mfbt/LinuxSignal.h
author Sam Sneddon <me@gsnedders.com>
Tue, 05 Mar 2019 12:19:18 +0000
changeset 464592 ed02da4c6be28b064d9c6168f54c7f84036fa9e1
parent 454520 5f4630838d46dd81dadb13220a4af0da9e23a619
child 465194 a8e6586172fdefe46349797d8aef9cc5e7147d3b
permissions -rw-r--r--
Bug 1486514 [wpt PR 12695] - Make reftests 800x600 everywhere, a=testonly Automatic update from web-platform-tests Change reftest size to 800x600 everywhere (#12695) With Firefox, with the internal reftest runner (used by default), this doesn't actually change the reftest size in Firefox versions prior to 66 (currently on the beta channel); to get the correct behaviour with older versions of Firefox, you must pass `--reftest-external` to use the external reftest runner. -- wpt-commits: d5f07ed3b5186e553940a3d5c547067850a4e3f0 wpt-pr: 12695

/* 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