Ring3: Refactored EnterUserImage() into CallRing3().

MdeModulePkg/Core/Dxe/DxeMain.h

@@ -2845,15 +2845,11 @@ CoreBootServices (
   ...
   );
 
-VOID
+EFI_STATUS
 EFIAPI
-EnterUserImage (
+CallRing3 (
-  IN SWITCH_STACK_ENTRY_POINT  EntryPoint,
+  IN VOID  *EntryPoint,
-  IN VOID                      *Context1   OPTIONAL,
+  ...
-  IN VOID                      *Context2   OPTIONAL,
-  IN VOID                      *NewStack,
-  IN UINT16                    CodeSelector,
-  IN UINT16                    DataSelector
   );
 
 #endif

MdeModulePkg/Core/Dxe/Image/Image.c

@@ -1788,15 +1788,11 @@ CoreStartImage (
       Msr = (UINT64)(UINTN)CoreBootServices;
       AsmWriteMsr64 (MSR_IA32_LSTAR, Msr);
 
-      EnterUserImage (
+      Image->Status = CallRing3 (
-        (SWITCH_STACK_ENTRY_POINT)(UINTN)Image->EntryPoint,
+                        (VOID *)Image->EntryPoint,
-        ImageHandle,
+                        ImageHandle,
-        Image->Info.SystemTable,
+                        Image->Info.SystemTable
-        gRing3CallStackTop,
+                        );
-        (UINT16)RING3_CODE64_SEL,
-        (UINT16)RING3_DATA64_SEL
-        );
-      Image->Status = EFI_SUCCESS;
     }
 
     //

MdeModulePkg/Core/Dxe/SysCall/BootServices.c

@@ -32,17 +32,6 @@ CallInstallMultipleProtocolInterfaces (
   IN VOID        *Function
   );
 
-VOID
-EFIAPI
-InternalEnterUserImage (
-  IN SWITCH_STACK_ENTRY_POINT  EntryPoint,
-  IN VOID                      *Context1   OPTIONAL,
-  IN VOID                      *Context2   OPTIONAL,
-  IN VOID                      *NewStack,
-  IN UINT16                    CodeSelector,
-  IN UINT16                    DataSelector
-  );
-
 typedef struct {
   UINTN  Argument1;
   UINTN  Argument2;
@@ -85,7 +74,9 @@ CallBootService (
   EFI_HANDLE CoreHandle;
 
   EFI_DRIVER_BINDING_PROTOCOL *CoreDriverBinding;
-
+  //
+  // TODO: Check User variables.
+  //
   gCpu->GetMemoryAttributes (gCpu, (EFI_PHYSICAL_ADDRESS)UserRsp, &Attributes);
   ASSERT ((Attributes & EFI_MEMORY_USER) != 0);
 
@@ -230,25 +221,3 @@ CallBootService (
 
   return EFI_UNSUPPORTED;
 }
-
-VOID
-EFIAPI
-EnterUserImage (
-  IN SWITCH_STACK_ENTRY_POINT  EntryPoint,
-  IN VOID                      *Context1   OPTIONAL,
-  IN VOID                      *Context2   OPTIONAL,
-  IN VOID                      *NewStack,
-  IN UINT16                    CodeSelector,
-  IN UINT16                    DataSelector
-  )
-{
-  ASSERT (EntryPoint != NULL);
-  ASSERT (NewStack != NULL);
-
-  //
-  // New stack must be aligned with CPU_STACK_ALIGNMENT
-  //
-  ASSERT (((UINTN)NewStack & (CPU_STACK_ALIGNMENT - 1)) == 0);
-
-  InternalEnterUserImage (EntryPoint, Context1, Context2, NewStack, CodeSelector, DataSelector);
-}

MdeModulePkg/Core/Dxe/SysCall/SupportedProtocols.c

@@ -18,16 +18,6 @@ typedef enum {
   UserCallMax
 } USER_CALL_TYPE;
 
-EFI_STATUS
-EFIAPI
-CallRing3 (
-  IN UINT8  Type,
-  IN UINT16 CodeSelector,
-  IN UINT16 DataSelector,
-  IN VOID   *FunctionAddress,
-  ...
-  );
-
 EFI_STATUS
 EFIAPI
 CoreDriverBindingSupported (
@@ -37,9 +27,6 @@ CoreDriverBindingSupported (
   )
 {
   return CallRing3 (
-           UserDriverBindingSupported,
-           (UINT16)RING3_CODE64_SEL,
-           (UINT16)RING3_DATA64_SEL,
            (VOID *)mUserDriverBindingSupported,
            This,
            ControllerHandle,
@@ -56,9 +43,6 @@ CoreDriverBindingStart (
   )
 {
   return CallRing3 (
-           UserDriverBindingStart,
-           (UINT16)RING3_CODE64_SEL,
-           (UINT16)RING3_DATA64_SEL,
            (VOID *)mUserDriverBindingStart,
            This,
            ControllerHandle,
@@ -76,9 +60,6 @@ CoreDriverBindingStop (
   )
 {
   return CallRing3 (
-           UserDriverBindingStop,
-           (UINT16)RING3_CODE64_SEL,
-           (UINT16)RING3_DATA64_SEL,
            (VOID *)mUserDriverBindingStop,
            This,
            ControllerHandle,

MdeModulePkg/Core/Dxe/SysCall/X64/CoreBootServices.nasm

@@ -5,14 +5,18 @@
 ;
 ;------------------------------------------------------------------------------
 
-DEFAULT REL
+#include <Register/Intel/ArchitecturalMsr.h>
-SECTION .text
 
 extern ASM_PFX(CallBootService)
 extern ASM_PFX(gCoreSysCallStackTop)
 extern ASM_PFX(gRing3CallStackTop)
 extern ASM_PFX(gRing3EntryPoint)
 
+extern ASM_PFX(AsmReadMsr64)
+
+DEFAULT REL
+SECTION .text
+
 ;------------------------------------------------------------------------------
 ; VOID
 ; EFIAPI
@@ -167,92 +171,69 @@ o64 sysret
     ; SYSRET copies the value in RCX into RIP and loads RFLAGS from R11.
 
