compiler/linker/arm/relative_patcher_thumb2.cc - platform/art - Git at Google

 /*
  * Copyright (C) 2015 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 "linker/arm/relative_patcher_thumb2.h"

 #include <sstream>

 #include "arch/arm/asm_support_arm.h"
 #include "art_method.h"
 #include "base/bit_utils.h"
 #include "base/malloc_arena_pool.h"
 #include "compiled_method.h"
 #include "entrypoints/quick/quick_entrypoints_enum.h"
 #include "linker/linker_patch.h"
 #include "lock_word.h"
 #include "mirror/array-inl.h"
 #include "mirror/object.h"
 #include "read_barrier.h"
 #include "utils/arm/assembler_arm_vixl.h"

 namespace art {
 namespace linker {

 // PC displacement from patch location; Thumb2 PC is always at instruction address + 4.
 static constexpr int32_t kPcDisplacement = 4;

 // Maximum positive and negative displacement for method call measured from the patch location.
 // (Signed 25 bit displacement with the last bit 0 has range [-2^24, 2^24-2] measured from
 // the Thumb2 PC pointing right after the BL, i.e. 4 bytes later than the patch location.)
 constexpr uint32_t kMaxMethodCallPositiveDisplacement = (1u << 24) - 2 + kPcDisplacement;
 constexpr uint32_t kMaxMethodCallNegativeDisplacement = (1u << 24) - kPcDisplacement;

 // Maximum positive and negative displacement for a conditional branch measured from the patch
 // location. (Signed 21 bit displacement with the last bit 0 has range [-2^20, 2^20-2] measured
 // from the Thumb2 PC pointing right after the B.cond, i.e. 4 bytes later than the patch location.)
 constexpr uint32_t kMaxBcondPositiveDisplacement = (1u << 20) - 2u + kPcDisplacement;
 constexpr uint32_t kMaxBcondNegativeDisplacement = (1u << 20) - kPcDisplacement;

 Thumb2RelativePatcher::Thumb2RelativePatcher(RelativePatcherThunkProvider* thunk_provider,
                                              RelativePatcherTargetProvider* target_provider)
     : ArmBaseRelativePatcher(thunk_provider, target_provider, InstructionSet::kThumb2) {
 }

 void Thumb2RelativePatcher::PatchCall(std::vector<uint8_t>* code,
                                       uint32_t literal_offset,
                                       uint32_t patch_offset,
                                       uint32_t target_offset) {
   DCHECK_LE(literal_offset + 4u, code->size());
   DCHECK_EQ(literal_offset & 1u, 0u);
   DCHECK_EQ(patch_offset & 1u, 0u);
   DCHECK_EQ(target_offset & 1u, 1u);  // Thumb2 mode bit.
   uint32_t displacement = CalculateMethodCallDisplacement(patch_offset, target_offset & ~1u);
   displacement -= kPcDisplacement;  // The base PC is at the end of the 4-byte patch.
   DCHECK_EQ(displacement & 1u, 0u);
   DCHECK((displacement >> 24) == 0u || (displacement >> 24) == 255u);  // 25-bit signed.
   uint32_t signbit = (displacement >> 31) & 0x1;
   uint32_t i1 = (displacement >> 23) & 0x1;
   uint32_t i2 = (displacement >> 22) & 0x1;
   uint32_t imm10 = (displacement >> 12) & 0x03ff;
   uint32_t imm11 = (displacement >> 1) & 0x07ff;
   uint32_t j1 = i1 ^ (signbit ^ 1);
   uint32_t j2 = i2 ^ (signbit ^ 1);
   uint32_t value = (signbit << 26) | (j1 << 13) | (j2 << 11) | (imm10 << 16) | imm11;
   value |= 0xf000d000;  // BL

   // Check that we're just overwriting an existing BL.
   DCHECK_EQ(GetInsn32(code, literal_offset) & 0xf800d000, 0xf000d000);
   // Write the new BL.
   SetInsn32(code, literal_offset, value);
 }

 void Thumb2RelativePatcher::PatchPcRelativeReference(std::vector<uint8_t>* code,
                                                      const LinkerPatch& patch,
                                                      uint32_t patch_offset,
                                                      uint32_t target_offset) {
   uint32_t literal_offset = patch.LiteralOffset();
   uint32_t pc_literal_offset = patch.PcInsnOffset();
   uint32_t pc_base = patch_offset + (pc_literal_offset - literal_offset) + 4u /* PC adjustment */;
   uint32_t diff = target_offset - pc_base;

