[edk2,v4] ArmPkg/AArch64Mmu: disable MMU during page table manipulations

Message ID 1460648907-18866-1-git-send-email-ard.biesheuvel@linaro.org
State Accepted
Commit 61b02ba1f2a3f80fa06f5006f0aea1572093a067
Headers show

Commit Message

Ard Biesheuvel April 14, 2016, 3:48 p.m.
On ARM, manipulating live page tables is cumbersome since the architecture
mandates the use of break-before-make, i.e., replacing a block entry with
a table entry requires an intermediate step via an invalid entry, or TLB
conflicts may occur.

Since it is not generally feasible to decide in the page table manipulation
routines whether such an invalid entry will result in those routines
themselves to become unavailable, use a function that is callable with
the MMU off (i.e., a leaf function that does not access the stack) to
perform the change of a block entry into a table entry.

Note that the opposite should never occur, i.e., table entries are never
coalesced into block entries.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 ArmPkg/Include/Library/ArmLib.h                       |  6 ++
 ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf          |  5 +-
 ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c | 36 ++++++++++++
 ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c            | 17 +++++-
 ArmPkg/Library/ArmLib/AArch64/AArch64Support.S        | 62 ++++++++++++++++++++
 5 files changed, 124 insertions(+), 2 deletions(-)

-- 
2.5.0

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Comments

Mark Rutland April 14, 2016, 3:59 p.m. | #1
On Thu, Apr 14, 2016 at 05:48:27PM +0200, Ard Biesheuvel wrote:
> On ARM, manipulating live page tables is cumbersome since the architecture

> mandates the use of break-before-make, i.e., replacing a block entry with

> a table entry requires an intermediate step via an invalid entry, or TLB

> conflicts may occur.

> 

> Since it is not generally feasible to decide in the page table manipulation

> routines whether such an invalid entry will result in those routines

> themselves to become unavailable, use a function that is callable with

> the MMU off (i.e., a leaf function that does not access the stack) to

> perform the change of a block entry into a table entry.

> 

> Note that the opposite should never occur, i.e., table entries are never

> coalesced into block entries.

> 

> Contributed-under: TianoCore Contribution Agreement 1.0

> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>


Acked-by: Mark Rutland <mark.rutland@arm.com>


Mark.

> ---

>  ArmPkg/Include/Library/ArmLib.h                       |  6 ++

>  ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf          |  5 +-

>  ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c | 36 ++++++++++++

>  ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c            | 17 +++++-

>  ArmPkg/Library/ArmLib/AArch64/AArch64Support.S        | 62 ++++++++++++++++++++

>  5 files changed, 124 insertions(+), 2 deletions(-)

> 

> diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h

> index 15f610d82e1d..1689f0072db6 100644

> --- a/ArmPkg/Include/Library/ArmLib.h

> +++ b/ArmPkg/Include/Library/ArmLib.h

> @@ -613,4 +613,10 @@ ArmClearMemoryRegionReadOnly (

>    IN  UINT64                    Length

>    );

>  

> +VOID

> +ArmReplaceLiveTranslationEntry (

> +  IN  UINT64  *Entry,

> +  IN  UINT64  Value

> +  );

> +

>  #endif // __ARM_LIB__

> diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf

> index dd585dea91fb..58684e8492f2 100644

> --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf

> +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf

> @@ -17,9 +17,10 @@ [Defines]

>    INF_VERSION                    = 0x00010005

>    BASE_NAME                      = AArch64Lib

>    FILE_GUID                      = ef20ddf5-b334-47b3-94cf-52ff44c29138

> -  MODULE_TYPE                    = DXE_DRIVER

> +  MODULE_TYPE                    = BASE

>    VERSION_STRING                 = 1.0

>    LIBRARY_CLASS                  = ArmLib

> +  CONSTRUCTOR                    = AArch64LibConstructor

>  

>  [Sources.AARCH64]

>    AArch64Lib.c

> @@ -31,6 +32,7 @@ [Sources.AARCH64]

