// Be very cautious and default to not handling; we don't want to accidentally
// silence real crashes from real bugs.
static bool
HandleSignal(int signum, siginfo_t *info, void *ctx)
{
AsmJSActivation *activation = InnermostAsmJSActivation();
if (!activation)
return false;
CONTEXT *context = (CONTEXT *)ctx;
uint8_t **ppc = ContextToPC(context);
uint8_t *pc = *ppc;
const AsmJSModule &module = activation->module();
if (!module.containsPC(pc))
return false;
void *faultingAddress = info->si_addr;
// If we faulted trying to execute code in 'module', this must be an
// operation callback (see TriggerOperationCallbackForAsmJSCode). Redirect
// execution to a trampoline which will call js_HandleExecutionInterrupt.
// The trampoline will jump to activation->resumePC if execution isn't
// interrupted.
if (module.containsPC(faultingAddress)) {
activation->setResumePC(pc);
*ppc = module.operationCallbackExit();
mprotect(module.functionCode(), module.functionBytes(), PROT_EXEC);
return true;
}
# if defined(JS_CPU_X64)
// These checks aren't necessary, but, since we can, check anyway to make
// sure we aren't covering up a real bug.
if (!module.maybeHeap() ||
faultingAddress < module.maybeHeap() ||
faultingAddress >= module.maybeHeap() + AsmJSBufferProtectedSize)
{
return false;
}
const AsmJSHeapAccess *heapAccess = LookupHeapAccess(module, pc);
if (!heapAccess)
return false;
// We now know that this is an out-of-bounds access made by an asm.js
// load/store that we should handle. If this is a load, assign the
// JS-defined result value to the destination register (ToInt32(undefined)
// or ToNumber(undefined), determined by the type of the destination
// register) and set the PC to the next op. Upon return from the handler,
// execution will resume at this next PC.
if (heapAccess->isLoad())
SetRegisterToCoercedUndefined(context, heapAccess->isFloat32Load(), heapAccess->loadedReg());
*ppc += heapAccess->opLength();
return true;
# else
return false;
# endif
}
static bool
HandleException(PEXCEPTIONREPORTRECORD pReport,
PCONTEXTRECORD pContext)
{
if (pReport->ExceptionNum != XCPT_ACCESS_VIOLATION)
return false;
AsmJSActivation *activation = InnermostAsmJSActivation();
if (!activation)
return false;
uint8_t **ppc = ContextToPC(pContext);
uint8_t *pc = *ppc;
JS_ASSERT(pc == pReport->ExceptionAddress);
const AsmJSModule &module = activation->module();
if (!module.containsPC(pc))
return false;
if (pReport->cParameters < 2)
return false;
void *faultingAddress = (void*)pReport->ExceptionInfo[1];
// If we faulted trying to execute code in 'module', this must be an
// operation callback (see TriggerOperationCallbackForAsmJSCode). Redirect
// execution to a trampoline which will call js_HandleExecutionInterrupt.
// The trampoline will jump to activation->resumePC if execution isn't
// interrupted.
if (module.containsPC(faultingAddress)) {
activation->setResumePC(pc);
*ppc = module.operationCallbackExit();
if (!DosSetMem(module.functionCode(), module.functionBytes(), PAG_COMMIT | PAG_DEFAULT))
MOZ_CRASH();
return true;
}
return false;
}
static bool
HandleMachException(JSRuntime *rt, const ExceptionRequest &request)
{
// Get the port of the JSRuntime's thread from the message.
mach_port_t rtThread = request.body.thread.name;
// Read out the JSRuntime thread's register state.
x86_thread_state_t state;
unsigned int count = x86_THREAD_STATE_COUNT;
kern_return_t kret;
kret = thread_get_state(rtThread, x86_THREAD_STATE, (thread_state_t)&state, &count);
if (kret != KERN_SUCCESS)
return false;
AsmJSActivation *activation = rt->mainThread.asmJSActivationStackFromAnyThread();
if (!activation)
return false;
uint8_t **ppc = ContextToPC(state);
uint8_t *pc = *ppc;
const AsmJSModule &module = activation->module();
if (!module.containsPC(pc))
return false;
if (request.body.exception != EXC_BAD_ACCESS || request.body.codeCnt != 2)
return false;
void *faultingAddress = (void*)request.body.code[1];
// If we faulted trying to execute code in 'module', this must be an
// operation callback (see TriggerOperationCallbackForAsmJSCode). Redirect
// execution to a trampoline which will call js_HandleExecutionInterrupt.
