[dfsan] Introduce dfsan_flush().

Summary:
dfsan_flush() allows to restart tain tracking from scratch in the same process.
The primary purpose right now is to allow more efficient data flow tracing
for DFT fuzzing: https://github.com/google/oss-fuzz/issues/1632

Reviewers: pcc

Reviewed By: pcc

Subscribers: delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D63037

llvm-svn: 363321

1 files changed, 6 insertions, 0 deletions

diff --git a/compiler-rt/include/sanitizer/dfsan_interface.h b/compiler-rt/include/sanitizer/dfsan_interface.h
index b6edf22ad04..c189ee55790 100644
--- a/compiler-rt/include/sanitizer/dfsan_interface.h
+++ b/compiler-rt/include/sanitizer/dfsan_interface.h
@@ -79,6 +79,12 @@ dfsan_label dfsan_has_label_with_desc(dfsan_label label, const char *desc);
 /// Returns the number of labels allocated.
 size_t dfsan_get_label_count(void);
 
+/// Flushes the DFSan shadow, i.e. forgets about all labels currently associated
+/// with the application memory. Will work only if there are no other
+/// threads executing DFSan-instrumented code concurrently.
+/// Use this call to start over the taint tracking within the same procces.
+void dfsan_flush(void);
+
 /// Sets a callback to be invoked on calls to write().  The callback is invoked
 /// before the write is done.  The write is not guaranteed to succeed when the
 /// callback executes.  Pass in NULL to remove any callback.