Ring3: Added support for ARM User page table.

acidanthera · Dec 19, 2024 · 75c5b9e · 75c5b9e
1 parent d051ccd
commit 75c5b9e
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Showing 4 changed files with 86 additions and 16 deletions.
diff --git a/ArmPkg/Include/AsmMacroIoLib.h b/ArmPkg/Include/AsmMacroIoLib.h
@@ -21,6 +21,16 @@
 
 #define ASM_FUNC(Name)  _ASM_FUNC(ASM_PFX(Name), .text. ## Name)
 
+#define _ASM_FUNC_ALIGN(Name, Section, Align)       \
+  .global   Name                                  ; \
+  .section  #Section, "ax"                        ; \
+  .type     Name, %function                       ; \
+  .balign   Align                                 ; \
+  Name:
+
+#define ASM_FUNC_ALIGN(Name, Align)  \
+  _ASM_FUNC_ALIGN(ASM_PFX(Name), .text. ## Name, Align)
+
 #define MOV32(Reg, Val)                       \
   movw      Reg, #(Val) & 0xffff            ; \
   movt      Reg, #(Val) >> 16

diff --git a/ArmPkg/Library/ArmExceptionLib/Arm/ExceptionSupport.S b/ArmPkg/Library/ArmExceptionLib/Arm/ExceptionSupport.S
@@ -11,6 +11,7 @@
 #------------------------------------------------------------------------------
 
 #include <Library/PcdLib.h>
+#include <AsmMacroIoLib.h>
 
 /*
 
@@ -59,8 +60,10 @@ GCC_ASM_EXPORT(CommonCExceptionHandler)
 #if !defined(__APPLE__)
 .fpu neon    @ makes vpush/vpop assemble
 #endif
-.align 5
 
+ASM_FUNC_ALIGN(ExceptionHandlerBase, 4096)
+
+.align 5
 
 //
 // This code gets copied to the ARM vector table
@@ -117,6 +120,8 @@ ASM_PFX(UndefinedInstructionEntry):
   bx        R1
 
 ASM_PFX(SoftwareInterruptEntry):
+  cpsid     if
+  isb
   srsdb     #0x13!                    @ Store return state on SVC stack
                                       @ We are already in SVC mode
   stmfd     SP!,{LR}                  @ Store the link register for the current mode
@@ -250,6 +255,24 @@ NoAdjustNeeded:
   vpush     {d0-d15}                @ save vstm registers in case they are used in optimizations
 #endif
 
+  ldr       R5, [SP, #0x40]         @ Saved Processor Status Register
+  and       R5, R5, #0xF
+  cmp       R5, 0                   @ Check whether EL0 process was interrupted
+  bne       NoTTBR0Switch
+  mrc       p15,0,R5,c2,c0,0        @ R5 == TTBR0
+  ADRL      (R6, UserPageTable)
+  str       R5, [R6]
+  and       R5, R5, #0x7F           @ Preserve TTBR0 attributes
+  LDRL      (R6, ASM_PFX(CorePageTable))
+  orr       R6, R6, R5              @ Assign TTBR0 attributes
+  mcr       p15,0,R6,c2,c0,0        @ TTBR0 == R6
+  mcr       p15,0,r0,c8,c7,0        @ TLBIALL, TLB Invalidate All.
+  mcr       p15,0,r0,c7,c5,6        @ BPIALL, Branch Predictor Invalidate All.
+  dsb
+  isb
+
+NoTTBR0Switch:
+
   mov       R4, SP                  @ Save current SP
   tst       R4, #4
   subne     SP, SP, #4              @ Adjust SP if not 8-byte aligned
@@ -269,6 +292,19 @@ CommonCExceptionHandler (
 
   mov       SP, R4                  @ Restore SP
 
+  ldr       R4, [SP, #0x40]         @ Saved Processor Status Register
+  and       R4, R4, #0xF
+  cmp       R4, 0                   @ Check whether EL0 process was interrupted
+  bne       NoTTBR0Switch2
+  LDRL      (R4, UserPageTable)
+  mcr       p15,0,R4,c2,c0,0        @ TTBR0 == R4
+  mcr       p15,0,r0,c8,c7,0        @ TLBIALL, TLB Invalidate All.
+  mcr       p15,0,r0,c7,c5,6        @ BPIALL, Branch Predictor Invalidate All.
+  dsb
+  isb
+
+NoTTBR0Switch2:
+
 #if (FixedPcdGet32(PcdVFPEnabled))
   vpop      {d0-d15}
 #endif
@@ -290,3 +326,19 @@ CommonCExceptionHandler (
   add       SP,SP,#0x20             @ Clear out the remaining stack space
   ldmfd     SP!,{LR}                @ restore the link register for this context
   rfefd     SP!                     @ return from exception via srsfd stack slot
+
+ASM_FUNC_ALIGN(ExceptionHandlerFinal, 4096)
+
+.data
+
+.global ASM_PFX(CorePageTable)
+.balign 4096
+ASM_PFX(CorePageTable):
+.ds.l 1
+
+UserPageTable:
+.ds.l 1
+
+.balign 4096
+Padding:
+.ds.b 1
diff --git a/MdeModulePkg/Core/Dxe/SysCall/ARM/CoreBootServices.S b/MdeModulePkg/Core/Dxe/SysCall/ARM/CoreBootServices.S
@@ -51,6 +51,7 @@ call:
   pop   {R4-R8, LR}
   bx    LR
 
