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platform_system_core/libunwindstack/Regs.cpp
Christopher Ferris eb4a6dbf5c Speed up StepIfSignalHandler path. 
The StepIfSignalHandler code reads from the process memory object, which
is currently the slowest way to read memory. Change the code to read from
the elf memory object which will almost always be a memory mapped file and
should be really fast.

Also, move the tests for StepIfSignalHandler to its own file.

Bug: 23762183

Test: Unit tests pass.
Change-Id: I1100b50554e5ef736a87babd484f3f34e9071caa
2017-07-19 21:35:46 +00:00

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/*
* Copyright (C) 2016 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 <elf.h>
#include <stdint.h>
#include <sys/ptrace.h>
#include <sys/uio.h>
#include <vector>
#include <unwindstack/Elf.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include "Check.h"
#include "Machine.h"
#include "Ucontext.h"
#include "User.h"
namespace unwindstack {
template <typename AddressType>
bool RegsImpl<AddressType>::GetReturnAddressFromDefault(Memory* memory, uint64_t* value) {
switch (return_loc_.type) {
case LOCATION_REGISTER:
CHECK(return_loc_.value < total_regs_);
*value = regs_[return_loc_.value];
return true;
case LOCATION_SP_OFFSET:
AddressType return_value;
if (!memory->Read(sp_ + return_loc_.value, &return_value, sizeof(return_value))) {
return false;
}
*value = return_value;
return true;
case LOCATION_UNKNOWN:
default:
return false;
}
}
RegsArm::RegsArm()
: RegsImpl<uint32_t>(ARM_REG_LAST, ARM_REG_SP, Location(LOCATION_REGISTER, ARM_REG_LR)) {}
uint64_t RegsArm::GetAdjustedPc(uint64_t rel_pc, Elf* elf) {
if (!elf->valid()) {
return rel_pc;
}
uint64_t load_bias = elf->interface()->load_bias();
if (rel_pc < load_bias) {
return rel_pc;
}
uint64_t adjusted_rel_pc = rel_pc - load_bias;
if (adjusted_rel_pc < 5) {
return rel_pc;
}
if (adjusted_rel_pc & 1) {
// This is a thumb instruction, it could be 2 or 4 bytes.
uint32_t value;
if (rel_pc < 5 || !elf->memory()->Read(adjusted_rel_pc - 5, &value, sizeof(value)) ||
(value & 0xe000f000) != 0xe000f000) {
return rel_pc - 2;
}
}
return rel_pc - 4;
}
void RegsArm::SetFromRaw() {
set_pc(regs_[ARM_REG_PC]);
set_sp(regs_[ARM_REG_SP]);
}
RegsArm64::RegsArm64()
: RegsImpl<uint64_t>(ARM64_REG_LAST, ARM64_REG_SP, Location(LOCATION_REGISTER, ARM64_REG_LR)) {}
uint64_t RegsArm64::GetAdjustedPc(uint64_t rel_pc, Elf* elf) {
if (!elf->valid()) {
return rel_pc;
}
if (rel_pc < 4) {
return rel_pc;
}
return rel_pc - 4;
}
void RegsArm64::SetFromRaw() {
set_pc(regs_[ARM64_REG_PC]);
set_sp(regs_[ARM64_REG_SP]);
}
RegsX86::RegsX86()
: RegsImpl<uint32_t>(X86_REG_LAST, X86_REG_SP, Location(LOCATION_SP_OFFSET, -4)) {}
uint64_t RegsX86::GetAdjustedPc(uint64_t rel_pc, Elf* elf) {
if (!elf->valid()) {
return rel_pc;
}
if (rel_pc == 0) {
return 0;
}
return rel_pc - 1;
}
void RegsX86::SetFromRaw() {
set_pc(regs_[X86_REG_PC]);
set_sp(regs_[X86_REG_SP]);
}
RegsX86_64::RegsX86_64()
: RegsImpl<uint64_t>(X86_64_REG_LAST, X86_64_REG_SP, Location(LOCATION_SP_OFFSET, -8)) {}
uint64_t RegsX86_64::GetAdjustedPc(uint64_t rel_pc, Elf* elf) {
if (!elf->valid()) {
return rel_pc;
}
if (rel_pc == 0) {
return 0;
}
return rel_pc - 1;
}
void RegsX86_64::SetFromRaw() {
set_pc(regs_[X86_64_REG_PC]);
set_sp(regs_[X86_64_REG_SP]);
}
static Regs* ReadArm(void* remote_data) {
arm_user_regs* user = reinterpret_cast<arm_user_regs*>(remote_data);
RegsArm* regs = new RegsArm();
