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SubjectRe: [PATCH] MIPS: Support large stack.
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在 2021/3/5 11:12, HongJieDeng 写道:
> From: Hongjie Deng <deng.hongjie@h3c.com>
>
> We need more stack space, xori/ori no longer apply when
> _THREAD_MASK exceeds 16 bits
>
> Signed-off-by: Hongjie Deng <deng.hongjie@h3c.com>
> ---
> arch/mips/include/asm/stackframe.h | 8 ++++++++
> arch/mips/kernel/genex.S | 6 ++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
> index aa430a6..6ebc39f 100644
> --- a/arch/mips/include/asm/stackframe.h
> +++ b/arch/mips/include/asm/stackframe.h
> @@ -278,8 +278,16 @@
> sll k0, 3 /* extract cu0 bit */
> bltz k0, 9f
>
> +#if _THREAD_MASK < (1 << 16 - 1)
> ori $28, sp, _THREAD_MASK
> xori $28, _THREAD_MASK
> +#else
> + li $28, _THREAD_MASK
> + or $28, sp, $28
> + li $24, _THREAD_MASK
> + xor $28, $28, $24

Hi Hongjie,

li breaks MIPS64, please try PTR_LI instead.
Also loading immediate cost a lot on MIPS,
you may save a unnecessary li by:

+ PTR_LI v1, _THREAD_MASK
+ or gp, sp, v1
+ xor gp, gp, v1

Also clobber v0/v1 seems much more reasonable than $24 here....

> +#endif
> +
> #ifdef CONFIG_CPU_CAVIUM_OCTEON
> .set mips64
> pref 0, 0($28) /* Prefetch the current pointer */
> diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
> index bcce32a..5ea4fe4 100644
> --- a/arch/mips/kernel/genex.S
> +++ b/arch/mips/kernel/genex.S
> @@ -662,8 +662,14 @@ isrdhwr:
> #endif
> MTC0 k0, CP0_EPC
> /* I hope three instructions between MTC0 and ERET are enough... */
> +#if _THREAD_MASK < (1 << 16 - 1)
> ori k1, _THREAD_MASK
> xori k1, _THREAD_MASK
> +#else
> + li $24 ,_THREAD_MASK
> + or k1, k1, $24
> + xor k1, k1, $24
> +#endif
Ditto.

Actually another possible solution could be `.set at=v1` around it
and let aeembler to decide if it needs a extra register.

Thanks.

- Jiaxun
> LONG_L v1, TI_TP_VALUE(k1)
> .set push
> .set arch=r4000

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