The CPU exception handler library code was rewritten at some point to
populate the vector code templates with absolute references at runtime,
given that the XCODE linker does not permit absolute references in
executable code when creating PIE executables.
This is rather unfortunate, as this prevents us from using strict
permissions on the memory mappings, given that the .text section needs
to be writable at runtime for this arrangement to work.
So let's make this hack XCODE-only, by setting a preprocessor #define
from the command line when using the XCODE toolchain, and only including
the runtime fixup code when the macro is defined.
While at it, rename the Xcode5ExceptionHandlerAsm.nasm source file and
drop the Xcode5 prefix: this code is used by other toolchains too.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Currently, we use the non-Xcode5 version of ExceptionHandlerAsm.nasm
only for the SEC and PEI phases, and this version was not compatible
with the XCODE or LLD linkers, which do not permit absolute relocations
in read-only sections.
Given that SEC and PEI code typically executes in place from flash and
does not use page alignment for sections, we can simply emit the code
carrying the absolute symbol references into the .data segment instead.
This works around the linker's objections, and the resulting image will
be mapped executable in its entirety anyway. Since this is only needed
for XCODE, let's make this change conditionally using a preprocessor
macro.
Let's rename the .nasm file to reflect the fact that is used for the
SecPei flavor of this library only, and while at it, remove some
unnecessary absolute references.
Also update the Xcode specific version of this library, and use this
source file instead. This is necesessary, as the Xcode specific version
modifies its own code at runtime, which is not permitted in SEC or PEI.
Note that this also removes CET support from the Xcode5 specific build
of the SEC/PEI version of this library, but this is not needed this
early in any case, and this aligns it with other toolchains, which use
this version of the library, which does not have CET support either.
1. Change for non-XCODE SecPeiCpuExceptionHandlerLib:
. Use SecPeiExceptionHandlerAsm.nasm (renamed from
ExceptionHandlerAsm.nasm)
. Removed some unnecessary absolute references
(32 IDT stubs are still in .text.)
2. Change for XCODE SecPeiCpuExceptionHandlerLib:
. Use SecPeiExceptionHandlerAsm.nasm instead of
Xcode5ExceptionHandlerAsm.nasm
. CET logic is not in SecPeiExceptionHandlerAsm.nasm (but aligns to
non-XCODE lib instance)
. Fixed a bug that does runtime fixup in TEXT section in SPI flash.
. Emitted the code carrying the absolute symbol references into the
.data which XCODE or LLD linkers allow.
. Then fixup can be done by other build tools such as GenFv if the code
runs in SPI flash, or by PE coff loader if the code is loaded to
memory.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Today the DXE instance allocates code page and then copies the IDT
vectors to the allocated code page. Then it fixes up the vector number
in the IDT vector.
But if we update the NASM file to generate 256 IDT vectors, there is
no need to do the copy and fix-up.
A side effect is 4096 bytes (HOOKAFTER_STUB_SIZE * 256) is used for
256 IDT vectors while 32 IDT vectors only require 512 bytes without
this change, in following library instances:
1. 32bit SecPeiCpuExceptionHandlerLib and PeiCpuExceptionHandlerLib
2. 64bit PeiCpuExceptionHandlerLib
But considering the code logic simplification, 3.5K extra space is
not a big deal.
If 3.5K is too much, we can enhance the code further to generate 32
vectors for above mentioned library instances.
Signed-off-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Acked-by: Eric Dong <eric.dong@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3790
Replace Opcode with the corresponding instructions.
The code changes have been verified with CompareBuild.py tool, which
can be used to compare the results of two different EDK II builds to
determine if they generate the same binaries.
(tool link: https://github.com/mdkinney/edk2/tree/sandbox/CompareBuild)
Signed-off-by: Jason Lou <yun.lou@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
Add base support to handle #VC exceptions. Update the common exception
handlers to invoke the VmgExitHandleVc () function of the VmgExitLib
library when a #VC is encountered. A non-zero return code will propagate
to the targeted exception handler.
