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Reapply r310365 (by emaste):

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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
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D8869

Reapply r351610:

Update libunwind custom frame register and deregister functions for
FreeBSD: use the new doubly underscored names for unw_add_dynamic_fde
and unw_remove_dynamic_fde.

NOTE: this should be upstreamed...
This commit is contained in:
Dimitry Andric 2020-08-02 18:12:14 +00:00
parent 71daeec70a
commit 9f287522ce
1 changed files with 41 additions and 1 deletions
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42
contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c
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@ -234,6 +234,46 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
#if defined(__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 // defined(__FreeBSD__)
/// 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
@ -243,7 +283,6 @@ _LIBUNWIND_EXPORT void __register_frame(const void *fde) {
__unw_add_dynamic_fde((unw_word_t)(uintptr_t)fde);
}
/// Called by programs with dynamic code generators that want
/// to unregister a dynamically generated FDE.
/// This function has existed on Mac OS X since 10.4, but
@ -253,6 +292,7 @@ _LIBUNWIND_EXPORT void __deregister_frame(const void *fde) {
__unw_remove_dynamic_fde((unw_word_t)(uintptr_t)fde);
}
#endif // defined(__FreeBSD__)
// The following register/deregister functions are gcc extensions.
// They have existed on Mac OS X, but have never worked because Mac OS X