From 9f287522cec9feac040d7cb845a440a8f6b7b90e Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Sun, 2 Aug 2020 18:12:14 +0000 Subject: [PATCH] Reapply r310365 (by emaste): 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... --- .../libunwind/src/UnwindLevel1-gcc-ext.c | 42 ++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) diff --git a/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c b/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c index 310b836d129e..30f9cabf241f 100644 --- a/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c +++ b/contrib/llvm-project/libunwind/src/UnwindLevel1-gcc-ext.c @@ -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