linux-kernel - Re: [PATCH v4 06/10] powerpc/mm: Use generic_get_unmapped_area() and call it from arch_get_unmapped

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Date:   Thu, 09 Dec 2021 19:50:07 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     "alex@...ti.fr" <alex@...ti.fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>
Cc:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v4 06/10] powerpc/mm: Use generic_get_unmapped_area() and
 call it from arch_get_unmapped_area()

Excerpts from Christophe Leroy's message of December 9, 2021 3:18 am:
> Use the generic version of arch_get_unmapped_area() which
> is now available at all time instead of its copy
> radix__arch_get_unmapped_area()
> 
> Instead of setting mm->get_unmapped_area() to either
> arch_get_unmapped_area() or generic_get_unmapped_area(),
> always set it to arch_get_unmapped_area() and call
> generic_get_unmapped_area() from there when radix is enabled.
> 
> Do the same with radix__arch_get_unmapped_area_topdown()
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>  arch/powerpc/mm/mmap.c | 127 ++---------------------------------------
>  1 file changed, 6 insertions(+), 121 deletions(-)
> 
> diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
> index 9b0d6e395bc0..46781d0103d1 100644
> --- a/arch/powerpc/mm/mmap.c
> +++ b/arch/powerpc/mm/mmap.c
> @@ -81,115 +81,15 @@ static inline unsigned long mmap_base(unsigned long rnd,
>  }
>  
>  #ifdef HAVE_ARCH_UNMAPPED_AREA
> -#ifdef CONFIG_PPC_RADIX_MMU
> -/*
> - * Same function as generic code used only for radix, because we don't need to overload
> - * the generic one. But we will have to duplicate, because hash select
> - * HAVE_ARCH_UNMAPPED_AREA
> - */
> -static unsigned long
> -radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
> -			     unsigned long len, unsigned long pgoff,
> -			     unsigned long flags)
> -{
> -	struct mm_struct *mm = current->mm;
> -	struct vm_area_struct *vma;
> -	int fixed = (flags & MAP_FIXED);
> -	unsigned long high_limit;
> -	struct vm_unmapped_area_info info;
> -
> -	high_limit = DEFAULT_MAP_WINDOW;
> -	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
> -		high_limit = TASK_SIZE;

Does 64s radix need to define arch_get_mmap_end() to do the above now?

Otherwise great to consolidate this with core code, nice patch.

Thanks,
Nick