From 5f8de423f190bbb79a62f804151bc24824fa32d8 Mon Sep 17 00:00:00 2001 From: "Matt A. Tobin" Date: Fri, 2 Feb 2018 04:16:08 -0500 Subject: Add m-esr52 at 52.6.0 --- mfbt/LinuxSignal.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 mfbt/LinuxSignal.h (limited to 'mfbt/LinuxSignal.h') diff --git a/mfbt/LinuxSignal.h b/mfbt/LinuxSignal.h new file mode 100644 index 000000000..83c2bf81f --- /dev/null +++ b/mfbt/LinuxSignal.h @@ -0,0 +1,45 @@ +/* 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 +__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) + +#else // __arm__ + +# define MOZ_SIGNAL_TRAMPOLINE(h) (h) + +#endif // __arm__ + +} // namespace mozilla + +#endif // mozilla_LinuxSignal_h -- cgit v1.2.3