linux-kernel - Re: [patch 1/4] sparc/mm/highmem: Flush cache and TLB

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Date:   Wed, 13 Jan 2021 08:44:24 +0100
From:   Andreas Larsson <andreas@...sler.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Peter Zijlstra <peterz@...radead.org>,
        "David S. Miller" <davem@...emloft.net>,
        sparclinux@...r.kernel.org, Paul Cercueil <paul@...pouillou.net>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [patch 1/4] sparc/mm/highmem: Flush cache and TLB


On 2021-01-12 18:01, Thomas Gleixner wrote:
> The recent conversion to the generic kmap_local infrastructure failed to
> assign the proper pre/post map/unmap flush operations for sparc.
> 
> Sparc requires cache flush before map/unmap and tlb flush afterwards.
> 
> Fixes: 3293efa97807 ("sparc/mm/highmem: Switch to generic kmap atomic")
> Reported-by: Andreas Larsson <andreas@...sler.com>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: sparclinux@...r.kernel.org
> ---
>   arch/sparc/include/asm/highmem.h |    9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> --- a/arch/sparc/include/asm/highmem.h
> +++ b/arch/sparc/include/asm/highmem.h
> @@ -50,10 +50,11 @@ extern pte_t *pkmap_page_table;
>   
>   #define flush_cache_kmaps()	flush_cache_all()
>   
> -/* FIXME: Use __flush_tlb_one(vaddr) instead of flush_cache_all() -- Anton */
> -#define arch_kmap_local_post_map(vaddr, pteval)	flush_cache_all()
> -#define arch_kmap_local_post_unmap(vaddr)	flush_cache_all()
> -
> +/* FIXME: Use __flush_*_one(vaddr) instead of flush_*_all() -- Anton */
> +#define arch_kmap_local_pre_map(vaddr, pteval)	flush_cache_all()
> +#define arch_kmap_local_pre_unmap(vaddr)	flush_cache_all()
> +#define arch_kmap_local_post_map(vaddr, pteval)	flush_tlb_all()
> +#define arch_kmap_local_post_unmap(vaddr)	flush_tlb_all()
>   
>   #endif /* __KERNEL__ */

Yes! I found, just an hour before your patched was posted, that an
equivalent fix helped back where the switch-to-generic patch first
occurred. This patch was successfully tested on master.

Tested-by: Andreas Larsson <andreas@...sler.com>

-- 
Andreas Larsson
Cobham Gaisler