/*
* Copyright 2011-2012, 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.
*/
#ifndef ELF_OBJECT_HXX
#define ELF_OBJECT_HXX
#include "ELFHeader.h"
#include "ELFReloc.h"
#include "ELFSection.h"
#include "ELFSectionHeaderTable.h"
#include "StubLayout.h"
#include "GOT.h"
#include "ELF.h"
#include <llvm/ADT/SmallVector.h>
#include "utils/rsl_assert.h"
template <unsigned Bitwidth>
template <typename Archiver>
inline ELFObject<Bitwidth> *
ELFObject<Bitwidth>::read(Archiver &AR) {
llvm::OwningPtr<ELFObjectTy> object(new ELFObjectTy());
// Read header
object->header.reset(ELFHeaderTy::read(AR));
if (!object->header) {
return 0;
}
// Read section table
object->shtab.reset(ELFSectionHeaderTableTy::read(AR, object.get()));
if (!object->shtab) {
return 0;
}
// Read each section
llvm::SmallVector<size_t, 4> progbits_ndx;
for (size_t i = 0; i < object->header->getSectionHeaderNum(); ++i) {
if ((*object->shtab)[i]->getType() == SHT_PROGBITS) {
object->stab.push_back(NULL);
progbits_ndx.push_back(i);
} else {
llvm::OwningPtr<ELFSectionTy> sec(
ELFSectionTy::read(AR, object.get(), (*object->shtab)[i]));
object->stab.push_back(sec.take());
}
}
object->shtab->buildNameMap();
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(object->getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
symtab->buildNameMap();
for (size_t i = 0; i < progbits_ndx.size(); ++i) {
size_t index = progbits_ndx[i];
llvm::OwningPtr<ELFSectionTy> sec(
ELFSectionTy::read(AR, object.get(), (*object->shtab)[index]));
object->stab[index] = sec.take();
}
return object.take();
}
template <unsigned Bitwidth>
inline char const *ELFObject<Bitwidth>::getSectionName(size_t i) const {
ELFSectionTy const *sec = stab[header->getStringSectionIndex()];
if (sec) {
ELFSectionStrTabTy const &st =
static_cast<ELFSectionStrTabTy const &>(*sec);
return st[i];
}
return NULL;
}
template <unsigned Bitwidth>
inline ELFSection<Bitwidth> const *
ELFObject<Bitwidth>::getSectionByIndex(size_t i) const {
return stab[i];
}
template <unsigned Bitwidth>
inline ELFSection<Bitwidth> *
ELFObject<Bitwidth>::getSectionByIndex(size_t i) {
return stab[i];
}
template <unsigned Bitwidth>
inline ELFSection<Bitwidth> const *
ELFObject<Bitwidth>::getSectionByName(std::string const &str) const {
size_t idx = getSectionHeaderTable()->getByName(str)->getIndex();
return stab[idx];
}
template <unsigned Bitwidth>
inline ELFSection<Bitwidth> *
ELFObject<Bitwidth>::getSectionByName(std::string const &str) {
ELFObjectTy const *const_this = this;
ELFSectionTy const *sptr = const_this->getSectionByName(str);
// Const cast for the same API's const and non-const versions.
return const_cast<ELFSectionTy *>(sptr);
}
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::
relocateARM(void *(*find_sym)(void *context, char const *name),
void *context,
ELFSectionRelTableTy *reltab,
ELFSectionProgBitsTy *text) {
// FIXME: Should be implement in independent files.
rsl_assert(Bitwidth == 32 && "ARM only have 32 bits.");
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
for (size_t i = 0; i < reltab->size(); ++i) {
// FIXME: Can not implement here, use Fixup!
