Fix unary operator handling of probe reads with parens

Testing for bpf_probe_read should not include parenethes when walking the tree, since the inner operation will have already been rewritten. Fixes: iovisor#289 Signed-off-by: Brenden Blanco <[email protected]>
nanshuaibo · Nov 12, 2015 · 80667b7 · 80667b7
1 parent 66a33c8
commit 80667b7
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diff --git a/src/cc/frontends/clang/b_frontend_action.cc b/src/cc/frontends/clang/b_frontend_action.cc
@@ -109,6 +109,9 @@ class ProbeChecker : public RecursiveASTVisitor<ProbeChecker> {
  needs_probe_ = false;
  return false;
  }
+ bool VisitParenExpr(ParenExpr *E) {
+ return false;
+ }
  bool VisitDeclRefExpr(DeclRefExpr *E) {
  if (ptregs_.find(E->getDecl()) != ptregs_.end())
  needs_probe_ = true;

diff --git a/tests/cc/test_clang.py b/tests/cc/test_clang.py
@@ -249,5 +249,19 @@ def test_probe_simple_assign(self):
  return 0;
 }""", debug=4)
 
+ def test_unop_probe_read(self):
+ text = """
+#include <linux/blkdev.h>
+int trace_entry(struct pt_regs *ctx, struct request *req) {
+ if (!(req->bio->bi_rw & 1))
+ return 1;
+ if (((req->bio->bi_rw)))
+ return 1;
+ return 0;
+}
+"""
+ b = BPF(text=text)
+ fn = b.load_func("trace_entry", BPF.KPROBE)
+
 if __name__ == "__main__":
  main()