ArmPkg/CpuDxe: ignore attribute changes during SyncCacheConfig()

To prevent the initial MMU->GCD memory space map synchronization from
stripping permissions attributes [which we cannot use in the GCD memory
space map, unfortunately], implement the same approach as x86, and ignore
SetMemoryAttributes() calls during the time SyncCacheConfig() is in
progress. This is a horrible hack, but is currently the only way we can
implement strict permissions on arbitrary memory regions [as opposed to
PE/COFF text/data sections only]

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

3 files changed, 8 insertions, 0 deletions

diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.c b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
index 5aa5b87414..5e923d45b7 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.c
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
@@ -17,6 +17,7 @@
 

 #include <Guid/IdleLoopEvent.h>

 

+BOOLEAN                   mIsFlushingGCD;

 

 /**

   This function flushes the range of addresses from Start to Start+Length

@@ -261,7 +262,9 @@ CpuDxeInitialize (
   // and that calls EFI_CPU_ARCH_PROTOCOL.SetMemoryAttributes, so this code needs to go

   // after the protocol is installed

   //

+  mIsFlushingGCD = TRUE;

   SyncCacheConfig (&mCpu);

+  mIsFlushingGCD = FALSE;

 

   // If the platform is a MPCore system then install the Configuration Table describing the

   // secondary core states

diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.h b/ArmPkg/Drivers/CpuDxe/CpuDxe.h
index a00fc30643..a46db8d257 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.h
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.h
@@ -37,6 +37,7 @@
 #include <Protocol/DebugSupportPeriodicCallback.h>

 #include <Protocol/LoadedImage.h>

 

+extern BOOLEAN mIsFlushingGCD;

 

 /**

   This function registers and enables the handler specified by InterruptHandler for a processor

diff --git a/ArmPkg/Drivers/CpuDxe/CpuMmuCommon.c b/ArmPkg/Drivers/CpuDxe/CpuMmuCommon.c
index ebe593d1c3..0f36a05840 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuMmuCommon.c
+++ b/ArmPkg/Drivers/CpuDxe/CpuMmuCommon.c
@@ -188,6 +188,10 @@ CpuSetMemoryAttributes (
   UINTN       RegionLength;

   UINTN       RegionArmAttributes;

 

+  if (mIsFlushingGCD) {

+    return EFI_SUCCESS;

+  }

+

   if ((BaseAddress & (SIZE_4KB - 1)) != 0) {

     // Minimum granularity is SIZE_4KB (4KB on ARM)

     DEBUG ((EFI_D_PAGE, "CpuSetMemoryAttributes(%lx, %lx, %lx): Minimum ganularity is SIZE_4KB\n", BaseAddress, Length, EfiAttributes));