[PATCH v3 20/30] perf clang jit: add PerfModule::doJIT to JIT perfhook functions

[Wang Nan]

PerfModule::doJIT JIT compile perfhook functions and saves result into
a map. Add a test case for it.

At this stage perfhook functions can do no useful things because they
can't invoke external functions and can't return value. Following
commits are going to make improvment.

Don't hook functions right after jitted because bpf_object is unavailable
during jitting but it should be the context of jitted functions.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/tests/bpf-script-example.c |  8 ++++
 tools/perf/tests/clang.c              |  4 ++
 tools/perf/util/c++/clang-c.h         |  2 +
 tools/perf/util/c++/clang-test.cpp    | 32 +++++++++++++++-
 tools/perf/util/c++/clang.cpp         | 71 +++++++++++++++++++++++++++++++++++
 tools/perf/util/c++/clang.h           | 13 +++++++
 6 files changed, 128 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
index 268e5f8..265036e 100644
--- a/tools/perf/tests/bpf-script-example.c
+++ b/tools/perf/tests/bpf-script-example.c
@@ -46,3 +46,11 @@ int bpf_func__SyS_epoll_wait(void *ctx)
 }
 char _license[] SEC("license") = "GPL";
 int _version SEC("version") = LINUX_VERSION_CODE;
+
+#ifdef TEST_PERF_HOOK
+SEC("perfhook:test")
+void hook_test(void)
+{
+	return;
+}
+#endif
diff --git a/tools/perf/tests/clang.c b/tools/perf/tests/clang.c
index 2964c06..f274e62 100644
--- a/tools/perf/tests/clang.c
+++ b/tools/perf/tests/clang.c
@@ -16,6 +16,10 @@ static struct {
 		.func = test__clang_to_obj,
 		.desc = "Test builtin clang compile C source to ELF object",
 	},
+	{
+		.func = test__clang_jit,
+		.desc = "Test builtin clang compile mixed BPF and native code",
+	},
 #endif
 };
 
diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h
index 0eadd79..5ebcb41 100644
--- a/tools/perf/util/c++/clang-c.h
+++ b/tools/perf/util/c++/clang-c.h
@@ -14,6 +14,7 @@ extern void perf_clang__cleanup(void);
 
 extern int test__clang_to_IR(void);
 extern int test__clang_to_obj(void);
+extern int test__clang_jit(void);
 
 extern int perf_clang__compile_bpf(const char *filename,
 				   void **p_obj_buf,
@@ -26,6 +27,7 @@ static inline void perf_clang__cleanup(void) { }
 
 static inline int test__clang_to_IR(void) { return -1; }
 static inline int test__clang_to_obj(void) { return -1;}
+static inline int test__clang_jit(void) { return -1;}
 
 static inline int
 perf_clang__compile_bpf(const char *filename __maybe_unused,
diff --git a/tools/perf/util/c++/clang-test.cpp b/tools/perf/util/c++/clang-test.cpp
index fb05e56..2b4aa8d 100644
--- a/tools/perf/util/c++/clang-test.cpp
+++ b/tools/perf/util/c++/clang-test.cpp
@@ -5,6 +5,7 @@
 
 #include <util-cxx.h>
 #include <tests/llvm.h>
+#include <perf-hooks.h>
 #include <string>
 
 class perf_clang_scope {
@@ -14,7 +15,7 @@ public:
 };
 
 static std::unique_ptr<perf::PerfModule>
-__test__clang_to_IR(void)
+__test__clang_to_IR(bool perfhook)
 {
 	unsigned int kernel_version;
 
@@ -23,14 +24,22 @@ __test__clang_to_IR(void)
 
 	std::string cflag_kver("-DLINUX_VERSION_CODE=" +
 				std::to_string(kernel_version));
+	std::string cflag_perfhook(perfhook ? "-DTEST_PERF_HOOK=1" : "");
 
 	std::unique_ptr<perf::PerfModule> M =
-		perf::getModuleFromSource({cflag_kver.c_str()},
+		perf::getModuleFromSource({cflag_kver.c_str(),
+					   cflag_perfhook.c_str()},
 					  "perf-test.c",
 					  test_llvm__bpf_base_prog);
 	return M;
 }
 
+static std::unique_ptr<perf::PerfModule>
+__test__clang_to_IR(void)
+{
+	return __test__clang_to_IR(false);
+}
+
 extern "C" {
 int test__clang_to_IR(void)
 {
@@ -59,4 +68,23 @@ int test__clang_to_obj(void)
 	return 0;
 }
 
