REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1093
Return Stack Buffer (RSB) is used to predict the target of RET
instructions. When the RSB underflows, some processors may fall back to
using branch predictors. This might impact software using the retpoline
mitigation strategy on those processors.
This commit will add RSB stuffing logic before returning from SMM (the RSM
instruction) to avoid interfering with non-SMM usage of the retpoline
technique.
After the stuffing, RSB entries will contain a trap like:
@SpecTrap:
pause
lfence
jmp @SpecTrap
A more detailed explanation of the purpose of commit is under the
'Branch target injection mitigation' section of the below link:
https://software.intel.com/security-software-guidance/insights/host-firmware-speculative-execution-side-channel-mitigation
Please note that this commit requires further actions (BZ 1091) to remove
the duplicated 'StuffRsb.inc' files and merge them into one under a
UefiCpuPkg package-level directory (such as UefiCpuPkg/Include/).
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1091
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
---
UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm | 3 ++
UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm | 3 ++
UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc | 55 ++++++++++++++++++++
UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm | 3 ++
UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm | 3 ++
UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc | 55 ++++++++++++++++++++
6 files changed, 122 insertions(+)
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
index 509e7a0a66..6bbc339c53 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
@@ -18,6 +18,8 @@
;
;-------------------------------------------------------------------------------
+%include "StuffRsb.inc"
+
%define MSR_IA32_MISC_ENABLE 0x1A0
%define MSR_EFER 0xc0000080
%define MSR_EFER_XD 0x800
@@ -204,6 +206,7 @@ ASM_PFX(SmiHandler):
wrmsr
.7:
+ StuffRsb32
rsm
ASM_PFX(gcSmiHandlerSize): DW $ - _SmiEntryPoint
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm
index 5ff3cd2e73..322b1ab556 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm
@@ -18,6 +18,8 @@
;
;-------------------------------------------------------------------------------
+%include "StuffRsb.inc"
+
extern ASM_PFX(SmmInitHandler)
extern ASM_PFX(mRebasedFlag)
extern ASM_PFX(mSmmRelocationOriginalAddress)
@@ -75,6 +77,7 @@ BITS 32
mov esp, strict dword 0 ; source operand will be patched
ASM_PFX(gPatchSmmInitStack):
call ASM_PFX(SmmInitHandler)
+ StuffRsb32
rsm
BITS 16
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc
new file mode 100644
index 0000000000..14267c3fde
--- /dev/null
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc
@@ -0,0 +1,55 @@
+;------------------------------------------------------------------------------
+;
+; 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.
+;
+; Abstract:
+;
+; This file provides macro definitions for stuffing the Return Stack Buffer (RSB).
+;
+;------------------------------------------------------------------------------
+
+%define RSB_STUFF_ENTRIES 0x20
+
+;
+; parameters:
+; @param 1: register to use as counter (e.g. IA32:eax, X64:rax)
+; @param 2: stack pointer to restore (IA32:esp, X64:rsp)
+; @param 3: the size of a stack frame (IA32:4, X64:8)
+;
+%macro StuffRsb 3
+ mov %1, RSB_STUFF_ENTRIES / 2
+ %%Unroll1:
+ call %%Unroll2
+ %%SpecTrap1:
+ pause
+ lfence
+ jmp %%SpecTrap1
+ %%Unroll2:
+ call %%StuffLoop
+ %%SpecTrap2:
+ pause
+ lfence
+ jmp %%SpecTrap2
+ %%StuffLoop:
+ dec %1
+ jnz %%Unroll1
+ add %2, RSB_STUFF_ENTRIES * %3 ; Restore the stack pointer
+%endmacro
+
+;
+; RSB stuffing macros for IA32 and X64
+;
+%macro StuffRsb32 0
+ StuffRsb eax, esp, 4
+%endmacro
+
+%macro StuffRsb64 0
+ StuffRsb rax, rsp, 8
+%endmacro
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
index 97c7b01d0d..315d0f8670 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
@@ -18,6 +18,8 @@
;
;-------------------------------------------------------------------------------
+%include "StuffRsb.inc"
+
;
; Variables referrenced by C code
;
@@ -217,6 +219,7 @@ _SmiHandler:
wrmsr
.1:
+ StuffRsb64
rsm
ASM_PFX(gcSmiHandlerSize) DW $ - _SmiEntryPoint
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm
index 0b0c3f28e5..24357d5870 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm
@@ -18,6 +18,8 @@
;
;-------------------------------------------------------------------------------
+%include "StuffRsb.inc"
+
extern ASM_PFX(SmmInitHandler)
extern ASM_PFX(mRebasedFlag)
extern ASM_PFX(mSmmRelocationOriginalAddress)
@@ -101,6 +103,7 @@ ASM_PFX(gPatchSmmInitStack):
movdqa xmm4, [rsp + 0x40]
movdqa xmm5, [rsp + 0x50]
+ StuffRsb64
rsm
BITS 16
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc
new file mode 100644
index 0000000000..14267c3fde
--- /dev/null
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc
@@ -0,0 +1,55 @@
+;------------------------------------------------------------------------------
+;
+; 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.
