path: root/lib/Analysis/NaCl/PNaClABIVerifyModule.cpp

//===- PNaClABIVerifyModule.cpp - Verify PNaCl ABI rules --------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Verify module-level PNaCl ABI requirements (specifically those that do not
// require looking at the function bodies)
//
//
//===----------------------------------------------------------------------===//

#include "llvm/Pass.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/NaCl.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

#include "PNaClABITypeChecker.h"
using namespace llvm;

namespace llvm {
cl::opt<bool>
PNaClABIAllowDebugMetadata("pnaclabi-allow-debug-metadata",
  cl::desc("Allow debug metadata during PNaCl ABI verification."),
  cl::init(false));

}

static cl::opt<bool>
PNaClABIAllowDevIntrinsics("pnaclabi-allow-dev-intrinsics",
  cl::desc("Allow all LLVM intrinsics during PNaCl ABI verification."),
  cl::init(true));  // TODO(jvoung): Make this false by default.

namespace {
// This pass should not touch function bodies, to stay streaming-friendly
class PNaClABIVerifyModule : public ModulePass {
 public:
  static char ID;
  PNaClABIVerifyModule() :
      ModulePass(ID),
      Reporter(new PNaClABIErrorReporter),
      ReporterIsOwned(true) {
    initializePNaClABIVerifyModulePass(*PassRegistry::getPassRegistry());
  }
  explicit PNaClABIVerifyModule(PNaClABIErrorReporter *Reporter_) :
      ModulePass(ID),
      Reporter(Reporter_),
      ReporterIsOwned(false) {
    initializePNaClABIVerifyModulePass(*PassRegistry::getPassRegistry());
  }
  ~PNaClABIVerifyModule() {
    if (ReporterIsOwned)
      delete Reporter;
  }
  bool runOnModule(Module &M);
  virtual void print(raw_ostream &O, const Module *M) const;
 private:
  void CheckGlobalValueCommon(const GlobalValue *GV);
  bool IsWhitelistedIntrinsic(const Function* F, unsigned ID);
  bool IsWhitelistedMetadata(const NamedMDNode *MD);
  PNaClABITypeChecker TC;
  PNaClABIErrorReporter *Reporter;
  bool ReporterIsOwned;
};

static const char *linkageName(GlobalValue::LinkageTypes LT) {
  // This logic is taken from PrintLinkage in lib/VMCore/AsmWriter.cpp
  switch (LT) {
    case GlobalValue::ExternalLinkage: return "external";
    case GlobalValue::PrivateLinkage:       return "private ";
    case GlobalValue::LinkerPrivateLinkage: return "linker_private ";
    case GlobalValue::LinkerPrivateWeakLinkage: return "linker_private_weak ";
    case GlobalValue::InternalLinkage:      return "internal ";
    case GlobalValue::LinkOnceAnyLinkage:   return "linkonce ";
    case GlobalValue::LinkOnceODRLinkage:   return "linkonce_odr ";
    case GlobalValue::LinkOnceODRAutoHideLinkage:
      return "linkonce_odr_auto_hide ";
    case GlobalValue::WeakAnyLinkage:       return "weak ";
    case GlobalValue::WeakODRLinkage:       return "weak_odr ";
    case GlobalValue::CommonLinkage:        return "common ";
    case GlobalValue::AppendingLinkage:     return "appending ";
    case GlobalValue::DLLImportLinkage:     return "dllimport ";
    case GlobalValue::DLLExportLinkage:     return "dllexport ";
    case GlobalValue::ExternalWeakLinkage:  return "extern_weak ";
    case GlobalValue::AvailableExternallyLinkage:
      return "available_externally ";
    default:
      return "unknown";
  }
}

} // end anonymous namespace

// Check linkage type and section attributes, which are the same for
// GlobalVariables and Functions.
void PNaClABIVerifyModule::CheckGlobalValueCommon(const GlobalValue *GV) {
  assert(!isa<GlobalAlias>(GV));
  const char *GVTypeName = isa<GlobalVariable>(GV) ?
      "Variable " : "Function ";
  switch (GV->getLinkage()) {
    // TODO(dschuff): Disallow external linkage
    case GlobalValue::ExternalLinkage:
    case GlobalValue::AvailableExternallyLinkage:
    case GlobalValue::InternalLinkage:
    case GlobalValue::PrivateLinkage:
      break;
    default:
      Reporter->addError() << GVTypeName << GV->getName()
                           << " has disallowed linkage type: "
                           << linkageName(GV->getLinkage()) << "\n";
  }
  if (GV->hasSection()) {
    Reporter->addError() << GVTypeName << GV->getName() <<
        " has disallowed \"section\" attribute\n";
  }
}

bool PNaClABIVerifyModule::IsWhitelistedIntrinsic(const Function* F,
                                                  unsigned ID) {
  // Keep 3 categories of intrinsics for now.
  // (1) Allowed always
  // (2) Never allowed
  // (3) "Dev" intrinsics, which may or may not be allowed.
  // "Dev" intrinsics are controlled by the PNaClABIAllowDevIntrinsics flag.
  // Please keep these sorted within each category.
  switch(ID) {
    // Disallow by default.
    default: return false;
    // (1) Always allowed.
    case Intrinsic::invariant_end:
    case Intrinsic::invariant_start:
    case Intrinsic::lifetime_end:
    case Intrinsic::lifetime_start:
    case Intrinsic::memcpy:
    case Intrinsic::memmove:
    case Intrinsic::memset:
    case Intrinsic::nacl_read_tp:
    case Intrinsic::trap:
      return true;

