linux-kernel - Re: [PATCH 2/3] x86/hash: swap parameters of crc32

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: <530B0AF2020000780011E97B@nat28.tlf.novell.com>
Date:	Mon, 24 Feb 2014 08:03:46 +0000
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"Daniel Borkmann" <dborkman@...hat.com>
Cc:	<davem@...emloft.net>, <mingo@...e.hu>, <tglx@...utronix.de>,
	<ffusco@...hat.com>, <tgraf@...hat.com>,
	<linux-kernel@...r.kernel.org>, <hpa@...or.com>
Subject: Re: [PATCH 2/3] x86/hash: swap parameters of crc32_u32()

>>> On 22.02.14 at 13:09, Daniel Borkmann <dborkman@...hat.com> wrote:
> On 02/21/2014 11:33 AM, Jan Beulich wrote:
>> ... to match its two callers (i.e. the alternative would have been to
>> swap the arguments at the call sites).
>>
>> Signed-off-by: Jan Beulich <jbeulich@...e.com>
>> Cc: Francesco Fusco <ffusco@...hat.com>
>> Cc: Daniel Borkmann <dborkman@...hat.com>
>> Cc: Thomas Graf <tgraf@...hat.com>
>> Cc: David S. Miller <davem@...emloft.net>
>> ---
>>   arch/x86/lib/hash.c |    2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> --- 3.14-rc3-x86-hash-crc32.orig/arch/x86/lib/hash.c
>> +++ 3.14-rc3-x86-hash-crc32/arch/x86/lib/hash.c
>> @@ -37,7 +37,7 @@
>>   #include <asm/cpufeature.h>
>>   #include <asm/hash.h>
>>
>> -static inline u32 crc32_u32(u32 crc, u32 val)
>> +static inline u32 crc32_u32(u32 val, u32 crc)
>>   {
>>   #ifdef CONFIG_AS_CRC32
>>   	asm ("crc32l %1,%0\n" : "+r" (crc) : "rm" (val));
> 
> Can you elaborate?
> 
> Sorry, I need to ask here (even if it's a stupid question ;)) if this
> change is safe to do; are referring to a cleanup or fixing a concrete
> bug? The code is a modified version of the DPDK hash which you can find
> in [1]. Arguments of the caller are in the correct order, afaik.
> 
>    [1] http://dpdk.org/browse/dpdk/tree/lib/librte_hash/rte_hash_crc.h 

Yes, that file appears to be correct:

rte_hash_crc_4byte(uint32_t data, uint32_t init_val)

as opposed to 

static inline u32 crc32_u32(u32 crc, u32 val)

(quite obviously data <-> val and crc <-> init_val, supported
by the second argument in each caller being named "seed").

Jan

--
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/