Hi,
> Implement the link layout that CONFIG_EFI_STUB_DRTM requires. This maps
> vmlinux into the Dynamic Launch Measured Environment (DLME) defined by the
> spec.
>
> Broadly, Image fits into the spec defined DLME region memory layout in
> this order:
> - Program headers and padding up to _stext. EFI can write to these while
> loading the stub so they do not have a stable measurement.
> - All the boot-time immutable data, including .text, .data, .init
> and so on (measured)
> - Data written by the EFI stub
> - .bss, padding and other 0'd data up to _end
> - The "DLME Data" written by the launch process. This is a datastructure
> the post launch kernel will parse to get trusted information about th
> launch.
>
> New linker symbols are added to mark these areas and their offsets are
> placed into the efi_image_info so both stubs can get them.
>
> The spec's design of the DLME was intended to fit a typical OS image like
> this, with two areas that are unmeasured and an inner measured region.
>
> Linux zeroes the unmeasured area of .bss/etc after the DRTM launch so it
> also reaches a known value. The DLME data is written by the launch and is
> trusted. The EFI stub data is either ignored or will have to be sanitized.
>
> Add a section for the unmeasured data before the PECOFF padding. This is
> an allocated section so it is zero'd in the image and is only 64 bytes in
> my builds. There is a high chance it gets absorbed into the padding
> region.
>
> The post-launch kernel will have to reserve the "DLME Data" before
> starting the allocator since it falls outside the linker map. This will
> happen in the first series to consume this data.
>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> ---
> arch/arm64/include/asm/image.h | 8 +++++
> arch/arm64/kernel/vmlinux.lds.S | 64 ++++++++++++++++++++++++++++++++-
> 2 files changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/image.h b/arch/arm64/include/asm/image.h
> index b18ce23a2cba7f..36afe95ffa7544 100644
> --- a/arch/arm64/include/asm/image.h
> +++ b/arch/arm64/include/asm/image.h
> @@ -5,7 +5,11 @@
>
> #define ARM64_IMAGE_MAGIC "ARM\x64"
>
> +#ifdef CONFIG_ARM64_DRTM
> +#define EFI_IMAGE_INFO_SIZE 40
Small nit. I know according to #13, This should be 40 with drtm_entry
and arm64_drtm_handoff. but in this patch, should EFI_IMAGE_INFO_SIZE
be 24 and be change to 40 at #13?
> +#else
> #define EFI_IMAGE_INFO_SIZE 8
> +#endif
>
> #define ARM64_IMAGE_FLAG_BE_SHIFT 0
> #define ARM64_IMAGE_FLAG_PAGE_SIZE_SHIFT (ARM64_IMAGE_FLAG_BE_SHIFT + 1)
> @@ -62,6 +66,10 @@ struct arm64_image_header {
> */
> struct efi_image_info {
> u64 code_size;
> +#ifdef CONFIG_ARM64_DRTM
> + u64 drtm_measured_start;
> + u64 dlme_measured_size;
> +#endif
> };
> static_assert(sizeof(struct efi_image_info) == EFI_IMAGE_INFO_SIZE);
>
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index 8305b47995954b..5c14decf0dd4d3 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -190,10 +190,24 @@ SECTIONS
>
> .head.text : {
> _text = .;
> +#ifdef CONFIG_ARM64_DRTM
> + /* DEN0113 R314010: The DLME region must start at a 4KB aligned
> address. */
> + ASSERT((_text & (SZ_4K - 1)) == 0,
> + "DLME region is not 4 KiB aligned");
> +#endif
> HEAD_TEXT
> }
> .text : ALIGN(SEGMENT_ALIGN) { /* Real text segment */
> _stext = .; /* Text and read-only data */
> +#ifdef CONFIG_ARM64_DRTM
> + __drtm_measured_start = _stext;
> + /*
> + * DEN0113 R314020: The DLME image must start at a 4KB aligned
> + * address. This happens always because SEGMENT_ALIGN is big.
> + */
> + ASSERT((__drtm_measured_start & (SZ_4K - 1)) == 0,
> + "DLME measured start is not 4 KiB aligned");
> +#endif
> IRQENTRY_TEXT
> SOFTIRQENTRY_TEXT
> ENTRY_TEXT
> @@ -285,6 +299,11 @@ SECTIONS
> EFI_IMAGE_INFO(
> /* code_size */
> EFI_IMAGE_INFO_OFFSET(__inittext_end);
> +#ifdef CONFIG_ARM64_DRTM
> + EFI_IMAGE_INFO_OFFSET(__drtm_measured_start);
> + /* dlme_measured_size */
> + EFI_IMAGE_INFO_ENTRY(__drtm_measured_end -
> __drtm_measured_start);
> +#endif
> )
> }
> .exit.data : {
> @@ -348,6 +367,44 @@ SECTIONS
> __mmuoff_data_end = .;
> }
>
> + /*
> + * DRTM layout for DEN0113 as it relates to the link layout, refer
> + * to Figure 8 in 1.4b. In that language:
> + * "Free Space 1" is the PE header and padding between _text and
> + * __drtm_measured_start (_stext)
> + * "DLME Image" is from __drtm_measured_start to __drtm_measured_end
> + * "Free Space 2" is kernel efi data/bss/etc till __drtm_dlme_start
> + * "DLME Data" is a memory sized "Minimum Size of DLME data"
> + * and is retained after boot for use by the kernel
> + *
> + * Thus, the DRTM_PARAMETERS follow from that:
> + * DLME Region Address = _text's PA ie the start of Image
> + * DLME Region Size = DLME Data Offset + "Minimum Size of DLME data"
> + * DLME Image Start Offset = __drtm_measured_start - _text
> + * DLME Image Size = __drtm_measured_end - __drtm_measured_start
> + * DLME Data Offset = __drtm_dlme_start - _text
> + * Normal World DCE region address = PA of __drtm_dlme_start +
> + * "Minimum Size of DLME data"
> + *
> + * The EFI stub will place any optional "Normal World DCE" region
> + * immediately after the "DLME data". It is only used internally by the
> + * FW during the launch and has no effect on the link layout.
> + */
> +#ifdef CONFIG_ARM64_DRTM
> + __drtm_measured_end = .;
> +
> + /*
> + * Writable EFI stub state. When DRTM is being used the stub's mutable
> + * data cannot reside in the normal .init.data because that section
> + * will be measured.
> + */
> + .unmeasured.data : {
> + *(.unmeasured.data)
> + *(.init.efidata .init.efidata.*)
> + *(.init.efibss .init.efibss.*)
> + }
> +#endif
> +
> PECOFF_EDATA_PADDING
> __pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
> _edata = .;
> @@ -370,10 +427,15 @@ SECTIONS
>
> . += SZ_4K; /* stack for the early C runtime */
> early_init_stack = .;
> -
> . = ALIGN(SEGMENT_ALIGN);
> __pecoff_data_size = ABSOLUTE(. - __initdata_begin);
> _end = .;
> +#ifdef CONFIG_ARM64_DRTM
> + /* DEN0113 R314030: The DLME data must start at a 4KB aligned address.
> */
> + __drtm_dlme_start = .;
> + ASSERT((__drtm_dlme_start & (SZ_4K - 1)) == 0,
> + "DLME data is not 4 KiB aligned")
> +#endif
> __pi__end = .;
>
> STABS_DEBUG
> --
> 2.43.0
>
>
--
Sincerely,
Yeoreum Yun
