Re: [PATCH v3] MIPS: Implement ieee754 NAN2008 emulation mode

Jiaxun Yang
2024-06-27T11:22:02Z

在2024年6月27日六月 上午11:58，Thomas Bogendoerfer写道：
> On Wed, Jun 12, 2024 at 09:38:19AM +0100, Jiaxun Yang wrote:
>> +++ b/arch/mips/kernel/elf.c
>> @@ -318,6 +318,10 @@ void mips_set_personality_nan(struct arch_elf_state *state)
>> t->thread.fpu.fcr31 = c->fpu_csr31;
>> switch (state->nan_2008) {
>> case 0:
>> + if (!(c->fpu_msk31 & FPU_CSR_NAN2008))
>> + t->thread.fpu.fcr31 &= ~FPU_CSR_NAN2008;
>> + if (!(c->fpu_msk31 & FPU_CSR_ABS2008))
>> + t->thread.fpu.fcr31 &= ~FPU_CSR_ABS2008;
>
> why is this needed?

Because t->thread.fpu.fcr31 comes from c->fpu_csr31, in this case we the default
value of c->fpu_csr31 is read from hardware and we don't know what would that be.

Thanks
>
> Thomas.
>
> --
> Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
> good idea. [ RFC1925, 2.3 ]

--
- Jiaxun