Include libbpf.h in some places, cleanup constants

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

src/cc/b_frontend_action.cc

@@ -25,9 +25,7 @@
 
 #include "b_frontend_action.h"
 
-extern "C"
-int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
-                   int max_entries);
+#include "libbpf.h"
 
 namespace ebpf {
 
@@ -90,7 +88,7 @@ bool BTypeVisitor::VisitFunctionDecl(FunctionDecl *D) {
   // put each non-static non-inline function decl in its own section, to be
   // extracted by the MemoryManager
   if (D->isExternallyVisible() && D->hasBody()) {
-    string attr = string("__attribute__((section(\".bpf.fn.") + D->getName().str() + "\")))\n";
+    string attr = string("__attribute__((section(\"") + BPF_FN_PREFIX + D->getName().str() + "\")))\n";
     rewriter_.InsertText(D->getLocStart(), attr);
     // remember the arg names of the current function...first one is the ctx
     fn_args_.clear();

src/cc/bpf_module.cc

@@ -63,6 +63,7 @@
 #include "b_frontend_action.h"
 #include "bpf_module.h"
 #include "kbuild_helper.h"
+#include "libbpf.h"
 
 namespace ebpf {
 

src/cc/codegen_llvm.cc

@@ -38,9 +38,7 @@
 #include "cc/lexer.h"
 #include "cc/type_helper.h"
 #include "linux/bpf.h"
-
-extern "C"
-int bpf_create_map(int map_type, int key_size, int value_size, int max_entries);
+#include "libbpf.h"
 
 namespace ebpf {
 namespace cc {
@@ -801,7 +799,7 @@ StatusTuple CodegenLLVM::visit_table_index_expr_node(TableIndexExprNode *n) {
   // result = lookup(key)
   Value *lookup1 = B.CreateBitCast(B.CreateCall(lookup_fn, vector<Value *>({pseudo_map_fd, key_ptr})), leaf_ptype);
 
-  Value *result;
+  Value *result = nullptr;
   if (n->table_->policy_id()->name_ == "AUTO") {
     Function *parent = B.GetInsertBlock()->getParent();
     BasicBlock *label_start = B.GetInsertBlock();
@@ -1079,7 +1077,7 @@ StatusTuple CodegenLLVM::visit_table_decl_stmt_node(TableDeclStmtNode *n) {
     auto leaf = scopes_->top_struct()->lookup(n->leaf_id()->name_, /*search_local*/true);
     if (!leaf) return mkstatus_(n, "cannot find leaf %s", n->leaf_id()->name_.c_str());
 
-    int map_type = BPF_MAP_TYPE_UNSPEC;
+    bpf_map_type map_type = BPF_MAP_TYPE_UNSPEC;
     if (n->type_id()->name_ == "FIXED_MATCH")
       map_type = BPF_MAP_TYPE_HASH;
     else if (n->type_id()->name_ == "INDEXED")

src/cc/codegen_llvm.h

@@ -37,8 +37,6 @@ class StructType;
 class SwitchInst;
 }
 
-#define BPF_FN_PREFIX ".bpf.fn."
-
 namespace ebpf {
 namespace cc {
 

src/libbpf.h

@@ -49,6 +49,10 @@ int bpf_detach_kprobe(const char *event_desc);
 #define LOG_BUF_SIZE 65536
 extern char bpf_log_buf[LOG_BUF_SIZE];
 
+// Put non-static/inline functions in their own section with this prefix +
+// fn_name to enable discovery by the bcc library.
+#define BPF_FN_PREFIX ".bpf.fn."
+
 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
 
 #define BPF_ALU64_REG(OP, DST, SRC)				\