+;
+; Abstract:
+;
+; This file provides macro definitions for stuffing the Return Stack Buffer (RSB).
+;
+;------------------------------------------------------------------------------
+
+%define RSB_STUFF_ENTRIES 0x20
+
+;
+; parameters:
+; @param 1: register to use as counter (e.g. IA32:eax, X64:rax)
+; @param 2: stack pointer to restore (IA32:esp, X64:rsp)
+; @param 3: the size of a stack frame (IA32:4, X64:8)
+;
+%macro StuffRsb 3
+ mov %1, RSB_STUFF_ENTRIES / 2
+ %%Unroll1:
+ call %%Unroll2
+ %%SpecTrap1:
+ pause
+ lfence
+ jmp %%SpecTrap1
+ %%Unroll2:
+ call %%StuffLoop
+ %%SpecTrap2:
+ pause
+ lfence
+ jmp %%SpecTrap2
+ %%StuffLoop:
+ dec %1
+ jnz %%Unroll1
+ add %2, RSB_STUFF_ENTRIES * %3 ; Restore the stack pointer
+%endmacro
+
+;
+; RSB stuffing macros for IA32 and X64
+;
+%macro StuffRsb32 0
+ StuffRsb eax, esp, 4
+%endmacro
+
+%macro StuffRsb64 0
+ StuffRsb rax, rsp, 8
+%endmacro
--
2.12.0.windows.1
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On 08/17/18 04:35, Hao Wu wrote: > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1093 > > Return Stack Buffer (RSB) is used to predict the target of RET > instructions. When the RSB underflows, some processors may fall back to > using branch predictors. This might impact software using the retpoline > mitigation strategy on those processors. > > This commit will add RSB stuffing logic before returning from SMM (the RSM > instruction) to avoid interfering with non-SMM usage of the retpoline > technique. > > After the stuffing, RSB entries will contain a trap like: > > @SpecTrap: > pause > lfence > jmp @SpecTrap > > A more detailed explanation of the purpose of commit is under the > 'Branch target injection mitigation' section of the below link: > https://software.intel.com/security-software-guidance/insights/host-firmware-speculative-execution-side-channel-mitigation > > Please note that this commit requires further actions (BZ 1091) to remove > the duplicated 'StuffRsb.inc' files and merge them into one under a > UefiCpuPkg package-level directory (such as UefiCpuPkg/Include/). > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1091 > > Cc: Jiewen Yao <jiewen.yao@intel.com> > Cc: Eric Dong <eric.dong@intel.com> > Cc: Laszlo Ersek <lersek@redhat.com> > Cc: Michael D Kinney <michael.d.kinney@intel.com> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Hao Wu <hao.a.wu@intel.com> > Acked-by: Laszlo Ersek <lersek@redhat.com> > Regression-tested-by: Laszlo Ersek <lersek@redhat.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm | 3 ++ > UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm | 3 ++ > UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc | 55 ++++++++++++++++++++ > UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm | 3 ++ > UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm | 3 ++ > UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc | 55 ++++++++++++++++++++ > 6 files changed, 122 insertions(+) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > index 509e7a0a66..6bbc339c53 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > @@ -18,6 +18,8 @@ > ; > ;------------------------------------------------------------------------------- > > +%include "StuffRsb.inc" > + > %define MSR_IA32_MISC_ENABLE 0x1A0 > %define MSR_EFER 0xc0000080 > %define MSR_EFER_XD 0x800 > @@ -204,6 +206,7 @@ ASM_PFX(SmiHandler): > wrmsr > > .7: > + StuffRsb32 > rsm > > ASM_PFX(gcSmiHandlerSize): DW $ - _SmiEntryPoint > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > index 5ff3cd2e73..322b1ab556 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmInit.nasm > @@ -18,6 +18,8 @@ > ; > ;------------------------------------------------------------------------------- > > +%include "StuffRsb.inc" > + > extern ASM_PFX(SmmInitHandler) > extern ASM_PFX(mRebasedFlag) > extern ASM_PFX(mSmmRelocationOriginalAddress) > @@ -75,6 +77,7 @@ BITS 32 > mov esp, strict dword 0 ; source operand will be patched > ASM_PFX(gPatchSmmInitStack): > call ASM_PFX(SmmInitHandler) > + StuffRsb32 > rsm > > BITS 16 > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc > new file mode 100644 > index 0000000000..14267c3fde > --- /dev/null > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/StuffRsb.inc > @@ -0,0 +1,55 @@ > +;------------------------------------------------------------------------------ > +; > +; 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. > +; > +; Abstract: > +; > +; This file provides macro definitions for stuffing the Return Stack Buffer (RSB). > +; > +;------------------------------------------------------------------------------ > + > +%define RSB_STUFF_ENTRIES 0x20 > + > +; > +; parameters: > +; @param 1: register to use as counter (e.g. IA32:eax, X64:rax) > +; @param 2: stack pointer to restore (IA32:esp, X64:rsp) > +; @param 3: the size of a stack frame (IA32:4, X64:8) > +; > +%macro StuffRsb 3 > + mov %1, RSB_STUFF_ENTRIES / 2 > + %%Unroll1: > + call %%Unroll2 > + %%SpecTrap1: > + pause > + lfence > + jmp %%SpecTrap1 > + %%Unroll2: > + call %%StuffLoop > + %%SpecTrap2: > + pause > + lfence > + jmp %%SpecTrap2 > + %%StuffLoop: > + dec %1 > + jnz %%Unroll1 > + add %2, RSB_STUFF_ENTRIES * %3 ; Restore the stack pointer > +%endmacro > + > +; > +; RSB stuffing macros for IA32 and X64 > +; > +%macro StuffRsb32 0 > + StuffRsb eax, esp, 4 > +%endmacro > + > +%macro StuffRsb64 0 > + StuffRsb rax, rsp, 8 > +%endmacro > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > index 97c7b01d0d..315d0f8670 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > @@ -18,6 +18,8 @@ > ; > ;------------------------------------------------------------------------------- > > +%include "StuffRsb.inc" > + > ; > ; Variables referrenced by C code > ; > @@ -217,6 +219,7 @@ _SmiHandler: > wrmsr > > .1: > + StuffRsb64 > rsm > > ASM_PFX(gcSmiHandlerSize) DW $ - _SmiEntryPoint > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm > index 0b0c3f28e5..24357d5870 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmInit.nasm > @@ -18,6 +18,8 @@ > ; > ;------------------------------------------------------------------------------- > > +%include "StuffRsb.inc" > + > extern ASM_PFX(SmmInitHandler) > extern ASM_PFX(mRebasedFlag) > extern ASM_PFX(mSmmRelocationOriginalAddress) > @@ -101,6 +103,7 @@ ASM_PFX(gPatchSmmInitStack): > movdqa xmm4, [rsp + 0x40] > movdqa xmm5, [rsp + 0x50] > > + StuffRsb64 > rsm > > BITS 16 > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc > new file mode 100644 > index 0000000000..14267c3fde > --- /dev/null > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/StuffRsb.inc > @@ -0,0 +1,55 @@ > +;------------------------------------------------------------------------------ > +; > +; 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. > +; > +; Abstract: > +; > +; This file provides macro definitions for stuffing the Return Stack Buffer (RSB). > +; > +;------------------------------------------------------------------------------ > + > +%define RSB_STUFF_ENTRIES 0x20 > + > +; > +; parameters: > +; @param 1: register to use as counter (e.g. IA32:eax, X64:rax) > +; @param 2: stack pointer to restore (IA32:esp, X64:rsp) > +; @param 3: the size of a stack frame (IA32:4, X64:8) > +; > +%macro StuffRsb 3 > + mov %1, RSB_STUFF_ENTRIES / 2 > + %%Unroll1: > + call %%Unroll2 > + %%SpecTrap1: > + pause > + lfence > + jmp %%SpecTrap1 > + %%Unroll2: > + call %%StuffLoop > + %%SpecTrap2: > + pause > + lfence > + jmp %%SpecTrap2 > + %%StuffLoop: > + dec %1 > + jnz %%Unroll1 > + add %2, RSB_STUFF_ENTRIES * %3 ; Restore the stack pointer > +%endmacro > + > +; > +; RSB stuffing macros for IA32 and X64 > +; > +%macro StuffRsb32 0 > + StuffRsb eax, esp, 4 > +%endmacro > + > +%macro StuffRsb64 0 > + StuffRsb rax, rsp, 8 > +%endmacro > Thank you Hao, this looks great. Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
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