ArmPlatformPkg: Change the memory model for the ARM Platform components

In the former memory model, the UEFI firmware was expected to be located
at the top of the system memory. Stacks & Pi memory regions were set below
the firmware.
On some platform, the UEFI firmware could be shadowed by the ROM firmware
(case of the BeagleBoard) and in some cases the firmware is copied at the
beginning of the system memory.

With this new memory model, stack and Pi/DXE memory regions are set at the
top of the system memory wherever the UEFI firmware is located in the memory
map.
Because DXE core does not support shadowed firmwares, the system memory covered
by the UEFI firmware is marked as 'Non Present' to avoid to be overlapped by
DXE allocations.



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11992 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 39 insertions, 20 deletions

diff --git a/ArmPlatformPkg/PrePi/ModuleEntryPoint.asm b/ArmPlatformPkg/PrePi/ModuleEntryPoint.asm
index 52690f8ecd..00abcb304a 100644
--- a/ArmPlatformPkg/PrePi/ModuleEntryPoint.asm
+++ b/ArmPlatformPkg/PrePi/ModuleEntryPoint.asm
@@ -31,28 +31,51 @@ _ModuleEntryPoint
   mrc   p15, 0, r0, c0, c0, 5

   and   r0, #0xf

 

-_UefiMemoryBase

-#if FixedPcdGet32(PcdStandalone)

+_SetSVCMode

+  // Enter SVC mode

+  mov     r1, #0x13|0x80|0x40

+  msr     CPSR_c, r1

+

+// Check if we can install the size at the top of the System Memory or if we need

+// to install the stacks at the bottom of the Firmware Device (case the FD is located

+// at the top of the DRAM)

+_SetupStackPosition

   // Compute Top of System Memory

   LoadConstantToReg (FixedPcdGet32(PcdSystemMemoryBase), r1)

   LoadConstantToReg (FixedPcdGet32(PcdSystemMemorySize), r2)

   add   r1, r1, r2      // r1 = SystemMemoryTop = PcdSystemMemoryBase + PcdSystemMemorySize

-#else

-  // If it is not a Standalone, we must compute the top of the UEFI memory with the base of the FD

-  LoadConstantToReg (FixedPcdGet32(PcdNormalFdBaseAddress), r1)

-#endif

 

-  // Compute Base of UEFI Memory

-  LoadConstantToReg (FixedPcdGet32(PcdSystemMemoryUefiRegionSize), r2)

-  sub   r1, r1, r2      // r1 = SystemMemoryTop - PcdSystemMemoryUefiRegionSize = UefiMemoryBase

+  // Calculate Top of the Firmware Device

+  LoadConstantToReg (FixedPcdGet32(PcdNormalFdBaseAddress), r2)

+  LoadConstantToReg (FixedPcdGet32(PcdNormalFdSize), r3)

+  add   r3, r3, r2      // r4 = FdTop = PcdNormalFdBaseAddress + PcdNormalFdSize

+

+  // UEFI Memory Size (stacks are allocated in this region)

+  LoadConstantToReg (FixedPcdGet32(PcdSystemMemoryUefiRegionSize), r4)

+

+  //

+  // Reserve the memory for the UEFI region (contain stacks on its top)

+  //

+

+  // Calculate how much space there is between the top of the Firmware and the Top of the System Memory

+  subs	r5, r1, r3		// r5 = SystemMemoryTop - FdTop

+  bmi	_SetupStack		// Jump if negative (FdTop > SystemMemoryTop)

+  cmp	r5, r4

+  bge	_SetupStack

+

+  // Case the top of stacks is the FdBaseAddress

+  mov	r1, r2

 

 _SetupStack

   // Compute Base of Normal stacks for CPU Cores

-  LoadConstantToReg (FixedPcdGet32(PcdCPUCoresNonSecStackSize), r2)

-  mul   r3, r0, r2      // r3 = core_id * stack_size = offset from the stack base

-  sub   sp, r1, r3      // r3 = UefiMemoryBase - StackOffset = TopOfStack

+  LoadConstantToReg (FixedPcdGet32(PcdCPUCoresNonSecStackSize), r5)

+  mul   r3, r0, r5      // r3 = core_id * stack_size = offset from the stack base

+  sub   sp, r1, r3      // r3 = (SystemMemoryTop|FdBaseAddress) - StackOffset = TopOfStack

+

+  // Calculate the Base of the UEFI Memory

+  sub	r1, r1, r4

 

-  // Only allocate memory in top of the primary core stack

+  // Only allocate memory for global variables at top of the primary core stack

   cmp   r0, #0

   bne   _PrepareArguments

 

@@ -66,17 +89,13 @@ _AllocateGlobalPrePiVariables
   sub   sp, sp, r4

 

 _PrepareArguments

-  // Pass the StackBase to the C Entrypoint (UefiMemoryBase - StackSize - StackOffset)

-  sub   r2, r1, r2

-  sub   r2, r3

   // Move sec startup address into a data register

   // Ensure we're jumping to FV version of the code (not boot remapped alias)

-  ldr   r3, StartupAddr

+  ldr   r2, StartupAddr

 

-  // jump to PrePiCore C code

+  // Jump to PrePiCore C code

   //    r0 = core_id

   //    r1 = UefiMemoryBase

-  //    r2 = StackBase

-  blx   r3

+  blx   r2

 

   END