ELFRelocTy *rel = (*reltab)[i];
ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
// FIXME: May be not uint32_t *.
typedef int32_t Inst_t;
Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
Inst_t P = (Inst_t)(int64_t)inst;
Inst_t A = 0;
Inst_t S = (Inst_t)(int64_t)sym->getAddress(EM_ARM);
Inst_t T = 0;
if (sym->isConcreteFunc() && (sym->getValue() & 0x1)) {
T = 1;
}
word_t reltype = rel->getType();
switch (reltype) {
default:
rsl_assert(0 && "Not implemented relocation type.");
break;
case R_ARM_ABS32:
{
if (S == 0 && sym->getType() == STT_NOTYPE) {
void *ext_sym = find_sym(context, sym->getName());
if (!ext_sym) {
missingSymbols = true;
}
S = (Inst_t)(uintptr_t)ext_sym;
sym->setAddress(ext_sym);
}
A = *inst;
*inst = (S + A) | T;
}
break;
// FIXME: Predefine relocation codes.
case R_ARM_CALL:
case R_ARM_THM_CALL:
case R_ARM_JUMP24:
case R_ARM_THM_JUMP24:
{
#define SIGN_EXTEND(x, l) (((x)^(1<<((l)-1)))-(1<<(l-1)))
if (reltype == R_ARM_CALL || reltype == R_ARM_JUMP24) {
A = (Inst_t)(int64_t)SIGN_EXTEND(*inst & 0xFFFFFF, 24);
A <<= 2;
} else {
// Hack for two 16bit.
*inst = ((*inst >> 16) & 0xFFFF) | (*inst << 16);
Inst_t s = (*inst >> 26) & 0x1u, // 26
u = (*inst >> 16) & 0x3FFu, // 25-16
l = *inst & 0x7FFu, // 10-0
j1 = (*inst >> 13) & 0x1u, // 13
j2 = (*inst >> 11) & 0x1u; // 11
Inst_t i1 = (~(j1 ^ s)) & 0x1u,
i2 = (~(j2 ^ s)) & 0x1u;
// [31-25][24][23][22][21-12][11-1][0]
// 0 s i1 i2 u l 0
A = SIGN_EXTEND((s << 23) | (i1 << 22) | (i2 << 21) | (u << 11) | l, 24);
A <<= 1;
}
#undef SIGN_EXTEND
void *callee_addr = sym->getAddress(EM_ARM);
switch (sym->getType()) {
default:
rsl_assert(0 && "Wrong type for R_ARM_CALL relocation.");
abort();
break;
case STT_FUNC:
// NOTE: Callee function is in the object file, but it may be
// in different PROGBITS section (which may be far call).
if (callee_addr == 0) {
rsl_assert(0 && "We should get function address at previous "
"sym->getAddress(EM_ARM) function call.");
abort();
}
break;
case STT_NOTYPE:
// NOTE: Callee function is an external function. Call find_sym
// if it has not resolved yet.
if (callee_addr == 0) {
callee_addr = find_sym(context, sym->getName());
if (!callee_addr) {
missingSymbols = true;
}
sym->setAddress(callee_addr);
}
break;
}
// Get the stub for this function
StubLayout *stub_layout = text->getStubLayout();
if (!stub_layout) {
llvm::errs() << "unable to get stub layout." << "\n";
abort();
}
void *stub = stub_layout->allocateStub(callee_addr);
if (!stub) {
llvm::errs() << "unable to allocate stub." << "\n";
abort();
}
//LOGI("Function %s: using stub %p\n", sym->getName(), stub);
S = (uint32_t)(uintptr_t)stub;
if (reltype == R_ARM_CALL || reltype == R_ARM_JUMP24) {
// Relocate the R_ARM_CALL relocation type
uint32_t result = (S + A - P) >> 2;
if (result > 0x007FFFFF && result < 0xFF800000) {
rsl_assert(0 && "Stub is still too far");
abort();
}
*inst = ((result) & 0x00FFFFFF) | (*inst & 0xFF000000);
} else {
P &= ~0x3; // Base address align to 4 bytes. (For BLX.)
