diff options
| author | Jussi Kivilinna <jussi.kivilinna@mbnet.fi> | 2011-12-20 12:20:21 +0200 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2012-01-13 16:38:39 +1100 |
| commit | 4c58464b8034cef4317593bf4ccbfc19d5bb3a77 (patch) | |
| tree | 1c6de45e35919b4260a924f27c508a4372f6e865 | |
| parent | a522ee85ba979e7897a75b1c97db1b0304b68b5c (diff) | |
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.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 b05aa163d55..2970110d2ce 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; |