hwasan: Untag unwound stack frames by wrapping personality functions.

One problem with untagging memory in landing pads is that it only works
correctly if the function that catches the exception is instrumented.
If the function is uninstrumented, we have no opportunity to untag the
memory.

To address this, replace landing pad instrumentation with personality function
wrapping. Each function with an instrumented stack has its personality function
replaced with a wrapper provided by the runtime. Functions that did not have
a personality function to begin with also get wrappers if they may be unwound
past. As the unwinder calls personality functions during stack unwinding,
the original personality function is called and the function's stack frame is
untagged by the wrapper if the personality function instructs the unwinder
to keep unwinding. If unwinding stops at a landing pad, the function is
still responsible for untagging its stack frame if it resumes unwinding.

The old landing pad mechanism is preserved for compatibility with old runtimes.

Differential Revision: https://reviews.llvm.org/D66377

llvm-svn: 369721

1 files changed, 7 insertions, 2 deletions

diff --git a/compiler-rt/test/hwasan/lit.cfg.py b/compiler-rt/test/hwasan/lit.cfg.py
index 06a860d1850..d2e71ba6d57 100644
--- a/compiler-rt/test/hwasan/lit.cfg.py
+++ b/compiler-rt/test/hwasan/lit.cfg.py
@@ -11,13 +11,17 @@ config.test_source_root = os.path.dirname(__file__)
 # Setup default compiler flags used with -fsanitize=memory option.
 clang_cflags = [config.target_cflags] + config.debug_info_flags
 clang_cxxflags = config.cxx_mode_flags + clang_cflags
-clang_hwasan_cflags = clang_cflags + ["-fsanitize=hwaddress", "-mllvm", "-hwasan-globals", "-fuse-ld=lld"]
+clang_hwasan_oldrt_cflags = clang_cflags + ["-fsanitize=hwaddress", "-fuse-ld=lld"]
 if config.target_arch == 'x86_64':
   # This does basically the same thing as tagged-globals on aarch64. Because
   # the x86_64 implementation is for testing purposes only there is no
   # equivalent target feature implemented on x86_64.
-  clang_hwasan_cflags += ["-mcmodel=large"]
+  clang_hwasan_oldrt_cflags += ["-mcmodel=large"]
+clang_hwasan_cflags = clang_hwasan_oldrt_cflags + ["-mllvm", "-hwasan-globals",
+                                                   "-mllvm", "-hwasan-instrument-landing-pads=0",
+                                                   "-mllvm", "-hwasan-instrument-personality-functions"]
 clang_hwasan_cxxflags = config.cxx_mode_flags + clang_hwasan_cflags
+clang_hwasan_oldrt_cxxflags = config.cxx_mode_flags + clang_hwasan_oldrt_cflags
 
 def build_invocation(compile_flags):
   return " " + " ".join([config.clang] + compile_flags) + " "
@@ -25,6 +29,7 @@ def build_invocation(compile_flags):
 config.substitutions.append( ("%clangxx ", build_invocation(clang_cxxflags)) )
 config.substitutions.append( ("%clang_hwasan ", build_invocation(clang_hwasan_cflags)) )
 config.substitutions.append( ("%clangxx_hwasan ", build_invocation(clang_hwasan_cxxflags)) )
+config.substitutions.append( ("%clangxx_hwasan_oldrt ", build_invocation(clang_hwasan_oldrt_cxxflags)) )
 config.substitutions.append( ("%compiler_rt_libdir", config.compiler_rt_libdir) )
 
 default_hwasan_opts_str = ':'.join(['disable_allocator_tagging=1', 'random_tags=0'] + config.default_sanitizer_opts)