Kernel+LibSystem: Add a 4th syscall argument

Let's allow passing 4 function arguments to a syscall. The 4th argument goes into ESI or RSI.
fleximus · Jul 25, 2021 · deff554 · deff554
1 parent 9b78ae5
commit deff554
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Showing 5 changed files with 33 additions and 8 deletions.
diff --git a/Kernel/API/Syscall.h b/Kernel/API/Syscall.h
@@ -531,6 +531,17 @@ inline uintptr_t invoke(Function function, T1 arg1, T2 arg2, T3 arg3)
  : "memory");
  return result;
 }
+
+template<typename T1, typename T2, typename T3, typename T4>
+inline uintptr_t invoke(Function function, T1 arg1, T2 arg2, T3 arg3, T4 arg4)
+{
+ uintptr_t result;
+ asm volatile("int $0x82"
+ : "=a"(result)
+ : "a"(function), "d"((uintptr_t)arg1), "c"((uintptr_t)arg2), "b"((uintptr_t)arg3), "S"((uintptr_t)arg4)
+ : "memory");
+ return result;
+}
 #endif
 
 }

diff --git a/Kernel/Arch/x86/RegisterState.h b/Kernel/Arch/x86/RegisterState.h
@@ -104,18 +104,20 @@ struct [[gnu::packed]] RegisterState {
 #endif
  }
 
- void capture_syscall_params(FlatPtr& function, FlatPtr& arg1, FlatPtr& arg2, FlatPtr& arg3) const
+ void capture_syscall_params(FlatPtr& function, FlatPtr& arg1, FlatPtr& arg2, FlatPtr& arg3, FlatPtr& arg4) const
  {
 #if ARCH(I386)
  function = eax;
  arg1 = edx;
  arg2 = ecx;
  arg3 = ebx;
+ arg4 = esi;
 #else
  function = rax;
  arg1 = rdx;
  arg2 = rcx;
  arg3 = rbx;
+ arg4 = rsi;
 #endif
  }
 

diff --git a/Kernel/Syscall.cpp b/Kernel/Syscall.cpp
@@ -80,15 +80,15 @@ NEVER_INLINE NAKED void syscall_asm_entry()
 
 namespace Syscall {
 
-static KResultOr<FlatPtr> handle(RegisterState&, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3);
+static KResultOr<FlatPtr> handle(RegisterState&, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3, FlatPtr arg4);
 
 UNMAP_AFTER_INIT void initialize()
 {
  register_user_callable_interrupt_handler(syscall_vector, syscall_asm_entry);
 }
 
 #pragma GCC diagnostic ignored "-Wcast-function-type"
-typedef KResultOr<FlatPtr> (Process::*Handler)(FlatPtr, FlatPtr, FlatPtr);
+typedef KResultOr<FlatPtr> (Process::*Handler)(FlatPtr, FlatPtr, FlatPtr, FlatPtr);
 typedef KResultOr<FlatPtr> (Process::*HandlerWithRegisterState)(RegisterState&);
 struct HandlerMetadata {
  Handler handler;
@@ -101,15 +101,15 @@ static const HandlerMetadata s_syscall_table[] = {
 };
 #undef __ENUMERATE_SYSCALL
 
-KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3)
+KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3, FlatPtr arg4)
 {
  VERIFY_INTERRUPTS_ENABLED();
  auto current_thread = Thread::current();
  auto& process = current_thread->process();
  current_thread->did_syscall();
 
  if (function >= Function::__Count) {
- dbgln("Unknown syscall {} requested ({:p}, {:p}, {:p})", function, arg1, arg2, arg3);
+ dbgln("Unknown syscall {} requested ({:p}, {:p}, {:p}, {:p})", function, arg1, arg2, arg3, arg4);
  return ENOSYS;
  }
 
@@ -153,7 +153,7 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
  auto handler = (HandlerWithRegisterState)syscall_metadata.handler;
  result = (process.*(handler))(regs);
  } else {
- result = (process.*(syscall_metadata.handler))(arg1, arg2, arg3);
+ result = (process.*(syscall_metadata.handler))(arg1, arg2, arg3, arg4);
  }
 
  return result;
@@ -207,9 +207,10 @@ NEVER_INLINE void syscall_handler(TrapFrame* trap)
  FlatPtr arg1;
  FlatPtr arg2;
  FlatPtr arg3;
- regs.capture_syscall_params(function, arg1, arg2, arg3);
+ FlatPtr arg4;
+ regs.capture_syscall_params(function, arg1, arg2, arg3, arg4);
 
- auto result = Syscall::handle(regs, function, arg1, arg2, arg3);
+ auto result = Syscall::handle(regs, function, arg1, arg2, arg3, arg4);
 
  if (result.is_error()) {
  regs.set_return_reg(result.error());

diff --git a/Userland/Libraries/LibSystem/syscall.cpp b/Userland/Libraries/LibSystem/syscall.cpp
@@ -28,4 +28,9 @@ uintptr_t syscall3(uintptr_t function, uintptr_t arg0, uintptr_t arg1, uintptr_t
 {
  return Syscall::invoke((Syscall::Function)function, arg0, arg1, arg2);
 }
+
+uintptr_t syscall4(uintptr_t function, uintptr_t arg0, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3)
+{
+ return Syscall::invoke((Syscall::Function)function, arg0, arg1, arg2, arg3);
+}
 }
diff --git a/Userland/Libraries/LibSystem/syscall.h b/Userland/Libraries/LibSystem/syscall.h
@@ -15,6 +15,7 @@ uintptr_t syscall0(uintptr_t function);
 uintptr_t syscall1(uintptr_t function, uintptr_t arg0);
 uintptr_t syscall2(uintptr_t function, uintptr_t arg0, uintptr_t arg1);
 uintptr_t syscall3(uintptr_t function, uintptr_t arg0, uintptr_t arg1, uintptr_t arg2);
+uintptr_t syscall4(uintptr_t function, uintptr_t arg0, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3);
 }
 
 #ifdef __cplusplus
@@ -39,4 +40,9 @@ inline uintptr_t syscall(auto function, auto arg0, auto arg1, auto arg2)
  return syscall3((uintptr_t)function, (uintptr_t)arg0, (uintptr_t)arg1, (uintptr_t)arg2);
 }
 
+inline uintptr_t syscall(auto function, auto arg0, auto arg1, auto arg2, auto arg3)
+{
+ return syscall4((uintptr_t)function, (uintptr_t)arg0, (uintptr_t)arg1, (uintptr_t)arg2, (uintptr_t)arg3);
+}
+
 #endif