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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.11.2024 15:02, Frediano Ziglio wrote:
> On Tue, Nov 5, 2024 at 2:52 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> 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.
> 
> I thought this patch was already applied.
> I didn't remember any clang issue.
> As far as I know, this was delayed by an issue that turned out to be 
> different.
> So, any reason why not to merge the original patch?

Afaict the alternative would result in tidier code, and hence might indeed be
preferable. But since the reason I didn't long commit the patch is Andrew
wanting it to not be committed, it'll need to be him to chime in here. Even
if only to indicate that I'm misremembering.

Jan