Re: [PATCH 5.11 225/254] arm64/mm: define arch_get_mappable_range()

[Naresh Kamboju]

On Mon, 29 Mar 2021 at 14:10, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>
> [ Upstream commit 03aaf83fba6e5af08b5dd174c72edee9b7d9ed9b ]
>
> This overrides arch_get_mappable_range() on arm64 platform which will be
> used with recently added generic framework.  It drops
> inside_linear_region() and subsequent check in arch_add_memory() which are
> no longer required.  It also adds a VM_BUG_ON() check that would ensure
> that mhp_range_allowed() has already been called.
>
> Link: https://lkml.kernel.org/r/1612149902-7867-3-git-send-email-anshuman.khandual@xxxxxxx
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
> Cc: Jason Wang <jasowang@xxxxxxxxxx>
> Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Pankaj Gupta <pankaj.gupta@xxxxxxxxxxxxxxx>
> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
> Cc: teawater <teawaterz@xxxxxxxxxxxxxxxxx>
> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  arch/arm64/mm/mmu.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 6f0648777d34..92b3be127796 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1443,16 +1443,19 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
>         free_empty_tables(start, end, PAGE_OFFSET, PAGE_END);
>  }
>
> -static bool inside_linear_region(u64 start, u64 size)
> +struct range arch_get_mappable_range(void)
>  {
> +       struct range mhp_range;
> +
>         /*
>          * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
>          * accommodating both its ends but excluding PAGE_END. Max physical
>          * range which can be mapped inside this linear mapping range, must
>          * also be derived from its end points.
>          */
> -       return start >= __pa(_PAGE_OFFSET(vabits_actual)) &&
> -              (start + size - 1) <= __pa(PAGE_END - 1);
> +       mhp_range.start = __pa(_PAGE_OFFSET(vabits_actual));
> +       mhp_range.end =  __pa(PAGE_END - 1);
> +       return mhp_range;
>  }
>
>  int arch_add_memory(int nid, u64 start, u64 size,
> @@ -1460,11 +1463,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
>  {
>         int ret, flags = 0;
>
> -       if (!inside_linear_region(start, size)) {
> -               pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size);
> -               return -EINVAL;
> -       }
> -
> +       VM_BUG_ON(!mhp_range_allowed(start, size, true));
>         if (rodata_full || debug_pagealloc_enabled())
>                 flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;

The stable rc 5.10 and 5.11 builds failed for arm64 architecture
due to below warnings / errors,

> Anshuman Khandual <anshuman.khandual@xxxxxxx>
>     arm64/mm: define arch_get_mappable_range()


  arch/arm64/mm/mmu.c: In function 'arch_add_memory':
  arch/arm64/mm/mmu.c:1483:13: error: implicit declaration of function
'mhp_range_allowed'; did you mean 'cpu_map_prog_allowed'?
[-Werror=implicit-function-declaration]
    VM_BUG_ON(!mhp_range_allowed(start, size, true));
               ^
  include/linux/build_bug.h:30:63: note: in definition of macro
'BUILD_BUG_ON_INVALID'
   #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
                                                                 ^
  arch/arm64/mm/mmu.c:1483:2: note: in expansion of macro 'VM_BUG_ON'
    VM_BUG_ON(!mhp_range_allowed(start, size, true));
    ^~~~~~~~~

Build link,
https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-5.11/DISTRO=lkft,MACHINE=juno,label=docker-buster-lkft/41/consoleText
https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-5.10/DISTRO=lkft,MACHINE=dragonboard-410c,label=docker-buster-lkft/120/consoleFull

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