linux-kernel - Re: [PATCH] efi/x86: Move mixed-mode thunk to efi/libstub

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Date:   Wed, 4 Mar 2020 19:39:23 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     linux-efi <linux-efi@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] efi/x86: Move mixed-mode thunk to efi/libstub

On Wed, 4 Mar 2020 at 19:37, Arvind Sankar <nivedita@...m.mit.edu> wrote:
>
> Commit c2d0b470154c ("efi/libstub/x86: Incorporate eboot.c into
> libstub") moved all the callers of the mixed-mode thunk into
> efi/libstub, so move the thunk itself as well for completeness.
>
> Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>

Thanks for the patch, but I'd prefer to leave the .S pieces under arch/
(unless there's some benefit I'm not seeing)

> ---
>  arch/x86/boot/compressed/Makefile                                | 1 -
>  drivers/firmware/efi/libstub/Makefile                            | 1 +
>  .../firmware/efi/libstub/x86_64-thunk.S                          | 0
>  3 files changed, 1 insertion(+), 1 deletion(-)
>  rename arch/x86/boot/compressed/efi_thunk_64.S => drivers/firmware/efi/libstub/x86_64-thunk.S (100%)
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index e51879bdc51c..047004d39a55 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -88,7 +88,6 @@ endif
>  vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
>
>  vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
> -vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
>
>  # The compressed kernel is built with -fPIC/-fPIE so that a boot loader
>  # can place it anywhere in memory and it will still run. However, since
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 4d6246c6f651..85b66e5e5d1f 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -55,6 +55,7 @@ lib-$(CONFIG_EFI_ARMSTUB)     += arm-stub.o fdt.o string.o \
>  lib-$(CONFIG_ARM)              += arm32-stub.o
>  lib-$(CONFIG_ARM64)            += arm64-stub.o
>  lib-$(CONFIG_X86)              += x86-stub.o
> +lib-$(CONFIG_EFI_MIXED)                += x86_64-thunk.o
>  CFLAGS_arm32-stub.o            := -DTEXT_OFFSET=$(TEXT_OFFSET)
>  CFLAGS_arm64-stub.o            := -DTEXT_OFFSET=$(TEXT_OFFSET)
>
> diff --git a/arch/x86/boot/compressed/efi_thunk_64.S b/drivers/firmware/efi/libstub/x86_64-thunk.S
> similarity index 100%
> rename from arch/x86/boot/compressed/efi_thunk_64.S
> rename to drivers/firmware/efi/libstub/x86_64-thunk.S
> --
> 2.24.1
>