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//===-- xray_utils.cc -------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of XRay, a dynamic runtime instrumentation system.
//
//===----------------------------------------------------------------------===//
#include "xray_utils.h"
#include "sanitizer_common/sanitizer_common.h"
#include "xray_defs.h"
#include "xray_flags.h"
#include <cstdio>
#include <fcntl.h>
#include <iterator>
#include <sys/types.h>
#include <tuple>
#include <unistd.h>
#include <utility>
#if defined(__x86_64__)
#include "xray_x86_64.h"
#elif defined(__arm__) || defined(__aarch64__)
#include "xray_emulate_tsc.h"
#else
#error "Unsupported CPU Architecture"
#endif /* CPU architecture */
namespace __xray {
void PrintToStdErr(const char *Buffer) XRAY_NEVER_INSTRUMENT {
fprintf(stderr, "%s", Buffer);
}
void retryingWriteAll(int Fd, char *Begin, char *End) XRAY_NEVER_INSTRUMENT {
if (Begin == End)
return;
auto TotalBytes = std::distance(Begin, End);
while (auto Written = write(Fd, Begin, TotalBytes)) {
if (Written < 0) {
if (errno == EINTR)
continue; // Try again.
Report("Failed to write; errno = %d\n", errno);
return;
}
TotalBytes -= Written;
if (TotalBytes == 0)
break;
Begin += Written;
}
}
std::pair<ssize_t, bool> retryingReadSome(int Fd, char *Begin,
char *End) XRAY_NEVER_INSTRUMENT {
auto BytesToRead = std::distance(Begin, End);
ssize_t BytesRead;
ssize_t TotalBytesRead = 0;
while (BytesToRead && (BytesRead = read(Fd, Begin, BytesToRead))) {
if (BytesRead == -1) {
if (errno == EINTR)
continue;
Report("Read error; errno = %d\n", errno);
return std::make_pair(TotalBytesRead, false);
}
TotalBytesRead += BytesRead;
BytesToRead -= BytesRead;
Begin += BytesRead;
}
return std::make_pair(TotalBytesRead, true);
}
bool readValueFromFile(const char *Filename,
long long *Value) XRAY_NEVER_INSTRUMENT {
int Fd = open(Filename, O_RDONLY | O_CLOEXEC);
if (Fd == -1)
return false;
static constexpr size_t BufSize = 256;
char Line[BufSize] = {};
ssize_t BytesRead;
bool Success;
std::tie(BytesRead, Success) = retryingReadSome(Fd, Line, Line + BufSize);
if (!Success)
return false;
close(Fd);
char *End = nullptr;
long long Tmp = internal_simple_strtoll(Line, &End, 10);
bool Result = false;
if (Line[0] != '\0' && (*End == '\n' || *End == '\0')) {
*Value = Tmp;
Result = true;
}
return Result;
}
long long getCPUFrequency() XRAY_NEVER_INSTRUMENT {
// Get the cycle frequency from SysFS on Linux.
long long CPUFrequency = -1;
#if defined(__x86_64__)
if (readValueFromFile("/sys/devices/system/cpu/cpu0/tsc_freq_khz",
&CPUFrequency)) {
CPUFrequency *= 1000;
} else if (readValueFromFile(
"/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq",
&CPUFrequency)) {
CPUFrequency *= 1000;
} else {
Report("Unable to determine CPU frequency for TSC accounting.\n");
}
#elif defined(__arm__) || defined(__aarch64__)
// There is no instruction like RDTSCP in user mode on ARM. ARM's CP15 does
// not have a constant frequency like TSC on x86(_64), it may go faster
// or slower depending on CPU turbo or power saving mode. Furthermore,
// to read from CP15 on ARM a kernel modification or a driver is needed.
// We can not require this from users of compiler-rt.
// So on ARM we use clock_gettime() which gives the result in nanoseconds.
// To get the measurements per second, we scale this by the number of
// nanoseconds per second, pretending that the TSC frequency is 1GHz and
// one TSC tick is 1 nanosecond.
CPUFrequency = NanosecondsPerSecond;
#else
#error "Unsupported CPU Architecture"
#endif /* CPU architecture */
return CPUFrequency;
}
int getLogFD() XRAY_NEVER_INSTRUMENT {
// FIXME: Figure out how to make this less stderr-dependent.
SetPrintfAndReportCallback(PrintToStdErr);
// Open a temporary file once for the log.
static char TmpFilename[256] = {};
static char TmpWildcardPattern[] = "XXXXXX";
auto Argv = GetArgv();
const char *Progname = Argv[0] == nullptr ? "(unknown)" : Argv[0];
const char *LastSlash = internal_strrchr(Progname, '/');
if (LastSlash != nullptr)
Progname = LastSlash + 1;
const int HalfLength = sizeof(TmpFilename) / 2 - sizeof(TmpWildcardPattern);
int NeededLength = internal_snprintf(
TmpFilename, sizeof(TmpFilename), "%.*s%.*s.%s", HalfLength,
flags()->xray_logfile_base, HalfLength, Progname, TmpWildcardPattern);
if (NeededLength > int(sizeof(TmpFilename))) {
Report("XRay log file name too long (%d): %s\n", NeededLength, TmpFilename);
return -1;
}
int Fd = mkstemp(TmpFilename);
if (Fd == -1) {
Report("XRay: Failed opening temporary file '%s'; not logging events.\n",
TmpFilename);
return -1;
}
if (Verbosity())
fprintf(stderr, "XRay: Log file in '%s'\n", TmpFilename);
return Fd;
}
} // namespace __xray
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