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Kernel: Conditionally acquire the big lock based on syscall metadata

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This commit is contained in:
Brian Gianforcaro 2021-07-18 10:42:22 -07:00 • committed by Gunnar Beutner
parent bb1fa019de
commit 120b9bc05b
1 changed files with 25 additions and 18 deletions
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43
Kernel/Syscall.cpp
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@ -108,8 +108,26 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
auto& process = current_thread->process();
current_thread->did_syscall();
if (function >= Function::__Count) {
dbgln("Unknown syscall {} requested ({:08x}, {:08x}, {:08x})", function, arg1, arg2, arg3);
return ENOSYS;
}
const auto syscall_metadata = s_syscall_table[function];
if (syscall_metadata.handler == nullptr) {
dbgln("Null syscall {} requested, you probably need to rebuild this program!", function);
return ENOSYS;
}
MutexLocker mutex_locker;
const auto needs_big_lock = syscall_metadata.needs_lock == NeedsBigProcessLock::Yes;
if (needs_big_lock) {
mutex_locker.attach_and_lock(process.big_lock());
};
if (function == SC_exit || function == SC_exit_thread) {
// These syscalls need special handling since they never return to the caller.
// In these cases the process big lock will get released on the exit of the thread.
if (auto* tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
regs.set_return_reg(0);
@ -129,23 +147,16 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
}
}
KResultOr<FlatPtr> result { FlatPtr(nullptr) };
if (function == SC_fork || function == SC_sigreturn) {
// These syscalls want the RegisterState& rather than individual parameters.
auto handler = (HandlerWithRegisterState)s_syscall_table[function].handler;
return (process.*(handler))(regs);
auto handler = (HandlerWithRegisterState)syscall_metadata.handler;
result = (process.*(handler))(regs);
} else {
result = (process.*(syscall_metadata.handler))(arg1, arg2, arg3);
}
if (function >= Function::__Count) {
dbgln("Unknown syscall {} requested ({:08x}, {:08x}, {:08x})", function, arg1, arg2, arg3);
return ENOSYS;
}
if (s_syscall_table[function].handler == nullptr) {
dbgln("Null syscall {} requested, you probably need to rebuild this program!", function);
return ENOSYS;
}
return (process.*(s_syscall_table[function].handler))(arg1, arg2, arg3);
return result;
}
}
@ -204,18 +215,14 @@ NEVER_INLINE void syscall_handler(TrapFrame* trap)
FlatPtr arg3;
regs.capture_syscall_params(function, arg1, arg2, arg3);
process.big_lock().lock();
auto result = Syscall::handle(regs, function, arg1, arg2, arg3);
if (result.is_error()) {
regs.set_return_reg(result.error());
} else {
regs.set_return_reg(result.value());
}
process.big_lock().unlock();
if (auto tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
tracer->set_trace_syscalls(false);
process.tracer_trap(*current_thread, regs); // this triggers SIGTRAP and stops the thread!