Add ability to set custom cflags when loading programs

Example: b = bcc.BPF("myprog.c", cflags=["-DMYCUSTOMFLAG1", ...]) Signed-off-by: Brenden Blanco <[email protected]>
iovisor · Jan 6, 2016 · 9358850 · 9358850
1 parent 4386195
commit 9358850
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Showing 8 changed files with 40 additions and 23 deletions.
diff --git a/src/cc/bpf_common.cc b/src/cc/bpf_common.cc
@@ -26,18 +26,18 @@ void * bpf_module_create_b(const char *filename, const char *proto_filename, uns
  return mod;
 }
 
-void * bpf_module_create_c(const char *filename, unsigned flags) {
+void * bpf_module_create_c(const char *filename, unsigned flags, const char *cflags[], int ncflags) {
  auto mod = new ebpf::BPFModule(flags);
- if (mod->load_c(filename) != 0) {
+ if (mod->load_c(filename, cflags, ncflags) != 0) {
  delete mod;
  return nullptr;
  }
  return mod;
 }
 
-void * bpf_module_create_c_from_string(const char *text, unsigned flags) {
+void * bpf_module_create_c_from_string(const char *text, unsigned flags, const char *cflags[], int ncflags) {
  auto mod = new ebpf::BPFModule(flags);
- if (mod->load_string(text) != 0) {
+ if (mod->load_string(text, cflags, ncflags) != 0) {
  delete mod;
  return nullptr;
  }

diff --git a/src/cc/bpf_common.h b/src/cc/bpf_common.h
@@ -25,8 +25,8 @@ extern "C" {
 #endif
 
 void * bpf_module_create_b(const char *filename, const char *proto_filename, unsigned flags);
-void * bpf_module_create_c(const char *filename, unsigned flags);
-void * bpf_module_create_c_from_string(const char *text, unsigned flags);
+void * bpf_module_create_c(const char *filename, unsigned flags, const char *cflags[], int ncflags);
+void * bpf_module_create_c_from_string(const char *text, unsigned flags, const char *cflags[], int ncflags);
 void bpf_module_destroy(void *program);
 char * bpf_module_license(void *program);
 unsigned bpf_module_kern_version(void *program);

diff --git a/src/cc/bpf_module.cc b/src/cc/bpf_module.cc
@@ -299,9 +299,9 @@ unique_ptr<ExecutionEngine> BPFModule::finalize_rw(unique_ptr<Module> m) {
 }
 
 // load an entire c file as a module
-int BPFModule::load_cfile(const string &file, bool in_memory) {
+int BPFModule::load_cfile(const string &file, bool in_memory, const char *cflags[], int ncflags) {
  clang_loader_ = make_unique<ClangLoader>(&*ctx_, flags_);
- if (clang_loader_->parse(&mod_, &tables_, file, in_memory))
+ if (clang_loader_->parse(&mod_, &tables_, file, in_memory, cflags, ncflags))
  return -1;
  return 0;
 }
@@ -313,7 +313,7 @@ int BPFModule::load_cfile(const string &file, bool in_memory) {
 // build an ExecutionEngine.
 int BPFModule::load_includes(const string &tmpfile) {
  clang_loader_ = make_unique<ClangLoader>(&*ctx_, flags_);
- if (clang_loader_->parse(&mod_, &tables_, tmpfile, false))
+ if (clang_loader_->parse(&mod_, &tables_, tmpfile, false, nullptr, 0))
  return -1;
  return 0;
 }
@@ -668,7 +668,7 @@ int BPFModule::load_b(const string &filename, const string &proto_filename) {
 }
 
 // load a C file
-int BPFModule::load_c(const string &filename) {
+int BPFModule::load_c(const string &filename, const char *cflags[], int ncflags) {
  if (!sections_.empty()) {
  fprintf(stderr, "Program already initialized\n");
  return -1;
@@ -677,7 +677,7 @@ int BPFModule::load_c(const string &filename) {
  fprintf(stderr, "Invalid filename\n");
  return -1;
  }
- if (int rc = load_cfile(filename, false))
+ if (int rc = load_cfile(filename, false, cflags, ncflags))
  return rc;
  if (int rc = annotate())
  return rc;
@@ -687,12 +687,12 @@ int BPFModule::load_c(const string &filename) {
 }
 
 // load a C text string
-int BPFModule::load_string(const string &text) {
+int BPFModule::load_string(const string &text, const char *cflags[], int ncflags) {
  if (!sections_.empty()) {
  fprintf(stderr, "Program already initialized\n");
  return -1;
  }
- if (int rc = load_cfile(text, true))
+ if (int rc = load_cfile(text, true, cflags, ncflags))
  return rc;
  if (int rc = annotate())
  return rc;

diff --git a/src/cc/bpf_module.h b/src/cc/bpf_module.h
@@ -48,15 +48,15 @@ class BPFModule {
  void dump_ir(llvm::Module &mod);
  int load_file_module(std::unique_ptr<llvm::Module> *mod, const std::string &file, bool in_memory);
  int load_includes(const std::string &tmpfile);
- int load_cfile(const std::string &file, bool in_memory);
+ int load_cfile(const std::string &file, bool in_memory, const char *cflags[], int ncflags);
  int kbuild_flags(const char *uname_release, std::vector<std::string> *cflags);
  int run_pass_manager(llvm::Module &mod);
  public:
  BPFModule(unsigned flags);
  ~BPFModule();
  int load_b(const std::string &filename, const std::string &proto_filename);
- int load_c(const std::string &filename);
- int load_string(const std::string &text);
+ int load_c(const std::string &filename, const char *cflags[], int ncflags);
+ int load_string(const std::string &text, const char *cflags[], int ncflags);
  size_t num_functions() const;
  uint8_t * function_start(size_t id) const;
  uint8_t * function_start(const std::string &name) const;