   uint32_t insn = GetInsn32(code, literal_offset);
   DCHECK_EQ(insn & 0xff7ff0ffu, 0xf2400000u);  // MOVW/MOVT, unpatched (imm16 == 0).
   uint32_t diff16 = ((insn & 0x00800000u) != 0u) ? (diff >> 16) : (diff & 0xffffu);
   uint32_t imm4 = (diff16 >> 12) & 0xfu;
   uint32_t imm = (diff16 >> 11) & 0x1u;
   uint32_t imm3 = (diff16 >> 8) & 0x7u;
   uint32_t imm8 = diff16 & 0xffu;
   insn = (insn & 0xfbf08f00u) | (imm << 26) | (imm4 << 16) | (imm3 << 12) | imm8;
   SetInsn32(code, literal_offset, insn);
 }

 void Thumb2RelativePatcher::PatchBakerReadBarrierBranch(std::vector<uint8_t>* code,
                                                         const LinkerPatch& patch,
                                                         uint32_t patch_offset) {
   DCHECK_ALIGNED(patch_offset, 2u);
   uint32_t literal_offset = patch.LiteralOffset();
   DCHECK_ALIGNED(literal_offset, 2u);
   DCHECK_LT(literal_offset, code->size());
   uint32_t insn = GetInsn32(code, literal_offset);
   DCHECK_EQ(insn, 0xf0408000);  // BNE +0 (unpatched)
   ThunkKey key = GetBakerThunkKey(patch);
   uint32_t target_offset = GetThunkTargetOffset(key, patch_offset);
   DCHECK_ALIGNED(target_offset, 4u);
   uint32_t disp = target_offset - (patch_offset + kPcDisplacement);
   DCHECK((disp >> 20) == 0u || (disp >> 20) == 0xfffu);   // 21-bit signed.
   insn |= ((disp << (26 - 20)) & 0x04000000u) |           // Shift bit 20 to 26, "S".
           ((disp >> (19 - 11)) & 0x00000800u) |           // Shift bit 19 to 13, "J1".
           ((disp >> (18 - 13)) & 0x00002000u) |           // Shift bit 18 to 11, "J2".
           ((disp << (16 - 12)) & 0x003f0000u) |           // Shift bits 12-17 to 16-25, "imm6".
           ((disp >> (1 - 0)) & 0x000007ffu);              // Shift bits 1-12 to 0-11, "imm11".
   SetInsn32(code, literal_offset, insn);
 }

 uint32_t Thumb2RelativePatcher::MaxPositiveDisplacement(const ThunkKey& key) {
   switch (key.GetType()) {
     case ThunkType::kMethodCall:
       return kMaxMethodCallPositiveDisplacement;
     case ThunkType::kBakerReadBarrier:
       return kMaxBcondPositiveDisplacement;
   }
 }

 uint32_t Thumb2RelativePatcher::MaxNegativeDisplacement(const ThunkKey& key) {
   switch (key.GetType()) {
     case ThunkType::kMethodCall:
       return kMaxMethodCallNegativeDisplacement;
     case ThunkType::kBakerReadBarrier:
       return kMaxBcondNegativeDisplacement;
   }
 }

 void Thumb2RelativePatcher::SetInsn32(std::vector<uint8_t>* code, uint32_t offset, uint32_t value) {
   DCHECK_LE(offset + 4u, code->size());
   DCHECK_ALIGNED(offset, 2u);
   uint8_t* addr = &(*code)[offset];
   addr[0] = (value >> 16) & 0xff;
   addr[1] = (value >> 24) & 0xff;
   addr[2] = (value >> 0) & 0xff;
   addr[3] = (value >> 8) & 0xff;
 }

 uint32_t Thumb2RelativePatcher::GetInsn32(ArrayRef<const uint8_t> code, uint32_t offset) {
   DCHECK_LE(offset + 4u, code.size());
   DCHECK_ALIGNED(offset, 2u);
   const uint8_t* addr = &code[offset];
   return
       (static_cast<uint32_t>(addr[0]) << 16) +
       (static_cast<uint32_t>(addr[1]) << 24) +
       (static_cast<uint32_t>(addr[2]) << 0)+
       (static_cast<uint32_t>(addr[3]) << 8);
 }

 template <typename Vector>
 uint32_t Thumb2RelativePatcher::GetInsn32(Vector* code, uint32_t offset) {
   static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
   return GetInsn32(ArrayRef<const uint8_t>(*code), offset);
 }

 uint32_t Thumb2RelativePatcher::GetInsn16(ArrayRef<const uint8_t> code, uint32_t offset) {
   DCHECK_LE(offset + 2u, code.size());
   DCHECK_ALIGNED(offset, 2u);
   const uint8_t* addr = &code[offset];
   return (static_cast<uint32_t>(addr[0]) << 0) + (static_cast<uint32_t>(addr[1]) << 8);
 }

 template <typename Vector>
 uint32_t Thumb2RelativePatcher::GetInsn16(Vector* code, uint32_t offset) {
   static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
   return GetInsn16(ArrayRef<const uint8_t>(*code), offset);
 }

