66443d80f1
Summary: Use TSC emulation in cases where RDTSCP isn't available on the host running an XRay instrumented binary. We can then fall back into emulation instead of not even installing XRay's runtime functionality. We only do this for now in the naive/basic logging implementation, but should be useful in even FDR mode. Should fix http://llvm.org/PR32148. Reviewers: pelikan, rnk, sdardis Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D30677 llvm-svn: 297800
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
//===-- xray_tsc.h ----------------------------------------------*- 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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//===----------------------------------------------------------------------===//
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#ifndef XRAY_EMULATE_TSC_H
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#define XRAY_EMULATE_TSC_H
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namespace __xray {
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static constexpr uint64_t NanosecondsPerSecond = 1000ULL * 1000 * 1000;
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}
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#if defined(__x86_64__)
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#include "xray_x86_64.inc"
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#elif defined(__powerpc64__)
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#include "xray_powerpc64.inc"
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#elif defined(__arm__) || defined(__aarch64__) || defined(__mips__)
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// Emulated TSC.
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// There is no instruction like RDTSCP in user mode on ARM. ARM's CP15 does
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// not have a constant frequency like TSC on x86(_64), it may go faster
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// or slower depending on CPU turbo or power saving mode. Furthermore,
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// to read from CP15 on ARM a kernel modification or a driver is needed.
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// We can not require this from users of compiler-rt.
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// So on ARM we use clock_gettime() which gives the result in nanoseconds.
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// To get the measurements per second, we scale this by the number of
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// nanoseconds per second, pretending that the TSC frequency is 1GHz and
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// one TSC tick is 1 nanosecond.
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#include "sanitizer_common/sanitizer_common.h"
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#include "sanitizer_common/sanitizer_internal_defs.h"
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#include "xray_defs.h"
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#include <cerrno>
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#include <cstdint>
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#include <time.h>
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namespace __xray {
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inline bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
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ALWAYS_INLINE uint64_t readTSC(uint8_t &CPU) XRAY_NEVER_INSTRUMENT {
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timespec TS;
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int result = clock_gettime(CLOCK_REALTIME, &TS);
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if (result != 0) {
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Report("clock_gettime(2) returned %d, errno=%d.", result, int(errno));
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TS.tv_sec = 0;
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TS.tv_nsec = 0;
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}
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CPU = 0;
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return TS.tv_sec * NanosecondsPerSecond + TS.tv_nsec;
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}
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inline uint64_t getTSCFrequency() XRAY_NEVER_INSTRUMENT {
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return NanosecondsPerSecond;
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}
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} // namespace __xray
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#else
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#error Target architecture is not supported.
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#endif // CPU architecture
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#endif // XRAY_EMULATE_TSC_H
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