memcpy(regs->RawData(), &user->regs[0], ARM_REG_LAST * sizeof(uint32_t));
regs->SetFromRaw();
return regs;
}
static Regs* ReadArm64(void* remote_data) {
arm64_user_regs* user = reinterpret_cast<arm64_user_regs*>(remote_data);
RegsArm64* regs = new RegsArm64();
memcpy(regs->RawData(), &user->regs[0], (ARM64_REG_R31 + 1) * sizeof(uint64_t));
uint64_t* reg_data = reinterpret_cast<uint64_t*>(regs->RawData());
reg_data[ARM64_REG_PC] = user->pc;
reg_data[ARM64_REG_SP] = user->sp;
regs->SetFromRaw();
return regs;
}
static Regs* ReadX86(void* remote_data) {
x86_user_regs* user = reinterpret_cast<x86_user_regs*>(remote_data);
RegsX86* regs = new RegsX86();
(*regs)[X86_REG_EAX] = user->eax;
(*regs)[X86_REG_EBX] = user->ebx;
(*regs)[X86_REG_ECX] = user->ecx;
(*regs)[X86_REG_EDX] = user->edx;
(*regs)[X86_REG_EBP] = user->ebp;
(*regs)[X86_REG_EDI] = user->edi;
(*regs)[X86_REG_ESI] = user->esi;
(*regs)[X86_REG_ESP] = user->esp;
(*regs)[X86_REG_EIP] = user->eip;
regs->SetFromRaw();
return regs;
}
static Regs* ReadX86_64(void* remote_data) {
x86_64_user_regs* user = reinterpret_cast<x86_64_user_regs*>(remote_data);
RegsX86_64* regs = new RegsX86_64();
(*regs)[X86_64_REG_RAX] = user->rax;
(*regs)[X86_64_REG_RBX] = user->rbx;
(*regs)[X86_64_REG_RCX] = user->rcx;
(*regs)[X86_64_REG_RDX] = user->rdx;
(*regs)[X86_64_REG_R8] = user->r8;
(*regs)[X86_64_REG_R9] = user->r9;
(*regs)[X86_64_REG_R10] = user->r10;
(*regs)[X86_64_REG_R11] = user->r11;
(*regs)[X86_64_REG_R12] = user->r12;
(*regs)[X86_64_REG_R13] = user->r13;
(*regs)[X86_64_REG_R14] = user->r14;
(*regs)[X86_64_REG_R15] = user->r15;
(*regs)[X86_64_REG_RDI] = user->rdi;
(*regs)[X86_64_REG_RSI] = user->rsi;
(*regs)[X86_64_REG_RBP] = user->rbp;
(*regs)[X86_64_REG_RSP] = user->rsp;
(*regs)[X86_64_REG_RIP] = user->rip;
regs->SetFromRaw();
return regs;
}
// This function assumes that reg_data is already aligned to a 64 bit value.
// If not this could crash with an unaligned access.
Regs* Regs::RemoteGet(pid_t pid, uint32_t* machine_type) {
// Make the buffer large enough to contain the largest registers type.
std::vector<uint64_t> buffer(MAX_USER_REGS_SIZE / sizeof(uint64_t));
struct iovec io;
io.iov_base = buffer.data();
io.iov_len = buffer.size() * sizeof(uint64_t);
if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, reinterpret_cast<void*>(&io)) == -1) {
return nullptr;
}
switch (io.iov_len) {
case sizeof(x86_user_regs):
*machine_type = EM_386;
return ReadX86(buffer.data());
case sizeof(x86_64_user_regs):
*machine_type = EM_X86_64;
return ReadX86_64(buffer.data());
case sizeof(arm_user_regs):
*machine_type = EM_ARM;
return ReadArm(buffer.data());
case sizeof(arm64_user_regs):
*machine_type = EM_AARCH64;
return ReadArm64(buffer.data());
}
return nullptr;
}
static Regs* CreateFromArmUcontext(void* ucontext) {
arm_ucontext_t* arm_ucontext = reinterpret_cast<arm_ucontext_t*>(ucontext);
RegsArm* regs = new RegsArm();
memcpy(regs->RawData(), &arm_ucontext->uc_mcontext.regs[0], ARM_REG_LAST * sizeof(uint32_t));
regs->SetFromRaw();
return regs;
}
static Regs* CreateFromArm64Ucontext(void* ucontext) {
arm64_ucontext_t* arm64_ucontext = reinterpret_cast<arm64_ucontext_t*>(ucontext);
RegsArm64* regs = new RegsArm64();
memcpy(regs->RawData(), &arm64_ucontext->uc_mcontext.regs[0], ARM64_REG_LAST * sizeof(uint64_t));
regs->SetFromRaw();
return regs;
}
void RegsX86::SetFromUcontext(x86_ucontext_t* ucontext) {
// Put the registers in the expected order.
