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4031e4b95d
Summary: Adds a CMake check for whether the compiler used to build the XRay library supports XRay-instrumentation. If the compiler we're using does support the `-fxray-instrument` flag (i.e. recently-built Clang), we define the XRAY_NEVER_INSTRUMENT macro that then makes sure that the XRay runtime functions never get XRay-instrumented. This prevents potential weirdness involved with building the XRay library with a Clang that supports XRay-instrumentation, and is attempting to XRay-instrument the build of compiler-rt. Reviewers: majnemer, rSerge, echristo Subscribers: mehdi_amini, llvm-commits, mgorny Differential Revision: https://reviews.llvm.org/D26597 llvm-svn: 287068
71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
//===-- xray_init.cc --------------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of XRay, a dynamic runtime instrumentation system.
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//
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// XRay initialisation logic.
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//===----------------------------------------------------------------------===//
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#include <atomic>
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#include <fcntl.h>
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#include <strings.h>
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#include <unistd.h>
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#include "sanitizer_common/sanitizer_common.h"
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#include "xray_defs.h"
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#include "xray_flags.h"
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#include "xray_interface_internal.h"
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extern "C" {
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void __xray_init();
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extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
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extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
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}
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using namespace __sanitizer;
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using namespace __xray;
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// When set to 'true' this means the XRay runtime has been initialised. We use
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// the weak symbols defined above (__start_xray_inst_map and
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// __stop_xray_instr_map) to initialise the instrumentation map that XRay uses
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// for runtime patching/unpatching of instrumentation points.
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//
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// FIXME: Support DSO instrumentation maps too. The current solution only works
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// for statically linked executables.
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std::atomic<bool> XRayInitialized{false};
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// This should always be updated before XRayInitialized is updated.
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std::atomic<__xray::XRaySledMap> XRayInstrMap{};
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// __xray_init() will do the actual loading of the current process' memory map
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// and then proceed to look for the .xray_instr_map section/segment.
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void __xray_init() XRAY_NEVER_INSTRUMENT {
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InitializeFlags();
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if (__start_xray_instr_map == nullptr) {
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Report("XRay instrumentation map missing. Not initializing XRay.\n");
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return;
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}
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// Now initialize the XRayInstrMap global struct with the address of the
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// entries, reinterpreted as an array of XRaySledEntry objects. We use the
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// virtual pointer we have from the section to provide us the correct
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// information.
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__xray::XRaySledMap SledMap{};
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SledMap.Sleds = __start_xray_instr_map;
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SledMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
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XRayInstrMap.store(SledMap, std::memory_order_release);
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XRayInitialized.store(true, std::memory_order_release);
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if (flags()->patch_premain)
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__xray_patch();
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}
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__attribute__((section(".preinit_array"),
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used)) void (*__local_xray_preinit)(void) = __xray_init;
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