Re: [PATCH] MdePkg/BaseLib: implement SpeculationBarrier() for ARM and AArch64

["Gao, Liming" <liming.gao@intel.com>]

Ard:
  I have no comments on this patch. Reviewed-by: Liming Gao <liming.gao@intel.com>

> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: Wednesday, February 6, 2019 8:08 AM
> To: edk2-devel@lists.01.org
> Cc: leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org>
> Subject: [PATCH] MdePkg/BaseLib: implement SpeculationBarrier() for ARM and AArch64
> 
> Replace the dummy C implementation of SpeculationBarrier() with
> implementations consisting of the recommended DSB SY + ISB sequence,
> as recommended by ARM in the whitepaper "Cache Speculation Side-channels"
> version 2.4, dated October 2018.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.S   | 39 ++++++++++++++++++++
>  MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.asm | 38 +++++++++++++++++++
>  MdePkg/Library/BaseLib/Arm/SpeculationBarrier.S       | 39 ++++++++++++++++++++
>  MdePkg/Library/BaseLib/Arm/SpeculationBarrier.asm     | 39 ++++++++++++++++++++
>  MdePkg/Library/BaseLib/Arm/SpeculationBarrier.c       | 30 ---------------
>  MdePkg/Library/BaseLib/BaseLib.inf                    |  7 +++-
>  6 files changed, 160 insertions(+), 32 deletions(-)
> 
> diff --git a/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.S b/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.S
> new file mode 100644
> index 000000000000..500bdadca5d2
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.S
> @@ -0,0 +1,39 @@
> +##------------------------------------------------------------------------------
> +#
> +# SpeculationBarrier() for AArch64
> +#
> +# Copyright (c) 2019, Linaro Ltd. 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.
> +#
> +##------------------------------------------------------------------------------
> +
> +.text
> +.p2align 2
> +
> +GCC_ASM_EXPORT(SpeculationBarrier)
> +
> +
> +#/**
> +#  Uses as a barrier to stop speculative execution.
> +#
> +#  Ensures that no later instruction will execute speculatively, until all prior
> +#  instructions have completed.
> +#
> +#**/
> +#VOID
> +#EFIAPI
> +#SpeculationBarrier (
> +#  VOID
> +#  );
> +#
> +ASM_PFX(SpeculationBarrier):
> +    dsb  sy
> +    isb
> +    ret
> diff --git a/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.asm b/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.asm
> new file mode 100644
> index 000000000000..0c4b915b7798
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/AArch64/SpeculationBarrier.asm
> @@ -0,0 +1,38 @@
> +;------------------------------------------------------------------------------
> +;
> +; SpeculationBarrier() for AArch64
> +;
> +; Copyright (c) 2019, Linaro Ltd. 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.
> +;
> +;------------------------------------------------------------------------------
> +
> +  EXPORT SpeculationBarrier
> +  AREA BaseLib_LowLevel, CODE, READONLY
> +
> +;/**
> +;  Uses as a barrier to stop speculative execution.
> +;
> +;  Ensures that no later instruction will execute speculatively, until all prior
> +;  instructions have completed.
> +;
> +;**/
> +;VOID
> +;EFIAPI
> +;SpeculationBarrier (
> +;  VOID
> +;  );
> +;
> +SpeculationBarrier
> +    dsb   sy
> +    isb
> +    ret
> +
> +  END
> diff --git a/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.S b/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.S
> new file mode 100644
> index 000000000000..7857558aba17
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.S
> @@ -0,0 +1,39 @@
> +##------------------------------------------------------------------------------
> +#
> +# SpeculationBarrier() for AArch64
> +#
> +# Copyright (c) 2019, Linaro Ltd. 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.
> +#
> +##------------------------------------------------------------------------------
> +
> +.text
> +.p2align 2
> +
> +GCC_ASM_EXPORT(SpeculationBarrier)
