1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * llvm C frontend for perf. Support dynamically compile C file
4 *
5 * Inspired by clang example code:
6 * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
7 *
8 * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
9 * Copyright (C) 2016 Huawei Inc.
10 */
11
12 #include "clang/Basic/Version.h"
13 #include "clang/CodeGen/CodeGenAction.h"
14 #include "clang/Frontend/CompilerInvocation.h"
15 #include "clang/Frontend/CompilerInstance.h"
16 #include "clang/Frontend/TextDiagnosticPrinter.h"
17 #include "clang/Tooling/Tooling.h"
18 #include "llvm/IR/LegacyPassManager.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/Option/Option.h"
21 #include "llvm/Support/FileSystem.h"
22 #include "llvm/Support/ManagedStatic.h"
23 #include "llvm/Support/TargetRegistry.h"
24 #include "llvm/Support/TargetSelect.h"
25 #include "llvm/Target/TargetMachine.h"
26 #include "llvm/Target/TargetOptions.h"
27 #include <memory>
28
29 #include "clang.h"
30 #include "clang-c.h"
31
32 namespace perf {
33
34 static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
35
36 using namespace clang;
37
38 static CompilerInvocation *
createCompilerInvocation(llvm::opt::ArgStringList CFlags,StringRef & Path,DiagnosticsEngine & Diags)39 createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
40 DiagnosticsEngine& Diags)
41 {
42 llvm::opt::ArgStringList CCArgs {
43 "-cc1",
44 "-triple", "bpf-pc-linux",
45 "-fsyntax-only",
46 "-ferror-limit", "19",
47 "-fmessage-length", "127",
48 "-O2",
49 "-nostdsysteminc",
50 "-nobuiltininc",
51 "-vectorize-loops",
52 "-vectorize-slp",
53 "-Wno-unused-value",
54 "-Wno-pointer-sign",
55 "-x", "c"};
56
57 CCArgs.append(CFlags.begin(), CFlags.end());
58 CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
59
60 FrontendOptions& Opts = CI->getFrontendOpts();
61 Opts.Inputs.clear();
62 Opts.Inputs.emplace_back(Path,
63 FrontendOptions::getInputKindForExtension("c"));
64 return CI;
65 }
66
67 static std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags,StringRef Path,IntrusiveRefCntPtr<vfs::FileSystem> VFS)68 getModuleFromSource(llvm::opt::ArgStringList CFlags,
69 StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
70 {
71 CompilerInstance Clang;
72 Clang.createDiagnostics();
73
74 Clang.setVirtualFileSystem(&*VFS);
75
76 #if CLANG_VERSION_MAJOR < 4
77 IntrusiveRefCntPtr<CompilerInvocation> CI =
78 createCompilerInvocation(std::move(CFlags), Path,
79 Clang.getDiagnostics());
80 Clang.setInvocation(&*CI);
81 #else
82 std::shared_ptr<CompilerInvocation> CI(
83 createCompilerInvocation(std::move(CFlags), Path,
84 Clang.getDiagnostics()));
85 Clang.setInvocation(CI);
86 #endif
87
88 std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
89 if (!Clang.ExecuteAction(*Act))
90 return std::unique_ptr<llvm::Module>(nullptr);
91
92 return Act->takeModule();
93 }
94
95 std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags,StringRef Name,StringRef Content)96 getModuleFromSource(llvm::opt::ArgStringList CFlags,
97 StringRef Name, StringRef Content)
98 {
99 using namespace vfs;
100
101 llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
102 new OverlayFileSystem(getRealFileSystem()));
103 llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
104 new InMemoryFileSystem(true));
105
106 /*
107 * pushOverlay helps setting working dir for MemFS. Must call
108 * before addFile.
109 */
110 OverlayFS->pushOverlay(MemFS);
111 MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
112
113 return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
114 }
115
116 std::unique_ptr<llvm::Module>
getModuleFromSource(llvm::opt::ArgStringList CFlags,StringRef Path)117 getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
118 {
119 IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
120 return getModuleFromSource(std::move(CFlags), Path, VFS);
121 }
122
123 std::unique_ptr<llvm::SmallVectorImpl<char>>
getBPFObjectFromModule(llvm::Module * Module)124 getBPFObjectFromModule(llvm::Module *Module)
125 {
126 using namespace llvm;
127
128 std::string TargetTriple("bpf-pc-linux");
129 std::string Error;
130 const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
131 if (!Target) {
132 llvm::errs() << Error;
133 return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
134 }
135
136 llvm::TargetOptions Opt;
137 TargetMachine *TargetMachine =
138 Target->createTargetMachine(TargetTriple,
139 "generic", "",
140 Opt, Reloc::Static);
141
142 Module->setDataLayout(TargetMachine->createDataLayout());
143 Module->setTargetTriple(TargetTriple);
144
145 std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
146 raw_svector_ostream ostream(*Buffer);
147
148 legacy::PassManager PM;
149 bool NotAdded;
150 #if CLANG_VERSION_MAJOR < 7
151 NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream,
152 TargetMachine::CGFT_ObjectFile);
153 #else
154 NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream, nullptr,
155 TargetMachine::CGFT_ObjectFile);
156 #endif
157 if (NotAdded) {
158 llvm::errs() << "TargetMachine can't emit a file of this type\n";
159 return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
160 }
161 PM.run(*Module);
162
163 return Buffer;
164 }
165
166 }
167
168 extern "C" {
perf_clang__init(void)169 void perf_clang__init(void)
170 {
171 perf::LLVMCtx.reset(new llvm::LLVMContext());
172 LLVMInitializeBPFTargetInfo();
173 LLVMInitializeBPFTarget();
174 LLVMInitializeBPFTargetMC();
175 LLVMInitializeBPFAsmPrinter();
176 }
177
perf_clang__cleanup(void)178 void perf_clang__cleanup(void)
179 {
180 perf::LLVMCtx.reset(nullptr);
181 llvm::llvm_shutdown();
182 }
183
perf_clang__compile_bpf(const char * filename,void ** p_obj_buf,size_t * p_obj_buf_sz)184 int perf_clang__compile_bpf(const char *filename,
185 void **p_obj_buf,
186 size_t *p_obj_buf_sz)
187 {
188 using namespace perf;
189
190 if (!p_obj_buf || !p_obj_buf_sz)
191 return -EINVAL;
192
193 llvm::opt::ArgStringList CFlags;
194 auto M = getModuleFromSource(std::move(CFlags), filename);
195 if (!M)
196 return -EINVAL;
197 auto O = getBPFObjectFromModule(&*M);
198 if (!O)
199 return -EINVAL;
200
201 size_t size = O->size_in_bytes();
202 void *buffer;
203
204 buffer = malloc(size);
205 if (!buffer)
206 return -ENOMEM;
207 memcpy(buffer, O->data(), size);
208 *p_obj_buf = buffer;
209 *p_obj_buf_sz = size;
210 return 0;
211 }
212 }
213