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Date: Sat, 23 Mar 2019 00:17:36 +0100
From: Stefan Agner <stefan@...er.ch>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, Andy Polyakov <appro@...nssl.org>, Eric Biggers
<ebiggers@...gle.com>, Russell King <linux@...linux.org.uk>,
linux-arm-kernel@...ts.infradead.org, Samuel Neves <sneves@....uc.pt>,
Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>, Andy Lutomirski
<luto@...nel.org>, Greg KH <gregkh@...uxfoundation.org>, Andrew Morton
<akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>,
kernel-hardening@...ts.openwall.com, linux-kernel-owner@...r.kernel.org
Subject: Re: [PATCH net-next v9 05/19] zinc: ChaCha20 ARM and ARM64
implementations
Hi Jason,
I gave this a try with some prelineary patches to enable the integrated
assembler for ARM32, and caught a small issue:
On 22.03.2019 08:11, Jason A. Donenfeld wrote:
> These ARM implementations come from Andy Polyakov's implementation, as
> well as an ultra-fast unrolled scalar version optimized for ARMv7 from
> Eric Biggers, which performs well on platforms with slow NEON like
> Cortex A7 and A5.
>
> This commit delivers approximately the same or much better performance than
> the existing crypto API's code and has been measured to do as such on:
>
> - ARM1176JZF-S [ARMv6]
> - Cortex-A7 [ARMv7]
> - Cortex-A8 [ARMv7]
> - Cortex-A9 [ARMv7]
> - Cortex-A17 [ARMv7]
> - Cortex-A53 [ARMv8]
> - Cortex-A55 [ARMv8]
> - Cortex-A73 [ARMv8]
> - Cortex-A75 [ARMv8]
>
> Interestingly, Andy Polyakov's scalar code is slower than Eric Biggers',
> but is also significantly shorter. This has the advantage that it does
> not evict other code from L1 cache -- particularly on ARM11 chips -- and
> so in certain circumstances it can actually be faster. However, it wasn't
> found that this had an affect on any code existing in the kernel today.
>
> While this is CRYPTOGAMS code, the originating code for this happens to
> be the same as OpenSSL's commit 9925a82146f2503b4dd11423d0eba649b43450c0
>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
> Co-authored-by: Andy Polyakov <appro@...nssl.org>
> Co-authored-by: Eric Biggers <ebiggers@...gle.com>
> Cc: Andy Polyakov <appro@...nssl.org>
> Cc: Russell King <linux@...linux.org.uk>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: Samuel Neves <sneves@....uc.pt>
> Cc: Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>
> Cc: Andy Lutomirski <luto@...nel.org>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: kernel-hardening@...ts.openwall.com
> Cc: linux-crypto@...r.kernel.org
> ---
> lib/zinc/Makefile | 4 +-
> lib/zinc/chacha20/chacha20-arm-glue.c | 98 ++
> lib/zinc/chacha20/chacha20-arm.pl | 1227 +++++++++++++++++++++
> lib/zinc/chacha20/chacha20-arm64.pl | 1163 +++++++++++++++++++
> lib/zinc/chacha20/chacha20-unrolled-arm.S | 461 ++++++++
> lib/zinc/chacha20/chacha20.c | 2 +
> 6 files changed, 2954 insertions(+), 1 deletion(-)
> create mode 100644 lib/zinc/chacha20/chacha20-arm-glue.c
> create mode 100644 lib/zinc/chacha20/chacha20-arm.pl
> create mode 100644 lib/zinc/chacha20/chacha20-arm64.pl
> create mode 100644 lib/zinc/chacha20/chacha20-unrolled-arm.S
>
<snip>
> diff --git a/lib/zinc/chacha20/chacha20-unrolled-arm.S
> b/lib/zinc/chacha20/chacha20-unrolled-arm.S
> new file mode 100644
> index 000000000000..2140319b64a0
> --- /dev/null
> +++ b/lib/zinc/chacha20/chacha20-unrolled-arm.S
> @@ -0,0 +1,461 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2018 Google, Inc.
