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authorJussi Kivilinna <jussi.kivilinna@mbnet.fi>2011-12-20 11:20:21 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2012-01-13 06:38:39 +0100
commit4c58464b8034cef4317593bf4ccbfc19d5bb3a77 (patch)
tree1c6de45e35919b4260a924f27c508a4372f6e865
parentcrypto: twofish-x86_64-3way - blacklist pentium4 and atom (diff)
downloadlinux-4c58464b8034cef4317593bf4ccbfc19d5bb3a77.tar.xz
linux-4c58464b8034cef4317593bf4ccbfc19d5bb3a77.zip
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: Jussi Kivilinna <jussi.kivilinna@mbnet.fi> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r--arch/x86/crypto/blowfish_glue.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/arch/x86/crypto/blowfish_glue.c b/arch/x86/crypto/blowfish_glue.c
index b05aa163d55a..2970110d2cea 100644
--- a/arch/x86/crypto/blowfish_glue.c
+++ b/arch/x86/crypto/blowfish_glue.c
@@ -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;