* [PATCH v2] efi: use 32-bit alignment for efi_guid_t
@ 2023-01-28 4:56 Masahisa Kojima
2023-01-30 8:05 ` Ilias Apalodimas
0 siblings, 1 reply; 2+ messages in thread
From: Masahisa Kojima @ 2023-01-28 4:56 UTC (permalink / raw)
To: u-boot; +Cc: Heinrich Schuchardt, Ilias Apalodimas, Masahisa Kojima
Current U-Boot implements 64-bit boundary for efi_guid_t structure.
It follows the UEFI specification, page 21 of the UEFI Specification v2.10
says about EFI_GUID:
128-bit buffer containing a unique identifier value. Unless
otherwise specified, aligned on a 64-bit boundary.
On the other hand, page 163 of the UEFI specification v2.10 and
EDK2 reference implementation both define EFI_GUID as
struct { u32 a; u16; b; u16 c; u8 d[8]; }; and so the implied
alignment is 32-bit not 64-bit like U-Boot efi_guid_t.
Due to this alignment difference, EDK2 application "CapsuleApp.efi -P"
does not work as expected.
This calls EFI_FIRMWARE_MANAGEMENT_PROTOCOL.GetImageInfo()
and dump the EFI_FIRMWARE_IMAGE_DESCRIPTOR structure,
offsetof(EFI_FIRMWARE_IMAGE_DESCRIPTOR, ImageTypeId) is different,
8 in U-Boot and 4 in EDK2(CapsuleApp.efi).
Here is the wrong EFI_GUID dump.
wrong dump : ImageTypeId - 00000000-7D83-058B-D550-474CA19560D8
expected : ImageTypeId - 058B7D83-50D5-4C47-A195-60D86AD341C4
EFI_FIRMWARE_IMAGE_DESCRIPTOR structure is defined in UEFI specification:
typedef struct {
UINT8 ImageIndex;
EFI_GUID ImageTypeId;
UINT64 ImageId
<snip>
} EFI_FIRMWARE_IMAGE_DESCRIPTOR;
There was the relevant patch for linux kernel to use 32-bit alignment
for efi_guid_t [1].
U-Boot should get aligned to EDK2 reference implementation and
linux kernel.
Due to this alignment change, efi_hii_ref structure in include/efi_api.h
is affected, but it is not used in the current U-Boot code.
[1] https://lore.kernel.org/all/20190202094119.13230-5-ard.biesheuvel@linaro.org/
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---
Changes in v2:
- add source code comment to describe why the efi_guid_t structure is
4-byte aligned
include/efi.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/efi.h b/include/efi.h
index 42f4e58a91..c3087d3da2 100644
--- a/include/efi.h
+++ b/include/efi.h
@@ -54,9 +54,18 @@
struct efi_device_path;
+/*
+ * The EFI spec defines the EFI_GUID as
+ * "128-bit buffer containing a unique identifier value. Unless otherwise specified,
+ * aligned on a 64-bit boundary".
+ * Page 163 of the UEFI specification v2.10 and
+ * EDK2 reference implementation both define EFI_GUID as
+ * struct { u32 a; u16; b; u16 c; u8 d[8]; }; which is 4-byte
+ * aligned.
+ */
typedef struct {
u8 b[16];
-} efi_guid_t __attribute__((aligned(8)));
+} efi_guid_t __attribute__((aligned(4)));
#define EFI_BITS_PER_LONG (sizeof(long) * 8)
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] efi: use 32-bit alignment for efi_guid_t
2023-01-28 4:56 [PATCH v2] efi: use 32-bit alignment for efi_guid_t Masahisa Kojima
@ 2023-01-30 8:05 ` Ilias Apalodimas
0 siblings, 0 replies; 2+ messages in thread
From: Ilias Apalodimas @ 2023-01-30 8:05 UTC (permalink / raw)
To: Masahisa Kojima; +Cc: u-boot, Heinrich Schuchardt
On Sat, 28 Jan 2023 at 06:56, Masahisa Kojima
<masahisa.kojima@linaro.org> wrote:
>
> Current U-Boot implements 64-bit boundary for efi_guid_t structure.
> It follows the UEFI specification, page 21 of the UEFI Specification v2.10
> says about EFI_GUID:
> 128-bit buffer containing a unique identifier value. Unless
> otherwise specified, aligned on a 64-bit boundary.
>
> On the other hand, page 163 of the UEFI specification v2.10 and
> EDK2 reference implementation both define EFI_GUID as
> struct { u32 a; u16; b; u16 c; u8 d[8]; }; and so the implied
> alignment is 32-bit not 64-bit like U-Boot efi_guid_t.
>
> Due to this alignment difference, EDK2 application "CapsuleApp.efi -P"
> does not work as expected.
> This calls EFI_FIRMWARE_MANAGEMENT_PROTOCOL.GetImageInfo()
> and dump the EFI_FIRMWARE_IMAGE_DESCRIPTOR structure,
> offsetof(EFI_FIRMWARE_IMAGE_DESCRIPTOR, ImageTypeId) is different,
> 8 in U-Boot and 4 in EDK2(CapsuleApp.efi).
> Here is the wrong EFI_GUID dump.
> wrong dump : ImageTypeId - 00000000-7D83-058B-D550-474CA19560D8
> expected : ImageTypeId - 058B7D83-50D5-4C47-A195-60D86AD341C4
>
> EFI_FIRMWARE_IMAGE_DESCRIPTOR structure is defined in UEFI specification:
> typedef struct {
> UINT8 ImageIndex;
> EFI_GUID ImageTypeId;
> UINT64 ImageId
> <snip>
>
> } EFI_FIRMWARE_IMAGE_DESCRIPTOR;
>
> There was the relevant patch for linux kernel to use 32-bit alignment
> for efi_guid_t [1].
> U-Boot should get aligned to EDK2 reference implementation and
> linux kernel.
>
> Due to this alignment change, efi_hii_ref structure in include/efi_api.h
> is affected, but it is not used in the current U-Boot code.
>
> [1] https://lore.kernel.org/all/20190202094119.13230-5-ard.biesheuvel@linaro.org/
>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
> Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> ---
> Changes in v2:
> - add source code comment to describe why the efi_guid_t structure is
> 4-byte aligned
>
> include/efi.h | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/include/efi.h b/include/efi.h
> index 42f4e58a91..c3087d3da2 100644
> --- a/include/efi.h
> +++ b/include/efi.h
> @@ -54,9 +54,18 @@
>
> struct efi_device_path;
>
> +/*
> + * The EFI spec defines the EFI_GUID as
> + * "128-bit buffer containing a unique identifier value. Unless otherwise specified,
> + * aligned on a 64-bit boundary".
> + * Page 163 of the UEFI specification v2.10 and
> + * EDK2 reference implementation both define EFI_GUID as
> + * struct { u32 a; u16; b; u16 c; u8 d[8]; }; which is 4-byte
> + * aligned.
> + */
> typedef struct {
> u8 b[16];
> -} efi_guid_t __attribute__((aligned(8)));
> +} efi_guid_t __attribute__((aligned(4)));
>
> #define EFI_BITS_PER_LONG (sizeof(long) * 8)
>
> --
> 2.17.1
>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
^ permalink raw reply [flat|nested] 2+ messages in thread
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