> + */
> +
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +
> +/*
> + * Design notes:
> + *
> + * 16 registers would be needed to hold the state matrix, but only 14 are
> + * available because 'sp' and 'pc' cannot be used. So we spill the elements
> + * (x8, x9) to the stack and swap them out with (x10, x11). This adds one
> + * 'ldrd' and one 'strd' instruction per round.
> + *
> + * All rotates are performed using the implicit rotate operand accepted by the
> + * 'add' and 'eor' instructions. This is faster than using explicit rotate
> + * instructions. To make this work, we allow the values in the second and last
> + * rows of the ChaCha state matrix (rows 'b' and 'd') to temporarily have the
> + * wrong rotation amount. The rotation amount is then fixed up just in time
> + * when the values are used. 'brot' is the number of bits the values
> in row 'b'
> + * need to be rotated right to arrive at the correct values, and 'drot'
> + * similarly for row 'd'. (brot, drot) start out as (0, 0) but we make it such
> + * that they end up as (25, 24) after every round.
> + */
> +
> + // ChaCha state registers
> + X0 .req r0
> + X1 .req r1
> + X2 .req r2
> + X3 .req r3
> + X4 .req r4
> + X5 .req r5
> + X6 .req r6
> + X7 .req r7
> + X8_X10 .req r8 // shared by x8 and x10
> + X9_X11 .req r9 // shared by x9 and x11
> + X12 .req r10
> + X13 .req r11
> + X14 .req r12
> + X15 .req r14
> +
> +.Lexpand_32byte_k:
> + // "expand 32-byte k"
> + .word 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
> +
> +#ifdef __thumb2__
> +# define adrl adr
> +#endif
It seems that Clang does not like adrl.
lib/zinc/chacha20/chacha20-unrolled-arm.S:415:2: error: invalid
instruction, did you mean: adr?
adrl X3, .Lexpand_32byte_k
^
make[3]: *** [scripts/Makefile.build:369:
lib/zinc/chacha20/chacha20-unrolled-arm.o] Error 1
make[2]: *** [scripts/Makefile.build:489: lib/zinc] Error 2
make[1]: *** [/home/sag/projects/linux/Makefile:1045: lib] Error 2
make[1]: *** Waiting for unfinished jobs....
We probably should use
#if defined(__thumb2__) || defined(__clang__)
here?
All other ARM32 assembly assembled fine with the integrated assembler!
Also nothing really concerning as there are still plenty of other issues
with using the integrated assembler to build ARM32 Linux.
--
Stefan
> +
> +.macro __rev out, in, t0, t1, t2
> +.if __LINUX_ARM_ARCH__ >= 6
> + rev \out, \in
> +.else
> + lsl \t0, \in, #24
> + and \t1, \in, #0xff00
> + and \t2, \in, #0xff0000
> + orr \out, \t0, \in, lsr #24
> + orr \out, \out, \t1, lsl #8
> + orr \out, \out, \t2, lsr #8
> +.endif
> +.endm
> +
> +.macro _le32_bswap x, t0, t1, t2
> +#ifdef __ARMEB__
> + __rev \x, \x, \t0, \t1, \t2
> +#endif
> +.endm
> +
> +.macro _le32_bswap_4x a, b, c, d, t0, t1, t2
> + _le32_bswap \a, \t0, \t1, \t2
> + _le32_bswap \b, \t0, \t1, \t2
