How to make sure that the cryptographic hardware accelerator is being used in am335x?

Question

I want to use the AES hardware accelerator in am335x. I was able to generate the cryptodev.ko and cryptosoft.ko drivers. From my application program I am making use of openssl apis in CBC mode, and I wanted to verify the hardware accelerator usage.

I could trace the control flow until driver/omap-aes.c. But for cat /proc/interrupts I got the entry for sham@53100000 but not for aes@53500000. What was the reason for this? How can I make sure that the hardware accelerator for AES is being used?

Answer 1

There is a TI wiki page for the Crypto hardware on the AM335x here. On that page there is a tutorial on how to compare the performance of the hardware accelerator versus the pure software implementation.

After the modules are installed, OpenSSL commands may be executed which take advantage of the hardware accelerators through the OCF-Linux driver. The following example demonstrates the OpenSSL built-in speed test to demonstrate performance. The addition of the parameter -engine cryptodev tells OpenSSL to use the OCF-Linux driver if it exists.

Running time -v openssl speed -evp aes-128-cbc -engine cryptodev and time -v openssl speed -evp aes-128-cbc should produce very different results if the hardware accelerator is enabled and working correctly. You may also need to remove the crypto driver as that page suggests to see the difference. If you run those tests and see no appreciable difference in performance, that probably means the hardware isn't working, and you should make sure you properly configured the kernel (that information is also in the provided link).