>  

>    ../Common/AArch64/ArmLibSupport.S

>    ../Common/ArmLib.c

> +  AArch64LibConstructor.c

>  

>  [Packages]

>    ArmPkg/ArmPkg.dec

> @@ -38,6 +40,7 @@ [Packages]

>  

>  [LibraryClasses]

>    MemoryAllocationLib

> +  CacheMaintenanceLib

>  

>  [Protocols]

>    gEfiCpuArchProtocolGuid

> diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c b/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c

> new file mode 100644

> index 000000000000..d2d0d3c15ee3

> --- /dev/null

> +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c

> @@ -0,0 +1,36 @@

> +#/* @file

> +#

> +#  Copyright (c) 2016, Linaro Limited. All rights reserved.

> +#

> +#  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 <Base.h>

> +

> +#include <Library/ArmLib.h>

> +#include <Library/CacheMaintenanceLib.h>

> +

> +RETURN_STATUS

> +EFIAPI

> +AArch64LibConstructor (

> +  VOID

> +  )

> +{

> +  extern UINT32 ArmReplaceLiveTranslationEntrySize;

> +

> +  //

> +  // The ArmReplaceLiveTranslationEntry () helper function may be invoked

> +  // with the MMU off so we have to ensure that it gets cleaned to the PoC

> +  //

> +  WriteBackDataCacheRange (ArmReplaceLiveTranslationEntry,

> +    ArmReplaceLiveTranslationEntrySize);

> +

> +  return RETURN_SUCCESS;

> +}

> diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c

> index b7d23c6f3286..2cc6fc45aecf 100644

> --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c

> +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c

> @@ -169,6 +169,20 @@ GetRootTranslationTableInfo (

>  

>  STATIC

>  VOID

> +ReplaceLiveEntry (

> +  IN  UINT64  *Entry,

> +  IN  UINT64  Value

> +  )

> +{

> +  if (!ArmMmuEnabled ()) {

> +    *Entry = Value;

> +  } else {

> +    ArmReplaceLiveTranslationEntry (Entry, Value);

> +  }

> +}

> +

> +STATIC

> +VOID

>  LookupAddresstoRootTable (

>    IN  UINT64  MaxAddress,

>    OUT UINTN  *T0SZ,

> @@ -330,7 +344,8 @@ GetBlockEntryListFromAddress (

>          }

>  

>          // Fill the BlockEntry with the new TranslationTable

> -        *BlockEntry = ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TableAttributes | TT_TYPE_TABLE_ENTRY;

> +        ReplaceLiveEntry (BlockEntry,

> +          ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TableAttributes | TT_TYPE_TABLE_ENTRY);

>        }

>      } else {

>        if (IndexLevel != PageLevel) {

> diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S

> index 1a3023b79487..43f7a795acec 100644

> --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S

> +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S

> @@ -56,6 +56,8 @@ GCC_ASM_EXPORT (ArmReadIdPfr1)

>  GCC_ASM_EXPORT (ArmWriteHcr)

>  GCC_ASM_EXPORT (ArmReadHcr)

>  GCC_ASM_EXPORT (ArmReadCurrentEL)

> +GCC_ASM_EXPORT (ArmReplaceLiveTranslationEntry)

> +GCC_ASM_EXPORT (ArmReplaceLiveTranslationEntrySize)

>  

>  .set CTRL_M_BIT,      (1 << 0)

>  .set CTRL_A_BIT,      (1 << 1)

> @@ -481,4 +483,64 @@ ASM_PFX(ArmReadCurrentEL):

>    mrs   x0, CurrentEL

>    ret

>  

> +

> +  .macro __replace_entry, el

> +

> +  // disable the MMU

> +  mrs   x8, sctlr_el\el

> +  bic   x9, x8, #CTRL_M_BIT

> +  msr   sctlr_el\el, x9

> +  isb

> +

> +  // write updated entry

> +  str   x1, [x0]