> + _le32_bswap \c, \t0, \t1, \t2
> + _le32_bswap \d, \t0, \t1, \t2
> +.endm
> +
> +.macro __ldrd a, b, src, offset
> +#if __LINUX_ARM_ARCH__ >= 6
> + ldrd \a, \b, [\src, #\offset]
> +#else
> + ldr \a, [\src, #\offset]
> + ldr \b, [\src, #\offset + 4]
> +#endif
> +.endm
> +
> +.macro __strd a, b, dst, offset
> +#if __LINUX_ARM_ARCH__ >= 6
> + strd \a, \b, [\dst, #\offset]
> +#else
> + str \a, [\dst, #\offset]
> + str \b, [\dst, #\offset + 4]
> +#endif
> +.endm
> +
> +.macro _halfround a1, b1, c1, d1, a2, b2, c2, d2
> +
> + // a += b; d ^= a; d = rol(d, 16);
> + add \a1, \a1, \b1, ror #brot
> + add \a2, \a2, \b2, ror #brot
> + eor \d1, \a1, \d1, ror #drot
> + eor \d2, \a2, \d2, ror #drot
> + // drot == 32 - 16 == 16
> +
> + // c += d; b ^= c; b = rol(b, 12);
> + add \c1, \c1, \d1, ror #16
> + add \c2, \c2, \d2, ror #16
> + eor \b1, \c1, \b1, ror #brot
> + eor \b2, \c2, \b2, ror #brot
> + // brot == 32 - 12 == 20
> +
> + // a += b; d ^= a; d = rol(d, 8);
> + add \a1, \a1, \b1, ror #20
> + add \a2, \a2, \b2, ror #20
> + eor \d1, \a1, \d1, ror #16
> + eor \d2, \a2, \d2, ror #16
> + // drot == 32 - 8 == 24
> +
> + // c += d; b ^= c; b = rol(b, 7);
> + add \c1, \c1, \d1, ror #24
> + add \c2, \c2, \d2, ror #24
> + eor \b1, \c1, \b1, ror #20
> + eor \b2, \c2, \b2, ror #20
> + // brot == 32 - 7 == 25
> +.endm
> +
> +.macro _doubleround
> +
> + // column round
> +
> + // quarterrounds: (x0, x4, x8, x12) and (x1, x5, x9, x13)
> + _halfround X0, X4, X8_X10, X12, X1, X5, X9_X11, X13
> +
> + // save (x8, x9); restore (x10, x11)
> + __strd X8_X10, X9_X11, sp, 0
> + __ldrd X8_X10, X9_X11, sp, 8
> +
> + // quarterrounds: (x2, x6, x10, x14) and (x3, x7, x11, x15)
> + _halfround X2, X6, X8_X10, X14, X3, X7, X9_X11, X15
> +
> + .set brot, 25
> + .set drot, 24
> +
> + // diagonal round
> +
> + // quarterrounds: (x0, x5, x10, x15) and (x1, x6, x11, x12)
> + _halfround X0, X5, X8_X10, X15, X1, X6, X9_X11, X12
> +
> + // save (x10, x11); restore (x8, x9)
> + __strd X8_X10, X9_X11, sp, 8
> + __ldrd X8_X10, X9_X11, sp, 0
> +
> + // quarterrounds: (x2, x7, x8, x13) and (x3, x4, x9, x14)
> + _halfround X2, X7, X8_X10, X13, X3, X4, X9_X11, X14
> +.endm
> +
> +.macro _chacha_permute nrounds
> + .set brot, 0
> + .set drot, 0
> + .rept \nrounds / 2
> + _doubleround
> + .endr
> +.endm
> +
> +.macro _chacha nrounds
> +
> +.Lnext_block\@:
> + // Stack: unused0-unused1 x10-x11 x0-x15 OUT IN LEN
> + // Registers contain x0-x9,x12-x15.
> +
> + // Do the core ChaCha permutation to update x0-x15.
> + _chacha_permute \nrounds
> +
> + add sp, #8
> + // Stack: x10-x11 orig_x0-orig_x15 OUT IN LEN
> + // Registers contain x0-x9,x12-x15.
> + // x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
> +
> + // Free up some registers (r8-r12,r14) by pushing (x8-x9,x12-x15).
