clang/loader: Add support for specifying absolute path of kernel sources

Many developers have kernel sources at an specific location. Allow clang to build from there by allowing to specify a single absolute path to the kernel sources through a new env var BCC_KERNEL_SOURCE. Signed-off-by: Joel Fernandes <[email protected]>
linuxzjs · Feb 6, 2018 · 11f3a27 · 11f3a27
1 parent 3613ff8
commit 11f3a27
Showing 1 changed file with 19 additions and 4 deletions.
diff --git a/src/cc/frontends/clang/loader.cc b/src/cc/frontends/clang/loader.cc
@@ -29,6 +29,7 @@
 #include <unistd.h>
 #include <utility>
 #include <vector>
+#include <iostream>
 #include <linux/bpf.h>
 
 #include <clang/Basic/FileManager.h>
@@ -108,11 +109,24 @@ int ClangLoader::parse(unique_ptr<llvm::Module> *mod, TableStorage &ts,
  unique_ptr<llvm::MemoryBuffer> main_buf;
  struct utsname un;
  uname(&un);
- string kdir = string(KERNEL_MODULES_DIR) + "/" + un.release;
- auto kernel_path_info = get_kernel_path_info (kdir);
+ string kdir, kpath;
+ const char *kpath_env = ::getenv("BCC_KERNEL_SOURCE");
+ bool has_kpath_source = false;
+
+ if (kpath_env) {
+ kpath = string(kpath_env);
+ } else {
+ kdir = string(KERNEL_MODULES_DIR) + "/" + un.release;
+ auto kernel_path_info = get_kernel_path_info(kdir);
+ has_kpath_source = kernel_path_info.first;
+ kpath = kdir + "/" + kernel_path_info.second;
+ }
+
+ if (flags_ & DEBUG_PREPROCESSOR)
+ std::cout << "Running from kernel directory at: " << kpath.c_str() << "\n";
 
  // clang needs to run inside the kernel dir
- DirStack dstack(kdir + "/" + kernel_path_info.second);
+ DirStack dstack(kpath);
  if (!dstack.ok())
  return -1;
 
@@ -143,7 +157,8 @@ int ClangLoader::parse(unique_ptr<llvm::Module> *mod, TableStorage &ts,
  "-fno-asynchronous-unwind-tables",
  "-x", "c", "-c", abs_file.c_str()});
 
- KBuildHelper kbuild_helper(kdir, kernel_path_info.first);
+ KBuildHelper kbuild_helper(kpath_env ? kpath : kdir, has_kpath_source);
+
  vector<string> kflags;
  if (kbuild_helper.get_flags(un.machine, &kflags))
  return -1;