Re: [PATCH] MIPS: clean up CONFIG_MIPS_PGD_C0_CONTEXT handling

[Huang Pei <huangpei@loongson.cn>]

Hi, 
On Mon, Mar 01, 2021 at 12:00:28AM +0100, Maciej W. Rozycki wrote:
> On Sat, 27 Feb 2021, Huang Pei wrote:
> 
> > index 2000bb2b0220..517509ad8596 100644
> > --- a/arch/mips/Kconfig
> > +++ b/arch/mips/Kconfig
> > @@ -2142,6 +2142,7 @@ config CPU_SUPPORTS_HUGEPAGES
> >  	depends on !(32BIT && (ARCH_PHYS_ADDR_T_64BIT || EVA))
> >  config MIPS_PGD_C0_CONTEXT
> >  	bool
> > +	depends on 64BIT
> >  	default y if 64BIT && (CPU_MIPSR2 || CPU_MIPSR6) && !CPU_XLP
> 
>  I guess you want:
> 
> 	default y if (CPU_MIPSR2 || CPU_MIPSR6) && !CPU_XLP
> 
> at the same time too.  Otherwise you have cruft left behind.
> 
Yes, it is much better
> > diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
> > index a7521b8f7658..5bb9724578f7 100644
> > --- a/arch/mips/mm/tlbex.c
> > +++ b/arch/mips/mm/tlbex.c
> > @@ -1106,6 +1106,7 @@ struct mips_huge_tlb_info {
> >  	bool need_reload_pte;
> >  };
> >  
> > +#ifdef CONFIG_64BIT
> >  static struct mips_huge_tlb_info
> >  build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
> >  			       struct uasm_reloc **r, unsigned int tmp,
> 
>  Does it actually build without a warning for !CONFIG_64BIT given the 
> reference below?

No, my bad, my first reaction when seeing "IS_ENABLED(CONFIG_64BIT)" is
"#ifdef CONFIG_64BIT"
> 
> > @@ -1164,8 +1165,8 @@ build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
> >  
> >  	if (pgd_reg == -1) {
> >  		vmalloc_branch_delay_filled = 1;
> > -		/* 1 0	1 0 1  << 6  xkphys cached */
> > -		uasm_i_ori(p, ptr, ptr, 0x540);
> > +		/* insert bit[63:59] of CAC_BASE into bit[11:6] of ptr */
> > +		uasm_i_ori(p, ptr, ptr, (CAC_BASE >> 53));
> 
>  Instead I'd paper the issue over by casting the constant to `s64'.
> 
>  Or better yet fixed it properly by defining CAC_BASE, etc. as `unsigned
> long long' long rather than `unsigned long' to stop all this nonsense 
> (e.g. PHYS_TO_XKPHYS already casts the result to `s64').  Thomas, WDYT?
Sorry, I do not get it , on MIPS32, how can CAC_BASE be unsigned long
long ?


If this did not work, how about one step back, just explicit comment
wihtout "(CAC_BASE << 53)" ?
> 
>   Maciej