+ASM_FUNC_ALIGN(SysCallBase, 4096)
 //------------------------------------------------------------------------------
 // EFI_STATUS
 // EFIAPI
@@ -63,13 +64,15 @@ call:
 //   (r2) gRing3EntryPoint
 //   (r3) gCoreSysCallStackTop
 //
-//   (On Core Stack) &CoreSp
+//   (On Core Stack) &CoreSp, gUserPageTable
 //------------------------------------------------------------------------------
 ASM_FUNC(ArmCallRing3)
   // Save registers.
   push  {R4-R12, LR}
   // R6 is &CoreSp
   ldr   R6, [SP, #0x28]
+  // R7 is gUserPageTable
+  ldr   R7, [SP, #0x2C]
 
 #if (FixedPcdGet32(PcdVFPEnabled))
   // Save vstm registers in case they are used in optimizations.
@@ -94,10 +97,21 @@ ASM_FUNC(ArmCallRing3)
   str   R5, [R6]
   mov   SP, R3
 
+  // Switch to UserPageTable.
+  mrc   p15,0,R8,c2,c0,0   // R8 == TTBR0
+  and   R8, R8, #0x7F      // Preserve Core TTBR0 attributes.
+  orr   R7, R7, R8         // Assign Core attributes to UserPageTable.
+  mcr   p15,0,R7,c2,c0,0   // TTBR0 == UserPageTable
+  mcr   p15,0,r0,c8,c7,0   // TLBIALL, TLB Invalidate All.
+  mcr   p15,0,r0,c7,c5,6   // BPIALL, Branch Predictor Invalidate All.
+  dsb
+  isb
+
   push  {R4}
   push  {R2}
   rfefd SP
 
+ASM_FUNC_ALIGN(SysCallEnd, 4096)
 //------------------------------------------------------------------------------
 // VOID
 // EFIAPI

diff --git a/MdeModulePkg/Core/Dxe/SysCall/ARM/InitializeARM.c b/MdeModulePkg/Core/Dxe/SysCall/ARM/InitializeARM.c
@@ -12,7 +12,7 @@
 #include "DxeMain.h"
 
 STATIC UINTN  mCoreSp;
-extern UINTN  gUartBaseAddress;
+UINTN         gUserPageTable;
 
 EFI_STATUS
 EFIAPI
@@ -21,7 +21,8 @@ ArmCallRing3 (
   IN VOID            *StackPointer,
   IN VOID            *EntryPoint,
   IN VOID            *SysCallStack,
-  IN VOID            *CoreStack
+  IN VOID            *CoreStack,
+  IN UINTN           UserPageTable
   );
 
 VOID
@@ -52,6 +53,8 @@ SysCallBootService (
   EFI_STATUS              Status;
   EFI_PHYSICAL_ADDRESS    Physical;
 
+  ArmEnableInterrupts ();
+
   Status = CoreAllocatePages (
              AllocateAnyPages,
              EfiRing3MemoryType,
@@ -71,12 +74,6 @@ SysCallBootService (
   // All remaining arguments are on User Stack.
   //
   CopyMem ((VOID *)((UINTN)Physical + 5 * sizeof (UINTN)), (VOID *)UserRsp, 4 * sizeof (UINTN));
-
-  SetUefiImageMemoryAttributes (
-    gUartBaseAddress,
-    EFI_PAGE_SIZE,
-    EFI_MEMORY_XP
-    );
   ForbidSupervisorAccessToUserMemory ();
 
   Status = CallBootService (
@@ -89,11 +86,7 @@ SysCallBootService (
   //
   CoreFreePages (Physical, EFI_SIZE_TO_PAGES (9 * sizeof (UINTN)));
 
-  SetUefiImageMemoryAttributes (
-    gUartBaseAddress,
-    EFI_PAGE_SIZE,
-    EFI_MEMORY_XP | EFI_MEMORY_USER
-    );
+  ArmDisableInterrupts ();
 
   return Status;
 }
@@ -141,6 +134,7 @@ InitializeMsr (
   }
 
   InitializeSysCallHandler (SysCallBootService);
+  SetExceptionAddresses (NULL, 0);
 }
 
 VOID
@@ -171,5 +165,5 @@ CallRing3 (
   IN RING3_CALL_DATA *Data
   )
 {
-  return ArmCallRing3 (Data, gRing3CallStackTop, gRing3EntryPoint, gCoreSysCallStackTop, &mCoreSp);
+  return ArmCallRing3 (Data, gRing3CallStackTop, gRing3EntryPoint, gCoreSysCallStackTop, &mCoreSp, gUserPageTable);
 }