svn commit: r310365 - head/contrib/llvm/projects/libunwind/src

[Ed Maste]

Author: emaste
Date: Wed Dec 21 14:06:44 2016
New Revision: 310365
URL: https://svnweb.freebsd.org/changeset/base/310365

Log:
  libunwind: make __{de,}register_frame compatible with libgcc API
  
  The libgcc __register_frame and __deregister_frame functions take a
  pointer to a set of FDE/CIEs, terminated by an entry where length is 0.
  
  In Apple's libunwind implementation the pointer is taken to be to a
  single FDE. I suspect this was just an Apple bug, compensated by Apple-
  specific code in LLVM.
  
  See lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp and
  http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html
  for more detail.
  
  This change is based on the LLVM RTDyldMemoryManager.cpp. It should
  later be changed to be alignment-safe.
  
  Reported by:	dim
  Reviewed by:	dim
  MFC after:	1 month
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D8869

Modified:
  head/contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c

Modified: head/contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c
==============================================================================
--- head/contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c	Wed Dec 21 11:34:16 2016	(r310364)
+++ head/contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c	Wed Dec 21 14:06:44 2016	(r310365)
@@ -224,6 +224,47 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetI
 
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
 
+#ifdef __FreeBSD__
+
+// Based on LLVM's lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
+// and XXX should be fixed to be alignment-safe.
+static void processFDE(const char *addr, bool isDeregister) {
+  uint64_t length;
+  while ((length = *((const uint32_t *)addr)) != 0) {
+    const char *p = addr + 4;
+    if (length == 0xffffffff) {
+      length = *((const uint64_t *)p);
+      p += 8;
+    }
+    uint32_t offset = *((const uint32_t *)p);
+    if (offset != 0) {
+      if (isDeregister)
+        _unw_remove_dynamic_fde((unw_word_t)(uintptr_t)addr);
+      else
+        _unw_add_dynamic_fde((unw_word_t)(uintptr_t)addr);
+    }
+    addr = p + length;
+  }
+}
+
+/// Called by programs with dynamic code generators that want to register
+/// dynamically generated FDEs, with a libgcc-compatible API.
+
+_LIBUNWIND_EXPORT void __register_frame(const void *addr) {
+  _LIBUNWIND_TRACE_API("__register_frame(%p)", addr);
+  processFDE(addr, false);
+}
+
+/// Called by programs with dynamic code generators that want to unregister
+/// dynamically generated FDEs, with a libgcc-compatible API.
+_LIBUNWIND_EXPORT void __deregister_frame(const void *addr) {
+  _LIBUNWIND_TRACE_API("__deregister_frame(%p)", addr);
+  processFDE(addr, true);
+}
+
+
+#else
+
 /// Called by programs with dynamic code generators that want
 /// to register a dynamically generated FDE.
 /// This function has existed on Mac OS X since 10.4, but
@@ -243,6 +284,7 @@ _LIBUNWIND_EXPORT void __deregister_fram
   _unw_remove_dynamic_fde((unw_word_t)(uintptr_t) fde);
 }
 
+#endif
 
 // The following register/deregister functions are gcc extensions.
 // They have existed on Mac OS X, but have never worked because Mac OS X