> + push {X8_X10, X9_X11, X12, X13, X14, X15}
> +
> + // Load (OUT, IN, LEN).
> + ldr r14, [sp, #96]
> + ldr r12, [sp, #100]
> + ldr r11, [sp, #104]
> +
> + orr r10, r14, r12
> +
> + // Use slow path if fewer than 64 bytes remain.
> + cmp r11, #64
> + blt .Lxor_slowpath\@
> +
> + // Use slow path if IN and/or OUT isn't 4-byte aligned. Needed even on
> + // ARMv6+, since ldmia and stmia (used below) still require alignment.
> + tst r10, #3
> + bne .Lxor_slowpath\@
> +
> + // Fast path: XOR 64 bytes of aligned data.
> +
> + // Stack: x8-x9 x12-x15 x10-x11 orig_x0-orig_x15 OUT IN LEN
> + // Registers: r0-r7 are x0-x7; r8-r11 are free; r12 is IN; r14 is OUT.
> + // x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
> +
> + // x0-x3
> + __ldrd r8, r9, sp, 32
> + __ldrd r10, r11, sp, 40
> + add X0, X0, r8
> + add X1, X1, r9
> + add X2, X2, r10
> + add X3, X3, r11
> + _le32_bswap_4x X0, X1, X2, X3, r8, r9, r10
> + ldmia r12!, {r8-r11}
> + eor X0, X0, r8
> + eor X1, X1, r9
> + eor X2, X2, r10
> + eor X3, X3, r11
> + stmia r14!, {X0-X3}
> +
> + // x4-x7
> + __ldrd r8, r9, sp, 48
> + __ldrd r10, r11, sp, 56
> + add X4, r8, X4, ror #brot
> + add X5, r9, X5, ror #brot
> + ldmia r12!, {X0-X3}
> + add X6, r10, X6, ror #brot
> + add X7, r11, X7, ror #brot
> + _le32_bswap_4x X4, X5, X6, X7, r8, r9, r10
> + eor X4, X4, X0
> + eor X5, X5, X1
> + eor X6, X6, X2
> + eor X7, X7, X3
> + stmia r14!, {X4-X7}
> +
> + // x8-x15
> + pop {r0-r7} // (x8-x9,x12-x15,x10-x11)
> + __ldrd r8, r9, sp, 32
> + __ldrd r10, r11, sp, 40
> + add r0, r0, r8 // x8
> + add r1, r1, r9 // x9
> + add r6, r6, r10 // x10
> + add r7, r7, r11 // x11
> + _le32_bswap_4x r0, r1, r6, r7, r8, r9, r10
> + ldmia r12!, {r8-r11}
> + eor r0, r0, r8 // x8
> + eor r1, r1, r9 // x9
> + eor r6, r6, r10 // x10
> + eor r7, r7, r11 // x11
> + stmia r14!, {r0,r1,r6,r7}
> + ldmia r12!, {r0,r1,r6,r7}
> + __ldrd r8, r9, sp, 48
> + __ldrd r10, r11, sp, 56
> + add r2, r8, r2, ror #drot // x12
> + add r3, r9, r3, ror #drot // x13
> + add r4, r10, r4, ror #drot // x14
> + add r5, r11, r5, ror #drot // x15
> + _le32_bswap_4x r2, r3, r4, r5, r9, r10, r11
> + ldr r9, [sp, #72] // load LEN
> + eor r2, r2, r0 // x12
> + eor r3, r3, r1 // x13
> + eor r4, r4, r6 // x14
> + eor r5, r5, r7 // x15
> + subs r9, #64 // decrement and check LEN
> + stmia r14!, {r2-r5}
> +
> + beq .Ldone\@
> +
> +.Lprepare_for_next_block\@:
> +
> + // Stack: x0-x15 OUT IN LEN
> +
> + // Increment block counter (x12)
> + add r8, #1
> +
> + // Store updated (OUT, IN, LEN)
> + str r14, [sp, #64]
> + str r12, [sp, #68]
> + str r9, [sp, #72]
> +
> + mov r14, sp
> +
> + // Store updated block counter (x12)
> + str r8, [sp, #48]
> +
> + sub sp, #16
> +
> + // Reload state and do next block
> + ldmia r14!, {r0-r11} // load x0-x11
> + __strd r10, r11, sp, 8 // store x10-x11 before state
> + ldmia r14, {r10-r12,r14} // load x12-x15
> + b .Lnext_block\@
> +
> +.Lxor_slowpath\@:
> + // Slow path: < 64 bytes remaining, or unaligned input or output buffer.
