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@xxxxxxxx>
---
arch/x86/crypto/blowfish_glue.c | 30 ++++++++++++++++++++++++++++++
1 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/arch/x86/crypto/blowfish_glue.c b/arch/x86/crypto/blowfish_glue.c
index b05aa16..2970110 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;
--
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