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//===-- xray_init.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.
//
// XRay initialisation logic.
//===----------------------------------------------------------------------===//
#include <fcntl.h>
#include <strings.h>
#include <unistd.h>
#include "sanitizer_common/sanitizer_common.h"
#include "xray_defs.h"
#include "xray_flags.h"
#include "xray_interface_internal.h"
extern "C" {
void __xray_init();
extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
extern const XRayFunctionSledIndex __start_xray_fn_idx[] __attribute__((weak));
extern const XRayFunctionSledIndex __stop_xray_fn_idx[] __attribute__((weak));
}
using namespace __xray;
// When set to 'true' this means the XRay runtime has been initialised. We use
// the weak symbols defined above (__start_xray_inst_map and
// __stop_xray_instr_map) to initialise the instrumentation map that XRay uses
// for runtime patching/unpatching of instrumentation points.
//
// FIXME: Support DSO instrumentation maps too. The current solution only works
// for statically linked executables.
__sanitizer::atomic_uint8_t XRayInitialized{0};
// This should always be updated before XRayInitialized is updated.
__sanitizer::SpinMutex XRayInstrMapMutex;
XRaySledMap XRayInstrMap;
// Global flag to determine whether the flags have been initialized.
__sanitizer::atomic_uint8_t XRayFlagsInitialized{0};
// A mutex to allow only one thread to initialize the XRay data structures.
__sanitizer::SpinMutex XRayInitMutex;
// __xray_init() will do the actual loading of the current process' memory map
// and then proceed to look for the .xray_instr_map section/segment.
void __xray_init() XRAY_NEVER_INSTRUMENT {
__sanitizer::SpinMutexLock Guard(&XRayInitMutex);
// Short-circuit if we've already initialized XRay before.
if (__sanitizer::atomic_load(&XRayInitialized,
__sanitizer::memory_order_acquire))
return;
if (!__sanitizer::atomic_load(&XRayFlagsInitialized,
__sanitizer::memory_order_acquire)) {
initializeFlags();
__sanitizer::atomic_store(&XRayFlagsInitialized, true,
__sanitizer::memory_order_release);
}
if (__start_xray_instr_map == nullptr) {
if (Verbosity())
Report("XRay instrumentation map missing. Not initializing XRay.\n");
return;
}
{
__sanitizer::SpinMutexLock Guard(&XRayInstrMapMutex);
XRayInstrMap.Sleds = __start_xray_instr_map;
XRayInstrMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
XRayInstrMap.SledsIndex = __start_xray_fn_idx;
XRayInstrMap.Functions = __stop_xray_fn_idx - __start_xray_fn_idx;
}
__sanitizer::atomic_store(&XRayInitialized, true,
__sanitizer::memory_order_release);
#ifndef XRAY_NO_PREINIT
if (flags()->patch_premain)
__xray_patch();
#endif
}
#if !defined(XRAY_NO_PREINIT) && SANITIZER_CAN_USE_PREINIT_ARRAY
// Only add the preinit array initialization if the sanitizers can.
__attribute__((section(".preinit_array"),
used)) void (*__local_xray_preinit)(void) = __xray_init;
#else
// If we cannot use the .preinit_array section, we should instead use dynamic
// initialisation.
static bool UNUSED __local_xray_dyninit = [] {
__xray_init();
return true;
}();
#endif
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