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Re: [PATCH v3 3/7] efi: implemented LoadFile2 initrd loading protocol fo
From: |
Daniel Kiper |
Subject: |
Re: [PATCH v3 3/7] efi: implemented LoadFile2 initrd loading protocol for Linux |
Date: |
Thu, 25 Nov 2021 16:52:09 +0100 |
User-agent: |
NeoMutt/20170113 (1.7.2) |
On Thu, Oct 28, 2021 at 11:31:16PM +0300, Nikita Ermakov wrote:
> From: Ard Biesheuvel <ard.biesheuvel@arm.com>
>
> Recent Linux kernels will invoke the LoadFile2 protocol installed on
> a well-known vendor media path to load the initrd if it is exposed by
> the firmware. Using this method is preferred for two reasons:
> - the Linux kernel is in charge of allocating the memory, and so it can
> implement any placement policy it wants (given that these tend to
> change between kernel versions),
> - it is no longer necessary to modify the device tree provided by the
> firmware.
>
> So let's install this protocol when handling the 'initrd' command if
> such a recent kernel was detected (based on the PE/COFF image version),
> and defer loading the initrd contents until the point where the kernel
> invokes the LoadFile2 protocol.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
> Signed-off-by: Nikita Ermakov <arei@altlinux.org>
> ---
> grub-core/loader/arm64/linux.c | 117 ++++++++++++++++++++++++++++++++-
> 1 file changed, 116 insertions(+), 1 deletion(-)
>
> diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
> index aed7a200b..6b03455d1 100644
> --- a/grub-core/loader/arm64/linux.c
> +++ b/grub-core/loader/arm64/linux.c
> @@ -48,9 +48,18 @@ static grub_uint32_t cmdline_size;
> static grub_addr_t initrd_start;
> static grub_addr_t initrd_end;
>
> +static struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };
> +static grub_efi_handle_t initrd_lf2_handle;
> +static int initrd_use_loadfile2;
Please explicitly initialize these two variables.
> +static grub_efi_guid_t load_file2_guid = GRUB_EFI_LOAD_FILE2_PROTOCOL_GUID;
> +static grub_efi_guid_t device_path_guid = GRUB_EFI_DEVICE_PATH_GUID;
> +
> grub_err_t
> grub_arch_efi_linux_check_image (struct linux_arch_kernel_header * lh)
> {
> + struct grub_pe32_coff_header *coff_header;
> + struct grub_pe32_optional_header *optional_header;
> +
> if (lh->magic != GRUB_LINUX_ARMXX_MAGIC_SIGNATURE)
> return grub_error(GRUB_ERR_BAD_OS, "invalid magic number");
>
> @@ -61,6 +70,21 @@ grub_arch_efi_linux_check_image (struct
> linux_arch_kernel_header * lh)
> grub_dprintf ("linux", "UEFI stub kernel:\n");
> grub_dprintf ("linux", "PE/COFF header @ %08x\n", lh->hdr_offset);
>
> + coff_header = (struct grub_pe32_coff_header *)((unsigned long)lh +
> lh->hdr_offset);
coff_header = (struct grub_pe32_coff_header *) ((grub_addr_t) lh +
lh->hdr_offset);
... please note missing spaces too.
> + optional_header = (struct grub_pe32_optional_header *)(coff_header + 1);
(struct grub_pe32_optional_header *) (coff_header + 1);
> + /*
> + * Linux kernels built for any architecture are guaranteed to support the
> + * LoadFile2 based initrd loading protocol if the image version is >= 1.
> + */
> + if (optional_header->major_image_version >= 1)
> + initrd_use_loadfile2 = 1;
> + else
> + initrd_use_loadfile2 = 0;
> +
> + grub_dprintf ("linux", "LoadFile2 initrd loading %sabled\n",
> + initrd_use_loadfile2 ? "en" : "dis");
> +
> return GRUB_ERR_NONE;
> }
>
> @@ -230,13 +254,86 @@ allocate_initrd_mem (int initrd_pages)
> GRUB_EFI_LOADER_DATA);
> }
>
> +struct initrd_media_device_path {
> + grub_efi_vendor_media_device_path_t vendor;
> + grub_efi_device_path_t end;
> +} GRUB_PACKED;
typedef struct initrd_media_device_path initrd_media_device_path_t;
And please use initrd_media_device_path_t instead of "struct
initrd_media_device_path".
> +
> +#define LINUX_EFI_INITRD_MEDIA_GUID \
> + { 0x5568e427, 0x68fc, 0x4f3d, \
> + { 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68 } \
> + }
Please move struct initrd_media_device_path and
LINUX_EFI_INITRD_MEDIA_GUID definitions to the include/grub/efi/api.h file.