regs_[X86_REG_EDI] = ucontext->uc_mcontext.edi;
regs_[X86_REG_ESI] = ucontext->uc_mcontext.esi;
regs_[X86_REG_EBP] = ucontext->uc_mcontext.ebp;
regs_[X86_REG_ESP] = ucontext->uc_mcontext.esp;
regs_[X86_REG_EBX] = ucontext->uc_mcontext.ebx;
regs_[X86_REG_EDX] = ucontext->uc_mcontext.edx;
regs_[X86_REG_ECX] = ucontext->uc_mcontext.ecx;
regs_[X86_REG_EAX] = ucontext->uc_mcontext.eax;
regs_[X86_REG_EIP] = ucontext->uc_mcontext.eip;
SetFromRaw();
}
static Regs* CreateFromX86Ucontext(void* ucontext) {
x86_ucontext_t* x86_ucontext = reinterpret_cast<x86_ucontext_t*>(ucontext);
RegsX86* regs = new RegsX86();
regs->SetFromUcontext(x86_ucontext);
return regs;
}
void RegsX86_64::SetFromUcontext(x86_64_ucontext_t* ucontext) {
// R8-R15
memcpy(&regs_[X86_64_REG_R8], &ucontext->uc_mcontext.r8, 8 * sizeof(uint64_t));
// Rest of the registers.
regs_[X86_64_REG_RDI] = ucontext->uc_mcontext.rdi;
regs_[X86_64_REG_RSI] = ucontext->uc_mcontext.rsi;
regs_[X86_64_REG_RBP] = ucontext->uc_mcontext.rbp;
regs_[X86_64_REG_RBX] = ucontext->uc_mcontext.rbx;
regs_[X86_64_REG_RDX] = ucontext->uc_mcontext.rdx;
regs_[X86_64_REG_RAX] = ucontext->uc_mcontext.rax;
regs_[X86_64_REG_RCX] = ucontext->uc_mcontext.rcx;
regs_[X86_64_REG_RSP] = ucontext->uc_mcontext.rsp;
regs_[X86_64_REG_RIP] = ucontext->uc_mcontext.rip;
SetFromRaw();
}
static Regs* CreateFromX86_64Ucontext(void* ucontext) {
x86_64_ucontext_t* x86_64_ucontext = reinterpret_cast<x86_64_ucontext_t*>(ucontext);
RegsX86_64* regs = new RegsX86_64();
regs->SetFromUcontext(x86_64_ucontext);
return regs;
}
Regs* Regs::CreateFromUcontext(uint32_t machine_type, void* ucontext) {
switch (machine_type) {
case EM_386:
return CreateFromX86Ucontext(ucontext);
case EM_X86_64:
return CreateFromX86_64Ucontext(ucontext);
case EM_ARM:
return CreateFromArmUcontext(ucontext);
case EM_AARCH64:
return CreateFromArm64Ucontext(ucontext);
}
return nullptr;
}
uint32_t Regs::GetMachineType() {
#if defined(__arm__)
return EM_ARM;
#elif defined(__aarch64__)
return EM_AARCH64;
#elif defined(__i386__)
return EM_386;
#elif defined(__x86_64__)
return EM_X86_64;
#else
abort();
#endif
}
Regs* Regs::CreateFromLocal() {
Regs* regs;
#if defined(__arm__)
regs = new RegsArm();
#elif defined(__aarch64__)
regs = new RegsArm64();
#elif defined(__i386__)
regs = new RegsX86();
#elif defined(__x86_64__)
regs = new RegsX86_64();
#else
abort();
#endif
return regs;
}
bool RegsArm::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
uint32_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
return false;
}
uint64_t offset = 0;
if (data == 0xe3a07077 || data == 0xef900077 || data == 0xdf002777) {
// non-RT sigreturn call.
// __restore:
//
// Form 1 (arm):
// 0x77 0x70 mov r7, #0x77
// 0xa0 0xe3 svc 0x00000000
//
// Form 2 (arm):
// 0x77 0x00 0x90 0xef svc 0x00900077
//
// Form 3 (thumb):
// 0x77 0x27 movs r7, #77
// 0x00 0xdf svc 0
if (!process_memory->Read(sp(), &data, sizeof(data))) {
return false;
}
if (data == 0x5ac3c35a) {
// SP + uc_mcontext offset + r0 offset.
offset = sp() + 0x14 + 0xc;
} else {
// SP + r0 offset
offset = sp() + 0xc;
}
} else if (data == 0xe3a070ad || data == 0xef9000ad || data == 0xdf0027ad) {
// RT sigreturn call.
