Linux: Add support for using set_robust_list2

Let FEX use this for both 32-bit and 64-bit robust futex lists, also wire it up so guest applications can use it. Currently no kernel version check wired up, and syscall number is subject to change.
FEX-Emu · Oct 11, 2024 · a8ec5b0 · a8ec5b0
1 parent 389ad73
commit a8ec5b0
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Showing 9 changed files with 120 additions and 21 deletions.
diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/Arm64/SyscallsEnum.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/Arm64/SyscallsEnum.h
@@ -348,6 +348,7 @@ enum Syscalls_Arm64 {
   SYSCALL_Arm64_lsm_set_self_attr = 460,
   SYSCALL_Arm64_lsm_list_modules = 461,
   SYSCALL_Arm64_mseal = 462,
+  SYSCALL_Arm64_set_robust_list2 = 468, // Subject to change
   SYSCALL_Arm64_MAX = 512,
 
   // Unsupported syscalls on this host

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls.cpp
@@ -62,6 +62,10 @@ desc: Glue logic, brk allocations
 #include <unistd.h>
 
 namespace FEX::HLE {
+int set_robust_list2(struct robust_list_head* head, int index, uint32_t flags) {
+  return ::syscall(SYSCALL_DEF(set_robust_list2), head, index, flags);
+}
+
 class SignalDelegator;
 SyscallHandler* _SyscallHandler {};
 

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls.h
@@ -65,6 +65,15 @@ namespace Core {
 
 namespace FEX::HLE {
 
+enum robust_list_type {
+  ROBUST_LIST_32BIT = 0,
+  ROBUST_LIST_64BIT = 1,
+};
+
+// TODO: Switch to a kernel version check where used.
+constexpr bool ENABLE_ROBUST_LIST2 = true;
+int set_robust_list2(struct robust_list_head* head, int index, uint32_t flags);
+
 class SyscallHandler;
 class SignalDelegator;
 class ThunkHandler;

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls/Passthrough.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/Syscalls/Passthrough.cpp
@@ -624,6 +624,14 @@ void RegisterCommon(FEX::HLE::SyscallHandler* Handler) {
   } else {
     REGISTER_SYSCALL_IMPL(mseal, UnimplementedSyscallSafe);
   }
+
+  // Kernel version subject to change
+  if (Handler->IsHostKernelVersionAtLeast(6, 11, 0)) {
+    REGISTER_SYSCALL_IMPL_PASS_FLAGS(set_robust_list2, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
+                                     SyscallPassthrough3<SYSCALL_DEF(set_robust_list2)>);
+  } else {
+    REGISTER_SYSCALL_IMPL(set_robust_list2, UnimplementedSyscallSafe);
+  }
 }
 
 namespace x64 {
@@ -730,10 +738,13 @@ namespace x64 {
                                          SyscallPassthrough6<SYSCALL_DEF(pselect6)>);
     REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(ppoll, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
                                          SyscallPassthrough5<SYSCALL_DEF(ppoll)>);
-    REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(set_robust_list, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
-                                         SyscallPassthrough2<SYSCALL_DEF(set_robust_list)>);
-    REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(get_robust_list, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
-                                         SyscallPassthrough3<SYSCALL_DEF(get_robust_list)>);
+    if (!ENABLE_ROBUST_LIST2) {
+      // Gets handled in x64/Thread.cpp
+      REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(set_robust_list, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
+                                           SyscallPassthrough2<SYSCALL_DEF(set_robust_list)>);
+      REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(get_robust_list, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
+                                           SyscallPassthrough3<SYSCALL_DEF(get_robust_list)>);
+    }
     REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(sync_file_range, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,
                                          SyscallPassthrough4<SYSCALL_DEF(sync_file_range)>);
     REGISTER_SYSCALL_IMPL_X64_PASS_FLAGS(vmsplice, SyscallFlags::OPTIMIZETHROUGH | SyscallFlags::NOSYNCSTATEONENTRY,

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h
@@ -31,7 +31,15 @@ struct ThreadStateObject : public FEXCore::Allocator::FEXAllocOperators {
     std::atomic<uint32_t> TID;
     int32_t* set_child_tid {0};
     int32_t* clear_child_tid {0};
-    uint64_t robust_list_head {0};
+
+    uint64_t robust_list_head_x64 {0};
+    uint64_t robust_list_head_x32 {0};
+
+    // Robust list index mappings.
+    // Start off as -1 to allow dynamic slot allocation from the kernel.
+    int robust_list_index_x64 {-1};
+    int robust_list_index_x32 {-1};
+
   } ThreadInfo {};
 
   struct {

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/x32/SyscallsEnum.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/x32/SyscallsEnum.h
@@ -480,6 +480,7 @@ enum Syscalls_x86 {
   SYSCALL_x86_lsm_set_self_attr = 460,
   SYSCALL_x86_lsm_list_modules = 461,
   SYSCALL_x86_mseal = 462,
+  SYSCALL_x86_set_robust_list2 = 468, // Subject to change
   SYSCALL_x86_MAX = 512,
 };
 } // namespace FEX::HLE::x32
diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/x32/Thread.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/x32/Thread.cpp
@@ -179,30 +179,57 @@ void RegisterThread(FEX::HLE::SyscallHandler* Handler) {
     return 0;
   });
 
-  REGISTER_SYSCALL_IMPL_X32(set_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, struct robust_list_head* head, size_t len) -> uint64_t {
-    if (len != 12) {
-      // Return invalid if the passed in length doesn't match what's expected.
-      return -EINVAL;
-    }
+  if (ENABLE_ROBUST_LIST2) {
+    REGISTER_SYSCALL_IMPL_X32(set_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, struct robust_list_head* head, size_t len) -> uint64_t {
+      if (len != 12) {
+        // Return invalid if the passed in length doesn't match what's expected.
+        return -EINVAL;
+      }
 
