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Commit 4c58464b authored by Jussi Kivilinna's avatar Jussi Kivilinna Committed by Herbert Xu
Browse files

crypto: blowfish-x86_64 - blacklist Pentium 4 



Implementation in blowfish-x86_64 uses 64bit rotations which are slow on P4,
making blowfish-x86_64 slower than generic C implementation. Therefore
blacklist P4.

Signed-off-by: default avatarJussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent a522ee85

arch/x86/crypto/blowfish_glue.c

+30 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
 *

 */



#include <asm/processor.h>

#include <crypto/blowfish.h>

#include <linux/crypto.h>

#include <linux/init.h>
@@ -446,10 +447,39 @@ static struct crypto_alg blk_ctr_alg = { 
	},

};



static bool is_blacklisted_cpu(void)

{

	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)

		return false;



	if (boot_cpu_data.x86 == 0x0f) {

		/*

		 * On Pentium 4, blowfish-x86_64 is slower than generic C

		 * implementation because use of 64bit rotates (which are really

		 * slow on P4). Therefore blacklist P4s.

		 */

		return true;

	}



	return false;

}



static int force;

module_param(force, int, 0);

MODULE_PARM_DESC(force, "Force module load, ignore CPU blacklist");



static int __init init(void)

{

	int err;



	if (!force && is_blacklisted_cpu()) {

		printk(KERN_INFO

			"blowfish-x86_64: performance on this CPU "

			"would be suboptimal: disabling "

			"blowfish-x86_64.\n");

		return -ENODEV;

	}



	err = crypto_register_alg(&bf_alg);

	if (err)

		goto bf_err;