orbis: implement initial guest signals support

orbis-kernel/include/orbis/thread/ProcessOps.hpp

@@ -73,6 +73,7 @@ struct ProcessOps {
   SysResult (*thr_kill2)(Thread *thread, pid_t pid, slong id, sint sig);
   SysResult (*thr_suspend)(Thread *thread, ptr<const timespec> timeout);
   SysResult (*thr_wake)(Thread *thread, slong id);
+  SysResult (*sigreturn)(Thread *thread, ptr<UContext> context);
   SysResult (*thr_set_name)(Thread *thread, slong id, ptr<const char> name);
 
   SysResult (*unmount)(Thread *thread, ptr<char> path, sint flags);

orbis-kernel/include/orbis/thread/Thread.hpp

@@ -41,6 +41,8 @@ struct Thread {
   kvector<SigInfo> queuedSignals;
   shared_atomic32 suspendFlags{0};
 
+  utils::shared_atomic32 interruptedMtx{ 0 };
+
   std::int64_t hostTid = -1;
   lwpid_t tid = -1;
   unsigned unblocked = 0;
@@ -64,13 +66,14 @@ struct Thread {
   // Print backtrace
   void where();
 
-  void unblock();
-  void block();
+  bool unblock();
+  bool block();
 
   void suspend();
   void resume();
   void sendSignal(int signo);
   void notifyUnblockedSignal(int signo);
+  void setSigMask(SigSet newSigMask);
 
   // FIXME: implement thread destruction
   void incRef() {}

orbis-kernel/include/orbis/ucontext.hpp

@@ -162,4 +162,10 @@ struct SigInfo {
     } spare;
   } reason;
 };
+
+struct SigFrame {
+  uint64_t handler;
+  UContext context;
+  SigInfo info;
+};
 } // namespace orbis

orbis-kernel/include/orbis/utils/SharedAtomic.hpp

@@ -23,7 +23,7 @@ static constexpr auto kRelaxSpinCount = 12;
 static constexpr auto kSpinCount = 16;
 
 inline namespace utils {
-inline thread_local void (*g_scopedUnblock)(bool) = nullptr;
+inline thread_local bool (*g_scopedUnblock)(bool) = nullptr;
 
 bool try_spin_wait(auto &&pred) {
   for (std::size_t i = 0; i < kSpinCount; ++i) {