Re: [v4 PATCH 2/3] RISC-V: Update image header

[Heinrich Schuchardt <heinrich.schuchardt@canonical.com>]

On 10/7/22 09:20, Ard Biesheuvel wrote:
> On Fri, 7 Oct 2022 at 01:51, Heinrich Schuchardt
> <heinrich.schuchardt@canonical.com> wrote:
>>
>>
>>
>> On 10/7/22 01:00, Atish Patra wrote:
>>> Update the RISC-V Linux kernel image headers as per the current header.
>>>
>>> Reference:
>>> <Linux kernel source>/Documentation/riscv/boot-image-header.rst
>>>
>>> 474efecb65dc: ("riscv: modify the Image header to improve compatibility with the ARM64 header")
>>>
>>> Signed-off-by: Atish Patra <atishp@rivosinc.com>
>>> ---
>>>    include/grub/riscv32/linux.h | 15 ++++++++-------
>>>    include/grub/riscv64/linux.h | 21 +++++++++++++--------
>>>    2 files changed, 21 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/include/grub/riscv32/linux.h b/include/grub/riscv32/linux.h
>>> index 512b777c8a41..de0dbdcd1be5 100644
>>> --- a/include/grub/riscv32/linux.h
>>> +++ b/include/grub/riscv32/linux.h
>>> @@ -19,20 +19,21 @@
>>>    #ifndef GRUB_RISCV32_LINUX_HEADER
>>>    #define GRUB_RISCV32_LINUX_HEADER 1
>>>
>>> -#define GRUB_LINUX_RISCV_MAGIC_SIGNATURE 0x52534356 /* 'RSCV' */
>>> +#define GRUB_LINUX_RISCV_MAGIC_SIGNATURE 0x05435352 /* 'RSC\0x5' */
>>
>> Thanks for following up on this series.
>>
>> Considering 69edb312056 ("loader/arm64/linux: Remove magic number header
>> field check") why should this constant exist in GRUB at all?
>>
>> In a follow up patch we could remove it together with
>> GRUB_LINUX_ARM_MAGIC_SIGNATURE, GRUB_LINUX_ARMXX_MAGIC_SIGNATURE, and
>> GRUB_LINUX_ARMXX_MAGIC_SIGNATURE.
>>
> 
> Indeed.
> 
> But by the same reasoning, why do we need per-arch kernel header
> typedefs at all?  The only fields we access are generic PE/COFF header
> fields.

That said I would suggest to put the series in without any further 
iterations and clean up afterwards.

Acked-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

> 
>>>
>>> -/* From linux/Documentation/riscv/booting.txt */
>>> +/* From linux/Documentation/riscv/boot-image-header.rst */
>>>    struct linux_riscv_kernel_header
>>>    {
>>>      grub_uint32_t code0;              /* Executable code */
>>>      grub_uint32_t code1;              /* Executable code */
>>> -  grub_uint64_t text_offset; /* Image load offset */
>>> -  grub_uint64_t res0;                /* reserved */
>>> -  grub_uint64_t res1;                /* reserved */
>>> +  grub_uint64_t text_offset; /* Image load offset, little endian */
>>> +  grub_uint64_t image_size;  /* Effective Image size, little endian */
>>> +  grub_uint64_t flags;               /* kernel flags, little endian */
>>> +  grub_uint32_t version;     /* Version of this header */
>>> +  grub_uint32_t res1;                /* reserved */
>>>      grub_uint64_t res2;               /* reserved */
>>>      grub_uint64_t res3;               /* reserved */
>>
>> According to tag next-20221006 of
>> Documentation/riscv/boot-image-header.rst and of
>> arch/riscv/include/asm/image.h this field is called 'magic' and filled
>> it with the string 'RISCV\0\0\0'.
>>
>>> -  grub_uint64_t res4;                /* reserved */
>>> -  grub_uint32_t magic;               /* Magic number, little endian, "RSCV" */
>>> +  grub_uint32_t magic;               /* Magic number, little endian, "RSC\x05" */
>>
>> The Linux kernel documentation calls this field magic2.
>>
>> Of course this is functionally irrelevant as we don't care about the
>> content of both fields.
>>
>>>      grub_uint32_t hdr_offset; /* Offset of PE/COFF header */
>>>    };
>>>
>>> diff --git a/include/grub/riscv64/linux.h b/include/grub/riscv64/linux.h
>>> index 3630c30fbf1a..ea77f8718222 100644
>>> --- a/include/grub/riscv64/linux.h
>>> +++ b/include/grub/riscv64/linux.h
>>> @@ -19,23 +19,28 @@
>>>    #ifndef GRUB_RISCV64_LINUX_HEADER
>>>    #define GRUB_RISCV64_LINUX_HEADER 1
>>>
>>> -#define GRUB_LINUX_RISCV_MAGIC_SIGNATURE 0x52534356 /* 'RSCV' */
>>> +#include <grub/efi/pe32.h>
>>> +
>>> +#define GRUB_LINUX_RISCV_MAGIC_SIGNATURE 0x05435352 /* 'RSC\0x5' */
>>
>> to be removed in future
>>
>> Best regards
>>
>> Heinrich
>>
>>>
>>>    #define GRUB_EFI_PE_MAGIC   0x5A4D
>>>
>>> -/* From linux/Documentation/riscv/booting.txt */
>>> +/* From linux/Documentation/riscv/boot-image-header.rst */
>>>    struct linux_riscv_kernel_header
>>>    {
>>>      grub_uint32_t code0;              /* Executable code */
>>>      grub_uint32_t code1;              /* Executable code */
>>> -  grub_uint64_t text_offset; /* Image load offset */
>>> -  grub_uint64_t res0;                /* reserved */
>>> -  grub_uint64_t res1;                /* reserved */
>>> +  grub_uint64_t text_offset; /* Image load offset, little endian */
>>> +  grub_uint64_t image_size;  /* Effective Image size, little endian */
>>> +  grub_uint64_t flags;               /* kernel flags, little endian */
>>> +  grub_uint32_t version;     /* Version of this header */
>>> +  grub_uint32_t res1;                /* reserved */
>>>      grub_uint64_t res2;               /* reserved */
>>> -  grub_uint64_t res3;                /* reserved */
>>> -  grub_uint64_t res4;                /* reserved */
>>> -  grub_uint32_t magic;               /* Magic number, little endian, "RSCV" */
>>> +  grub_uint64_t magic;               /* magic (RISC-V specifc, deprecated)*/
>>> +  grub_uint32_t magic2;              /* Magic number 2 (to match the ARM64 'magic' field pos) */
>>>      grub_uint32_t hdr_offset; /* Offset of PE/COFF header */
>>> +
>>> +  struct grub_coff_image_header coff_image_header;
>>>    };
>>>
>>>    #define linux_arch_kernel_header linux_riscv_kernel_header