Add signal handling to the register object.

- Add the StepIfSignalHandler function to the Regs object that checks
  if the code is in a signal handler.
- Add tests for new code, also add a test that unwinds through a signal
  handler.
- Slight modification to Elf to fail if a bad machine type is encountered.
  Add tests for this.

Bug: 23762183

Test: Ran unit tests.
Change-Id: Idafa1105d00b91a9343d7464ac9ed1cb95830963
diff --git a/libunwindstack/tests/RegsTest.cpp b/libunwindstack/tests/RegsTest.cpp
index 3613689..9622166 100644
--- a/libunwindstack/tests/RegsTest.cpp
+++ b/libunwindstack/tests/RegsTest.cpp
@@ -23,6 +23,8 @@
 #include <unwindstack/MapInfo.h>
 #include <unwindstack/Regs.h>
 
+#include "Machine.h"
+
 #include "MemoryFake.h"
 
 namespace unwindstack {
@@ -60,6 +62,7 @@
 
   uint64_t GetAdjustedPc(uint64_t, Elf*) override { return 0; }
   void SetFromRaw() override {}
+  bool StepIfSignalHandler(Memory*) override { return false; }
 };
 
 class RegsTest : public ::testing::Test {
@@ -72,7 +75,10 @@
   }
 
   template <typename AddressType>
-  void regs_return_address_register();
+  void RegsReturnAddressRegister();
+
+  void ArmStepIfSignalHandlerNonRt(uint32_t pc_data);
+  void ArmStepIfSignalHandlerRt(uint32_t pc_data);
 
   ElfInterfaceFake* elf_interface_;
   MemoryFake* memory_;
@@ -126,7 +132,7 @@
 }
 
 template <typename AddressType>
-void RegsTest::regs_return_address_register() {
+void RegsTest::RegsReturnAddressRegister() {
   RegsTestImpl<AddressType> regs(20, 10, Regs::Location(Regs::LOCATION_REGISTER, 5));
 
   regs[5] = 0x12345;
@@ -136,11 +142,11 @@
 }
 
 TEST_F(RegsTest, regs32_return_address_register) {
-  regs_return_address_register<uint32_t>();
+  RegsReturnAddressRegister<uint32_t>();
 }
 
 TEST_F(RegsTest, regs64_return_address_register) {
-  regs_return_address_register<uint64_t>();
+  RegsReturnAddressRegister<uint64_t>();
 }
 
 TEST_F(RegsTest, regs32_return_address_sp_offset) {
@@ -285,4 +291,160 @@
   EXPECT_EQ(0x4900000000U, x86_64.pc());
 }
 