diff --git a/src/cc/frontends/clang/loader.cc b/src/cc/frontends/clang/loader.cc
@@ -65,7 +65,7 @@ ClangLoader::ClangLoader(llvm::LLVMContext *ctx, unsigned flags)
 ClangLoader::~ClangLoader() {}
 
 int ClangLoader::parse(unique_ptr<llvm::Module> *mod, unique_ptr<vector<TableDesc>> *tables,
- const string &file, bool in_memory) {
+ const string &file, bool in_memory, const char *cflags[], int ncflags) {
  using namespace clang;
 
  struct utsname un;
@@ -103,6 +103,10 @@ int ClangLoader::parse(unique_ptr<llvm::Module> *mod, unique_ptr<vector<TableDes
  kflags.push_back(BCC_INSTALL_PREFIX "/share/bcc/include");
  for (auto it = kflags.begin(); it != kflags.end(); ++it)
  flags_cstr.push_back(it->c_str());
+ if (cflags) {
+ for (auto i = 0; i < ncflags; ++i)
+ flags_cstr.push_back(cflags[i]);
+ }
 
  // set up the error reporting class
  IntrusiveRefCntPtr<DiagnosticOptions> diag_opts(new DiagnosticOptions());

diff --git a/src/cc/frontends/clang/loader.h b/src/cc/frontends/clang/loader.h
@@ -39,7 +39,7 @@ class ClangLoader {
  explicit ClangLoader(llvm::LLVMContext *ctx, unsigned flags);
  ~ClangLoader();
  int parse(std::unique_ptr<llvm::Module> *mod, std::unique_ptr<std::vector<TableDesc>> *tables,
- const std::string &file, bool in_memory);
+ const std::string &file, bool in_memory, const char *cflags[], int ncflags);
  private:
  llvm::LLVMContext *ctx_;
  unsigned flags_;

diff --git a/src/python/bcc/__init__.py b/src/python/bcc/__init__.py
@@ -30,9 +30,11 @@
 lib.bpf_module_create_b.restype = ct.c_void_p
 lib.bpf_module_create_b.argtypes = [ct.c_char_p, ct.c_char_p, ct.c_uint]
 lib.bpf_module_create_c.restype = ct.c_void_p
-lib.bpf_module_create_c.argtypes = [ct.c_char_p, ct.c_uint]
+lib.bpf_module_create_c.argtypes = [ct.c_char_p, ct.c_uint,
+ ct.POINTER(ct.c_char_p), ct.c_int]
 lib.bpf_module_create_c_from_string.restype = ct.c_void_p
-lib.bpf_module_create_c_from_string.argtypes = [ct.c_char_p, ct.c_uint]
+lib.bpf_module_create_c_from_string.argtypes = [ct.c_char_p, ct.c_uint,
+ ct.POINTER(ct.c_char_p), ct.c_int]
 lib.bpf_module_destroy.restype = None
 lib.bpf_module_destroy.argtypes = [ct.c_void_p]
 lib.bpf_module_license.restype = ct.c_char_p
@@ -395,7 +397,7 @@ def _find_file(filename):
  raise Exception("Could not find file %s" % filename)
  return filename
 
- def __init__(self, src_file="", hdr_file="", text=None, cb=None, debug=0):
+ def __init__(self, src_file="", hdr_file="", text=None, cb=None, debug=0, cflags=[]):
  """Create a a new BPF module with the given source code.
 
  Note:
@@ -416,8 +418,11 @@ def __init__(self, src_file="", hdr_file="", text=None, cb=None, debug=0):
  self.debug = debug
  self.funcs = {}
  self.tables = {}
+ cflags_array = (ct.c_char_p * len(cflags))()
+ for i, s in enumerate(cflags): cflags_array[i] = s.encode("ascii")
  if text:
- self.module = lib.bpf_module_create_c_from_string(text.encode("ascii"), self.debug)
+ self.module = lib.bpf_module_create_c_from_string(text.encode("ascii"),
+ self.debug, cflags_array, len(cflags_array))
  else:
  src_file = BPF._find_file(src_file)
  hdr_file = BPF._find_file(hdr_file)
@@ -426,7 +431,7 @@ def __init__(self, src_file="", hdr_file="", text=None, cb=None, debug=0):
  hdr_file.encode("ascii"), self.debug)
  else:
  self.module = lib.bpf_module_create_c(src_file.encode("ascii"),
- self.debug)
+ self.debug, cflags_array, len(cflags_array))
 
  if self.module == None:
  raise Exception("Failed to compile BPF module %s" % src_file)

diff --git a/tests/cc/test_clang.py b/tests/cc/test_clang.py
@@ -287,5 +287,13 @@ def test_complex_leaf_types(self):
  import ctypes
  self.assertEqual(ctypes.sizeof(b["t3"].Leaf), 8)
 
+ def test_cflags(self):
+ text = """
+#ifndef MYFLAG
+#error "MYFLAG not set as expected"
+#endif
+"""
+ b = BPF(text=text, cflags=["-DMYFLAG"])
+
 if __name__ == "__main__":
  main()