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/* 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 */
#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__
#endif // __arm__
} // namespace mozilla
#endif // mozilla_LinuxSignal_h