On Tue, Nov 29, 2022 at 10:06:39PM +0100, Jason A. Donenfeld wrote: > diff --git a/arch/x86/entry/vdso/vgetrandom-chacha.S b/arch/x86/entry/vdso/vgetrandom-chacha.S > new file mode 100644 > index 000000000000..91fbb7ac7af4 > --- /dev/null > +++ b/arch/x86/entry/vdso/vgetrandom-chacha.S > @@ -0,0 +1,177 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2022 Jason A. Donenfeld <Jason@xxxxxxxxx>. All Rights Reserved. > + */ > + > +#include <linux/linkage.h> > +#include <asm/frame.h> > + > +.section .rodata.cst16.CONSTANTS, "aM", @progbits, 16 > +.align 16 > +CONSTANTS: .octa 0x6b20657479622d323320646e61707865 > +.text > + > +/* > + * Very basic SSE2 implementation of ChaCha20. Produces a given positive number > + * of blocks of output with a nonce of 0, taking an input key and 8-byte > + * counter. Importantly does not spill to the stack. Its arguments are: > + * > + * rdi: output bytes > + * rsi: 32-byte key input > + * rdx: 8-byte counter input/output > + * rcx: number of 64-byte blocks to write to output > + */ > +SYM_FUNC_START(__arch_chacha20_blocks_nostack) How was this ChaCha20 implementation tested? It really ought to have some sort of test. Wouldn't this be a good candidate for a KUnit test? - Eric
