From d4559ea0c6a41e973effe1bdda5fcfb33eb20956 Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Thu, 24 Jun 2021 19:26:03 -0700
Subject: [PATCH] Update host signal mask on guest update

Now that are aren't consuming all signals we need to more aggressively handle the host signal mask.
Now more signals are getting masked and blocked how they should be.
---
 .../Tests/LinuxSyscalls/SignalDelegator.cpp   | 72 +++++++++++++------
 1 file changed, 52 insertions(+), 20 deletions(-)

diff --git a/Source/Tests/LinuxSyscalls/SignalDelegator.cpp b/Source/Tests/LinuxSyscalls/SignalDelegator.cpp
index c4920e7b5..cb5c331ec 100644
--- a/Source/Tests/LinuxSyscalls/SignalDelegator.cpp
+++ b/Source/Tests/LinuxSyscalls/SignalDelegator.cpp
@@ -233,20 +233,19 @@ namespace FEX::HLE {
       SignalHandler.HostAction.sa_flags |= SA_NODEFER;
     }
 
-    /*
-     * XXX: This isn't quite as straightforward as a memcmp
-     * There are conflicting definitions between sigset_t and __sigset_t causing problems here
-    sigset_t EmptySet{};
-    sigemptyset(&EmptySet);
-    if (SignalHandler.GuestAction.sa_mask != EmptySet) {
-      // If the guest has masked some signals then we need to also mask those signals
-      SignalHandler.HostAction.sa_mask = SignalHandler.GuestAction.sa_mask;
+    // Walk the signals we have that are required and make sure to remove it from the mask
+    // This'll likely be SIGILL, SIGBUS, SIG63
 
-      // If the guest tried masking SIGILL or SIGBUS then too bad, we actually need this on the host
-      sigdelset(SignalHandler.HostAction.sa_mask, SIGILL);
-      sigdelset(SignalHandler.HostAction.sa_mask, SIGBUS);
+    // If the guest has masked some signals then we need to also mask those signals
+    sigemptyset(&SignalHandler.HostAction.sa_mask);
+    for (size_t i = 1; i < HostHandlers.size(); ++i) {
+      if (HostHandlers[i].Required) {
+        sigdelset(&SignalHandler.HostAction.sa_mask, i);
+      }
+      else if (SigIsMember(&SignalHandler.GuestAction.sa_mask, i)) {
+        sigaddset(&SignalHandler.HostAction.sa_mask, i);
+      }
     }
-    */
 
     // We don't care about the previous handler in this case
     int Result = sigaction(Signal, &SignalHandler.HostAction, &SignalHandler.OldAction);
@@ -284,15 +283,17 @@ namespace FEX::HLE {
       SignalHandler.HostAction.sa_sigaction = &SignalHandlerThunk;
     }
 
-    /*
-    if ((SignalHandler.GuestAction.sa_mask ^ SignalHandler.HostAction.sa_mask) & ~(SIGILL | SIGBUS)) {
-      // If the signal ignore mask has updated (avoiding the two we need for the host) then we need to update
-      SignalHandler.HostAction.sa_mask = SignalHandler.GuestAction.sa_mask;
-      sigdelset(SignalHandler.HostAction.sa_mask, SIGILL);
-      sigdelset(SignalHandler.HostAction.sa_mask, SIGBUS);
-      Changed = true;
+    // Walk the signals we have that are required and make sure to remove it from the mask
+    // This'll likely be SIGILL, SIGBUS, SIG63
+    sigemptyset(&SignalHandler.HostAction.sa_mask);
+    for (size_t i = 1; i < HostHandlers.size(); ++i) {
+      if (HostHandlers[i].Required) {
+        sigdelset(&SignalHandler.HostAction.sa_mask, i);
+      }
+      else if (SigIsMember(&SignalHandler.GuestAction.sa_mask, i)) {
+        sigaddset(&SignalHandler.HostAction.sa_mask, i);
+      }
     }
-    */
 
     // Only update our host signal here
     int Result = sigaction(Signal, &SignalHandler.HostAction, nullptr);
@@ -581,6 +582,24 @@ namespace FEX::HLE {
       else {
         return -EINVAL;
       }
+
+      // Now actually set the host mask
+      // This will hide from the guest that we are not actually setting all of the masks it wants
+      sigset_t HostSet{};
+      sigemptyset(&HostSet);
+
+      for (size_t i = 0; i < MAX_SIGNALS; ++i) {
+        if (HostHandlers[i + 1].Required) {
+          // If it is a required host signal then we can't mask it
+          continue;
+        }
+
+        if (ThreadData.CurrentSignalMask.Val & (1ULL << i)) {
+          sigaddset(&HostSet, i + 1);
+        }
+      }
+
+      pthread_sigmask(SIG_SETMASK, &HostSet, nullptr);
     }
 
     CheckForPendingSignals();
@@ -594,6 +613,19 @@ namespace FEX::HLE {
     }
 
     *set = ThreadData.PendingSignals;
+
+    sigset_t HostSet{};
+    if (sigpending(&HostSet) == 0) {
+      uint64_t HostSignals{};
+      for (size_t i = 0; i < MAX_SIGNALS; ++i) {
+        if (sigismember(&HostSet, i + 1)) {
+          HostSignals |= (1ULL << i);
+        }
+      }
+
+      // Merge the real pending signal mask as well
+      *set |= HostSignals;
+    }
     return 0;
   }