linux-kernel - Re: [PATCH] powerpc/64s: Rewrite __real

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Message-ID: <87o70duvuf.fsf@gmail.com>
Date: Sat, 11 Jan 2025 22:33:04 +0530
From: Ritesh Harjani (IBM) <ritesh.list@...il.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>, Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, Naveen N Rao <naveen@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] powerpc/64s: Rewrite __real_pte() as a static inline

Christophe Leroy <christophe.leroy@...roup.eu> writes:

> Rewrite __real_pte() as a static inline in order to avoid
> following warning/error when building with 4k page size:
>
> 	  CC      arch/powerpc/mm/book3s64/hash_tlb.o
> 	arch/powerpc/mm/book3s64/hash_tlb.c: In function 'hpte_need_flush':
> 	arch/powerpc/mm/book3s64/hash_tlb.c:49:16: error: variable 'offset' set but not used [-Werror=unused-but-set-variable]
> 	   49 |         int i, offset;
> 	      |                ^~~~~~
> 	cc1: all warnings being treated as errors
>
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202501081741.AYFwybsq-lkp@intel.com/

Great. Why not fix the other warning as well which is reported in above
link, which is...  

--
   arch/powerpc/mm/book3s64/hash_native.c: In function 'native_flush_hash_range':
>> arch/powerpc/mm/book3s64/hash_native.c:786:29: warning: variable 'index' set but not used [-Wunused-but-set-variable]
     786 |         unsigned long hash, index, hidx, shift, slot;
--

...similar to how we fixed this warning by making the macro as static
inline? That means something like this (not tested)?

-#define __rpte_to_hidx(r,index)        (pte_val(__rpte_to_pte(r)) >> H_PAGE_F_GIX_SHIFT)
+static inline unsigned long __rpte_to_hidx(real_pte_t r, unsigned long index)
+{
+       return pte_val(__rpte_to_pte(r)) >> H_PAGE_F_GIX_SHIFT;
+}


-ritesh


> Fixes: ff31e105464d ("powerpc/mm/hash64: Store the slot information at the right offset for hugetlb")
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>  arch/powerpc/include/asm/book3s/64/hash-4k.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> index c3efacab4b94..a7a68ba9c71b 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> @@ -77,7 +77,10 @@
>  /*
>   * With 4K page size the real_pte machinery is all nops.
>   */
> -#define __real_pte(e, p, o)		((real_pte_t){(e)})
> +static inline real_pte_t __real_pte(pte_t pte, pte_t *ptep, int offset)
> +{
> +	return (real_pte_t){pte};
> +}
>  #define __rpte_to_pte(r)	((r).pte)
>  #define __rpte_to_hidx(r,index)	(pte_val(__rpte_to_pte(r)) >> H_PAGE_F_GIX_SHIFT)
>  
> -- 
> 2.47.0