linux-kernel - Re: [PATCH] Export kmap_atomic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 27 Aug 2008 23:36:05 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Eric Anholt <eric@...olt.net>, Dave Airlie <airlied@...il.com>,
	linux-arch@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Export kmap_atomic_pfn for DRM-GEM.

On Wednesday 27 August 2008 05:43, Eric Anholt wrote:
> The driver would like to map IO space directly for copying data in when
> appropriate, to avoid CPU cache flushing for streaming writes.
> kmap_atomic_pfn lets us avoid IPIs associated with ioremap for this
> process.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
>  arch/x86/mm/highmem_32.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
> index 165c871..d52e91d 100644
> --- a/arch/x86/mm/highmem_32.c
> +++ b/arch/x86/mm/highmem_32.c
> @@ -137,6 +137,7 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type
> type)
>
>  	return (void*) vaddr;
>  }
> +EXPORT_SYMBOL(kmap_atomic_pfn);
>
>  struct page *kmap_atomic_to_page(void *ptr)
>  {


I wonder if you ever tested my vmap rework patches with this issue? It
seems somewhat x86 specific and also not conceptually so clean to use
kmap_atomic_pfn for this. vmap may not be used by all architectures but
I think it might be able to cover some of them.

As I said, there are some other possible improvements that can be made
to my vmap rewrite if performance isn't good enough, but I simply have
not seen numbers...

Thanks,
Nick
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/