diff options
| -rw-r--r-- | arch/x86/crypto/twofish_glue_3way.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/x86/crypto/twofish_glue_3way.c b/arch/x86/crypto/twofish_glue_3way.c index 7fee8c152f9..0afd134d8c9 100644 --- a/arch/x86/crypto/twofish_glue_3way.c +++ b/arch/x86/crypto/twofish_glue_3way.c @@ -25,6 +25,7 @@ * */ +#include <asm/processor.h> #include <linux/crypto.h> #include <linux/init.h> #include <linux/module.h> @@ -637,10 +638,56 @@ static struct crypto_alg blk_xts_alg = { }, }; +static bool is_blacklisted_cpu(void) +{ + if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) + return false; + + if (boot_cpu_data.x86 == 0x06 && + (boot_cpu_data.x86_model == 0x1c || + boot_cpu_data.x86_model == 0x26 || + boot_cpu_data.x86_model == 0x36)) { + /* + * On Atom, twofish-3way is slower than original assembler + * implementation. Twofish-3way trades off some performance in + * storing blocks in 64bit registers to allow three blocks to + * be processed parallel. Parallel operation then allows gaining + * more performance than was trade off, on out-of-order CPUs. + * However Atom does not benefit from this parallellism and + * should be blacklisted. + */ + return true; + } + + if (boot_cpu_data.x86 == 0x0f) { + /* + * On Pentium 4, twofish-3way is slower than original assembler + * implementation because excessive uses of 64bit rotate and + * left-shifts (which are really slow on P4) needed to store and + * handle 128bit block in two 64bit registers. + */ + return true; + } + + return false; +} + +static int force; +module_param(force, int, 0); +MODULE_PARM_DESC(force, "Force module load, ignore CPU blacklist"); + int __init init(void) { int err; + if (!force && is_blacklisted_cpu()) { + printk(KERN_INFO + "twofish-x86_64-3way: performance on this CPU " + "would be suboptimal: disabling " + "twofish-x86_64-3way.\n"); + return -ENODEV; + } + err = crypto_register_alg(&blk_ecb_alg); if (err) goto ecb_err; |