// Relocate the R_ARM_THM_CALL relocation type
uint32_t result = (S + A - P) >> 1;
if (result > 0x007FFFFF && result < 0xFF800000) {
rsl_assert(0 && "Stub is still too far");
abort();
}
//*inst &= 0xF800D000u;
// Rewrite instruction to BLX. (Stub is always ARM.)
*inst &= 0xF800C000u;
// [31-25][24][23][22][21-12][11-1][0]
// 0 s i1 i2 u l 0
Inst_t s = (result >> 23) & 0x1u, // 26
u = (result >> 11) & 0x3FFu, // 25-16
// For BLX, bit [0] is 0.
l = result & 0x7FEu, // 10-0
i1 = (result >> 22) & 0x1u,
i2 = (result >> 21) & 0x1u;
Inst_t j1 = ((~i1) ^ s) & 0x01u, // 13
j2 = ((~i2) ^ s) & 0x01u; // 11
*inst |= s << 26;
*inst |= u << 16;
*inst |= l;
*inst |= j1 << 13;
*inst |= j2 << 11;
// Hack for two 16bit.
*inst = ((*inst >> 16) & 0xFFFF) | (*inst << 16);
}
}
break;
case R_ARM_MOVT_ABS:
case R_ARM_MOVW_ABS_NC:
case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
{
if (S == 0 && sym->getType() == STT_NOTYPE) {
void *ext_sym = find_sym(context, sym->getName());
if (!ext_sym) {
missingSymbols = true;
}
S = (Inst_t)(uintptr_t)ext_sym;
sym->setAddress(ext_sym);
}
if (reltype == R_ARM_MOVT_ABS
|| reltype == R_ARM_THM_MOVT_ABS) {
S >>= 16;
}
if (reltype == R_ARM_MOVT_ABS
|| reltype == R_ARM_MOVW_ABS_NC) {
// No need sign extend.
A = ((*inst & 0xF0000) >> 4) | (*inst & 0xFFF);
uint32_t result = (S + A);
*inst = (((result) & 0xF000) << 4) |
((result) & 0xFFF) |
(*inst & 0xFFF0F000);
} else {
// Hack for two 16bit.
*inst = ((*inst >> 16) & 0xFFFF) | (*inst << 16);
// imm16: [19-16][26][14-12][7-0]
A = (((*inst >> 4) & 0xF000u) |
((*inst >> 15) & 0x0800u) |
((*inst >> 4) & 0x0700u) |
( *inst & 0x00FFu));
uint32_t result;
if (reltype == R_ARM_THM_MOVT_ABS) {
result = (S + A);
} else {
result = (S + A) | T;
}
// imm16: [19-16][26][14-12][7-0]
*inst &= 0xFBF08F00u;
*inst |= (result & 0xF000u) << 4;
*inst |= (result & 0x0800u) << 15;
*inst |= (result & 0x0700u) << 4;
*inst |= (result & 0x00FFu);
// Hack for two 16bit.
*inst = ((*inst >> 16) & 0xFFFF) | (*inst << 16);
}
}
break;
}
//llvm::errs() << "S: " << (void *)S << '\n';
//llvm::errs() << "A: " << (void *)A << '\n';
//llvm::errs() << "P: " << (void *)P << '\n';
//llvm::errs() << "S+A: " << (void *)(S+A) << '\n';
//llvm::errs() << "S+A-P: " << (void *)(S+A-P) << '\n';
}
}
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::
relocateX86_64(void *(*find_sym)(void *context, char const *name),
void *context,
ELFSectionRelTableTy *reltab,
ELFSectionProgBitsTy *text) {
rsl_assert(Bitwidth == 64 && "Only support X86_64.");
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
for (size_t i = 0; i < reltab->size(); ++i) {
// FIXME: Can not implement here, use Fixup!
