linux-kernel - Re: [PATCH] MIPS: c-r4k: Fix size calc when avoiding IPIs for small icache flushes

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]

Message-ID: <20160905142757.GD25853@jhogan-linux.le.imgtec.org>
Date:   Mon, 5 Sep 2016 15:27:57 +0100
From:   James Hogan <james.hogan@...tec.com>
To:     Paul Burton <paul.burton@...tec.com>,
        Ralf Baechle <ralf@...ux-mips.org>
CC:     <linux-mips@...ux-mips.org>, Huacai Chen <chenhc@...ote.com>,
        <linux-kernel@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH] MIPS: c-r4k: Fix size calc when avoiding IPIs for small
 icache flushes

On Mon, Sep 05, 2016 at 03:24:54PM +0100, Paul Burton wrote:
> Commit f70ddc07b637 ("MIPS: c-r4k: Avoid small flush_icache_range SMP
> calls") adds checks to force use of hit-type cache ops for small icache
> flushes where they are globalised & index-type cache ops aren't, in
> order to avoid the overhead of IPIs in those cases. However it
> calculated the size of the region being flushed incorrectly, subtracting
> the end address from the start address rather than the reverse. This
> would have led to an overflow with size wrapping round to some large
> value, and likely to the special case for avoiding IPIs not actually
> being hit.
> 
> Signed-off-by: Paul Burton <paul.burton@...tec.com>
> Cc: James Hogan <james.hogan@...tec.com>
> Fixes: f70ddc07b637 ("MIPS: c-r4k: Avoid small flush_icache_range SMP calls")

Good catch Paul! I've no idea how that happened.

Reviewed-by: James Hogan <james.hogan@...tec.com>

Ralf: It'd be great to get this into v4.8 if possible.

Thanks
James

> ---
> 
>  arch/mips/mm/c-r4k.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
> index 1af381f..69b1f10 100644
> --- a/arch/mips/mm/c-r4k.c
> +++ b/arch/mips/mm/c-r4k.c
> @@ -811,7 +811,7 @@ static void __r4k_flush_icache_range(unsigned long start, unsigned long end,
>  		 * If address-based cache ops don't require an SMP call, then
>  		 * use them exclusively for small flushes.
>  		 */
> -		size = start - end;
> +		size = end - start;
>  		cache_size = icache_size;
>  		if (!cpu_has_ic_fills_f_dc) {
>  			size *= 2;
> -- 
> 2.9.3
> 

Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)