> +
> +
> +#/**
> +#  Uses as a barrier to stop speculative execution.
> +#
> +#  Ensures that no later instruction will execute speculatively, until all prior
> +#  instructions have completed.
> +#
> +#**/
> +#VOID
> +#EFIAPI
> +#SpeculationBarrier (
> +#  VOID
> +#  );
> +#
> +ASM_PFX(SpeculationBarrier):
> +    dsb
> +    isb
> +    bx   lr
> diff --git a/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.asm b/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.asm
> new file mode 100644
> index 000000000000..425cd3de9e22
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.asm
> @@ -0,0 +1,39 @@
> +;------------------------------------------------------------------------------
> +;
> +; SpeculationBarrier() for AArch64
> +;
> +; Copyright (c) 2019, Linaro Ltd. 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.
> +;
> +;------------------------------------------------------------------------------
> +
> +    EXPORT SpeculationBarrier
> +
> +    AREA MemoryBarriers, CODE, READONLY
> +
> +;/**
> +;  Uses as a barrier to stop speculative execution.
> +;
> +;  Ensures that no later instruction will execute speculatively, until all prior
> +;  instructions have completed.
> +;
> +;**/
> +;VOID
> +;EFIAPI
> +;SpeculationBarrier (
> +;  VOID
> +;  );
> +;
> +SpeculationBarrier
> +    dsb
> +    isb
> +    bx    lr
> +
> +  END
> diff --git a/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.c b/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.c
> deleted file mode 100644
> index 8a6165a10227..000000000000
> --- a/MdePkg/Library/BaseLib/Arm/SpeculationBarrier.c
> +++ /dev/null
> @@ -1,30 +0,0 @@
> -/** @file
> -  SpeculationBarrier() function for ARM.
> -
> -  Copyright (C) 2018, Intel Corporation. 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.
> -
> -**/
> -
> -
> -/**
> -  Uses as a barrier to stop speculative execution.
> -
> -  Ensures that no later instruction will execute speculatively, until all prior
> -  instructions have completed.
> -
> -**/
> -VOID
> -EFIAPI
> -SpeculationBarrier (
> -  VOID
> -  )
> -{
> -}
> diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
> index d195c5417b2e..f25a067a2335 100644
> --- a/MdePkg/Library/BaseLib/BaseLib.inf
> +++ b/MdePkg/Library/BaseLib/BaseLib.inf
> @@ -552,7 +552,6 @@
>  [Sources.ARM]
>    Arm/InternalSwitchStack.c
>    Arm/Unaligned.c
> -  Arm/SpeculationBarrier.c
>    Math64.c                   | RVCT
>    Math64.c                   | MSFT
> 
> @@ -564,6 +563,7 @@
>    Arm/CpuPause.asm           | RVCT
>    Arm/CpuBreakpoint.asm      | RVCT
>    Arm/MemoryFence.asm        | RVCT
> +  Arm/SpeculationBarrier.S   | RVCT
> 
>    Arm/SwitchStack.asm        | MSFT
>    Arm/SetJumpLongJump.asm    | MSFT
> @@ -573,6 +573,7 @@
>    Arm/CpuPause.asm           | MSFT
>    Arm/CpuBreakpoint.asm      | MSFT
>    Arm/MemoryFence.asm        | MSFT
> +  Arm/SpeculationBarrier.asm | MSFT
> 
>    Arm/Math64.S                  | GCC
>    Arm/SwitchStack.S             | GCC
> @@ -582,11 +583,11 @@
>    Arm/SetJumpLongJump.S         | GCC
>    Arm/CpuBreakpoint.S           | GCC
>    Arm/MemoryFence.S             | GCC
> +  Arm/SpeculationBarrier.S      | GCC
> 
>  [Sources.AARCH64]
>    Arm/InternalSwitchStack.c
>    Arm/Unaligned.c
> -  Arm/SpeculationBarrier.c
>    Math64.c
> 
>    AArch64/MemoryFence.S             | GCC
> @@ -596,6 +597,7 @@
>    AArch64/GetInterruptsState.S      | GCC
>    AArch64/SetJumpLongJump.S         | GCC
>    AArch64/CpuBreakpoint.S           | GCC
> +  AArch64/SpeculationBarrier.S      | GCC
> 
>    AArch64/MemoryFence.asm           | MSFT
>    AArch64/SwitchStack.asm           | MSFT
> @@ -604,6 +606,7 @@
>    AArch64/GetInterruptsState.asm    | MSFT
>    AArch64/SetJumpLongJump.asm       | MSFT
>    AArch64/CpuBreakpoint.asm         | MSFT
> +  AArch64/SpeculationBarrier.asm    | MSFT
> 
>  [Packages]
>    MdePkg/MdePkg.dec
> --
> 2.17.1