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