 }  // namespace linker
 }  // namespace art
	/*
	* Copyright (C) 2015 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 "linker/arm/relative_patcher_thumb2.h"

	#include <sstream>

	#include "arch/arm/asm_support_arm.h"
	#include "art_method.h"
	#include "base/bit_utils.h"
	#include "base/malloc_arena_pool.h"
	#include "compiled_method.h"
	#include "entrypoints/quick/quick_entrypoints_enum.h"
	#include "linker/linker_patch.h"
	#include "lock_word.h"
	#include "mirror/array-inl.h"
	#include "mirror/object.h"
	#include "read_barrier.h"
	#include "utils/arm/assembler_arm_vixl.h"

	namespace art {
	namespace linker {

	// PC displacement from patch location; Thumb2 PC is always at instruction address + 4.
	static constexpr int32_t kPcDisplacement = 4;

	// Maximum positive and negative displacement for method call measured from the patch location.
	// (Signed 25 bit displacement with the last bit 0 has range [-2^24, 2^24-2] measured from
	// the Thumb2 PC pointing right after the BL, i.e. 4 bytes later than the patch location.)
	constexpr uint32_t kMaxMethodCallPositiveDisplacement = (1u << 24) - 2 + kPcDisplacement;
	constexpr uint32_t kMaxMethodCallNegativeDisplacement = (1u << 24) - kPcDisplacement;

	// Maximum positive and negative displacement for a conditional branch measured from the patch
	// location. (Signed 21 bit displacement with the last bit 0 has range [-2^20, 2^20-2] measured
	// from the Thumb2 PC pointing right after the B.cond, i.e. 4 bytes later than the patch location.)
	constexpr uint32_t kMaxBcondPositiveDisplacement = (1u << 20) - 2u + kPcDisplacement;
	constexpr uint32_t kMaxBcondNegativeDisplacement = (1u << 20) - kPcDisplacement;

	Thumb2RelativePatcher::Thumb2RelativePatcher(RelativePatcherThunkProvider* thunk_provider,
	RelativePatcherTargetProvider* target_provider)
	: ArmBaseRelativePatcher(thunk_provider, target_provider, InstructionSet::kThumb2) {
	}

	void Thumb2RelativePatcher::PatchCall(std::vector<uint8_t>* code,
	uint32_t literal_offset,
	uint32_t patch_offset,
	uint32_t target_offset) {
	DCHECK_LE(literal_offset + 4u, code->size());
	DCHECK_EQ(literal_offset & 1u, 0u);
	DCHECK_EQ(patch_offset & 1u, 0u);
	DCHECK_EQ(target_offset & 1u, 1u); // Thumb2 mode bit.
	uint32_t displacement = CalculateMethodCallDisplacement(patch_offset, target_offset & ~1u);
	displacement -= kPcDisplacement; // The base PC is at the end of the 4-byte patch.
	DCHECK_EQ(displacement & 1u, 0u);
	DCHECK((displacement >> 24) == 0u \|\| (displacement >> 24) == 255u); // 25-bit signed.
	uint32_t signbit = (displacement >> 31) & 0x1;
	uint32_t i1 = (displacement >> 23) & 0x1;
	uint32_t i2 = (displacement >> 22) & 0x1;
	uint32_t imm10 = (displacement >> 12) & 0x03ff;
	uint32_t imm11 = (displacement >> 1) & 0x07ff;
	uint32_t j1 = i1 ^ (signbit ^ 1);
	uint32_t j2 = i2 ^ (signbit ^ 1);
	uint32_t value = (signbit << 26) \| (j1 << 13) \| (j2 << 11) \| (imm10 << 16) \| imm11;
	value \|= 0xf000d000; // BL

	// Check that we're just overwriting an existing BL.
	DCHECK_EQ(GetInsn32(code, literal_offset) & 0xf800d000, 0xf000d000);
	// Write the new BL.
	SetInsn32(code, literal_offset, value);
	}

	void Thumb2RelativePatcher::PatchPcRelativeReference(std::vector<uint8_t>* code,
	const LinkerPatch& patch,
	uint32_t patch_offset,
	uint32_t target_offset) {
	uint32_t literal_offset = patch.LiteralOffset();
	uint32_t pc_literal_offset = patch.PcInsnOffset();
	uint32_t pc_base = patch_offset + (pc_literal_offset - literal_offset) + 4u /* PC adjustment */;
	uint32_t diff = target_offset - pc_base;

