1//===- FaultMaps.cpp ------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/CodeGen/FaultMaps.h"
10#include "llvm/ADT/Twine.h"
11#include "llvm/CodeGen/AsmPrinter.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCExpr.h"
14#include "llvm/MC/MCObjectFileInfo.h"
15#include "llvm/MC/MCStreamer.h"
16#include "llvm/Support/Debug.h"
17#include "llvm/Support/ErrorHandling.h"
18
19using namespace llvm;
20
21#define DEBUG_TYPE "faultmaps"
22
23static const int FaultMapVersion = 1;
24const char *FaultMaps::WFMP = "Fault Maps: ";
25
26FaultMaps::FaultMaps(AsmPrinter &AP) : AP(AP) {}
27
28void FaultMaps::recordFaultingOp(FaultKind FaultTy,
29                                 const MCSymbol *FaultingLabel,
30                                 const MCSymbol *HandlerLabel) {
31  MCContext &OutContext = AP.OutStreamer->getContext();
32
33  const MCExpr *FaultingOffset = MCBinaryExpr::createSub(
34      MCSymbolRefExpr::create(FaultingLabel, OutContext),
35      MCSymbolRefExpr::create(AP.CurrentFnSymForSize, OutContext), OutContext);
36
37  const MCExpr *HandlerOffset = MCBinaryExpr::createSub(
38      MCSymbolRefExpr::create(HandlerLabel, OutContext),
39      MCSymbolRefExpr::create(AP.CurrentFnSymForSize, OutContext), OutContext);
40
41  FunctionInfos[AP.CurrentFnSym].emplace_back(FaultTy, FaultingOffset,
42                                              HandlerOffset);
43}
44
45void FaultMaps::serializeToFaultMapSection() {
46  if (FunctionInfos.empty())
47    return;
48
49  MCContext &OutContext = AP.OutStreamer->getContext();
50  MCStreamer &OS = *AP.OutStreamer;
51
52  // Create the section.
53  MCSection *FaultMapSection =
54      OutContext.getObjectFileInfo()->getFaultMapSection();
55  OS.switchSection(FaultMapSection);
56
57  // Emit a dummy symbol to force section inclusion.
58  OS.emitLabel(OutContext.getOrCreateSymbol(Twine("__LLVM_FaultMaps")));
59
60  LLVM_DEBUG(dbgs() << "********** Fault Map Output **********\n");
61
62  // Header
63  OS.emitIntValue(FaultMapVersion, 1); // Version.
64  OS.emitIntValue(0, 1);               // Reserved.
65  OS.emitInt16(0);                     // Reserved.
66
67  LLVM_DEBUG(dbgs() << WFMP << "#functions = " << FunctionInfos.size() << "\n");
68  OS.emitInt32(FunctionInfos.size());
69
70  LLVM_DEBUG(dbgs() << WFMP << "functions:\n");
71
72  for (const auto &FFI : FunctionInfos)
73    emitFunctionInfo(FFI.first, FFI.second);
74}
75
76void FaultMaps::emitFunctionInfo(const MCSymbol *FnLabel,
77                                 const FunctionFaultInfos &FFI) {
78  MCStreamer &OS = *AP.OutStreamer;
79
80  LLVM_DEBUG(dbgs() << WFMP << "  function addr: " << *FnLabel << "\n");
81  OS.emitSymbolValue(FnLabel, 8);
82
83  LLVM_DEBUG(dbgs() << WFMP << "  #faulting PCs: " << FFI.size() << "\n");
84  OS.emitInt32(FFI.size());
85
86  OS.emitInt32(0); // Reserved
87
88  for (const auto &Fault : FFI) {
89    LLVM_DEBUG(dbgs() << WFMP << "    fault type: "
90                      << faultTypeToString(Fault.Kind) << "\n");
91    OS.emitInt32(Fault.Kind);
92
93    LLVM_DEBUG(dbgs() << WFMP << "    faulting PC offset: "
94                      << *Fault.FaultingOffsetExpr << "\n");
95    OS.emitValue(Fault.FaultingOffsetExpr, 4);
96
97    LLVM_DEBUG(dbgs() << WFMP << "    fault handler PC offset: "
98                      << *Fault.HandlerOffsetExpr << "\n");
99    OS.emitValue(Fault.HandlerOffsetExpr, 4);
100  }
101}
102
103const char *FaultMaps::faultTypeToString(FaultMaps::FaultKind FT) {
104  switch (FT) {
105  default:
106    llvm_unreachable("unhandled fault type!");
107  case FaultMaps::FaultingLoad:
108    return "FaultingLoad";
109  case FaultMaps::FaultingLoadStore:
110    return "FaultingLoadStore";
111  case FaultMaps::FaultingStore:
112    return "FaultingStore";
113  }
114}
115