> + // We handle it by storing the 64 bytes of keystream to the stack, then
> + // XOR-ing the needed portion with the data.
> +
> + // Allocate keystream buffer
> + sub sp, #64
> + mov r14, sp
> +
> + // Stack: ks0-ks15 x8-x9 x12-x15 x10-x11 orig_x0-orig_x15 OUT IN LEN
> + // Registers: r0-r7 are x0-x7; r8-r11 are free; r12 is IN; r14 is &ks0.
> + // x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
> +
> + // Save keystream for x0-x3
> + __ldrd r8, r9, sp, 96
> + __ldrd r10, r11, sp, 104
> + add X0, X0, r8
> + add X1, X1, r9
> + add X2, X2, r10
> + add X3, X3, r11
> + _le32_bswap_4x X0, X1, X2, X3, r8, r9, r10
> + stmia r14!, {X0-X3}
> +
> + // Save keystream for x4-x7
> + __ldrd r8, r9, sp, 112
> + __ldrd r10, r11, sp, 120
> + add X4, r8, X4, ror #brot
> + add X5, r9, X5, ror #brot
> + add X6, r10, X6, ror #brot
> + add X7, r11, X7, ror #brot
> + _le32_bswap_4x X4, X5, X6, X7, r8, r9, r10
> + add r8, sp, #64
> + stmia r14!, {X4-X7}
> +
> + // Save keystream for x8-x15
> + ldm r8, {r0-r7} // (x8-x9,x12-x15,x10-x11)
> + __ldrd r8, r9, sp, 128
> + __ldrd r10, r11, sp, 136
> + add r0, r0, r8 // x8
> + add r1, r1, r9 // x9
> + add r6, r6, r10 // x10
> + add r7, r7, r11 // x11
> + _le32_bswap_4x r0, r1, r6, r7, r8, r9, r10
> + stmia r14!, {r0,r1,r6,r7}
> + __ldrd r8, r9, sp, 144
> + __ldrd r10, r11, sp, 152
> + add r2, r8, r2, ror #drot // x12
> + add r3, r9, r3, ror #drot // x13
> + add r4, r10, r4, ror #drot // x14
> + add r5, r11, r5, ror #drot // x15
> + _le32_bswap_4x r2, r3, r4, r5, r9, r10, r11
> + stmia r14, {r2-r5}
> +
> + // Stack: ks0-ks15 unused0-unused7 x0-x15 OUT IN LEN
> + // Registers: r8 is block counter, r12 is IN.
> +
> + ldr r9, [sp, #168] // LEN
> + ldr r14, [sp, #160] // OUT
> + cmp r9, #64
> + mov r0, sp
> + movle r1, r9
> + movgt r1, #64
> + // r1 is number of bytes to XOR, in range [1, 64]
> +
> +.if __LINUX_ARM_ARCH__ < 6
> + orr r2, r12, r14
> + tst r2, #3 // IN or OUT misaligned?