// __restore_rt:
//
// Form 1 (arm):
// 0xad 0x70 mov r7, #0xad
// 0xa0 0xe3 svc 0x00000000
//
// Form 2 (arm):
// 0xad 0x00 0x90 0xef svc 0x009000ad
//
// Form 3 (thumb):
// 0xad 0x27 movs r7, #ad
// 0x00 0xdf svc 0
if (!process_memory->Read(sp(), &data, sizeof(data))) {
return false;
}
if (data == sp() + 8) {
// SP + 8 + sizeof(siginfo_t) + uc_mcontext_offset + r0 offset
offset = sp() + 8 + 0x80 + 0x14 + 0xc;
} else {
// SP + sizeof(siginfo_t) + uc_mcontext_offset + r0 offset
offset = sp() + 0x80 + 0x14 + 0xc;
}
}
if (offset == 0) {
return false;
}
if (!process_memory->Read(offset, regs_.data(), sizeof(uint32_t) * ARM_REG_LAST)) {
return false;
}
SetFromRaw();
return true;
}
bool RegsArm64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
return false;
}
// Look for the kernel sigreturn function.
// __kernel_rt_sigreturn:
// 0xd2801168 mov x8, #0x8b
// 0xd4000001 svc #0x0
if (data != 0xd4000001d2801168ULL) {
return false;
}
// SP + sizeof(siginfo_t) + uc_mcontext offset + X0 offset.
if (!process_memory->Read(sp() + 0x80 + 0xb0 + 0x08, regs_.data(),
sizeof(uint64_t) * ARM64_REG_LAST)) {
return false;
}
SetFromRaw();
return true;
}
bool RegsX86::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
return false;
}
if (data == 0x80cd00000077b858ULL) {
// Without SA_SIGINFO set, the return sequence is:
//
// __restore:
// 0x58 pop %eax
// 0xb8 0x77 0x00 0x00 0x00 movl 0x77,%eax
// 0xcd 0x80 int 0x80
//
// SP points at arguments:
// int signum
// struct sigcontext (same format as mcontext)
struct x86_mcontext_t context;
if (!process_memory->Read(sp() + 4, &context, sizeof(context))) {
return false;
}
regs_[X86_REG_EBP] = context.ebp;
regs_[X86_REG_ESP] = context.esp;
regs_[X86_REG_EBX] = context.ebx;
regs_[X86_REG_EDX] = context.edx;
regs_[X86_REG_ECX] = context.ecx;
regs_[X86_REG_EAX] = context.eax;
regs_[X86_REG_EIP] = context.eip;
SetFromRaw();
return true;
} else if ((data & 0x00ffffffffffffffULL) == 0x0080cd000000adb8ULL) {
// With SA_SIGINFO set, the return sequence is:
//
// __restore_rt:
// 0xb8 0xad 0x00 0x00 0x00 movl 0xad,%eax
// 0xcd 0x80 int 0x80
//
// SP points at arguments:
// int signum
// siginfo*
// ucontext*
// Get the location of the sigcontext data.
uint32_t ptr;
if (!process_memory->Read(sp() + 8, &ptr, sizeof(ptr))) {
return false;
}
// Only read the portion of the data structure we care about.
x86_ucontext_t x86_ucontext;
if (!process_memory->Read(ptr + 0x14, &x86_ucontext.uc_mcontext, sizeof(x86_mcontext_t))) {
return false;
}
SetFromUcontext(&x86_ucontext);
return true;
}
return false;
}
bool RegsX86_64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
uint64_t data;
Memory* elf_memory = elf->memory();
// Read from elf memory since it is usually more expensive to read from
// process memory.
if (!elf_memory->Read(rel_pc, &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
return false;
}
uint16_t data2;
if (!elf_memory->Read(rel_pc + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
return false;
}
// __restore_rt:
// 0x48 0xc7 0xc0 0x0f 0x00 0x00 0x00 mov $0xf,%rax
// 0x0f 0x05 syscall
// 0x0f nopl 0x0($rax)
// Read the mcontext data from the stack.
// sp points to the ucontext data structure, read only the mcontext part.
x86_64_ucontext_t x86_64_ucontext;
if (!process_memory->Read(sp() + 0x28, &x86_64_ucontext.uc_mcontext, sizeof(x86_64_mcontext_t))) {
return false;
}
SetFromUcontext(&x86_64_ucontext);
return true;
}
} // namespace unwindstack
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