// The trampoline will jump to activation->resumePC if execution isn't
// interrupted.
if (module.containsPC(faultingAddress)) {
activation->setResumePC(pc);
*ppc = module.operationCallbackExit();
mprotect(module.functionCode(), module.functionBytes(), PROT_EXEC);
// Update the thread state with the new pc.
kret = thread_set_state(rtThread, x86_THREAD_STATE, (thread_state_t)&state, x86_THREAD_STATE_COUNT);
return kret == KERN_SUCCESS;
}
# if defined(JS_CPU_X64)
// These checks aren't necessary, but, since we can, check anyway to make
// sure we aren't covering up a real bug.
if (!module.maybeHeap() ||
faultingAddress < module.maybeHeap() ||
faultingAddress >= module.maybeHeap() + AsmJSBufferProtectedSize)
{
return false;
}
const AsmJSHeapAccess *heapAccess = LookupHeapAccess(module, pc);
if (!heapAccess)
return false;
// We now know that this is an out-of-bounds access made by an asm.js
// load/store that we should handle. If this is a load, assign the
// JS-defined result value to the destination register (ToInt32(undefined)
// or ToNumber(undefined), determined by the type of the destination
// register) and set the PC to the next op. Upon return from the handler,
// execution will resume at this next PC.
if (heapAccess->isLoad()) {
if (!SetRegisterToCoercedUndefined(rtThread, state.uts.ts64, *heapAccess))
return false;
}
*ppc += heapAccess->opLength();
// Update the thread state with the new pc.
kret = thread_set_state(rtThread, x86_THREAD_STATE, (thread_state_t)&state, x86_THREAD_STATE_COUNT);
if (kret != KERN_SUCCESS)
return false;
return true;
# else
return false;
# endif
}
static bool
HandleException(PEXCEPTION_POINTERS exception)
{
EXCEPTION_RECORD *record = exception->ExceptionRecord;
CONTEXT *context = exception->ContextRecord;
if (record->ExceptionCode != EXCEPTION_ACCESS_VIOLATION)
return false;
AsmJSActivation *activation = InnermostAsmJSActivation();
if (!activation)
return false;
uint8_t **ppc = ContextToPC(context);
uint8_t *pc = *ppc;
JS_ASSERT(pc == record->ExceptionAddress);
const AsmJSModule &module = activation->module();
if (!module.containsPC(pc))
return false;
if (record->NumberParameters < 2)
return false;
void *faultingAddress = (void*)record->ExceptionInformation[1];
// If we faulted trying to execute code in 'module', this must be an
// operation callback (see TriggerOperationCallbackForAsmJSCode). Redirect
// execution to a trampoline which will call js_HandleExecutionInterrupt.
// The trampoline will jump to activation->resumePC if execution isn't
// interrupted.
if (module.containsPC(faultingAddress)) {
activation->setResumePC(pc);
*ppc = module.operationCallbackExit();
DWORD oldProtect;
if (!VirtualProtect(module.functionCode(), module.functionBytes(), PAGE_EXECUTE, &oldProtect))
MOZ_CRASH();
return true;
}
# if defined(JS_CPU_X64)
// These checks aren't necessary, but, since we can, check anyway to make
// sure we aren't covering up a real bug.
if (!module.maybeHeap() ||
faultingAddress < module.maybeHeap() ||
faultingAddress >= module.maybeHeap() + AsmJSBufferProtectedSize)
{
return false;
}
const AsmJSHeapAccess *heapAccess = LookupHeapAccess(module, pc);
if (!heapAccess)
return false;
// Also not necessary, but, since we can, do.
if (heapAccess->isLoad() != !record->ExceptionInformation[0])
return false;
// We now know that this is an out-of-bounds access made by an asm.js
// load/store that we should handle. If this is a load, assign the
// JS-defined result value to the destination register (ToInt32(undefined)
// or ToNumber(undefined), determined by the type of the destination
// register) and set the PC to the next op. Upon return from the handler,
// execution will resume at this next PC.
if (heapAccess->isLoad())
SetRegisterToCoercedUndefined(context, heapAccess->isFloat32Load(), heapAccess->loadedReg());
*ppc += heapAccess->opLength();
return true;
# else
return false;
# endif
}