> +static struct initrd_media_device_path initrd_lf2_device_path = {
> + {
> + {
> + GRUB_EFI_MEDIA_DEVICE_PATH_TYPE,
> + GRUB_EFI_VENDOR_MEDIA_DEVICE_PATH_SUBTYPE,
> + sizeof(grub_efi_vendor_media_device_path_t),
> + },
> + LINUX_EFI_INITRD_MEDIA_GUID
> + }, {
> + GRUB_EFI_END_DEVICE_PATH_TYPE,
> + GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE,
> + sizeof(grub_efi_device_path_t)
> + }
> +};
This declaration/initialization should be behind device_path_guid declaration.
> +static grub_efi_status_t
> +grub_efi_initrd_load_file2(grub_efi_load_file2_t *this,
> + grub_efi_device_path_t *device_path,
> + grub_efi_boolean_t boot_policy,
> + grub_efi_uintn_t *buffer_size,
> + void *buffer);
Please drop this...
> +
> +static grub_efi_load_file2_t initrd_lf2 = {
> + grub_efi_initrd_load_file2
> +};
... and move this behind grub_efi_initrd_load_file2() definition.
> +static grub_efi_status_t
> +grub_efi_initrd_load_file2(grub_efi_load_file2_t *this,
> + grub_efi_device_path_t *device_path,
> + grub_efi_boolean_t boot_policy,
> + grub_efi_uintn_t *buffer_size,
> + void *buffer)
This works only because UEFI RISC-V/ARM and "normal" RISC-V/ARM calling
conventions are the same. This will not work on x86_64. So, we have to
introduce something like __grub_efi_api macro. It should be empty for
at least for RISC-V and ARM but it should be "__attribute__ ((ms_abi))"
for at least for x86_64. I think the __grub_efi_api macro should be
defined in include/grub/efi/api.h next to efi_call_* definitions.
> +{
> + grub_efi_status_t status = GRUB_EFI_SUCCESS;
> + grub_efi_uintn_t initrd_size;
> +
> + if (!this || this != &initrd_lf2 || !buffer_size)
if (this == NULL || this != &initrd_lf2 || buffer_size == NULL)
Please use NULL explicitly below too...
> + return GRUB_EFI_INVALID_PARAMETER;
> +
> + if (device_path->type != GRUB_EFI_END_DEVICE_PATH_TYPE ||
> + device_path->subtype != GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE)
> + return GRUB_EFI_NOT_FOUND;
> +
> + if (boot_policy)
> + return GRUB_EFI_UNSUPPORTED;
> +
> + initrd_size = grub_get_initrd_size (&initrd_ctx);
> + if (!buffer || *buffer_size < initrd_size)
> + {
> + *buffer_size = initrd_size;
> + return GRUB_EFI_BUFFER_TOO_SMALL;
> + }
> +
> + grub_dprintf ("linux", "Providing initrd via LOAD_FILE2_PROTOCOL\n");
s/LOAD_FILE2_PROTOCOL/EFI_LOAD_FILE2_PROTOCOL/
> + if (grub_initrd_load (&initrd_ctx, buffer))
if (grub_initrd_load (&initrd_ctx, buffer) != GRUB_ERR_NONE))
> + status = GRUB_EFI_LOAD_ERROR;
According to the UEFI spec this should be GRUB_EFI_DEVICE_ERROR.
> + grub_initrd_close (&initrd_ctx);
> + return status;
> +}
> +
> static grub_err_t
> grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
> int argc, char *argv[])
> {
> - struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };
> int initrd_size, initrd_pages;
> void *initrd_mem = NULL;
> + grub_efi_boot_services_t *b;
grub_efi_boot_services_t *b = grub_efi_system_table->boot_services;
> + grub_efi_status_t status;
>
> if (argc == 0)
> {
> @@ -254,6 +351,24 @@ grub_cmd_initrd (grub_command_t cmd __attribute__
> ((unused)),
> if (grub_initrd_init (argc, argv, &initrd_ctx))
> goto fail;
>
> + if (initrd_use_loadfile2 && !initrd_lf2_handle)
> + {
> + b = grub_efi_system_table->boot_services;
... then you can drop this.
> + status = b->install_multiple_protocol_interfaces (&initrd_lf2_handle,
> + &load_file2_guid,
> + &initrd_lf2,
> + &device_path_guid,
> + &initrd_lf2_device_path,
> + NULL);
> + if (status == GRUB_EFI_OUT_OF_RESOURCES)
> + {
> + grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> + return grub_errno;
s/return grub_errno/goto fail/ otherwise your are leaking memory.
Or you can move protocols installation to the beginning of the function
and return immediately in case of error.
> + }
I think we should not ignore the other UEFI errors here.
> + grub_dprintf ("linux", "LoadFile2 initrd loading protocol
> installed\n");
> + return GRUB_ERR_NONE;
> + }
> +
> initrd_size = grub_get_initrd_size (&initrd_ctx);
> grub_dprintf ("linux", "Loading initrd\n");
Daniel
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