Re: [PATCH V2] efi/libstub: Call setup_graphics() before handle_kernel_image()

[Ard Biesheuvel <ardb@kernel.org>]

On Fri, 10 Mar 2023 at 03:18, Huacai Chen <chenhuacai@loongson.cn> wrote:
>
> Commit 42c8ea3dca094ab8 ("efi: libstub: Factor out EFI stub entrypoint
> into separate file") moves setup_graphics() into efi_stub_common() which
> is after handle_kernel_image(). This causes efifb no longer work because
> handle_kernel_image() may move the core kernel to its preferred address,
> which means the screen_info filled by the efistub will not be the same
> as the one accessed by the core kernel. So let us call setup_graphics()
> before handle_kernel_image() which restores the old behavior.
>
> The side effect is zboot will not call setup_graphics(), but I think
> zboot doesn't need it either.
>
> Fixes: 42c8ea3dca094ab8 ("efi: libstub: Factor out EFI stub entrypoint into separate file")
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Please drop this patch from the loonarch tree - it is causing a
conflict in linux-next.


> ---
> V2: Use static declaration for setup_graphics() to avoid build warnings.
>
>  drivers/firmware/efi/libstub/efi-stub-entry.c | 29 +++++++++++++++++++
>  drivers/firmware/efi/libstub/efi-stub.c       | 27 -----------------
>  2 files changed, 29 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/efi-stub-entry.c b/drivers/firmware/efi/libstub/efi-stub-entry.c
> index 5245c4f031c0..f971fd25a4eb 100644
> --- a/drivers/firmware/efi/libstub/efi-stub-entry.c
> +++ b/drivers/firmware/efi/libstub/efi-stub-entry.c
> @@ -5,6 +5,30 @@
>
>  #include "efistub.h"
>
> +static struct screen_info *setup_graphics(void)
> +{
> +       unsigned long size;
> +       efi_status_t status;
> +       efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
> +       void **gop_handle = NULL;
> +       struct screen_info *si = NULL;
> +
> +       size = 0;
> +       status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
> +                            &gop_proto, NULL, &size, gop_handle);
> +       if (status == EFI_BUFFER_TOO_SMALL) {
> +               si = alloc_screen_info();
> +               if (!si)
> +                       return NULL;
> +               status = efi_setup_gop(si, &gop_proto, size);
> +               if (status != EFI_SUCCESS) {
> +                       free_screen_info(si);
> +                       return NULL;
> +               }
> +       }
> +       return si;
> +}
> +
>  /*
>   * EFI entry point for the generic EFI stub used by ARM, arm64, RISC-V and
>   * LoongArch. This is the entrypoint that is described in the PE/COFF header
> @@ -22,6 +46,7 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
>         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
>         unsigned long reserve_addr = 0;
>         unsigned long reserve_size = 0;
> +       struct screen_info *si;
>
>         WRITE_ONCE(efi_system_table, systab);
>
> @@ -47,6 +72,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
>
>         efi_info("Booting Linux Kernel...\n");
>
> +       si = setup_graphics();
> +
>         status = handle_kernel_image(&image_addr, &image_size,
>                                      &reserve_addr,
>                                      &reserve_size,
> @@ -58,6 +85,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
>
>         status = efi_stub_common(handle, image, image_addr, cmdline_ptr);
>
> +       free_screen_info(si);
> +
>         efi_free(image_size, image_addr);
>         efi_free(reserve_size, reserve_addr);
>
> diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
> index 2955c1ac6a36..bc67af721412 100644
> --- a/drivers/firmware/efi/libstub/efi-stub.c
> +++ b/drivers/firmware/efi/libstub/efi-stub.c
> @@ -56,30 +56,6 @@ void __weak free_screen_info(struct screen_info *si)
>  {
>  }
>
> -static struct screen_info *setup_graphics(void)
> -{
> -       efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
> -       efi_status_t status;
> -       unsigned long size;
> -       void **gop_handle = NULL;
> -       struct screen_info *si = NULL;
> -
> -       size = 0;
> -       status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
> -                            &gop_proto, NULL, &size, gop_handle);
> -       if (status == EFI_BUFFER_TOO_SMALL) {
> -               si = alloc_screen_info();
> -               if (!si)
> -                       return NULL;
> -               status = efi_setup_gop(si, &gop_proto, size);
> -               if (status != EFI_SUCCESS) {
> -                       free_screen_info(si);
> -                       return NULL;
> -               }
> -       }
> -       return si;
> -}
> -
>  static void install_memreserve_table(void)
>  {
>         struct linux_efi_memreserve *rsv;
> @@ -163,14 +139,12 @@ efi_status_t efi_stub_common(efi_handle_t handle,
>                              unsigned long image_addr,
>                              char *cmdline_ptr)
>  {
> -       struct screen_info *si;
>         efi_status_t status;
>
>         status = check_platform_features();
>         if (status != EFI_SUCCESS)
>                 return status;
>
> -       si = setup_graphics();
>
>         efi_retrieve_tpm2_eventlog();
>
> @@ -190,7 +164,6 @@ efi_status_t efi_stub_common(efi_handle_t handle,
>
>         status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
>
> -       free_screen_info(si);
>         return status;
>  }
>
> --
> 2.39.1
>