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//===- bolt/RuntimeLibs/HugifyRuntimeLibrary.cpp - Hugify RT Library ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the HugifyRuntimeLibrary class.
//
//===----------------------------------------------------------------------===//
#include "bolt/RuntimeLibs/HugifyRuntimeLibrary.h"
#include "bolt/Core/BinaryFunction.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
using namespace bolt;
namespace opts {
extern cl::OptionCategory BoltOptCategory;
extern cl::opt<bool> HotText;
cl::opt<bool>
Hugify("hugify",
cl::desc("Automatically put hot code on 2MB page(s) (hugify) at "
"runtime. No manual call to hugify is needed in the binary "
"(which is what --hot-text relies on)."),
cl::ZeroOrMore, cl::cat(BoltOptCategory));
static cl::opt<std::string> RuntimeHugifyLib(
"runtime-hugify-lib",
cl::desc("specify file name of the runtime hugify library"), cl::ZeroOrMore,
cl::init("libbolt_rt_hugify.a"), cl::cat(BoltOptCategory));
} // namespace opts
void HugifyRuntimeLibrary::adjustCommandLineOptions(
const BinaryContext &BC) const {
if (opts::HotText) {
errs()
<< "BOLT-ERROR: -hot-text should be applied to binaries with "
"pre-compiled manual hugify support, while -hugify will add hugify "
"support automatcally. These two options cannot both be present.\n";
exit(1);
}
// After the check, we set HotText to be true because automated hugify support
// relies on it.
opts::HotText = true;
if (!BC.StartFunctionAddress) {
errs() << "BOLT-ERROR: hugify runtime libraries require a known entry "
"point of "
"the input binary\n";
exit(1);
}
}
void HugifyRuntimeLibrary::emitBinary(BinaryContext &BC, MCStreamer &Streamer) {
const BinaryFunction *StartFunction =
BC.getBinaryFunctionAtAddress(*(BC.StartFunctionAddress));
assert(!StartFunction->isFragment() && "expected main function fragment");
if (!StartFunction) {
errs() << "BOLT-ERROR: failed to locate function at binary start address\n";
exit(1);
}
const auto Flags = BinarySection::getFlags(/*IsReadOnly=*/false,
/*IsText=*/false,
/*IsAllocatable=*/true);
MCSectionELF *Section =
BC.Ctx->getELFSection(".bolt.hugify.entries", ELF::SHT_PROGBITS, Flags);
// __bolt_hugify_init_ptr stores the poiter the hugify library needs to
// jump to after finishing the init code.
MCSymbol *InitPtr = BC.Ctx->getOrCreateSymbol("__bolt_hugify_init_ptr");
Section->setAlignment(llvm::Align(BC.RegularPageSize));
Streamer.SwitchSection(Section);
Streamer.emitLabel(InitPtr);
Streamer.emitSymbolAttribute(InitPtr, MCSymbolAttr::MCSA_Global);
Streamer.emitValue(
MCSymbolRefExpr::create(StartFunction->getSymbol(), *(BC.Ctx)),
/*Size=*/8);
}
void HugifyRuntimeLibrary::link(BinaryContext &BC, StringRef ToolPath,
RuntimeDyld &RTDyld,
std::function<void(RuntimeDyld &)> OnLoad) {
std::string LibPath = getLibPath(ToolPath, opts::RuntimeHugifyLib);
loadLibrary(LibPath, RTDyld);
OnLoad(RTDyld);
RTDyld.finalizeWithMemoryManagerLocking();
if (RTDyld.hasError()) {
outs() << "BOLT-ERROR: RTDyld failed: " << RTDyld.getErrorString() << "\n";
exit(1);
}
assert(!RuntimeStartAddress &&
"We don't currently support linking multiple runtime libraries");
RuntimeStartAddress = RTDyld.getSymbol("__bolt_hugify_self").getAddress();
if (!RuntimeStartAddress) {
errs() << "BOLT-ERROR: instrumentation library does not define "
"__bolt_hugify_self: "
<< LibPath << "\n";
exit(1);
}
}
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