/* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef mozilla_LinuxSignal_h #define mozilla_LinuxSignal_h namespace mozilla { #if defined(__arm__) // Some (old) Linux kernels on ARM have a bug where a signal handler // can be called without clearing the IT bits in CPSR first. The result // is that the first few instructions of the handler could be skipped, // ultimately resulting in crashes. To workaround this bug, the handler // on ARM is a trampoline that starts with enough NOP instructions, so // that even if the IT bits are not cleared, only the NOP instructions // will be skipped over. template <void (*H)(int, siginfo_t*, void*)> __attribute__((naked)) void SignalTrampoline(int aSignal, siginfo_t* aInfo, void* aContext) { asm volatile ( "nop; nop; nop; nop" : : : "memory"); asm volatile ( "b %0" : : "X"(H) : "memory"); } # define MOZ_SIGNAL_TRAMPOLINE(h) (mozilla::SignalTrampoline<h>) #else // __arm__ # define MOZ_SIGNAL_TRAMPOLINE(h) (h) #endif // __arm__ } // namespace mozilla #endif // mozilla_LinuxSignal_h