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Message-ID: <4ef86adf-a7c7-5ffc-6acc-9d269ea089ba@canonical.com>
Date: Fri, 7 Oct 2022 09:50:30 +0200
From: Heinrich Schuchardt <heinrich.schuchardt@...onical.com>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Atish Patra <atishp@...osinc.com>,
Daniel Kiper <daniel.kiper@...cle.com>,
Fu Wei <tekkamanninja@...il.com>,
Leif Lindholm <quic_llindhol@...cinc.com>,
Nikita Ermakov <arei@...linux.org>,
Atish Patra <atishp@...shpatra.org>,
Julian Andres Klode <julian.klode@...onical.com>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>,
linux-kernel@...r.kernel.org
Subject: Re: [v4 PATCH 2/3] RISC-V: Update image header
On 10/7/22 09:20, Ard Biesheuvel wrote:
> On Fri, 7 Oct 2022 at 01:51, Heinrich Schuchardt
> <heinrich.schuchardt@...onical.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@...osinc.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@...onical.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
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