Identify BPF functions, JIT functions and maps during init. Functions in section starting with "perfhook:" are JIT functions. They will be JIT compiled and hooked at perfhooks.
During init of PerfModule, mark JIT functions as AvailableExternallyLinkage. LLVM skips functions with linkage like this so they won't be compiled into BPF objects. Signed-off-by: Wang Nan <wangn...@huawei.com> Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Cc: Alexei Starovoitov <a...@fb.com> Cc: He Kuang <heku...@huawei.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Zefan Li <lize...@huawei.com> Cc: pi3or...@163.com --- tools/perf/util/c++/clang.cpp | 32 ++++++++++++++++++++++++++++++++ tools/perf/util/c++/clang.h | 7 +++++++ 2 files changed, 39 insertions(+) diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp index d31b0a5..98d05e2 100644 --- a/tools/perf/util/c++/clang.cpp +++ b/tools/perf/util/c++/clang.cpp @@ -115,15 +115,47 @@ getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path) PerfModule::PerfModule(std::unique_ptr<llvm::Module>&& M) : Module(std::move(M)) { + for (llvm::Function& F : *Module) { + if (F.getLinkage() != llvm::GlobalValue::ExternalLinkage) + continue; + + if (StringRef(F.getSection()).startswith("perfhook:")) + JITFunctions.insert(&F); + else + BPFFunctions.insert(&F); + } + for (auto V = Module->global_begin(); V != Module->global_end(); V++) { + llvm::GlobalVariable *GV = &*V; + if (StringRef(GV->getSection()) == llvm::StringRef("maps")) + Maps.insert(GV); + } } +void PerfModule::prepareBPF(void) +{ + for (llvm::Function *F : JITFunctions) + F->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); + for (llvm::Function *F : BPFFunctions) + F->setLinkage(llvm::GlobalValue::ExternalLinkage); + +} + +void PerfModule::prepareJIT(void) +{ + for (llvm::Function *F : BPFFunctions) + F->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); + for (llvm::Function *F : JITFunctions) + F->setLinkage(llvm::GlobalValue::ExternalLinkage); + +} std::unique_ptr<llvm::SmallVectorImpl<char>> PerfModule::toBPFObject(void) { using namespace llvm; + prepareBPF(); std::string TargetTriple("bpf-pc-linux"); std::string Error; const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error); diff --git a/tools/perf/util/c++/clang.h b/tools/perf/util/c++/clang.h index cbb291b..1eb71a6 100644 --- a/tools/perf/util/c++/clang.h +++ b/tools/perf/util/c++/clang.h @@ -6,6 +6,7 @@ #include "llvm/IR/Module.h" #include "llvm/Option/Option.h" #include <memory> +#include <set> namespace perf { @@ -14,6 +15,12 @@ using namespace llvm; class PerfModule { private: std::unique_ptr<llvm::Module> Module; + + std::set<llvm::GlobalVariable *> Maps; + std::set<llvm::Function *> BPFFunctions; + std::set<llvm::Function *> JITFunctions; + void prepareBPF(void); + void prepareJIT(void); public: inline llvm::Module *getModule(void) { -- 2.10.1