[PATCH v2] ArmPkg/ArmSmcPsciResetSystemLib: add missing call to ExitBootServices()

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Our poor man's implementation of EnterS3WithImmediateWake () currently
sets a high TPL level to disable interrupts, and simply calls the
PEI entrypoint again after disabling the MMU.

Unfortunately, this is not sufficient: DMA capable devices such as
network controllers or USB controllers may still be enabled and
writing to memory, e.g., in response to incoming network packets.

So instead, do the full ExitBootServices() dance: allocate space and
get the memory map, call ExitBootServices(), and in case it fails, get
the memory map again and call ExitBootServices() again. This ensures
that all cleanup related to DMA capable devices is performed before
doing the warm reset.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
v2: - add asm routines to ensure that we don't access memory after
      disabling the MMU and caches
    - set MemMap to NULL

 ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.S              | 30 +++++++++++
 ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.asm            | 35 ++++++++++++
 ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.S                  | 29 ++++++++++
 ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.asm                | 34 ++++++++++++
 ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c   | 57 +++++++++++++++++---
 ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf |  8 +++
 6 files changed, 187 insertions(+), 6 deletions(-)

diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.S b/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.S
new file mode 100644
index 000000000000..1edca941cb8f
--- /dev/null
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.S
@@ -0,0 +1,30 @@
+/** @file
+  ResetSystemLib implementation using PSCI calls
+
+  Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <AsmMacroIoLibV8.h>
+
+ASM_FUNC(DisableMmuAndReenterPei)
+  stp   x29, x30, [sp, #-16]!
+  mov   x29, sp
+
+  bl    ArmDisableMmu
+
+  // no memory accesses after MMU and caches have been disabled
+
+  MOV64 (x0, FixedPcdGet64 (PcdFvBaseAddress))
+  blr   x0
+
+  // never returns
+  nop
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.asm b/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.asm
new file mode 100644
index 000000000000..b3dca150c150
--- /dev/null
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/AArch64/Reset.asm
@@ -0,0 +1,35 @@
+/** @file
+  ResetSystemLib implementation using PSCI calls
+
+  Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+  AREA Reset, CODE, READONLY
+
+  EXPORT DisableMmuAndReenterPei
+  IMPORT ArmDisableMmu
+
+DisableMmuAndReenterPei
+  stp   x29, x30, [sp, #-16]!
+  mov   x29, sp
+
+  bl    ArmDisableMmu
+
+  ; no memory accesses after MMU and caches have been disabled
+
+  movl  x0, FixedPcdGet64 (PcdFvBaseAddress)
+  blr   x0
+
+  ; never returns
+  nop
+
+  END
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.S b/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.S
new file mode 100644
index 000000000000..b6fe2bd82baa
--- /dev/null
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.S
@@ -0,0 +1,29 @@
+/** @file
+  ResetSystemLib implementation using PSCI calls
+
+  Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <AsmMacroIoLib.h>
+
+ASM_FUNC(DisableMmuAndReenterPei)
+  push  {lr}
+
+  bl    ArmDisableMmu
+
+  // no memory accesses after MMU and caches have been disabled
+
+  MOV32 (r0, FixedPcdGet64 (PcdFvBaseAddress))
+  blx   r0
+
+  // never returns
+  nop
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.asm b/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.asm
new file mode 100644
index 000000000000..f098b352418b
--- /dev/null
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/Arm/Reset.asm
@@ -0,0 +1,34 @@
+/** @file
+  ResetSystemLib implementation using PSCI calls
+
+  Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+    INCLUDE AsmMacroExport.inc
+    PRESERVE8
+
+    IMPORT ArmDisableMmu
+
+RVCT_ASM_EXPORT DisableMmuAndReenterPei
+  push  {lr}
+
+  bl    ArmDisableMmu
+
+  ; no memory accesses after MMU and caches have been disabled
+
+  mov32 r0, FixedPcdGet64 (PcdFvBaseAddress)
+  blx   r0
+
+  ; never returns
+  nop
+
+  END
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
index 10ceafd14d5d..3f7b8ae0b169 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
@@ -1,7 +1,7 @@
 /** @file
   ResetSystemLib implementation using PSCI calls
 
-  Copyright (c) 2017, Linaro Ltd. All rights reserved.<BR>
+  Copyright (c) 2017 - 2018, Linaro Ltd. All rights reserved.<BR>
 
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -81,6 +81,8 @@ ResetShutdown (
   ArmCallSmc (&ArmSmcArgs);
 }
 
+VOID DisableMmuAndReenterPei (VOID);
+
 /**
   This function causes the system to enter S3 and then wake up immediately.
 