ELFRelocTy *rel = (*reltab)[i];
ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
//typedef uint64_t Inst_t;
typedef int32_t Inst_t;
Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
Inst_t P = (Inst_t)(int64_t)inst;
Inst_t A = (Inst_t)(int64_t)rel->getAddend();
Inst_t S = (Inst_t)(int64_t)sym->getAddress(EM_X86_64);
if (S == 0) {
S = (Inst_t)(int64_t)find_sym(context, sym->getName());
if (!S) {
missingSymbols = true;
}
sym->setAddress((void *)S);
}
switch (rel->getType()) {
default:
rsl_assert(0 && "Not implemented relocation type.");
break;
// FIXME: XXX: R_X86_64_64 is 64 bit, there is a big problem here.
case 1: // R_X86_64_64
*inst = (S+A);
break;
case 2: // R_X86_64_PC32
*inst = (S+A-P);
break;
case 10: // R_X86_64_32
case 11: // R_X86_64_32S
*inst = (S+A);
break;
}
}
}
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::
relocateX86_32(void *(*find_sym)(void *context, char const *name),
void *context,
ELFSectionRelTableTy *reltab,
ELFSectionProgBitsTy *text) {
rsl_assert(Bitwidth == 32 && "Only support X86.");
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
for (size_t i = 0; i < reltab->size(); ++i) {
// FIXME: Can not implement here, use Fixup!
ELFRelocTy *rel = (*reltab)[i];
ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
//typedef uint64_t Inst_t;
typedef int32_t Inst_t;
Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
Inst_t P = (Inst_t)(uintptr_t)inst;
Inst_t A = (Inst_t)(uintptr_t)*inst;
Inst_t S = (Inst_t)(uintptr_t)sym->getAddress(EM_386);
if (S == 0) {
S = (Inst_t)(uintptr_t)find_sym(context, sym->getName());
if (!S) {
missingSymbols = true;
}
sym->setAddress((void *)S);
}
switch (rel->getType()) {
default:
rsl_assert(0 && "Not implemented relocation type.");
break;
case R_386_PC32:
*inst = (S+A-P);
break;
case R_386_32:
*inst = (S+A);
break;
}
}
}
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::
relocateMIPS(void *(*find_sym)(void *context, char const *name),
void *context,
ELFSectionRelTableTy *reltab,
ELFSectionProgBitsTy *text) {
rsl_assert(Bitwidth == 32 && "Only support 32-bit MIPS.");
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
for (size_t i = 0; i < reltab->size(); ++i) {
// FIXME: Can not implement here, use Fixup!
ELFRelocTy *rel = (*reltab)[i];
ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
typedef int32_t Inst_t;
Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
Inst_t P = (Inst_t)(uintptr_t)inst;
Inst_t A = (Inst_t)(uintptr_t)*inst;
Inst_t S = (Inst_t)(uintptr_t)sym->getAddress(EM_MIPS);
bool need_stub = false;
if (S == 0 && strcmp (sym->getName(), "_gp_disp") != 0) {
need_stub = true;
S = (Inst_t)(uintptr_t)find_sym(context, sym->getName());
if (!S) {
missingSymbols = true;
}
sym->setAddress((void *)S);
}
switch (rel->getType()) {
default:
rsl_assert(0 && "Not implemented relocation type.");
break;
case R_MIPS_NONE:
case R_MIPS_JALR: // ignore this
break;
case R_MIPS_16:
*inst &= 0xFFFF0000;
A = A & 0xFFFF;
A = S + (short)A;
rsl_assert(A >= -32768 && A <= 32767 && "R_MIPS_16 overflow.");
*inst |= (A & 0xFFFF);