> +

> +  // invalidate again to get rid of stale clean cachelines that may

> +  // have been filled speculatively since the last invalidate

> +  dmb   sy

> +  dc    ivac, x0

> +

> +  // flush the TLBs

> +  .if   \el == 1

> +  tlbi  vmalle1

> +  .else

> +  tlbi  alle\el

> +  .endif

> +  dsb   sy

> +

> +  // re-enable the MMU

> +  msr   sctlr_el\el, x8

> +  isb

> +  .endm

> +

> +//VOID

> +//ArmReplaceLiveTranslationEntry (

> +//  IN  UINT64  *Entry,

> +//  IN  UINT64  Value

> +//  )

> +ASM_PFX(ArmReplaceLiveTranslationEntry):

> +

> +  // disable interrupts

> +  mrs   x2, daif

> +  msr   daifset, #0xf

> +  isb

> +

> +  // clean and invalidate first so that we don't clobber

> +  // adjacent entries that are dirty in the caches

> +  dc    civac, x0

> +  dsb   ish

> +

> +  EL1_OR_EL2_OR_EL3(x3)

> +1:__replace_entry 1

> +  b     4f

> +2:__replace_entry 2

> +  b     4f

> +3:__replace_entry 3

> +

> +4:msr   daif, x2

> +  ret

> +

> +ASM_PFX(ArmReplaceLiveTranslationEntrySize):

> +  .long   . - ArmReplaceLiveTranslationEntry

> +

>  ASM_FUNCTION_REMOVE_IF_UNREFERENCED

> -- 

> 2.5.0

> 

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Patch

diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h
index 15f610d82e1d..1689f0072db6 100644
--- a/ArmPkg/Include/Library/ArmLib.h
+++ b/ArmPkg/Include/Library/ArmLib.h
@@ -613,4 +613,10 @@  ArmClearMemoryRegionReadOnly (
   IN  UINT64                    Length
   );
 
+VOID
+ArmReplaceLiveTranslationEntry (
+  IN  UINT64  *Entry,
+  IN  UINT64  Value
+  );
+
 #endif // __ARM_LIB__
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf
index dd585dea91fb..58684e8492f2 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.inf
@@ -17,9 +17,10 @@  [Defines]
   INF_VERSION                    = 0x00010005
   BASE_NAME                      = AArch64Lib
   FILE_GUID                      = ef20ddf5-b334-47b3-94cf-52ff44c29138
-  MODULE_TYPE                    = DXE_DRIVER
+  MODULE_TYPE                    = BASE
   VERSION_STRING                 = 1.0
   LIBRARY_CLASS                  = ArmLib
+  CONSTRUCTOR                    = AArch64LibConstructor
 
 [Sources.AARCH64]
   AArch64Lib.c
@@ -31,6 +32,7 @@  [Sources.AARCH64]
 
   ../Common/AArch64/ArmLibSupport.S
   ../Common/ArmLib.c
+  AArch64LibConstructor.c
 
 [Packages]
   ArmPkg/ArmPkg.dec
@@ -38,6 +40,7 @@  [Packages]
 
 [LibraryClasses]
   MemoryAllocationLib
+  CacheMaintenanceLib
 
 [Protocols]
   gEfiCpuArchProtocolGuid
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c b/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c
new file mode 100644
index 000000000000..d2d0d3c15ee3
--- /dev/null
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64LibConstructor.c
@@ -0,0 +1,36 @@ 
+#/* @file
+#
+#  Copyright (c) 2016, Linaro Limited. All rights reserved.
+#
+#  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 <Base.h>
+
+#include <Library/ArmLib.h>
+#include <Library/CacheMaintenanceLib.h>
+
+RETURN_STATUS
+EFIAPI
+AArch64LibConstructor (
+  VOID
+  )
+{
+  extern UINT32 ArmReplaceLiveTranslationEntrySize;
+
+  //
+  // The ArmReplaceLiveTranslationEntry () helper function may be invoked
+  // with the MMU off so we have to ensure that it gets cleaned to the PoC
+  //
+  WriteBackDataCacheRange (ArmReplaceLiveTranslationEntry,
+    ArmReplaceLiveTranslationEntrySize);
+
+  return RETURN_SUCCESS;
+}
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
index b7d23c6f3286..2cc6fc45aecf 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
@@ -169,6 +169,20 @@  GetRootTranslationTableInfo (
 