@@ -92,7 +94,12 @@ EnterS3WithImmediateWake (
   VOID
   )
 {
-  VOID (*Reset)(VOID);
+  EFI_PHYSICAL_ADDRESS        Alloc;
+  EFI_MEMORY_DESCRIPTOR       *MemMap;
+  UINTN                       MemMapSize;
+  UINTN                       MapKey, DescriptorSize;
+  UINT32                      DescriptorVersion;
+  EFI_STATUS                  Status;
 
   if (FeaturePcdGet (PcdArmReenterPeiForCapsuleWarmReboot) &&
       !EfiAtRuntime ()) {
@@ -101,11 +108,49 @@ EnterS3WithImmediateWake (
     // immediate wake (which is used by capsule update) by disabling the MMU
     // and interrupts, and jumping to the PEI entry point.
     //
-    Reset = (VOID (*)(VOID))(UINTN)FixedPcdGet64 (PcdFvBaseAddress);
 
-    gBS->RaiseTPL (TPL_HIGH_LEVEL);
-    ArmDisableMmu ();
-    Reset ();
+    //
+    // Obtain the size of the memory map
+    //
+    MemMapSize = 0;
+    MemMap = NULL;
+    Status = gBS->GetMemoryMap (&MemMapSize, MemMap, &MapKey, &DescriptorSize,
+                    &DescriptorVersion);
+    ASSERT (Status == EFI_BUFFER_TOO_SMALL);
+
+    //
+    // Add some slack to the allocation to cater for changes in the memory
+    // map if ExitBootServices () fails the first time around.
+    //
+    MemMapSize += SIZE_4KB;
+    Status = gBS->AllocatePages (AllocateAnyPages, EfiBootServicesData,
+                    EFI_SIZE_TO_PAGES (MemMapSize), &Alloc);
+    ASSERT_EFI_ERROR (Status);
+
+    MemMap = (EFI_MEMORY_DESCRIPTOR *)(UINTN)Alloc;
+
+    Status = gBS->GetMemoryMap (&MemMapSize, MemMap, &MapKey, &DescriptorSize,
+                    &DescriptorVersion);
+    ASSERT_EFI_ERROR (Status);
+
+    Status = gBS->ExitBootServices (gImageHandle, MapKey);
+    if (EFI_ERROR (Status)) {
+      //
+      // ExitBootServices () may fail the first time around if an event fired
+      // right after the call to GetMemoryMap() which allocated or freed memory.
+      // Since that first call to ExitBootServices () will disarm the timer,
+      // this is guaranteed not to happen again, so one additional attempt
+      // should suffice.
+      //
+      Status = gBS->GetMemoryMap (&MemMapSize, MemMap, &MapKey, &DescriptorSize,
+                      &DescriptorVersion);
+      ASSERT_EFI_ERROR (Status);
+
+      Status = gBS->ExitBootServices (gImageHandle, MapKey);
+      ASSERT_EFI_ERROR (Status);
+    }
+
+    DisableMmuAndReenterPei ();
   }
 }
 
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
index 19021cd1e8b6..3b8925c6f9cd 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
@@ -21,6 +21,14 @@
   VERSION_STRING                 = 1.0
   LIBRARY_CLASS                  = ResetSystemLib
 
+[Sources.AARCH64]
+  AArch64/Reset.S   | GCC
+  AArch64/Reset.asm | MSFT
+
+[Sources.ARM]
+  Arm/Reset.S       | GCC
+  Arm/Reset.asm     | RVCT
+
 [Sources]
   ArmSmcPsciResetSystemLib.c
 
-- 
2.17.1