+void RegsTest::ArmStepIfSignalHandlerNonRt(uint32_t pc_data) {
+  uint64_t addr = 0x1000;
+  RegsArm regs;
+  regs[ARM_REG_PC] = 0x5000;
+  regs[ARM_REG_SP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData32(0x5000, pc_data);
+
+  for (uint64_t index = 0; index <= 30; index++) {
+    memory_->SetData32(addr + index * 4, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0x100U, regs[ARM_REG_SP]);
+  EXPECT_EQ(0x120U, regs[ARM_REG_PC]);
+  EXPECT_EQ(0x100U, regs.sp());
+  EXPECT_EQ(0x120U, regs.pc());
+}
+
+TEST_F(RegsTest, arm_step_if_signal_handler_non_rt) {
+  // Form 1
+  ArmStepIfSignalHandlerNonRt(0xe3a07077);
+
+  // Form 2
+  ArmStepIfSignalHandlerNonRt(0xef900077);
+
+  // Form 3
+  ArmStepIfSignalHandlerNonRt(0xdf002777);
+}
+
+void RegsTest::ArmStepIfSignalHandlerRt(uint32_t pc_data) {
+  uint64_t addr = 0x1000;
+  RegsArm regs;
+  regs[ARM_REG_PC] = 0x5000;
+  regs[ARM_REG_SP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData32(0x5000, pc_data);
+
+  for (uint64_t index = 0; index <= 100; index++) {
+    memory_->SetData32(addr + index * 4, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0x350U, regs[ARM_REG_SP]);
+  EXPECT_EQ(0x370U, regs[ARM_REG_PC]);
+  EXPECT_EQ(0x350U, regs.sp());
+  EXPECT_EQ(0x370U, regs.pc());
+}
+
+TEST_F(RegsTest, arm_step_if_signal_handler_rt) {
+  // Form 1
+  ArmStepIfSignalHandlerRt(0xe3a070ad);
+
+  // Form 2
+  ArmStepIfSignalHandlerRt(0xef9000ad);
+
+  // Form 3
+  ArmStepIfSignalHandlerRt(0xdf0027ad);
+}
+
+TEST_F(RegsTest, arm64_step_if_signal_handler) {
+  uint64_t addr = 0x1000;
+  RegsArm64 regs;
+  regs[ARM64_REG_PC] = 0x8000;
+  regs[ARM64_REG_SP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData64(0x8000, 0xd4000001d2801168ULL);
+
+  for (uint64_t index = 0; index <= 100; index++) {
+    memory_->SetData64(addr + index * 8, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0x460U, regs[ARM64_REG_SP]);
+  EXPECT_EQ(0x470U, regs[ARM64_REG_PC]);
+  EXPECT_EQ(0x460U, regs.sp());
+  EXPECT_EQ(0x470U, regs.pc());
+}
+
+TEST_F(RegsTest, x86_step_if_signal_handler_no_siginfo) {
+  uint64_t addr = 0xa00;
+  RegsX86 regs;
+  regs[X86_REG_EIP] = 0x4100;
+  regs[X86_REG_ESP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData64(0x4100, 0x80cd00000077b858ULL);
+  for (uint64_t index = 0; index <= 25; index++) {
+    memory_->SetData32(addr + index * 4, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0x70U, regs[X86_REG_EBP]);
+  EXPECT_EQ(0x80U, regs[X86_REG_ESP]);
+  EXPECT_EQ(0x90U, regs[X86_REG_EBX]);
+  EXPECT_EQ(0xa0U, regs[X86_REG_EDX]);
+  EXPECT_EQ(0xb0U, regs[X86_REG_ECX]);
+  EXPECT_EQ(0xc0U, regs[X86_REG_EAX]);
+  EXPECT_EQ(0xf0U, regs[X86_REG_EIP]);
+  EXPECT_EQ(0x80U, regs.sp());
+  EXPECT_EQ(0xf0U, regs.pc());
+}
+
+TEST_F(RegsTest, x86_step_if_signal_handler_siginfo) {
+  uint64_t addr = 0xa00;
+  RegsX86 regs;
+  regs[X86_REG_EIP] = 0x4100;
+  regs[X86_REG_ESP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData64(0x4100, 0x0080cd000000adb8ULL);
+  addr += 8;
+  // Pointer to ucontext data.
+  memory_->SetData32(addr, 0x8100);
+
+  addr = 0x8100;
+  for (uint64_t index = 0; index <= 30; index++) {
+    memory_->SetData32(addr + index * 4, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0xb0U, regs[X86_REG_EBP]);
+  EXPECT_EQ(0xc0U, regs[X86_REG_ESP]);
+  EXPECT_EQ(0xd0U, regs[X86_REG_EBX]);
+  EXPECT_EQ(0xe0U, regs[X86_REG_EDX]);
+  EXPECT_EQ(0xf0U, regs[X86_REG_ECX]);
+  EXPECT_EQ(0x100U, regs[X86_REG_EAX]);
+  EXPECT_EQ(0x130U, regs[X86_REG_EIP]);
+  EXPECT_EQ(0xc0U, regs.sp());
+  EXPECT_EQ(0x130U, regs.pc());
+}
+
+TEST_F(RegsTest, x86_64_step_if_signal_handler) {
+  uint64_t addr = 0x500;
+  RegsX86_64 regs;
+  regs[X86_64_REG_RIP] = 0x7000;
+  regs[X86_64_REG_RSP] = addr;
+  regs.SetFromRaw();
+
+  memory_->SetData64(0x7000, 0x0f0000000fc0c748);
+  memory_->SetData16(0x7008, 0x0f05);
+
+  for (uint64_t index = 0; index <= 30; index++) {
+    memory_->SetData64(addr + index * 8, index * 0x10);
+  }
+
+  ASSERT_TRUE(regs.StepIfSignalHandler(memory_));
+  EXPECT_EQ(0x140U, regs[X86_64_REG_RSP]);
+  EXPECT_EQ(0x150U, regs[X86_64_REG_RIP]);
+  EXPECT_EQ(0x140U, regs.sp());
+  EXPECT_EQ(0x150U, regs.pc());
+}
+
 }  // namespace unwindstack