break;
case R_MIPS_32:
*inst = S + A;
break;
case R_MIPS_26:
*inst &= 0xFC000000;
if (need_stub == false) {
A = (A & 0x3FFFFFF) << 2;
if (sym->getBindingAttribute() == STB_LOCAL) { // local binding
A |= ((P + 4) & 0xF0000000);
A += S;
*inst |= ((A >> 2) & 0x3FFFFFF);
} else { // external binding
if (A & 0x08000000) // Sign extend from bit 27
A |= 0xF0000000;
A += S;
*inst |= ((A >> 2) & 0x3FFFFFF);
if (((P + 4) >> 28) != (A >> 28)) { // far local call
void *stub = text->getStubLayout()->allocateStub((void *)A);
rsl_assert(stub && "cannot allocate stub.");
sym->setAddress(stub);
S = (int32_t)(intptr_t)stub;
*inst |= ((S >> 2) & 0x3FFFFFF);
rsl_assert(((P + 4) >> 28) == (S >> 28) && "stub is too far.");
}
}
} else { // shared-library call
A = (A & 0x3FFFFFF) << 2;
rsl_assert(A == 0 && "R_MIPS_26 addend is not zero.");
void *stub = text->getStubLayout()->allocateStub((void *)S);
rsl_assert(stub && "cannot allocate stub.");
sym->setAddress(stub);
S = (int32_t)(intptr_t)stub;
*inst |= ((S >> 2) & 0x3FFFFFF);
rsl_assert(((P + 4) >> 28) == (S >> 28) && "stub is too far.");
}
break;
case R_MIPS_HI16:
*inst &= 0xFFFF0000;
A = (A & 0xFFFF) << 16;
// Find the nearest LO16 relocation type after this entry
for (size_t j = i + 1; j < reltab->size(); j++) {
ELFRelocTy *this_rel = (*reltab)[j];
ELFSymbolTy *this_sym = (*symtab)[this_rel->getSymTabIndex()];
if (this_rel->getType() == R_MIPS_LO16 && this_sym == sym) {
Inst_t *this_inst = (Inst_t *)&(*text)[this_rel->getOffset()];
Inst_t this_A = (Inst_t)(uintptr_t)*this_inst;
this_A = this_A & 0xFFFF;
A += (short)this_A;
break;
}
}
if (strcmp (sym->getName(), "_gp_disp") == 0) {
S = (int)(intptr_t)got_address() + GP_OFFSET - (int)P;
sym->setAddress((void *)S);
}
*inst |= (((S + A + (int)0x8000) >> 16) & 0xFFFF);
break;
case R_MIPS_LO16:
*inst &= 0xFFFF0000;
A = A & 0xFFFF;
if (strcmp (sym->getName(), "_gp_disp") == 0) {
S = (Inst_t)(intptr_t)sym->getAddress(EM_MIPS);
}
*inst |= ((S + A) & 0xFFFF);
break;
case R_MIPS_GOT16:
case R_MIPS_CALL16:
{
*inst &= 0xFFFF0000;
A = A & 0xFFFF;
if (rel->getType() == R_MIPS_GOT16) {
if (sym->getBindingAttribute() == STB_LOCAL) {
A <<= 16;
// Find the nearest LO16 relocation type after this entry
for (size_t j = i + 1; j < reltab->size(); j++) {
ELFRelocTy *this_rel = (*reltab)[j];
ELFSymbolTy *this_sym = (*symtab)[this_rel->getSymTabIndex()];
if (this_rel->getType() == R_MIPS_LO16 && this_sym == sym) {
Inst_t *this_inst = (Inst_t *)&(*text)[this_rel->getOffset()];
Inst_t this_A = (Inst_t)(uintptr_t)*this_inst;
this_A = this_A & 0xFFFF;
A += (short)this_A;
break;
}
}
} else {
rsl_assert(A == 0 && "R_MIPS_GOT16 addend is not 0.");
}
} else { // R_MIPS_CALL16
rsl_assert(A == 0 && "R_MIPS_CALL16 addend is not 0.");
}
int got_index = search_got((int)rel->getSymTabIndex(), (void *)(S + A),
sym->getBindingAttribute());
int got_offset = (got_index << 2) - GP_OFFSET;
*inst |= (got_offset & 0xFFFF);
}
break;
case R_MIPS_GPREL32:
*inst = A + S - ((int)(intptr_t)got_address() + GP_OFFSET);
break;
}
}
}
// TODO: Refactor all relocations.
