linux-kernel - Re: [PATCH] arm/mm: Convert PUD level pgtable helper macros into functions

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Date:   Fri, 20 Nov 2020 08:09:16 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Russell King <linux@...linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] arm/mm: Convert PUD level pgtable helper macros into
 functions



On 11/10/20 9:06 AM, Anshuman Khandual wrote:
> Macros used as functions can be problematic from the compiler perspective.
> There was a build failure report caused primarily because of non reference
> of an argument variable. Hence convert PUD level pgtable helper macros into
> functions in order to avoid such problems in the future. In the process, it
> fixes the argument variables sequence in set_pud() which probably remained
> hidden for being a macro.
> 
> https://lore.kernel.org/linux-mm/202011020749.5XQ3Hfzc-lkp@intel.com/
> https://lore.kernel.org/linux-mm/5fa49698.Vu2O3r+dU20UoEJ+%25lkp@intel.com/
> 
> Cc: Russell King <linux@...linux.org.uk>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
> Only build tested.

Hello Russel,

Any updates on this ? These changes come from an earlier discussion
on the mm list. Wondering if this too can also be submitted in the
arm patch tracking system. Thank you.

- Anshuman

+ Linus Walleij <linus.walleij@...aro.org>

> 
>  arch/arm/include/asm/pgtable-2level.h | 27 ++++++++++++++++++++++-----
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
> index 3502c2f..9d4f5ee 100644
> --- a/arch/arm/include/asm/pgtable-2level.h
> +++ b/arch/arm/include/asm/pgtable-2level.h
> @@ -177,11 +177,28 @@
>   * the pud: the pud entry is never bad, always exists, and can't be set or
>   * cleared.
>   */
> -#define pud_none(pud)		(0)
> -#define pud_bad(pud)		(0)
> -#define pud_present(pud)	(1)
> -#define pud_clear(pudp)		do { } while (0)
> -#define set_pud(pud,pudp)	do { } while (0)
> +static inline int pud_none(pud_t pud)
> +{
> +	return 0;
> +}
> +
> +static inline int pud_bad(pud_t pud)
> +{
> +	return 0;
> +}
> +
> +static inline int pud_present(pud_t pud)
> +{
> +	return 1;
> +}
> +
> +static inline void pud_clear(pud_t *pudp)
> +{
> +}
> +
> +static inline void set_pud(pud_t *pudp, pud_t pud)
> +{
> +}
>  
>  static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>  {
>