	uint32_t insn = GetInsn32(code, literal_offset);
	DCHECK_EQ(insn & 0xff7ff0ffu, 0xf2400000u); // MOVW/MOVT, unpatched (imm16 == 0).
	uint32_t diff16 = ((insn & 0x00800000u) != 0u) ? (diff >> 16) : (diff & 0xffffu);
	uint32_t imm4 = (diff16 >> 12) & 0xfu;
	uint32_t imm = (diff16 >> 11) & 0x1u;
	uint32_t imm3 = (diff16 >> 8) & 0x7u;
	uint32_t imm8 = diff16 & 0xffu;
	insn = (insn & 0xfbf08f00u) \| (imm << 26) \| (imm4 << 16) \| (imm3 << 12) \| imm8;
	SetInsn32(code, literal_offset, insn);
	}

	void Thumb2RelativePatcher::PatchBakerReadBarrierBranch(std::vector<uint8_t>* code,
	const LinkerPatch& patch,
	uint32_t patch_offset) {
	DCHECK_ALIGNED(patch_offset, 2u);
	uint32_t literal_offset = patch.LiteralOffset();
	DCHECK_ALIGNED(literal_offset, 2u);
	DCHECK_LT(literal_offset, code->size());
	uint32_t insn = GetInsn32(code, literal_offset);
	DCHECK_EQ(insn, 0xf0408000); // BNE +0 (unpatched)
	ThunkKey key = GetBakerThunkKey(patch);
	uint32_t target_offset = GetThunkTargetOffset(key, patch_offset);
	DCHECK_ALIGNED(target_offset, 4u);
	uint32_t disp = target_offset - (patch_offset + kPcDisplacement);
	DCHECK((disp >> 20) == 0u \|\| (disp >> 20) == 0xfffu); // 21-bit signed.
	insn \|= ((disp << (26 - 20)) & 0x04000000u) \| // Shift bit 20 to 26, "S".
	((disp >> (19 - 11)) & 0x00000800u) \| // Shift bit 19 to 13, "J1".
	((disp >> (18 - 13)) & 0x00002000u) \| // Shift bit 18 to 11, "J2".
	((disp << (16 - 12)) & 0x003f0000u) \| // Shift bits 12-17 to 16-25, "imm6".
	((disp >> (1 - 0)) & 0x000007ffu); // Shift bits 1-12 to 0-11, "imm11".
	SetInsn32(code, literal_offset, insn);
	}

	uint32_t Thumb2RelativePatcher::MaxPositiveDisplacement(const ThunkKey& key) {
	switch (key.GetType()) {
	case ThunkType::kMethodCall:
	return kMaxMethodCallPositiveDisplacement;
	case ThunkType::kBakerReadBarrier:
	return kMaxBcondPositiveDisplacement;
	}
	}

	uint32_t Thumb2RelativePatcher::MaxNegativeDisplacement(const ThunkKey& key) {
	switch (key.GetType()) {
	case ThunkType::kMethodCall:
	return kMaxMethodCallNegativeDisplacement;
	case ThunkType::kBakerReadBarrier:
	return kMaxBcondNegativeDisplacement;
	}
	}

	void Thumb2RelativePatcher::SetInsn32(std::vector<uint8_t>* code, uint32_t offset, uint32_t value) {
	DCHECK_LE(offset + 4u, code->size());
	DCHECK_ALIGNED(offset, 2u);
	uint8_t* addr = &(*code)[offset];
	addr[0] = (value >> 16) & 0xff;
	addr[1] = (value >> 24) & 0xff;
	addr[2] = (value >> 0) & 0xff;
	addr[3] = (value >> 8) & 0xff;
	}

	uint32_t Thumb2RelativePatcher::GetInsn32(ArrayRef<const uint8_t> code, uint32_t offset) {
	DCHECK_LE(offset + 4u, code.size());
	DCHECK_ALIGNED(offset, 2u);
	const uint8_t* addr = &code[offset];
	return
	(static_cast<uint32_t>(addr[0]) << 16) +
	(static_cast<uint32_t>(addr[1]) << 24) +
	(static_cast<uint32_t>(addr[2]) << 0)+
	(static_cast<uint32_t>(addr[3]) << 8);
	}

	template <typename Vector>
	uint32_t Thumb2RelativePatcher::GetInsn32(Vector* code, uint32_t offset) {
	static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
	return GetInsn32(ArrayRef<const uint8_t>(*code), offset);
	}

	uint32_t Thumb2RelativePatcher::GetInsn16(ArrayRef<const uint8_t> code, uint32_t offset) {
	DCHECK_LE(offset + 2u, code.size());
	DCHECK_ALIGNED(offset, 2u);
	const uint8_t* addr = &code[offset];
	return (static_cast<uint32_t>(addr[0]) << 0) + (static_cast<uint32_t>(addr[1]) << 8);
	}

	template <typename Vector>
	uint32_t Thumb2RelativePatcher::GetInsn16(Vector* code, uint32_t offset) {
	static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
	return GetInsn16(ArrayRef<const uint8_t>(*code), offset);
	}

	} // namespace linker
	} // namespace art