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::
relocate(void *(*find_sym)(void *context, char const *name), void *context) {
// Init SHNCommonDataSize.
// Need refactoring
size_t SHNCommonDataSize = 0;
ELFSectionSymTabTy *symtab =
static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
rsl_assert(symtab && "Symtab is required.");
for (size_t i = 0; i < symtab->size(); ++i) {
ELFSymbolTy *sym = (*symtab)[i];
if (sym->getType() != STT_OBJECT) {
continue;
}
size_t idx = (size_t)sym->getSectionIndex();
switch (idx) {
default:
if ((*shtab)[idx]->getType() == SHT_NOBITS) {
// FIXME(logan): This is a workaround for .lcomm directives
// bug of LLVM ARM MC code generator. Remove this when the
// LLVM bug is fixed.
size_t align = 16;
SHNCommonDataSize += (size_t)sym->getSize() + align;
}
break;
case SHN_COMMON:
{
size_t align = (size_t)sym->getValue();
SHNCommonDataSize += (size_t)sym->getSize() + align;
}
break;
case SHN_ABS:
case SHN_UNDEF:
case SHN_XINDEX:
break;
}
}
if (!initSHNCommonDataSize(SHNCommonDataSize)) {
rsl_assert("Allocate memory for common variable fail!");
// TODO: Refactor object loading to use proper status/error returns.
// We mark the object as having missing symbols and return early in this
// case to signal a loading error (usually due to running out of
// available memory to allocate).
missingSymbols = true;
return;
}
for (size_t i = 0; i < stab.size(); ++i) {
ELFSectionHeaderTy *sh = (*shtab)[i];
if (sh->getType() != SHT_REL && sh->getType() != SHT_RELA) {
continue;
}
ELFSectionRelTableTy *reltab =
static_cast<ELFSectionRelTableTy *>(stab[i]);
rsl_assert(reltab && "Relocation section can't be NULL.");
const char *reltab_name = sh->getName();
const char *need_rel_name;
if (sh->getType() == SHT_REL) {
need_rel_name = reltab_name + 4;
// ".rel.xxxx"
// ^ start from here.
} else {
need_rel_name = reltab_name + 5;
}
ELFSectionProgBitsTy *need_rel =
static_cast<ELFSectionProgBitsTy *>(getSectionByName(need_rel_name));
rsl_assert(need_rel && "Need be relocated section can't be NULL.");
switch (getHeader()->getMachine()) {
case EM_ARM:
relocateARM(find_sym, context, reltab, need_rel);
break;
case EM_386:
relocateX86_32(find_sym, context, reltab, need_rel);
break;
case EM_X86_64:
relocateX86_64(find_sym, context, reltab, need_rel);
break;
case EM_MIPS:
relocateMIPS(find_sym, context, reltab, need_rel);
break;
default:
rsl_assert(0 && "Only support ARM, MIPS, X86, and X86_64 relocation.");
break;
}
}
for (size_t i = 0; i < stab.size(); ++i) {
ELFSectionHeaderTy *sh = (*shtab)[i];
if (sh->getType() == SHT_PROGBITS || sh->getType() == SHT_NOBITS) {
if (stab[i]) {
static_cast<ELFSectionBitsTy *>(stab[i])->protect();
}
}
}
}
template <unsigned Bitwidth>
inline void ELFObject<Bitwidth>::print() const {
header->print();
shtab->print();
for (size_t i = 0; i < stab.size(); ++i) {
ELFSectionTy *sec = stab[i];
if (sec) {
sec->print();
}
}
}
#endif // ELF_OBJECT_HXX