diff --git a/libcxxabi/src/cxa_exception_storage.cpp b/libcxxabi/src/cxa_exception_storage.cpp index 1abf6143e59f..3a3233a1b927 100644 --- a/libcxxabi/src/cxa_exception_storage.cpp +++ b/libcxxabi/src/cxa_exception_storage.cpp @@ -12,18 +12,21 @@ #include "cxa_exception.h" -namespace __cxxabiv1 { +#include <__threading_support> #if defined(_LIBCXXABI_HAS_NO_THREADS) +namespace __cxxabiv1 { extern "C" { static __cxa_eh_globals eh_globals; __cxa_eh_globals *__cxa_get_globals() { return &eh_globals; } __cxa_eh_globals *__cxa_get_globals_fast() { return &eh_globals; } } // extern "C" +} // namespace __cxxabiv1 -#else +#elif defined(HAS_THREAD_LOCAL) +namespace __cxxabiv1 { namespace { __cxa_eh_globals *__globals() { static thread_local __cxa_eh_globals eh_globals; @@ -35,7 +38,66 @@ extern "C" { __cxa_eh_globals *__cxa_get_globals() { return __globals(); } __cxa_eh_globals *__cxa_get_globals_fast() { return __globals(); } } // extern "C" +} // namespace __cxxabiv1 +#else + +#include "abort_message.h" +#include "fallback_malloc.h" + +#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB) +#pragma comment(lib, "pthread") #endif +// In general, we treat all threading errors as fatal. +// We cannot call std::terminate() because that will in turn +// call __cxa_get_globals() and cause infinite recursion. + +namespace __cxxabiv1 { +namespace { + std::__libcpp_tls_key key_; + std::__libcpp_exec_once_flag flag_ = _LIBCPP_EXEC_ONCE_INITIALIZER; + + void _LIBCPP_TLS_DESTRUCTOR_CC destruct_(void *p) { + __free_with_fallback(p); + if (0 != std::__libcpp_tls_set(key_, NULL)) + abort_message("cannot zero out thread value for __cxa_get_globals()"); + } + + void construct_() { + if (0 != std::__libcpp_tls_create(&key_, destruct_)) + abort_message("cannot create thread specific key for __cxa_get_globals()"); + } +} // namespace + +extern "C" { + __cxa_eh_globals *__cxa_get_globals() { + // Try to get the globals for this thread + __cxa_eh_globals *retVal = __cxa_get_globals_fast(); + + // If this is the first time we've been asked for these globals, create them + if (NULL == retVal) { + retVal = static_cast<__cxa_eh_globals*>( + __calloc_with_fallback(1, sizeof(__cxa_eh_globals))); + if (NULL == retVal) + abort_message("cannot allocate __cxa_eh_globals"); + if (0 != std::__libcpp_tls_set(key_, retVal)) + abort_message("std::__libcpp_tls_set failure in __cxa_get_globals()"); + } + return retVal; + } + + // Note that this implementation will reliably return NULL if not + // preceded by a call to __cxa_get_globals(). This is an extension + // to the Itanium ABI and is taken advantage of in several places in + // libc++abi. + __cxa_eh_globals *__cxa_get_globals_fast() { + // First time through, create the key. + if (0 != std::__libcpp_execute_once(&flag_, construct_)) + abort_message("execute once failure in __cxa_get_globals_fast()"); + return static_cast<__cxa_eh_globals*>(std::__libcpp_tls_get(key_)); + } +} // extern "C" } // namespace __cxxabiv1 + +#endif diff --git a/libcxxabi/src/fallback_malloc.cpp b/libcxxabi/src/fallback_malloc.cpp index 759bb58f7c30..591efbefc8a5 100644 --- a/libcxxabi/src/fallback_malloc.cpp +++ b/libcxxabi/src/fallback_malloc.cpp @@ -270,6 +270,17 @@ void* __aligned_malloc_with_fallback(size_t size) { return fallback_malloc(size); } +void* __calloc_with_fallback(size_t count, size_t size) { + void* ptr = ::calloc(count, size); + if (NULL != ptr) + return ptr; + // if calloc fails, fall back to emergency stash + ptr = fallback_malloc(size * count); + if (NULL != ptr) + ::memset(ptr, 0, size * count); + return ptr; +} + void __aligned_free_with_fallback(void* ptr) { if (is_fallback_ptr(ptr)) fallback_free(ptr); diff --git a/libcxxabi/src/fallback_malloc.h b/libcxxabi/src/fallback_malloc.h index 528014b3456d..816e691ed231 100644 --- a/libcxxabi/src/fallback_malloc.h +++ b/libcxxabi/src/fallback_malloc.h @@ -17,6 +17,9 @@ namespace __cxxabiv1 { // Allocate some memory from _somewhere_ _LIBCXXABI_HIDDEN void * __aligned_malloc_with_fallback(size_t size); +// Allocate and zero-initialize memory from _somewhere_ +_LIBCXXABI_HIDDEN void * __calloc_with_fallback(size_t count, size_t size); + _LIBCXXABI_HIDDEN void __aligned_free_with_fallback(void *ptr); _LIBCXXABI_HIDDEN void __free_with_fallback(void *ptr);