The LoongArch build of the EFI stub is part of the core kernel image, and
therefore accesses section markers directly when it needs to figure out
the size of the various section.
The zboot decompressor does not have access to those symbols, but
doesn't really need that either. So let's move handle_kernel_image()
into a separate file (or rather, move everything else into a separate
file) so that the zboot build does not pull in unused code that links to
symbols that it does not define.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Currently, the EFI entry code for LoongArch is set up to copy the
executable image to the preferred offset, but instead of branching
directly into that image, it branches to the local copy of kernel_entry,
and relies on the logic in that function to switch to the link time
address instead.
This is a bit sloppy, and not something we can support once we merge the
EFI decompressor with the EFI stub. So let's clean this up a bit, by
adding a helper that computes the offset of kernel_entry from the start
of the image, and simply adding the result to VMLINUX_LOAD_ADDRESS.
And considering that we cannot execute from anywhere else anyway, let's
avoid efi_relocate_kernel() and just allocate the pages instead.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Factor out the expressions that describe the preferred placement of the
loaded image as well as the minimum alignment so we can reuse them in
the decompressor.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
LoongArch does not use FDT or DT natively [yet], and the only reason it
currently uses it is so that it can reuse the existing EFI stub code.
Overloading the DT with data passed between the EFI stub and the core
kernel has been a source of problems: there is the overlap between
information provided by EFI which DT can also provide (initrd base/size,
command line, memory descriptions), requiring us to reason about which
is which and what to prioritize. It has also resulted in ABI leaks,
i.e., internal ABI being promoted to external ABI inadvertently because
the bootloader can set the EFI stub's DT properties as well (e.g.,
"kaslr-seed"). This has become especially problematic with boot
environments that want to pretend that EFI boot is being done (to access
ACPI and SMBIOS tables, for instance) but have no ability to execute the
EFI stub, and so the environment that the EFI stub creates is emulated
[poorly, in some cases].
Another downside of treating DT like this is that the DT binary that the
kernel receives is different from the one created by the firmware, which
is undesirable in the context of secure and measured boot.
Given that LoongArch support in Linux is brand new, we can avoid these
pitfalls, and treat the DT strictly as a hardware description, and use a
separate handover method between the EFI stub and the kernel. Now that
initrd loading and passing the EFI memory map have been refactored into
pure EFI routines that use EFI configuration tables, the only thing we
need to pass directly is the kernel command line (even if we could pass
this via a config table as well, it is used extremely early, so passing
it directly is preferred in this case.)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
This patch adds efistub booting support, which is the standard UEFI boot
protocol for LoongArch to use.
We use generic efistub, which means we can pass boot information (i.e.,
system table, memory map, kernel command line, initrd) via a light FDT
and drop a lot of non-standard code.
We use a flat mapping to map the efi runtime in the kernel's address
space. In efi, VA = PA; in kernel, VA = PA + PAGE_OFFSET. As a result,
flat mapping is not identity mapping, SetVirtualAddressMap() is still
needed for the efi runtime.
Tested-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
[ardb: change fpic to fpie as suggested by Xi Ruoyao]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
