1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
//===- bolt/Rewrite/SDTRewriter.cpp ---------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implement support for System Tap Statically-Defined Trace points stored in
// .note.stapsdt section.
//
//===----------------------------------------------------------------------===//
#include "bolt/Core/BinaryFunction.h"
#include "bolt/Core/DebugData.h"
#include "bolt/Rewrite/MetadataRewriter.h"
#include "bolt/Rewrite/MetadataRewriters.h"
#include "bolt/Utils/CommandLineOpts.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Timer.h"
using namespace llvm;
using namespace bolt;
namespace opts {
static cl::opt<bool> PrintSDTMarkers("print-sdt",
cl::desc("print all SDT markers"),
cl::Hidden, cl::cat(BoltCategory));
}
namespace {
class SDTRewriter final : public MetadataRewriter {
ErrorOr<BinarySection &> SDTSection{std::errc::bad_address};
struct SDTMarkerInfo {
uint64_t PC;
uint64_t Base;
uint64_t Semaphore;
StringRef Provider;
StringRef Name;
StringRef Args;
/// The offset of PC within the note section
unsigned PCOffset;
};
/// Map SDT locations to SDT markers info
using SDTMarkersListType = std::unordered_map<uint64_t, SDTMarkerInfo>;
SDTMarkersListType SDTMarkers;
/// Read section to populate SDTMarkers.
void readSection();
void printSDTMarkers() const;
public:
SDTRewriter(StringRef Name, BinaryContext &BC) : MetadataRewriter(Name, BC) {}
Error preCFGInitializer() override;
Error postEmitFinalizer() override;
};
void SDTRewriter::readSection() {
SDTSection = BC.getUniqueSectionByName(".note.stapsdt");
if (!SDTSection)
return;
StringRef Buf = SDTSection->getContents();
DataExtractor DE = DataExtractor(Buf, BC.AsmInfo->isLittleEndian(),
BC.AsmInfo->getCodePointerSize());
uint64_t Offset = 0;
while (DE.isValidOffset(Offset)) {
uint32_t NameSz = DE.getU32(&Offset);
DE.getU32(&Offset); // skip over DescSz
uint32_t Type = DE.getU32(&Offset);
Offset = alignTo(Offset, 4);
if (Type != 3)
errs() << "BOLT-WARNING: SDT note type \"" << Type
<< "\" is not expected\n";
if (NameSz == 0)
errs() << "BOLT-WARNING: SDT note has empty name\n";
StringRef Name = DE.getCStr(&Offset);
if (!Name.equals("stapsdt"))
errs() << "BOLT-WARNING: SDT note name \"" << Name
<< "\" is not expected\n";
// Parse description
SDTMarkerInfo Marker;
Marker.PCOffset = Offset;
Marker.PC = DE.getU64(&Offset);
Marker.Base = DE.getU64(&Offset);
Marker.Semaphore = DE.getU64(&Offset);
Marker.Provider = DE.getCStr(&Offset);
Marker.Name = DE.getCStr(&Offset);
Marker.Args = DE.getCStr(&Offset);
Offset = alignTo(Offset, 4);
SDTMarkers[Marker.PC] = Marker;
}
if (opts::PrintSDTMarkers)
printSDTMarkers();
}
Error SDTRewriter::preCFGInitializer() {
// Populate SDTMarkers.
readSection();
// Mark nop instructions referenced by SDT and the containing function.
for (const uint64_t PC : llvm::make_first_range(SDTMarkers)) {
BinaryFunction *BF = BC.getBinaryFunctionContainingAddress(PC);
if (!BF || !BC.shouldEmit(*BF))
continue;
const uint64_t Offset = PC - BF->getAddress();
MCInst *Inst = BF->getInstructionAtOffset(Offset);
if (!Inst)
return createStringError(errc::executable_format_error,
"no instruction matches SDT offset");
if (!BC.MIB->isNoop(*Inst))
return createStringError(std::make_error_code(std::errc::not_supported),
"nop instruction expected at SDT offset");
BC.MIB->setOffset(*Inst, static_cast<uint32_t>(Offset));
BF->setHasSDTMarker(true);
}
return Error::success();
}
Error SDTRewriter::postEmitFinalizer() {
if (!SDTSection)
return Error::success();
SDTSection->registerPatcher(std::make_unique<SimpleBinaryPatcher>());
SimpleBinaryPatcher *SDTNotePatcher =
static_cast<SimpleBinaryPatcher *>(SDTSection->getPatcher());
for (auto &SDTInfoKV : SDTMarkers) {
const uint64_t OriginalAddress = SDTInfoKV.first;
const SDTMarkerInfo &SDTInfo = SDTInfoKV.second;
const BinaryFunction *F =
BC.getBinaryFunctionContainingAddress(OriginalAddress);
if (!F)
continue;
const uint64_t NewAddress =
F->translateInputToOutputAddress(OriginalAddress);
SDTNotePatcher->addLE64Patch(SDTInfo.PCOffset, NewAddress);
}
return Error::success();
}
void SDTRewriter::printSDTMarkers() const {
outs() << "BOLT-INFO: Number of SDT markers is " << SDTMarkers.size() << "\n";
for (const SDTMarkerInfo &Marker : llvm::make_second_range(SDTMarkers)) {
outs() << "BOLT-INFO: PC: " << utohexstr(Marker.PC)
<< ", Base: " << utohexstr(Marker.Base)
<< ", Semaphore: " << utohexstr(Marker.Semaphore)
<< ", Provider: " << Marker.Provider << ", Name: " << Marker.Name
<< ", Args: " << Marker.Args << "\n";
}
}
} // namespace
std::unique_ptr<MetadataRewriter>
llvm::bolt::createSDTRewriter(BinaryContext &BC) {
return std::make_unique<SDTRewriter>("sdt-rewriter", BC);
}
|