Under SEV-ES, a DR7 read or write intercept generates a #VC exception.
To avoid exception recursion, a #VC exception will not try to read and
push the actual debug registers into the EFI_SYSTEM_CONTEXT_X64 struct
and instead push zeroes. The #VC exception handler does not make use of
the debug registers from the saved context and the exception processing
exit code does not attempt to restore the debug register values.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2340
Now that an XCODE5 specific CpuExceptionHandlerLib library is in place,
revert the changes made to the ExceptionHandlerAsm.nasm in commit
2db0ccc2d7 ("UefiCpuPkg: Update CpuExceptionHandlerLib pass XCODE5 tool
chain") so that binary patching of flash code is not performed.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Liming Gao <liming.gao@intel.com>
Acked-by: Bret Barkelew <bret.barkelew@microsoft.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <810f67d8604c054c09d17a22f0bcfaeb41ee8e3b.1588856809.git.thomas.lendacky@amd.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2150
v4:
The v3 posting didn't do what it promised to do, so do it now for real.
V3 changes:
change to mov instruction (non locking instuction) instead
of xchg to simplify design.
V2 changes:
Add xchg 16 bit instructions to handle sgdt and sidt base
63:48 bits and 47:32 bits.
Add comment to explain why xchg 64bit isnt being used
Split lock happens when a locking instruction is used on mis-aligned data
that crosses two cachelines. If close source platform enables Alignment
Check Exception(#AC), They can hit a double fault due to split lock being
in CpuExceptionHandlerLib.
sigt and sgdt saves 10 bytes to memory, 8 bytes is base and 2 bytes is limit.
The data is mis-aligned, can cross two cacheline, and a xchg
instruction(locking instuction) is being utilize.
Signed-off-by: John E Lofgren <john.e.lofgren@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1576
The root cause of this issue is that non-stop mode of Heap Guard and
NULL Detection set TF bit (single-step) in EFLAG unconditionally in
the common handler in CpuExceptionLib.
If PcdCpuSmmStaticPageTable is FALSE, the SMM will only create page
table for memory below 4G. If SMM tries to access memory beyond 4G,
a page fault exception will be triggered and the memory to access
will be added to page table so that SMM code can continue the access.
Because of above issue, the TF bit is set after the page fault is
handled and then fall into another DEBUG exception. Since non-stop
mode of Heap Guard and NULL Detection are not enabled, no special
DEBUG exception handler is registered. The default handler just
prints exception context and go into dead loop.
Actually EFLAGS can be changed in any standard exception handler.
There's no need to do single-step setup in assembly code. So the fix
is to move the logic to C code part of page fault exception handler
so that we can fully validate the configuration and prevent TF bit
from being set unexpectedly.
Fixes: dcc026217f16b918bbaf
Test:
- Pass special test of accessing memory beyond 4G in SMM mode
- Boot to OS with Qemu emulator platform (Fedora27, Ubuntu18.04,
Windows7, Windows10)
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Once the #PF handler has set the page to be 'present', there should
be a way to reset it to 'not-present'. 'TF' bit in EFLAGS can be used
for this purpose. 'TF' bit will be set in interrupted function context
so that it can be triggered once the cpu control returns back to the
instruction causing #PF and re-execute it.
This is an necessary step to implement non-stop mode for Heap Guard
and NULL Pointer Detection feature.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
https://bugzilla.tianocore.org/show_bug.cgi?id=849
In V2, use mov rax, strict qword 0 to replace the hard code db.
Use the dummy address as jmp destination, and add the logic to fix up
the address to the absolute address at boot time.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
The BaseTools/Scripts/ConvertMasmToNasm.py script was used to convert
X64/ExceptionHandlerAsm.asm to X64/ExceptionHandlerAsm.nasm.
Then, manually update nasm to pass build.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Ard Biesheuvel
Ray Ni
Jason
Tom Lendacky
John E Lofgren
Michael D Kinney
Jian J Wang
Liming Gao