Add support to ESP32C3

[potsrevennil]

depends on #48

This PR added esp32c3 support to the build system
running

make PLATFORM=esp32-c3

should be able to compile the binary for all tests (test/speed/stack/nistkat).

Then flash to the esp32c3 device with

esptool.py -p <PORT> write_flash 0x0 build/esp32-c3/bin/<bin_name>.bin

where PORT start with /dev/tty and /dev/cu on Linux and macOS respectively.

This is not integrated to the tests script yet, there will be a separate PR for this.

You can receive serial output from the same device (after resetting the board) - the baud rate is 115200:

pyserial-miniterm <PORT> 115200 

Building the artifacts for esp32c3 is included in CI as well.

UPDATE:

Cycle Count

• CLOCK_BENCHMARK = 80MHZ (which is the max clock frequency for flash)

keypair cycles
4015868
encaps cycles
3736502
decaps cycles
4492722

• CLOCK_FAST = 160 MHZ, will get

keypair cycles
5426636
encaps cycles
4846023
decaps cycles
6056913

Stack Usage

keypair stack usage:
3600
encaps stack usage:
3648
decaps stack usage:
3616

• Does this PR change the input/output behaviour of a cryptographic algorithm (i.e., does it change known answer test values)? (If so, a version bump will be required from x.y.z to x.(y+1).0.)

[mkannwischer]

It's worth mentioning that the baud rate is 115200

[mkannwischer]

I tested that everything works. What is a little weird to me is that the flashing and the printing of the output are done over the same USB device? How do you run this in parallel?

What's printed as cycle counts seems way too low for me (this is for Kyber-512):

+
keypair cycles
94613
encaps cycles
80242
decaps cycles
106573
$

We should except something over 1M cycles for encapsulation according to https://eprint.iacr.org/2020/049.pdf.

[mkannwischer]

Do you think adding emulation with qemu is going to be easy?
Maybe @rpls has that lying around and can add it?

[potsrevennil]

What is a little weird to me is that the flashing and the printing of the output are done over the same USB device? How do you run this in parallel?

I flashed it, and run the pyserial then, reset the board.
So this might cause some issues to integrate this into the python script

[potsrevennil]

I will also look into the clock configuration as well

[potsrevennil]

Adding emulation with qemu might need to write another linker script, but if you already had some working examples, then it shouldn't be too hard or complicated I expect.

[potsrevennil]

For CLOCK_BENCHMARK = 80MHZ (which is the max clock frequency for flash), will get

keypair cycles
4015868
encaps cycles
3736502
decaps cycles
4492722

and for CLOCK_FAST = 160 MHZ, will get

keypair cycles
5426636
encaps cycles
4846023
decaps cycles
6056913

should be some reasonable cycle counts for me

[potsrevennil]

stack api are updated, and the resulting stack size is as follow

keypair stack usage:
3600
encaps stack usage:
3648
decaps stack usage:
3616

[mkannwischer]

It's confusing that if I run tests --list-platforms it lists esp32-c3, but if I run tests func esp32-c3 it prints unsupported platform {platform}.
Let's not offer the option in the scripts until it's support.

[mkannwischer]

Thanks @potsrevennil! This is looking great!
I've tested that I can correctly build and flash the binaries.
Outputs for tests, speed, and stack are looking good.

There is also some gibberish in the beginning of the output (that is sent at 115200 baud; while the rest is at 38400) . You'll either have to switch to 115200 everywhere or need to change the baud rate at an earlier boot stage. Or somehow turn off that that is printed. Here is the output

ESP-ROM:esp32c3-api1-20210207
Build:Feb  7 2021
rst:0x1 (POWERON),boot:0xc (SPI_FAST_FLASH_BOOT)

Integration with the scripts is still needed (and looks rather annoying since flashing and output are going through the same serial device). Please open an issue for that.

[mkannwischer]

Thanks! This all looks good now! We can merge this once CI passes!

Thanks for all this work, @potsrevennil!

We could consider putting this into https://github.com/mupq/pqriscv as well in case @rpls thinks it is useful.