 ;------------------------------------------------------------------------------
-; Routine Description:
+; EFI_STATUS
+; EFIAPI
+; CallRing3 (
+;   IN VOID  *EntryPoint,
+;   ...
+;   );
 ;
-;   Routine for transfering control to user image with 2 parameters
+;   (rcx) EntryPoint    - Entry point in User address space.
-;
-; Arguments:
-;
-;   (rcx) EntryPoint    - Entry point with new stack.
 ;   (rdx) Context1      - Parameter1 for entry point.
 ;   (r8)  Context2      - Parameter2 for entry point.
-;   (r9)  NewStack      - The pointer to new stack.
-;On stack CodeSelector  - Segment selector for code.
-;On stack DataSelector  - Segment selector for data.
-;
-; Returns:
-;
-;   None
-;
 ;------------------------------------------------------------------------------
-global ASM_PFX(InternalEnterUserImage)
+global ASM_PFX(CallRing3)
-ASM_PFX(InternalEnterUserImage):
+ASM_PFX(CallRing3):
-    ; Set Data selectors
+    ; Save input Arguments.
-    mov     rax, [rsp + 8*6]
+    push    r12
-    or      rax, 3H ; RPL = 3
+    push    r13
+    push    r14
+    mov     r12, rcx
+    mov     r13, rdx
+    mov     r14, r8
 
+    ; Extract User Data selector.
+    mov     rcx, MSR_IA32_STAR
+    call ASM_PFX(AsmReadMsr64)
+    ; rax = ((RING3_CODE64_SEL - 16) << 16 | RING0_CODE64_SEL) << 32
+    shr     rax, 48
+    add     rax, 8
+
+    ; Set Data selectors
+    or      rax, 3H ; RPL = 3
     mov     ds, ax
     mov     es, ax
     mov     fs, ax
     mov     gs, ax
 
-    ; Save Code selector
+    ; Prepare SYSRET arguments.
-    mov     r10, [rsp + 8*5]
+    mov     rcx, [gRing3EntryPoint]
-    or      r10, 3H ; RPL = 3
+    mov     rdx, r12
+    mov     r8, r13
+    mov     r9, r14
+    pushfq
+    pop     r11
 
-    ; Prepare stack before swithcing
+    ; Restore stack and registers.
-    push    rax     ;  ss
+    pop     r14
-    push    r9      ;  rsp
+    pop     r13
-    push    r10     ;  cs
+    pop     r12
-    push    rcx     ;  rip
 
-    ; Save 2 parameters
+    ; Save Core Stack pointers and switch to User Stack.
-    mov     rcx, rdx
+    mov     [ASM_PFX(CoreRsp)], rsp
-    mov     rdx, r8
+    mov     [ASM_PFX(CoreRbp)], rbp
+    mov     rsp, [ASM_PFX(gRing3CallStackTop)]
+    mov     rbp, rsp
 
     ; Pass control to user image
-    retfq
+o64 sysret
 
-;------------------------------------------------------------------------------
-; EFI_STATUS
-; EFIAPI
-; CallRing3 (
-;   IN UINT8  Type,
-;   IN UINT16 CodeSelector,
-;   IN UINT16 DataSelector,
-;   IN VOID   *FunctionAddress,
-;   ...
-;   );
-;
-;   (rcx) Type.
-;   (rdx) CodeSelector  - Segment selector for code.
-;   (r8)  DataSelector  - Segment selector for data.
-;   (r9)  FunctionAddress
-;
-;   (On User Stack) Argument 1, 2, 3, ...
-;------------------------------------------------------------------------------
-global ASM_PFX(CallRing3)
-ASM_PFX(CallRing3):
-    ; Set Data selectors
-    or      r8, 3H ; RPL = 3
-
-o16 mov     ds, r8
-o16 mov     es, r8
-o16 mov     fs, r8
-o16 mov     gs, r8
-
-    ; Save Code selector
-    or      rdx, 3H ; RPL = 3
-
-    ; Prepare stack before swithcing
-    push    r8                      ;  ss
-    push qword [gRing3CallStackTop] ;  rsp
-    push    rdx                     ;  cs
-    push qword [gRing3EntryPoint]   ;  rip
-
-    ; Copy Arguments from Core Stack to User Stack + return address
-
-    ; Pass control to User driver function.
-    retfq
 coreReturnAddress:
     ret
+
+SECTION .data
+ASM_PFX(CoreRsp):
+  resq 1
+
+ASM_PFX(CoreRbp):
+  resq 1

MdeModulePkg/Core/Dxe/SysCall/X64/Ring3Dxe.nasm

@@ -15,7 +15,18 @@ SECTION .text
 ;   IN EFI_HANDLE        ImageHandle,
 ;   IN EFI_SYSTEM_TABLE  *SystemTable
 ;   )
+;
+;   (rcx) _ModuleEntryPoint  - Used by SYSRET.
+;   (rdx) EntryPoint         - Function address in User address space.
+;   (r8)  Context1           - Parameter1 for entry point.
+;   (r9)  Context2           - Parameter2 for entry point.
 ;------------------------------------------------------------------------------
 global ASM_PFX(_ModuleEntryPoint)
 ASM_PFX(_ModuleEntryPoint):
-  ret
+    mov rcx, r8
+    mov r8, rdx
+    mov rdx, r9
+
+    call r8
+    
+    ret