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libunwind: make __{de,}register_frame compatible with libgcc API

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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
This commit is contained in:
Ed Maste 2016-12-21 14:06:44 +00:00
parent 3157c36886
commit 77ac8927fd
1 changed files with 42 additions and 0 deletions
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42
contrib/llvm/projects/libunwind/src/UnwindLevel1-gcc-ext.c
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@ -224,6 +224,47 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
#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_frame(const void *fde) {
_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