+int test__clang_jit(void)
+{
+	perf_clang_scope _scope;
+
+	auto M = __test__clang_to_IR(true);
+	if (!M)
+		return -1;
+
+	if (M->doJIT())
+		return -1;
+
+	std::unique_ptr<perf::PerfModule::HookMap> hooks(M->copyJITResult());
+	for (auto i : *hooks)
+		perf_hooks__set_hook(i.first.c_str(), i.second, NULL);
+
+	perf_hooks__invoke_test();
+	return 0;
+}
+
 }
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index 98d05e2..03012b2 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -14,9 +14,14 @@
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
+#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
+#include "llvm/ExecutionEngine/Orc/LambdaResolver.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Option/Option.h"
+#include "llvm/Support/DynamicLibrary.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/TargetRegistry.h"
@@ -24,11 +29,13 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include <memory>
+#include <vector>
 
 #include "clang.h"
 #include "clang-c.h"
 #include "llvm-utils.h"
 #include "util-cxx.h"
+#include "perf-hooks.h"
 
 namespace perf {
 
@@ -187,6 +194,66 @@ PerfModule::toBPFObject(void)
 	return std::move(Buffer);
 }
 
+/*
+ * Use a global memory manager so allocated code and data won't be released
+ * when object destroy.
+ */
+static llvm::SectionMemoryManager JITMemoryManager;
+
+int PerfModule::doJIT(void)
+{
+	using namespace orc;
+
+	prepareJIT();
+
+	std::unique_ptr<TargetMachine> TM(EngineBuilder().selectTarget());
+	if (!TM) {
+		llvm::errs() << "Can't get target machine\n";
+		return -1;
+	}
+	const DataLayout DL(TM->createDataLayout());
+	Module->setDataLayout(DL);
+	Module->setTargetTriple(TM->getTargetTriple().normalize());
+
+	ObjectLinkingLayer<> ObjectLayer;
+	IRCompileLayer<decltype(ObjectLayer)> CompileLayer(ObjectLayer, SimpleCompiler(*TM));
+
+	auto Resolver = createLambdaResolver(
+			[](const std::string &Name) {
+				return RuntimeDyld::SymbolInfo(nullptr);
+			},
+			[](const std::string &Name) {
+				return RuntimeDyld::SymbolInfo(nullptr);
+			});
+
+	std::vector<llvm::Module *> Ms;
+	Ms.push_back(getModule());
+	CompileLayer.addModuleSet(std::move(Ms),
+			&JITMemoryManager,
+			std::move(Resolver));
+
+
+	for (Function *F : JITFunctions) {
+		JITSymbol sym = CompileLayer.findSymbol(F->getName().str(), true);
+
+		/*
+		 * Type of F->getSection() is moving from
+		 * const char * to StringRef.
+		 * Convert it to std::string so we don't need
+		 * consider this API change.
+		 */
+		std::string sec(F->getSection());
+		std::string hook(&sec.c_str()[sizeof("perfhook:") - 1]);
+		perf_hook_func_t func = (perf_hook_func_t)(intptr_t)sym.getAddress();
+
+		if (JITResult[hook])
+			llvm::errs() << "Warning: multiple functions on hook "
+				     << hook << ", only one is used\n";
+		JITResult[hook] = func;
+	}
+	return 0;
+}
+
 class ClangOptions {
 	llvm::SmallString<PATH_MAX> FileName;
 	llvm::SmallString<64> KVerDef;
@@ -292,6 +359,10 @@ void perf_clang__init(void)
 	LLVMInitializeBPFTarget();
 	LLVMInitializeBPFTargetMC();
 	LLVMInitializeBPFAsmPrinter();
+
+	llvm::InitializeNativeTarget();
+	llvm::InitializeNativeTargetAsmPrinter();
+	llvm::InitializeNativeTargetAsmParser();
 }
 
 void perf_clang__cleanup(void)
diff --git a/tools/perf/util/c++/clang.h b/tools/perf/util/c++/clang.h
index 1eb71a6..df2eb8f 100644
--- a/tools/perf/util/c++/clang.h
+++ b/tools/perf/util/c++/clang.h
@@ -7,18 +7,26 @@
 #include "llvm/Option/Option.h"
 #include <memory>
 #include <set>
+#include <map>
+
+#include "util/perf-hooks.h"
 
 namespace perf {
 
 using namespace llvm;
 
 class PerfModule {
+public:
+	typedef std::map<std::string, perf_hook_func_t> HookMap;
 private:
 	std::unique_ptr<llvm::Module> Module;
 
 	std::set<llvm::GlobalVariable *> Maps;
 	std::set<llvm::Function *> BPFFunctions;
 	std::set<llvm::Function *> JITFunctions;
+
+	HookMap JITResult;
+
 	void prepareBPF(void);
 	void prepareJIT(void);
 public:
@@ -26,10 +34,15 @@ class PerfModule {
 	{
 		return Module.get();
 	}
+	inline HookMap *copyJITResult(void)
+	{
+		return new HookMap(JITResult);
+	}
 
 	PerfModule(std::unique_ptr<llvm::Module>&& M);
 
 	std::unique_ptr<llvm::SmallVectorImpl<char>> toBPFObject(void);
+	int doJIT(void);
 };
 
 std::unique_ptr<PerfModule>
-- 
2.10.1