143 lines
5.2 KiB
C++
143 lines
5.2 KiB
C++
//===-- xray_AArch64.cpp ----------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of XRay, a dynamic runtime instrumentation system.
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//
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// Implementation of AArch64-specific routines (64-bit).
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//
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//===----------------------------------------------------------------------===//
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#include "sanitizer_common/sanitizer_common.h"
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#include "xray_defs.h"
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#include "xray_interface_internal.h"
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#include <atomic>
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#include <cassert>
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extern "C" void __clear_cache(void *start, void *end);
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namespace __xray {
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// The machine codes for some instructions used in runtime patching.
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enum class PatchOpcodes : uint32_t {
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PO_StpX0X30SP_m16e = 0xA9BF7BE0, // STP X0, X30, [SP, #-16]!
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PO_LdrX16_12 = 0x58000070, // LDR X16, #12
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PO_BlrX16 = 0xD63F0200, // BLR X16
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PO_LdpX0X30SP_16 = 0xA8C17BE0, // LDP X0, X30, [SP], #16
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PO_B32 = 0x14000008 // B #32
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};
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inline static bool patchSled(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled,
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void (*TracingHook)()) XRAY_NEVER_INSTRUMENT {
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// When |Enable| == true,
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// We replace the following compile-time stub (sled):
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//
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// xray_sled_n:
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// B #32
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// 7 NOPs (24 bytes)
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//
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// With the following runtime patch:
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//
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// xray_sled_n:
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// STP X0, X30, [SP, #-16]! ; PUSH {r0, lr}
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// LDR W17, #12 ; W17 := function ID
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// LDR X16,#12 ; X16 := address of the trampoline
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// BLR X16
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// ;DATA: 32 bits of function ID
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// ;DATA: lower 32 bits of the address of the trampoline
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// ;DATA: higher 32 bits of the address of the trampoline
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// LDP X0, X30, [SP], #16 ; POP {r0, lr}
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//
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// Replacement of the first 4-byte instruction should be the last and atomic
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// operation, so that the user code which reaches the sled concurrently
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// either jumps over the whole sled, or executes the whole sled when the
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// latter is ready.
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//
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// When |Enable|==false, we set back the first instruction in the sled to be
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// B #32
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uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.address());
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uint32_t *CurAddress = FirstAddress + 1;
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if (Enable) {
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*CurAddress++ = 0x18000071; // ldr w17, #12
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*CurAddress = uint32_t(PatchOpcodes::PO_LdrX16_12);
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CurAddress++;
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*CurAddress = uint32_t(PatchOpcodes::PO_BlrX16);
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CurAddress++;
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*CurAddress = FuncId;
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CurAddress++;
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*reinterpret_cast<void (**)()>(CurAddress) = TracingHook;
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CurAddress += 2;
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*CurAddress = uint32_t(PatchOpcodes::PO_LdpX0X30SP_16);
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CurAddress++;
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std::atomic_store_explicit(
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reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
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uint32_t(PatchOpcodes::PO_StpX0X30SP_m16e), std::memory_order_release);
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} else {
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std::atomic_store_explicit(
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reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
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uint32_t(PatchOpcodes::PO_B32), std::memory_order_release);
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}
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__clear_cache(reinterpret_cast<char *>(FirstAddress),
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reinterpret_cast<char *>(CurAddress));
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return true;
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}
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bool patchFunctionEntry(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled,
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void (*Trampoline)()) XRAY_NEVER_INSTRUMENT {
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return patchSled(Enable, FuncId, Sled, Trampoline);
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}
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bool patchFunctionExit(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
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return patchSled(Enable, FuncId, Sled, __xray_FunctionExit);
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}
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bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
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return patchSled(Enable, FuncId, Sled, __xray_FunctionTailExit);
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}
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// AArch64AsmPrinter::LowerPATCHABLE_EVENT_CALL generates this code sequence:
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//
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// .Lxray_event_sled_N:
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// b 1f
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// save x0 and x1 (and also x2 for TYPED_EVENT_CALL)
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// set up x0 and x1 (and also x2 for TYPED_EVENT_CALL)
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// bl __xray_CustomEvent or __xray_TypedEvent
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// restore x0 and x1 (and also x2 for TYPED_EVENT_CALL)
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// 1f
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//
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// There are 6 instructions for EVENT_CALL and 9 for TYPED_EVENT_CALL.
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//
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// Enable: b .+24 => nop
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// Disable: nop => b .+24
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bool patchCustomEvent(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
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uint32_t Inst = Enable ? 0xd503201f : 0x14000006;
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std::atomic_store_explicit(
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reinterpret_cast<std::atomic<uint32_t> *>(Sled.address()), Inst,
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std::memory_order_release);
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return false;
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}
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// Enable: b +36 => nop
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// Disable: nop => b +36
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bool patchTypedEvent(const bool Enable, const uint32_t FuncId,
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const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
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uint32_t Inst = Enable ? 0xd503201f : 0x14000009;
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std::atomic_store_explicit(
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reinterpret_cast<std::atomic<uint32_t> *>(Sled.address()), Inst,
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std::memory_order_release);
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return false;
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}
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// FIXME: Maybe implement this better?
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bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
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} // namespace __xray
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