/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "instruction_set_features_arm.h"
#if defined(HAVE_ANDROID_OS) && defined(__arm__)
#include <sys/auxv.h>
#include <asm/hwcap.h>
#endif
#include "signal.h"
#include <fstream>
#include "base/stringprintf.h"
#include "utils.h" // For Trim.
#if defined(__arm__)
extern "C" bool artCheckForArmSdivInstruction();
#endif
namespace art {
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromVariant(
const std::string& variant, std::string* error_msg) {
// Assume all ARM processors are SMP.
// TODO: set the SMP support based on variant.
const bool smp = true;
// Look for variants that have divide support.
static const char* arm_variants_with_div[] = {
"cortex-a7", "cortex-a12", "cortex-a15", "cortex-a17", "cortex-a53", "cortex-a57",
"cortex-m3", "cortex-m4", "cortex-r4", "cortex-r5",
"cyclone", "denver", "krait", "swift"};
bool has_div = FindVariantInArray(arm_variants_with_div, arraysize(arm_variants_with_div),
variant);
// Look for variants that have LPAE support.
static const char* arm_variants_with_lpae[] = {
"cortex-a7", "cortex-a15", "krait", "denver"
};
bool has_lpae = FindVariantInArray(arm_variants_with_lpae, arraysize(arm_variants_with_lpae),
variant);
if (has_div == false && has_lpae == false) {
// Avoid unsupported variants.
static const char* unsupported_arm_variants[] = {
// ARM processors that aren't ARMv7 compatible aren't supported.
"arm2", "arm250", "arm3", "arm6", "arm60", "arm600", "arm610", "arm620",
"cortex-m0", "cortex-m0plus", "cortex-m1",
"fa526", "fa626", "fa606te", "fa626te", "fmp626", "fa726te",
"iwmmxt", "iwmmxt2",
"strongarm", "strongarm110", "strongarm1100", "strongarm1110",
"xscale"
};
if (FindVariantInArray(unsupported_arm_variants, arraysize(unsupported_arm_variants),
variant)) {
*error_msg = StringPrintf("Attempt to use unsupported ARM variant: %s", variant.c_str());
return nullptr;
}
// Warn if the variant is unknown.
// TODO: some of the variants below may have feature support, but that support is currently
// unknown so we'll choose conservative (sub-optimal) defaults without warning.
// TODO: some of the architectures may not support all features required by ART and should be
// moved to unsupported_arm_variants[] above.
static const char* arm_variants_without_known_features[] = {
"default",
"arm7", "arm7m", "arm7d", "arm7dm", "arm7di", "arm7dmi", "arm70", "arm700", "arm700i",
"arm710", "arm710c", "arm7100", "arm720", "arm7500", "arm7500fe", "arm7tdmi", "arm7tdmi-s",
"arm710t", "arm720t", "arm740t",
"arm8", "arm810",
"arm9", "arm9e", "arm920", "arm920t", "arm922t", "arm946e-s", "arm966e-s", "arm968e-s",
"arm926ej-s", "arm940t", "arm9tdmi",
"arm10tdmi", "arm1020t", "arm1026ej-s", "arm10e", "arm1020e", "arm1022e",
"arm1136j-s", "arm1136jf-s",
"arm1156t2-s", "arm1156t2f-s", "arm1176jz-s", "arm1176jzf-s",
"cortex-a5", "cortex-a8", "cortex-a9", "cortex-a9-mp", "cortex-r4f",
"marvell-pj4", "mpcore", "mpcorenovfp"
};
if (!FindVariantInArray(arm_variants_without_known_features,
arraysize(arm_variants_without_known_features),
variant)) {
LOG(WARNING) << "Unknown instruction set features for ARM CPU variant (" << variant
<< ") using conservative defaults";
}
}
return new ArmInstructionSetFeatures(smp, has_div, has_lpae);
}
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromBitmap(uint32_t bitmap) {
bool smp = (bitmap & kSmpBitfield) != 0;
bool has_div = (bitmap & kDivBitfield) != 0;
bool has_atomic_ldrd_strd = (bitmap & kAtomicLdrdStrdBitfield) != 0;
return new ArmInstructionSetFeatures(smp, has_div, has_atomic_ldrd_strd);
}
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromCppDefines() {
const bool smp = true;
#if defined(__ARM_ARCH_EXT_IDIV__)
const bool has_div = true;
#else
const bool has_div = false;
#endif
#if defined(__ARM_FEATURE_LPAE)
const bool has_lpae = true;
#else
const bool has_lpae = false;
#endif
return new ArmInstructionSetFeatures(smp, has_div, has_lpae);
}
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromCpuInfo() {
// Look in /proc/cpuinfo for features we need. Only use this when we can guarantee that
// the kernel puts the appropriate feature flags in here. Sometimes it doesn't.
bool smp = false;
bool has_lpae = false;
bool has_div = false;
std::ifstream in("/proc/cpuinfo");
if (!in.fail()) {
while (!in.eof()) {
std::string line;
std::getline(in, line);
if (!in.eof()) {
LOG(INFO) << "cpuinfo line: " << line;
if (line.find("Features") != std::string::npos) {
LOG(INFO) << "found features";
if (line.find("idivt") != std::string::npos) {
// We always expect both ARM and Thumb divide instructions to be available or not
// available.