    // (2) Known to be never allowed.
    case Intrinsic::not_intrinsic:
    case Intrinsic::adjust_trampoline:
    case Intrinsic::init_trampoline:
    case Intrinsic::stackprotector:
    case Intrinsic::vacopy:
    case Intrinsic::vaend:
    case Intrinsic::vastart:
      return false;

    // (3) Dev intrinsics.
    case Intrinsic::dbg_declare:
    case Intrinsic::dbg_value:
      return PNaClABIAllowDevIntrinsics || PNaClABIAllowDebugMetadata;
    case Intrinsic::bswap: // Support via compiler_rt if arch doesn't have it?
    case Intrinsic::cos: // Rounding not defined: support with fast-math?
    case Intrinsic::ctlz: // Support via compiler_rt if arch doesn't have it?
    case Intrinsic::ctpop: // Support via compiler_rt if arch doesn't have it?
    case Intrinsic::cttz: // Support via compiler_rt if arch doesn't have it?
    case Intrinsic::eh_dwarf_cfa: // For EH tests.
    case Intrinsic::exp: // Rounding not defined: support with fast-math?
    case Intrinsic::exp2: // Rounding not defined: support with fast-math?
    case Intrinsic::expect: // From __builtin_expect.
    case Intrinsic::flt_rounds:
    case Intrinsic::frameaddress: // Support for 0-level or not?
    case Intrinsic::log: // Rounding not defined: support with fast-math?
    case Intrinsic::log2: // Rounding not defined: support with fast-math?
    case Intrinsic::log10: // Rounding not defined: support with fast-math?
    case Intrinsic::nacl_target_arch: // Used by translator self-build.
    case Intrinsic::pow: // Rounding is supposed to be the same as libm.
    case Intrinsic::powi: // Rounding not defined: support with fast-math?
    case Intrinsic::prefetch: // Could ignore if target doesn't support?
    case Intrinsic::returnaddress: // Support for 0-level or not?
    case Intrinsic::sin: // Rounding not defined: support with fast-math?
    case Intrinsic::sqrt:
    case Intrinsic::stackrestore: // Used to support C99 VLAs.
    case Intrinsic::stacksave:
    // the *_with_overflow return struct types, so we'll need to fix these.
    case Intrinsic::sadd_with_overflow: // Introduced by -ftrapv
    case Intrinsic::ssub_with_overflow:
    case Intrinsic::uadd_with_overflow:
    case Intrinsic::usub_with_overflow:
    case Intrinsic::smul_with_overflow:
    case Intrinsic::umul_with_overflow: // Introduced by c++ new[x * y].
      return PNaClABIAllowDevIntrinsics;
  }
}

bool PNaClABIVerifyModule::IsWhitelistedMetadata(const NamedMDNode* MD) {
  return MD->getName().startswith("llvm.dbg.") && PNaClABIAllowDebugMetadata;
}

bool PNaClABIVerifyModule::runOnModule(Module &M) {
  for (Module::const_global_iterator MI = M.global_begin(), ME = M.global_end();
       MI != ME; ++MI) {
    // Check types of global variables and their initializers
    if (!TC.isValidType(MI->getType())) {
      // GVs are pointers, so print the pointed-to type for clarity
      Reporter->addError() << "Variable " << MI->getName() <<
          " has disallowed type: " <<
          PNaClABITypeChecker::getTypeName(MI->getType()->getContainedType(0))
          + "\n";
    } else if (MI->hasInitializer()) {
      // If the type of the global is bad, no point in checking its initializer
      Type *T = TC.checkTypesInConstant(MI->getInitializer());
      if (T) {
        Reporter->addError() << "Initializer for " << MI->getName() <<
            " has disallowed type: " <<
            PNaClABITypeChecker::getTypeName(T) << "\n";
      }
    }

    CheckGlobalValueCommon(MI);

    if (MI->isThreadLocal()) {
      Reporter->addError() << "Variable " << MI->getName() <<
          " has disallowed \"thread_local\" attribute\n";
    }
  }

  // No aliases allowed for now.
  for (Module::alias_iterator MI = M.alias_begin(),
           E = M.alias_end(); MI != E; ++MI) {
    Reporter->addError() << "Variable " << MI->getName() <<
        " is an alias (disallowed)\n";
  }

  for (Module::const_iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI) {
    // Check intrinsics.
    if (MI-