Re: [PATCH v4] Avoid crash calling PrintErrMesg from efi_multiboot2

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.08.2024 16:29, Frediano Ziglio wrote:
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -287,19 +287,36 @@ static bool __init match_guid(const EFI_GUID *guid1, 
> const EFI_GUID *guid2)
>  /* generic routine for printing error messages */
>  static void __init PrintErrMesg(const CHAR16 *mesg, EFI_STATUS ErrCode)
>  {
> -    static const CHAR16* const ErrCodeToStr[] __initconstrel = {
> -        [~EFI_ERROR_MASK & EFI_NOT_FOUND]           = L"Not found",
> -        [~EFI_ERROR_MASK & EFI_NO_MEDIA]            = L"The device has no 
> media",
> -        [~EFI_ERROR_MASK & EFI_MEDIA_CHANGED]       = L"Media changed",
> -        [~EFI_ERROR_MASK & EFI_DEVICE_ERROR]        = L"Device error",
> -        [~EFI_ERROR_MASK & EFI_VOLUME_CORRUPTED]    = L"Volume corrupted",
> -        [~EFI_ERROR_MASK & EFI_ACCESS_DENIED]       = L"Access denied",
> -        [~EFI_ERROR_MASK & EFI_OUT_OF_RESOURCES]    = L"Out of resources",
> -        [~EFI_ERROR_MASK & EFI_VOLUME_FULL]         = L"Volume is full",
> -        [~EFI_ERROR_MASK & EFI_SECURITY_VIOLATION]  = L"Security violation",
> -        [~EFI_ERROR_MASK & EFI_CRC_ERROR]           = L"CRC error",
> -        [~EFI_ERROR_MASK & EFI_COMPROMISED_DATA]    = L"Compromised data",
> -        [~EFI_ERROR_MASK & EFI_BUFFER_TOO_SMALL]    = L"Buffer too small",
> +#define ERROR_MESSAGE_LIST \
> +    ERROR_MESSAGE(EFI_NOT_FOUND, "Not found") \
> +    ERROR_MESSAGE(EFI_NO_MEDIA, "The device has no media") \
> +    ERROR_MESSAGE(EFI_MEDIA_CHANGED, "Media changed") \
> +    ERROR_MESSAGE(EFI_DEVICE_ERROR, "Device error") \
> +    ERROR_MESSAGE(EFI_VOLUME_CORRUPTED, "Volume corrupted") \
> +    ERROR_MESSAGE(EFI_ACCESS_DENIED, "Access denied") \
> +    ERROR_MESSAGE(EFI_OUT_OF_RESOURCES, "Out of resources") \
> +    ERROR_MESSAGE(EFI_VOLUME_FULL, "Volume is full") \
> +    ERROR_MESSAGE(EFI_SECURITY_VIOLATION, "Security violation") \
> +    ERROR_MESSAGE(EFI_CRC_ERROR, "CRC error") \
> +    ERROR_MESSAGE(EFI_COMPROMISED_DATA, "Compromised data") \
> +    ERROR_MESSAGE(EFI_BUFFER_TOO_SMALL, "Buffer too small")
> +
> +    static const struct ErrorStrings {
> +        CHAR16 start;
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) CHAR16 msg_ ## code[sizeof(str)];
> +        ERROR_MESSAGE_LIST
> +    } ErrorStrings __initconst = {
> +        0
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) , L ## str
> +        ERROR_MESSAGE_LIST
> +    };
> +    static const uint16_t ErrCodeToStr[] __initconst = {
> +#undef ERROR_MESSAGE
> +#define ERROR_MESSAGE(code, str) \
> +        [~EFI_ERROR_MASK & code] = offsetof(struct ErrorStrings, msg_ ## 
> code),
> +        ERROR_MESSAGE_LIST
>      };
>      EFI_STATUS ErrIdx = ErrCode & ~EFI_ERROR_MASK;
>  

A while ago Andrew and I discussed this, and I was apparently wrongly expecting
him to come back here, as (iirc; no record of this that I could find in the mail
archives, so I'm sorry if my recollection is wrong) he was the one to object. We
concluded that it wants at least considering to undo the respective part of
00d5d5ce23e6, finding a different solution to the Clang issue there.

Jan