| /* 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"); |
| |
| // Because the assembler may generate additional insturctions below, we |
| // need to ensure NOPs are inserted first by separating them out above. |
| |
| asm volatile ( |
| "bx %0" |
| : |
| : "r"(H), "l"(aSignal), "l"(aInfo), "l"(aContext) |
| : "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 |
