implement DEBUG_BTF flag (iovisor#2202)

silence BTF related warning messages by default. The DEBUG_BTF is added to enable such warning messages. Signed-off-by: Yonghong Song <[email protected]>
yingtaojuzi · Feb 14, 2019 · 75a1f3d · 75a1f3d
1 parent 6c79c68
commit 75a1f3d
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Showing 5 changed files with 31 additions and 6 deletions.
diff --git a/src/cc/bcc_btf.cc b/src/cc/bcc_btf.cc
@@ -15,9 +15,11 @@
  */
 
 #include "bcc_btf.h"
+#include <stdarg.h>
 #include <string.h>
 #include "linux/btf.h"
 #include "libbpf.h"
+#include "libbpf/src/libbpf.h"
 #include "libbpf/src/btf.h"
 #include <vector>
 
@@ -41,11 +43,27 @@ uint32_t BTFStringTable::addString(std::string S) {
  return Offset;
 }
 
+BTF::BTF(bool debug) : debug_(debug), btf_(nullptr), btf_ext_(nullptr) {
+ if (!debug)
+ libbpf_set_print(NULL);
+}
+
 BTF::~BTF() {
  btf__free(btf_);
  btf_ext__free(btf_ext_);
 }
 
+void BTF::warning(const char *format, ...) {
+ va_list args;
+
+ if (!debug_)
+ return;
+
+ va_start(args, format);
+ vfprintf(stderr, format, args);
+ va_end(args);
+}
+
 // The compiler doesn't have source code for remapped files.
 // So we modify .BTF and .BTF.ext sections here to add these
 // missing line source codes.
@@ -153,14 +171,14 @@ int BTF::load(uint8_t *btf_sec, uintptr_t btf_sec_size,
  btf = btf__new(btf_sec, btf_sec_size);
  }
  if (BCC_IS_ERR(btf)) {
- fprintf(stderr, "Processing .BTF section failure\n");
+ warning("Processing .BTF section failed\n");
  return -1;
  }
 
  btf_ext = btf_ext__new(btf_ext_sec, btf_ext_sec_size);
  if (BCC_IS_ERR(btf_ext)) {
  btf__free(btf);
- fprintf(stderr, "Processing .BTF.ext section failure\n");
+ warning("Processing .BTF.ext section failed\n");
  return -1;
  }
 
@@ -189,14 +207,14 @@ int BTF::get_btf_info(const char *fname,
  ret = btf_ext__reloc_func_info(btf_, btf_ext_, fname, 0,
  func_info, func_info_cnt);
  if (ret) {
- fprintf(stderr, ".BTF.ext reloc func_info not successful\n");
+ warning(".BTF.ext reloc func_info failed\n");
  return ret;
  }
 
  ret = btf_ext__reloc_line_info(btf_, btf_ext_, fname, 0,
  line_info, line_info_cnt);
  if (ret) {
- fprintf(stderr, ".BTF.ext reloc line_info not successful\n");
+ warning(".BTF.ext reloc line_info failed\n");
  return ret;
  }
 

diff --git a/src/cc/bcc_btf.h b/src/cc/bcc_btf.h
@@ -43,6 +43,7 @@ class BTFStringTable {
 
 class BTF {
  public:
+ BTF(bool debug);
  ~BTF();
  int load(uint8_t *btf_sec, uintptr_t btf_sec_size,
  uint8_t *btf_ext_sec, uintptr_t btf_ext_sec_size,
@@ -62,8 +63,10 @@ class BTF {
  uint8_t *btf_ext_sec, uintptr_t btf_ext_sec_size,
  std::map<std::string, std::string> &remapped_sources,
  uint8_t **new_btf_sec, uintptr_t *new_btf_sec_size);
+ void warning(const char *format, ...);
 
  private:
+ bool debug_;
  struct btf *btf_;
  struct btf_ext *btf_ext_;
 };

diff --git a/src/cc/bpf_module.cc b/src/cc/bpf_module.cc
@@ -258,7 +258,7 @@ void BPFModule::load_btf(std::map<std::string, std::tuple<uint8_t *, uintptr_t>>
  remapped_sources["/virtual/main.c"] = mod_src_;
  remapped_sources["/virtual/include/bcc/helpers.h"] = helpers_h->second;
 
- BTF *btf = new BTF();
+ BTF *btf = new BTF(flags_ & DEBUG_BTF);
  int ret = btf->load(btf_sec, btf_sec_size, btf_ext_sec, btf_ext_sec_size,
  remapped_sources);
  if (ret) {

diff --git a/src/cc/bpf_module.h b/src/cc/bpf_module.h
@@ -47,6 +47,8 @@ enum {
  DEBUG_SOURCE = 0x8,
  // Debug output register state on all instructions in addition to DEBUG_BPF.
  DEBUG_BPF_REGISTER_STATE = 0x10,
+ // Debug BTF.
+ DEBUG_BTF = 0x20,
 };
 
 class TableDesc;

diff --git a/src/python/bcc/__init__.py b/src/python/bcc/__init__.py
@@ -51,8 +51,10 @@ def _get_num_open_probes():
 DEBUG_PREPROCESSOR = 0x4
 # Debug output ASM instructions embedded with source.
 DEBUG_SOURCE = 0x8
-#Debug output register state on all instructions in addition to DEBUG_BPF.
+# Debug output register state on all instructions in addition to DEBUG_BPF.
 DEBUG_BPF_REGISTER_STATE = 0x10
+# Debug BTF.
+DEBUG_BTF = 0x20
 
 class SymbolCache(object):
  def __init__(self, pid):