-    auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
-    // Retain the robust list head but don't give it to the kernel
-    // The kernel would break if it tried parsing a 32bit robust list from a 64bit process
-    ThreadObject->ThreadInfo.robust_list_head = reinterpret_cast<uint64_t>(head);
-    return 0;
-  });
+      auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
+      int Result = FEX::HLE::set_robust_list2(head, ThreadObject->ThreadInfo.robust_list_index_x32, FEX::HLE::ROBUST_LIST_32BIT);
+      if (Result != -1) {
+        // Index is returned back to us.
+        ThreadObject->ThreadInfo.robust_list_index_x32 = Result;
+        ThreadObject->ThreadInfo.robust_list_head_x32 = reinterpret_cast<uint64_t>(head);
+        Result = 0;
+      }
+
+      SYSCALL_ERRNO();
+    });
+  } else {
+    REGISTER_SYSCALL_IMPL_X32(set_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, struct robust_list_head* head, size_t len) -> uint64_t {
+      if (len != 12) {
+        // Return invalid if the passed in length doesn't match what's expected.
+        return -EINVAL;
+      }
+
+      auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
+      // Retain the robust list head but don't give it to the kernel
+      // The kernel would break if it tried parsing a 32bit robust list from a 64bit process
+      ThreadObject->ThreadInfo.robust_list_head_x32 = static_cast<uint32_t>(reinterpret_cast<uint64_t>(head));
+      return 0;
+    });
+  }
 
   REGISTER_SYSCALL_IMPL_X32(
     get_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, int pid, struct robust_list_head** head, uint32_t* len_ptr) -> uint64_t {
       FaultSafeUserMemAccess::VerifyIsWritable(head, sizeof(uint32_t));
       FaultSafeUserMemAccess::VerifyIsWritable(len_ptr, sizeof(*len_ptr));
 
       auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
-      // Give the robust list back to the application
-      // Steam specifically checks to make sure the robust list is set
-      *(uint32_t*)head = (uint32_t)ThreadObject->ThreadInfo.robust_list_head;
-      *len_ptr = 12;
-      return 0;
+
+      if (pid == 0 || pid == ThreadObject->ThreadInfo.PID) {
+        FaultSafeUserMemAccess::VerifyIsWritable(head, sizeof(uint32_t));
+
+        // Give the robust list back to the application
+        // Steam specifically checks to make sure the robust list is set
+        *(uint32_t*)head = (uint32_t)ThreadObject->ThreadInfo.robust_list_head_x32;
+        *len_ptr = 12;
+        return 0;
+      }
+
+      return -EPERM;
     });
 
   REGISTER_SYSCALL_IMPL_X32(

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/x64/SyscallsEnum.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/x64/SyscallsEnum.h
@@ -400,6 +400,7 @@ enum Syscalls_x64 {
   SYSCALL_x64_lsm_set_self_attr = 460,
   SYSCALL_x64_lsm_list_modules = 461,
   SYSCALL_x64_mseal = 462,
+  SYSCALL_x64_set_robust_list2 = 468, // Subject to change
   SYSCALL_x64_MAX = 512,
 
   // Unsupported syscalls on this host

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/x64/Thread.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/x64/Thread.cpp
@@ -137,5 +137,42 @@ void RegisterThread(FEX::HLE::SyscallHandler* Handler) {
       auto* const* EnvpPtr = envp ? const_cast<char* const*>(Envp.data()) : nullptr;
       return FEX::HLE::ExecveHandler(Frame, pathname, ArgsPtr, EnvpPtr, AtArgs);
     }));
+
+  if (ENABLE_ROBUST_LIST2) {
+    REGISTER_SYSCALL_IMPL_X64(set_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, struct robust_list_head* head, size_t len) -> uint64_t {
+      if (len != sizeof(struct robust_list_head)) {
+        // Return invalid if the passed in length doesn't match what's expected.
+        return -EINVAL;
+      }
+
+      auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
+      int Result = FEX::HLE::set_robust_list2(head, ThreadObject->ThreadInfo.robust_list_index_x64, FEX::HLE::ROBUST_LIST_64BIT);
+      if (Result != -1) {
+        // Index is returned back to us.
+        ThreadObject->ThreadInfo.robust_list_index_x64 = Result;
+        ThreadObject->ThreadInfo.robust_list_head_x64 = reinterpret_cast<uint64_t>(head);
+        Result = 0;
+      }
+
+      SYSCALL_ERRNO();
+    });
+
+    REGISTER_SYSCALL_IMPL_X64(
+      get_robust_list, [](FEXCore::Core::CpuStateFrame* Frame, int pid, struct robust_list_head** head, uint32_t* len_ptr) -> uint64_t {
+        auto ThreadObject = FEX::HLE::ThreadManager::GetStateObjectFromCPUState(Frame);
+
+        if (pid == 0 || pid == ThreadObject->ThreadInfo.PID) {
+          FaultSafeUserMemAccess::VerifyIsWritable(head, sizeof(uint64_t));
+
+          // Give the robust list back to the application
+          // Steam specifically checks to make sure the robust list is set
+          *(uint64_t*)head = ThreadObject->ThreadInfo.robust_list_head_x64;
+          *len_ptr = sizeof(struct robust_list_head);
+          return 0;
+        }
+
+        return -EPERM;
+      });
+  }
 }
 } // namespace FEX::HLE::x64