Re: [patch V4 part 5 13/31] x86/irq: Convey vector as argument and not in ptregs

Thomas Gleixner
2020-05-11T14:36:33Z

Lai,

Lai Jiangshan <jiangshanlai+lkml@gmail.com> writes:
> On Tue, May 5, 2020 at 10:23 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> +SYM_CODE_START(irq_entries_start)
>> + vector=FIRST_EXTERNAL_VECTOR
>> + .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
>> + UNWIND_HINT_IRET_REGS
>> + .byte 0x6a, vector
>> + jmp common_interrupt
>> + .align 8
>> + vector=vector+1
>> + .endr
>> +SYM_CODE_END(irq_entries_start)
>
> Using ".byte 0x6a, vector" is somewhat ugly.
>
> I hope it should be " pushq $(s8_to_s64(vector))", which can also
> help to reduce bunches of comments about ".byte 0x6a, vector".
>
> However, I don't know how to implement s8_to_s64() here.

Neither do I.

> But at least the following code works (generates the same two-byte
> machine code as ".byte 0x6a, vector" does):
>
> .if vector < 128
> pushq $(vector)
> .else
> pushq $(0xffffffffffffff00+vector)
> .endif

Only slightly less ugly and needs as much commentry as the above.

Thanks,

tglx