CHECK_NE(line.find("idiva"), std::string::npos);
has_div = true;
}
if (line.find("lpae") != std::string::npos) {
has_lpae = true;
}
} else if (line.find("processor") != std::string::npos &&
line.find(": 1") != std::string::npos) {
smp = true;
}
}
}
in.close();
} else {
LOG(ERROR) << "Failed to open /proc/cpuinfo";
}
return new ArmInstructionSetFeatures(smp, has_div, has_lpae);
}
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromHwcap() {
bool smp = sysconf(_SC_NPROCESSORS_CONF) > 1;
bool has_div = false;
bool has_lpae = false;
#if defined(HAVE_ANDROID_OS) && defined(__arm__)
uint64_t hwcaps = getauxval(AT_HWCAP);
LOG(INFO) << "hwcaps=" << hwcaps;
if ((hwcaps & HWCAP_IDIVT) != 0) {
// We always expect both ARM and Thumb divide instructions to be available or not
// available.
CHECK_NE(hwcaps & HWCAP_IDIVA, 0U);
has_div = true;
}
if ((hwcaps & HWCAP_LPAE) != 0) {
has_lpae = true;
}
#endif
return new ArmInstructionSetFeatures(smp, has_div, has_lpae);
}
// A signal handler called by a fault for an illegal instruction. We record the fact in r0
// and then increment the PC in the signal context to return to the next instruction. We know the
// instruction is an sdiv (4 bytes long).
static void bad_divide_inst_handle(int signo ATTRIBUTE_UNUSED, siginfo_t* si ATTRIBUTE_UNUSED,
void* data) {
#if defined(__arm__)
struct ucontext *uc = (struct ucontext *)data;
struct sigcontext *sc = &uc->uc_mcontext;
sc->arm_r0 = 0; // Set R0 to #0 to signal error.
sc->arm_pc += 4; // Skip offending instruction.
#else
UNUSED(data);
#endif
}
const ArmInstructionSetFeatures* ArmInstructionSetFeatures::FromAssembly() {
const bool smp = true;
// See if have a sdiv instruction. Register a signal handler and try to execute an sdiv
// instruction. If we get a SIGILL then it's not supported.
struct sigaction sa, osa;
sa.sa_flags = SA_ONSTACK | SA_RESTART | SA_SIGINFO;
sa.sa_sigaction = bad_divide_inst_handle;
sigaction(SIGILL, &sa, &osa);
bool has_div = false;
#if defined(__arm__)
if (artCheckForArmSdivInstruction()) {
has_div = true;
}
#endif
// Restore the signal handler.
sigaction(SIGILL, &osa, nullptr);
// Use compile time features to "detect" LPAE support.
// TODO: write an assembly LPAE support test.
#if defined(__ARM_FEATURE_LPAE)
const bool has_lpae = true;
#else
const bool has_lpae = false;
#endif
return new ArmInstructionSetFeatures(smp, has_div, has_lpae);
}
bool ArmInstructionSetFeatures::Equals(const InstructionSetFeatures* other) const {
if (kArm != other->GetInstructionSet()) {
return false;
}
const ArmInstructionSetFeatures* other_as_arm = other->AsArmInstructionSetFeatures();
return IsSmp() == other_as_arm->IsSmp() &&
has_div_ == other_as_arm->has_div_ &&
has_atomic_ldrd_strd_ == other_as_arm->has_atomic_ldrd_strd_;
}
uint32_t ArmInstructionSetFeatures::AsBitmap() const {
return (IsSmp() ? kSmpBitfield : 0) |
(has_div_ ? kDivBitfield : 0) |
(has_atomic_ldrd_strd_ ? kAtomicLdrdStrdBitfield : 0);
}
std::string ArmInstructionSetFeatures::GetFeatureString() const {
std::string result;
if (IsSmp()) {
result += "smp";
} else {
result += "-smp";
}
if (has_div_) {
result += ",div";
} else {
result += ",-div";
}
if (has_atomic_ldrd_strd_) {
result += ",atomic_ldrd_strd";
} else {
result += ",-atomic_ldrd_strd";
}
return result;
}
const InstructionSetFeatures* ArmInstructionSetFeatures::AddFeaturesFromSplitString(
const bool smp, const std::vector<std::string>& features, std::string* error_msg) const {
bool has_atomic_ldrd_strd = has_atomic_ldrd_strd_;
bool has_div = has_div_;
for (auto i = features.begin(); i != features.end(); i++) {
std::string feature = Trim(*i);
if (feature == "div") {
has_div = true;
} else if (feature == "-div") {
has_div = false;
} else if (feature == "atomic_ldrd_strd") {
has_atomic_ldrd_strd = true;
} else if (feature == "-atomic_ldrd_strd") {
has_atomic_ldrd_strd = false;
} else {
*error_msg = StringPrintf("Unknown instruction set feature: '%s'", feature.c_str());
return nullptr;
}
}
return new ArmInstructionSetFeatures(smp, has_div, has_atomic_ldrd_strd);
}
} // namespace art