Re: [PATCH v2 4/6] crypto: x86/chacha20 - add XChaCha20 support

Hi Martin,

On Sat, Dec 01, 2018 at 05:40:40PM +0100, Martin Willi wrote:

quoted

An SSSE3 implementation of single-block HChaCha20 is also added so
that XChaCha20 can use it rather than the generic
implementation.  This required refactoring the ChaCha permutation
into its own function. 

quoted

[...]

quoted

+ENTRY(chacha20_block_xor_ssse3)
+	# %rdi: Input state matrix, s
+	# %rsi: up to 1 data block output, o
+	# %rdx: up to 1 data block input, i
+	# %rcx: input/output length in bytes
+
+	# x0..3 = s0..3
+	movdqa		0x00(%rdi),%xmm0
+	movdqa		0x10(%rdi),%xmm1
+	movdqa		0x20(%rdi),%xmm2
+	movdqa		0x30(%rdi),%xmm3
+	movdqa		%xmm0,%xmm8
+	movdqa		%xmm1,%xmm9
+	movdqa		%xmm2,%xmm10
+	movdqa		%xmm3,%xmm11
+
+	mov		%rcx,%rax
+	call		chacha20_permute
+
 	# o0 = i0 ^ (x0 + s0)
 	paddd		%xmm8,%xmm0
 	cmp		$0x10,%rax

@@ -189,6 +198,23 @@ ENTRY(chacha20_block_xor_ssse3)
 
 ENDPROC(chacha20_block_xor_ssse3)
 
+ENTRY(hchacha20_block_ssse3)
+	# %rdi: Input state matrix, s
+	# %rsi: output (8 32-bit words)
+
+	movdqa		0x00(%rdi),%xmm0
+	movdqa		0x10(%rdi),%xmm1
+	movdqa		0x20(%rdi),%xmm2
+	movdqa		0x30(%rdi),%xmm3
+
+	call		chacha20_permute

AFAIK, the general convention is to create proper stack frames using
FRAME_BEGIN/END for non leaf-functions. Should chacha20_permute()
callers do so?

Yes, I'll do that.  (Ard suggested similarly in the arm64 version too.)

- Eric