specific
trampoline implementation (see
`compiler-rt/lib/xray/xray_trampoline_x86_64.S` for reference).
This patch does not include any functionality to resolve function IDs
from DSOs for the provided logging/tracing modes. These modes still work
and will record calls from DSOs, but symbol resolution for these
functions in not available. Getting this to work properly requires
recording information about the loaded DSOs and should IMO be discussed
in a separate RFC, as there are mulitple feasible approaches.
@petrhosek @jplehr
The Clang built-in function is void __xray_typedevent(size_t, const void *, size_t),
but the LLVM intrinsics has smaller integer types. Since we only allow
64-bit ELF/Mach-O targets, we can change llvm.xray.typedevent to
i64/ptr/i64.
This allows encoding more information and avoids i16 legalization for
many non-X86 targets.
fdrLoggingHandleTypedEvent only supports uint16_t event type.
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
Compiler-rt support first before defining the __xray_typedevent() lowering in
llvm. I'm looking for some early feedback before I touch much more code.
Reviewers: dberris
Subscribers: delcypher, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D43668
llvm-svn: 330218
Summary:
Define a build-time configuration option for the XRay runtime to
determine whether the archive will add an entry to the `.preinit_array`
section of the binary. We also allow for initializing the XRay data
structures with an explicit call to __xray_init(). This allows us to
give users the capability to initialize the XRay data structures on
demand.
This can allow us to start porting XRay to platforms where
`.preinit_array` isn't a supported section. It also allows us to limit
the effects of XRay in the initialization sequence for applications that
are sensitive to this kind of interference (i.e. large binaries) or
those that want to package XRay control in libraries.
Future changes should allow us to build two different library archives
for the XRay runtime, and allow clang users to determine which version
to link.
Reviewers: dblaikie, kpw, pelikan
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D36080
llvm-svn: 309909
Summary:
This change implements support for the custom event logging sleds and
intrinsics at runtime. For now it only supports handling the sleds in
x86_64, with the implementations for other architectures stubbed out to
do nothing.
NOTE: Work in progress, uploaded for exposition/exploration purposes.
Depends on D27503, D30018, and D33032.
Reviewers: echristo, javed.absar, timshen
Subscribers: mehdi_amini, nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D30630
llvm-svn: 302857
Summary:
This change allows us to provide users and implementers of XRay handlers
a means of converting XRay function id's to addresses. This, in
combination with the facilities provided in D32695, allows users to find
out:
- How many function id's there are defined in the current binary.
- Get the address of the function associated with this function id.
- Patch only specific functions according to their requirements.
While we don't directly provide symbolization support in XRay, having
the function's address lets users determine this information easily
either during runtime, or offline with tools like 'addr2line'.
Reviewers: dblaikie, echristo, pelikan
Subscribers: kpw, llvm-commits
Differential Revision: https://reviews.llvm.org/D32846
llvm-svn: 302210
Summary:
This change allows us to patch/unpatch specific functions using the
function ID. This is useful in cases where implementations might want to
do coverage-style, or more fine-grained control of which functions to
patch or un-patch at runtime.
Depends on D32693.
Reviewers: dblaikie, echristo, kpw
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32695
llvm-svn: 302112
Summary:
Functions with the LOG_ARGS_ENTRY sled kind at their beginning will be handled
in a way to (optionally) pass their first call argument to your logging handler.
For practical and performance reasons, only the first argument is supported, and
only up to 64 bits.
Reviewers: javed.absar, dberris
Reviewed By: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29703
llvm-svn: 297000
Summary:
This change depends on D23986 which adds tail call-specific sleds. For
now we treat them first as normal exits, and in the future leave room
for implementing this as a different kind of log entry.
The reason for deferring the change is so that we can keep the naive
logging implementation more accurate without additional complexity for
reading the log. The accuracy is gained in effectively interpreting call
stacks like:
A()
B()
C()
Which when tail-call merged will end up not having any exit entries for
A() nor B(), but effectively in turn can be reasoned about as:
A()
B()
C()
Although we lose the fact that A() had called B() then had called C()
with the naive approach, a later iteration that adds the explicit tail
call entries would be a change in the log format and thus necessitate a
version change for the header. We can do this later to have a chance at
releasing some tools (in D21987) that are able to handle the naive log
format, then support higher version numbers of the log format too.
Reviewers: echristo, kcc, rSerge, majnemer
Subscribers: mehdi_amini, llvm-commits, dberris
Differential Revision: https://reviews.llvm.org/D23988
llvm-svn: 284178
This addresses some comments from D21612, which contains the following changes:
- Update __xray_patch() and __xray_unpatch() API documentation to not imply asynchrony.
- Introduce a scope cleanup mechanism to make sure we can roll-back changes to the XRayPatching global atomic.
- Introduce a few more comments for potential extension points for other platforms (for the implementation details of patching and un-patching).
Reviewers: eugenis, rnk, kcc, echristo, majnemer
Subscribers: llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D22911
llvm-svn: 277124
Summary:
This is a fixed-up version of D21612, to address failure identified post-commit.
Original commit description:
This patch implements the initialisation and patching routines for the XRay runtime, along with the necessary trampolines for function entry/exit handling. For now we only define the basic hooks for allowing an implementation to define a handler that gets run on function entry/exit. We expose a minimal API for controlling the behaviour of the runtime (patching, cleanup, and setting the handler to invoke when instrumenting).
Fixes include:
- Gating XRay build to only Linux x86_64 and with the right dependencies in case it is the only library being built
- Including <cstddef> to fix std::size_t issue
Reviewers: kcc, rnk, echristo
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D22611
llvm-svn: 276251
and also the follow-up "[xray] Only build xray on Linux for now"
Two build errors were reported on the llvm-commits list:
[ 88%] Building CXX object lib/xray/CMakeFiles/clang_rt.xray-x86_64.dir/xray_flags.cc.o
/mnt/b/sanitizer-buildbot1/sanitizer-x86_64-linux/build/llvm/projects/compiler-rt/lib/xray/xray_init.cc:23:10: fatal error: 'llvm/Support/ELF.h' file not found
#include "llvm/Support/ELF.h"
^
and
In file included from /w/src/llvm.org/projects/compiler-rt/lib/xray/xray_interface.cc:16:
/w/src/llvm.org/projects/compiler-rt/lib/xray/xray_interface_internal.h:36:8: error:
no type named 'size_t' in namespace 'std'
std::size_t Entries;
~~~~~^
llvm-svn: 276186
Summary:
This patch implements the initialisation and patching routines for the XRay runtime, along with the necessary trampolines for function entry/exit handling. For now we only define the basic hooks for allowing an implementation to define a handler that gets run on function entry/exit. We expose a minimal API for controlling the behaviour of the runtime (patching, cleanup, and setting the handler to invoke when instrumenting).
Depends on D19904
Reviewers: echristo, kcc, rnk
Subscribers: rnk, mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D21612
llvm-svn: 276117