 STATIC
 VOID
+ReplaceLiveEntry (
+  IN  UINT64  *Entry,
+  IN  UINT64  Value
+  )
+{
+  if (!ArmMmuEnabled ()) {
+    *Entry = Value;
+  } else {
+    ArmReplaceLiveTranslationEntry (Entry, Value);
+  }
+}
+
+STATIC
+VOID
 LookupAddresstoRootTable (
   IN  UINT64  MaxAddress,
   OUT UINTN  *T0SZ,
@@ -330,7 +344,8 @@  GetBlockEntryListFromAddress (
         }
 
         // Fill the BlockEntry with the new TranslationTable
-        *BlockEntry = ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TableAttributes | TT_TYPE_TABLE_ENTRY;
+        ReplaceLiveEntry (BlockEntry,
+          ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TableAttributes | TT_TYPE_TABLE_ENTRY);
       }
     } else {
       if (IndexLevel != PageLevel) {
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
index 1a3023b79487..43f7a795acec 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
@@ -56,6 +56,8 @@  GCC_ASM_EXPORT (ArmReadIdPfr1)
 GCC_ASM_EXPORT (ArmWriteHcr)
 GCC_ASM_EXPORT (ArmReadHcr)
 GCC_ASM_EXPORT (ArmReadCurrentEL)
+GCC_ASM_EXPORT (ArmReplaceLiveTranslationEntry)
+GCC_ASM_EXPORT (ArmReplaceLiveTranslationEntrySize)
 
 .set CTRL_M_BIT,      (1 << 0)
 .set CTRL_A_BIT,      (1 << 1)
@@ -481,4 +483,64 @@  ASM_PFX(ArmReadCurrentEL):
   mrs   x0, CurrentEL
   ret
 
+
+  .macro __replace_entry, el
+
+  // disable the MMU
+  mrs   x8, sctlr_el\el
+  bic   x9, x8, #CTRL_M_BIT
+  msr   sctlr_el\el, x9
+  isb
+
+  // write updated entry
+  str   x1, [x0]
+
+  // invalidate again to get rid of stale clean cachelines that may
+  // have been filled speculatively since the last invalidate
+  dmb   sy
+  dc    ivac, x0
+
+  // flush the TLBs
+  .if   \el == 1
+  tlbi  vmalle1
+  .else
+  tlbi  alle\el
+  .endif
+  dsb   sy
+
+  // re-enable the MMU
+  msr   sctlr_el\el, x8
+  isb
+  .endm
+
+//VOID
+//ArmReplaceLiveTranslationEntry (
+//  IN  UINT64  *Entry,
+//  IN  UINT64  Value
+//  )
+ASM_PFX(ArmReplaceLiveTranslationEntry):
+
+  // disable interrupts
+  mrs   x2, daif
+  msr   daifset, #0xf
+  isb
+
+  // clean and invalidate first so that we don't clobber
+  // adjacent entries that are dirty in the caches
+  dc    civac, x0
+  dsb   ish
+
+  EL1_OR_EL2_OR_EL3(x3)
+1:__replace_entry 1
+  b     4f
+2:__replace_entry 2
+  b     4f
+3:__replace_entry 3
+
+4:msr   daif, x2
+  ret
+
+ASM_PFX(ArmReplaceLiveTranslationEntrySize):
+  .long   . - ArmReplaceLiveTranslationEntry
+
 ASM_FUNCTION_REMOVE_IF_UNREFERENCED