ArmPlatformPkg/PrePi: avoid global variable write to mSystemMemoryEnd
The global variable mSystemMemoryEnd is initialized by PrePi only if
it has not been initialized by ArmPlatformPeiBootAction(). This allows
platforms executing under, e.g., ARM Trusted Firmware to dynamically
reserve a window at the top of memory that will be used by the secure
firmware.
However, PrePi is a SEC module, and writing to a global variable
violates the SEC constraints, since SEC and PEI may execute from NOR
flash.
So instead, initialize mSystemMemoryEnd statically. This will ensure
it holds the correct value for all implementations where the value
is not overridden, but still allows it to be overridden during the
call to ArmPlatformPeiBootAction().
Note that this patch also fixes a latent bug on 32-bit platforms where
a value of mSystemMemoryEnd exceeding 4 GB would be truncated to 32-bits
rather than limited to (4 GB - 1)
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
diff --git a/ArmPlatformPkg/PrePi/AArch64/ModuleEntryPoint.S b/ArmPlatformPkg/PrePi/AArch64/ModuleEntryPoint.S
index d0530a8..a81709d 100644
--- a/ArmPlatformPkg/PrePi/AArch64/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/PrePi/AArch64/ModuleEntryPoint.S
@@ -13,8 +13,6 @@
#include <AsmMacroIoLibV8.h>
-ASM_GLOBAL ASM_PFX(mSystemMemoryEnd)
-
ASM_FUNC(_ModuleEntryPoint)
// Do early platform specific actions
bl ASM_PFX(ArmPlatformPeiBootAction)
@@ -31,16 +29,6 @@
_SystemMemoryEndInit:
ldr x1, mSystemMemoryEnd
- // Is mSystemMemoryEnd initialized?
- cmp x1, #0
- bne _SetupStackPosition
-
- MOV64 (x1, FixedPcdGet64(PcdSystemMemoryBase) + FixedPcdGet64(PcdSystemMemorySize) - 1)
-
- // Update the global variable
- adr x2, mSystemMemoryEnd
- str x1, [x2]
-
_SetupStackPosition:
// r1 = SystemMemoryTop
@@ -129,5 +117,3 @@
_NeverReturn:
b _NeverReturn
-
-ASM_PFX(mSystemMemoryEnd): .8byte 0
diff --git a/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.S b/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.S
index 39030da..212cab6 100644
--- a/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.S
@@ -15,8 +15,6 @@
#include <Chipset/ArmV7.h>
-GCC_ASM_EXPORT(mSystemMemoryEnd)
-
ASM_FUNC(_ModuleEntryPoint)
// Do early platform specific actions
bl ASM_PFX(ArmPlatformPeiBootAction)
@@ -35,17 +33,11 @@
// to install the stacks at the bottom of the Firmware Device (case the FD is located
// at the top of the DRAM)
_SystemMemoryEndInit:
- ldr r1, mSystemMemoryEnd
-
- // Is mSystemMemoryEnd initialized?
- cmp r1, #0
- bne _SetupStackPosition
-
- MOV32 (r1, FixedPcdGet32(PcdSystemMemoryBase) + FixedPcdGet32(PcdSystemMemorySize) - 1)
-
- // Update the global variable
- adr r2, mSystemMemoryEnd
- str r1, [r2]
+ ADRL (r1, mSystemMemoryEnd)
+ ldrd r2, r3, [r1]
+ teq r3, #0
+ moveq r1, r2
+ mvnne r1, #0
_SetupStackPosition:
// r1 = SystemMemoryTop
@@ -136,5 +128,3 @@
_NeverReturn:
b _NeverReturn
-
-ASM_PFX(mSystemMemoryEnd): .8byte 0
diff --git a/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.asm b/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.asm
index 0233398..1e9daf5 100644
--- a/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.asm
+++ b/ArmPlatformPkg/PrePi/Arm/ModuleEntryPoint.asm
@@ -21,15 +21,14 @@
IMPORT ArmReadMpidr
IMPORT ArmPlatformPeiBootAction
IMPORT ArmPlatformStackSet
+ IMPORT mSystemMemoryEnd
EXPORT _ModuleEntryPoint
- EXPORT mSystemMemoryEnd
PRESERVE8
AREA PrePiCoreEntryPoint, CODE, READONLY
StartupAddr DCD CEntryPoint
-mSystemMemoryEnd DCQ 0
_ModuleEntryPoint
// Do early platform specific actions
@@ -49,19 +48,11 @@
// to install the stacks at the bottom of the Firmware Device (case the FD is located
// at the top of the DRAM)
_SystemMemoryEndInit
- ldr r1, mSystemMemoryEnd
-
- // Is mSystemMemoryEnd initialized?
- cmp r1, #0
- bne _SetupStackPosition
-
- mov32 r1, FixedPcdGet32(PcdSystemMemoryBase)
- mov32 r2, FixedPcdGet32(PcdSystemMemorySize)
- sub r2, r2, #1
- add r1, r1, r2
- // Update the global variable
- adr r2, mSystemMemoryEnd
- str r1, [r2]
+ mov32 r1, mSystemMemoryEnd
+ ldrd r2, r3, [r1]
+ teq r3, #0
+ moveq r1, r2
+ mvnne r1, #0
_SetupStackPosition
// r1 = SystemMemoryTop
diff --git a/ArmPlatformPkg/PrePi/PrePi.c b/ArmPlatformPkg/PrePi/PrePi.c
index 36928c6..e548cca 100644
--- a/ArmPlatformPkg/PrePi/PrePi.c
+++ b/ArmPlatformPkg/PrePi/PrePi.c
@@ -32,6 +32,9 @@
#define IS_XIP() (((UINT64)FixedPcdGet64 (PcdFdBaseAddress) > mSystemMemoryEnd) || \
((FixedPcdGet64 (PcdFdBaseAddress) + FixedPcdGet32 (PcdFdSize)) < FixedPcdGet64 (PcdSystemMemoryBase)))
+UINT64 mSystemMemoryEnd = FixedPcdGet64(PcdSystemMemoryBase) +
+ FixedPcdGet64(PcdSystemMemorySize) - 1;
+
EFI_STATUS
EFIAPI
ExtractGuidedSectionLibConstructor (
