Ard: I agree your comments not to add PCD until there is the real problem.
Thanks Liming >-----Original Message----- >From: edk2-devel [mailto:[email protected]] On Behalf Of Ard >Biesheuvel >Sent: Tuesday, February 12, 2019 1:32 AM >To: Leif Lindholm <[email protected]> >Cc: Kinney, Michael D <[email protected]>; edk2- >[email protected]; Gao, Liming <[email protected]> >Subject: Re: [edk2] [PATCH] MdePkg/BaseLib: implement SpeculationBarrier() >for ARM and AArch64 > >On Mon, 11 Feb 2019 at 15:41, Leif Lindholm <[email protected]> wrote: >> >> On Wed, Feb 06, 2019 at 12:08:22AM +0000, Ard Biesheuvel wrote: >> > 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 <[email protected]> >> >> Patch looks fine. >> Reviewed-by: Leif Lindholm <[email protected]> >> >> Question: do we expect performance impact to be sufficient to >> motivate a Pcd to be able to disable the barrier on unaffected >> processors? >> > >Currently, these are only used on some codepaths in the MM component >of the variable store, which do not look like hot paths to me. > >In general, I think it should be fine to defer doing something like >this until someone highlights it as an actual problem (and has the >numbers to prove it) > > >> > --- >> > 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 >> > >_______________________________________________ >edk2-devel mailing list >[email protected] >https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
