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SubjectRe: [RFC Part2 PATCH 05/30] x86: define RMP violation #PF error code
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On 3/24/21 1:03 PM, Dave Hansen wrote:
>> diff --git a/arch/x86/include/asm/trap_pf.h b/arch/x86/include/asm/trap_pf.h
>> index 10b1de500ab1..107f9d947e8d 100644
>> --- a/arch/x86/include/asm/trap_pf.h
>> +++ b/arch/x86/include/asm/trap_pf.h
>> @@ -12,6 +12,7 @@
>> * bit 4 == 1: fault was an instruction fetch
>> * bit 5 == 1: protection keys block access
>> * bit 15 == 1: SGX MMU page-fault
>> + * bit 31 == 1: fault was an RMP violation
>> */
>> enum x86_pf_error_code {
>> X86_PF_PROT = 1 << 0,
>> @@ -21,6 +22,7 @@ enum x86_pf_error_code {
>> X86_PF_INSTR = 1 << 4,
>> X86_PF_PK = 1 << 5,
>> X86_PF_SGX = 1 << 15,
>> + X86_PF_RMP = 1ull << 31,
>> };
> Man, I hope AMD and Intel are talking to each other about these bits. :)
>
> Either way, this is hitting the limits of what I know about how enums
> are implemented. I had internalized that they are just an 'int', but
> that doesn't seem quite right. It sounds like they must be implemented
> using *an* integer type, but not necessarily 'int' itself.
>
> Either way, '1<<31' doesn't fit in a 32-bit signed int. But, gcc at
> least doesn't seem to blow the enum up into a 64-bit type, which is nice.
>
> Could we at least start declaring these with BIT()?


Sure, I can bit the BIT() macro to define the bits. Do you want me to
update all of the fault codes to use BIT() or just the one I am adding
in this patch ?


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