> + bne .Lxor_next_byte\@
> +.endif
> +
> + // XOR a word at a time
> +.rept 16
> + subs r1, #4
> + blt .Lxor_words_done\@
> + ldr r2, [r12], #4
> + ldr r3, [r0], #4
> + eor r2, r2, r3
> + str r2, [r14], #4
> +.endr
> + b .Lxor_slowpath_done\@
> +.Lxor_words_done\@:
> + ands r1, r1, #3
> + beq .Lxor_slowpath_done\@
> +
> + // XOR a byte at a time
> +.Lxor_next_byte\@:
> + ldrb r2, [r12], #1
> + ldrb r3, [r0], #1
> + eor r2, r2, r3
> + strb r2, [r14], #1
> + subs r1, #1
> + bne .Lxor_next_byte\@
> +
> +.Lxor_slowpath_done\@:
> + subs r9, #64
> + add sp, #96
> + bgt .Lprepare_for_next_block\@
> +
> +.Ldone\@:
> +.endm // _chacha
> +
> +/*
> + * void chacha20_arm(u8 *out, const u8 *in, size_t len, const u32 key[8],
> + * const u32 iv[4]);
> + */
> +ENTRY(chacha20_arm)
> + cmp r2, #0 // len == 0?
> + reteq lr
> +
> + push {r0-r2,r4-r11,lr}
> +
> + // Push state x0-x15 onto stack.
> + // Also store an extra copy of x10-x11 just before the state.
> +
> + ldr r4, [sp, #48] // iv
> + mov r0, sp
> + sub sp, #80
> +
> + // iv: x12-x15
> + ldm r4, {X12,X13,X14,X15}
> + stmdb r0!, {X12,X13,X14,X15}
> +
> + // key: x4-x11
> + __ldrd X8_X10, X9_X11, r3, 24
> + __strd X8_X10, X9_X11, sp, 8
> + stmdb r0!, {X8_X10, X9_X11}
> + ldm r3, {X4-X9_X11}
> + stmdb r0!, {X4-X9_X11}
> +
> + // constants: x0-x3
> + adrl X3, .Lexpand_32byte_k
> + ldm X3, {X0-X3}
> + __strd X0, X1, sp, 16
> + __strd X2, X3, sp, 24
> +
> + _chacha 20
> +
> + add sp, #76
> + pop {r4-r11, pc}
> +ENDPROC(chacha20_arm)
> +
> +/*
> + * void hchacha20_arm(const u32 state[16], u32 out[8]);
> + */
> +ENTRY(hchacha20_arm)
> + push {r1,r4-r11,lr}
> +
> + mov r14, r0
> + ldmia r14!, {r0-r11} // load x0-x11
> + push {r10-r11} // store x10-x11 to stack
> + ldm r14, {r10-r12,r14} // load x12-x15
> + sub sp, #8
> +
> + _chacha_permute 20
> +
> + // Skip over (unused0-unused1, x10-x11)
> + add sp, #16
> +
> + // Fix up rotations of x12-x15
> + ror X12, X12, #drot
> + ror X13, X13, #drot
> + pop {r4} // load 'out'
> + ror X14, X14, #drot
> + ror X15, X15, #drot
> +
> + // Store (x0-x3,x12-x15) to 'out'
> + stm r4, {X0,X1,X2,X3,X12,X13,X14,X15}
> +
> + pop {r4-r11,pc}
> +ENDPROC(hchacha20_arm)
> diff --git a/lib/zinc/chacha20/chacha20.c b/lib/zinc/chacha20/chacha20.c
> index b47aefd65e80..d4e6316eb5a3 100644
> --- a/lib/zinc/chacha20/chacha20.c
> +++ b/lib/zinc/chacha20/chacha20.c
> @@ -18,6 +18,8 @@
>
> #if defined(CONFIG_ZINC_ARCH_X86_64)
> #include "chacha20-x86_64-glue.c"
> +#elif defined(CONFIG_ZINC_ARCH_ARM) || defined(CONFIG_ZINC_ARCH_ARM64)
> +#include "chacha20-arm-glue.c"
> #else
> static bool *const chacha20_nobs[] __initconst = { };
> static void __init chacha20_fpu_init(void)
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