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>
Ard Biesheuvel