461 lines
11 KiB
ArmAsm
Executable file
461 lines
11 KiB
ArmAsm
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2018 Google, Inc.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* Design notes:
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*
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* 16 registers would be needed to hold the state matrix, but only 14 are
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* available because 'sp' and 'pc' cannot be used. So we spill the elements
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* (x8, x9) to the stack and swap them out with (x10, x11). This adds one
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* 'ldrd' and one 'strd' instruction per round.
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*
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* All rotates are performed using the implicit rotate operand accepted by the
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* 'add' and 'eor' instructions. This is faster than using explicit rotate
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* instructions. To make this work, we allow the values in the second and last
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* rows of the ChaCha state matrix (rows 'b' and 'd') to temporarily have the
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* wrong rotation amount. The rotation amount is then fixed up just in time
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* when the values are used. 'brot' is the number of bits the values in row 'b'
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* need to be rotated right to arrive at the correct values, and 'drot'
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* similarly for row 'd'. (brot, drot) start out as (0, 0) but we make it such
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* that they end up as (25, 24) after every round.
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*/
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// ChaCha state registers
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X0 .req r0
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X1 .req r1
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X2 .req r2
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X3 .req r3
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X4 .req r4
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X5 .req r5
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X6 .req r6
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X7 .req r7
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X8_X10 .req r8 // shared by x8 and x10
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X9_X11 .req r9 // shared by x9 and x11
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X12 .req r10
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X13 .req r11
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X14 .req r12
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X15 .req r14
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.macro __rev out, in, t0, t1, t2
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.if __LINUX_ARM_ARCH__ >= 6
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rev \out, \in
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.else
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lsl \t0, \in, #24
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and \t1, \in, #0xff00
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and \t2, \in, #0xff0000
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orr \out, \t0, \in, lsr #24
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orr \out, \out, \t1, lsl #8
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orr \out, \out, \t2, lsr #8
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.endif
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.endm
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.macro _le32_bswap x, t0, t1, t2
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#ifdef __ARMEB__
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__rev \x, \x, \t0, \t1, \t2
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#endif
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.endm
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.macro _le32_bswap_4x a, b, c, d, t0, t1, t2
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_le32_bswap \a, \t0, \t1, \t2
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_le32_bswap \b, \t0, \t1, \t2
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_le32_bswap \c, \t0, \t1, \t2
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_le32_bswap \d, \t0, \t1, \t2
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.endm
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.macro __ldrd a, b, src, offset
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#if __LINUX_ARM_ARCH__ >= 6
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ldrd \a, \b, [\src, #\offset]
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#else
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ldr \a, [\src, #\offset]
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ldr \b, [\src, #\offset + 4]
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#endif
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.endm
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.macro __strd a, b, dst, offset
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#if __LINUX_ARM_ARCH__ >= 6
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strd \a, \b, [\dst, #\offset]
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#else
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str \a, [\dst, #\offset]
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str \b, [\dst, #\offset + 4]
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#endif
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.endm
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.macro _halfround a1, b1, c1, d1, a2, b2, c2, d2
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// a += b; d ^= a; d = rol(d, 16);
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add \a1, \a1, \b1, ror #brot
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add \a2, \a2, \b2, ror #brot
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eor \d1, \a1, \d1, ror #drot
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eor \d2, \a2, \d2, ror #drot
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// drot == 32 - 16 == 16
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// c += d; b ^= c; b = rol(b, 12);
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add \c1, \c1, \d1, ror #16
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add \c2, \c2, \d2, ror #16
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eor \b1, \c1, \b1, ror #brot
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eor \b2, \c2, \b2, ror #brot
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// brot == 32 - 12 == 20
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// a += b; d ^= a; d = rol(d, 8);
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add \a1, \a1, \b1, ror #20
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add \a2, \a2, \b2, ror #20
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eor \d1, \a1, \d1, ror #16
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eor \d2, \a2, \d2, ror #16
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// drot == 32 - 8 == 24
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// c += d; b ^= c; b = rol(b, 7);
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add \c1, \c1, \d1, ror #24
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add \c2, \c2, \d2, ror #24
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eor \b1, \c1, \b1, ror #20
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eor \b2, \c2, \b2, ror #20
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// brot == 32 - 7 == 25
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.endm
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.macro _doubleround
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// column round
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// quarterrounds: (x0, x4, x8, x12) and (x1, x5, x9, x13)
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_halfround X0, X4, X8_X10, X12, X1, X5, X9_X11, X13
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// save (x8, x9); restore (x10, x11)
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__strd X8_X10, X9_X11, sp, 0
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__ldrd X8_X10, X9_X11, sp, 8
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// quarterrounds: (x2, x6, x10, x14) and (x3, x7, x11, x15)
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_halfround X2, X6, X8_X10, X14, X3, X7, X9_X11, X15
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.set brot, 25
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.set drot, 24
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// diagonal round
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// quarterrounds: (x0, x5, x10, x15) and (x1, x6, x11, x12)
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_halfround X0, X5, X8_X10, X15, X1, X6, X9_X11, X12
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// save (x10, x11); restore (x8, x9)
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__strd X8_X10, X9_X11, sp, 8
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__ldrd X8_X10, X9_X11, sp, 0
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// quarterrounds: (x2, x7, x8, x13) and (x3, x4, x9, x14)
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_halfround X2, X7, X8_X10, X13, X3, X4, X9_X11, X14
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.endm
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.macro _chacha_permute nrounds
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.set brot, 0
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.set drot, 0
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.rept \nrounds / 2
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_doubleround
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.endr
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.endm
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.macro _chacha nrounds
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.Lnext_block\@:
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// Stack: unused0-unused1 x10-x11 x0-x15 OUT IN LEN
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// Registers contain x0-x9,x12-x15.
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// Do the core ChaCha permutation to update x0-x15.
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_chacha_permute \nrounds
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add sp, #8
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// Stack: x10-x11 orig_x0-orig_x15 OUT IN LEN
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// Registers contain x0-x9,x12-x15.
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// x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
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// Free up some registers (r8-r12,r14) by pushing (x8-x9,x12-x15).
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push {X8_X10, X9_X11, X12, X13, X14, X15}
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// Load (OUT, IN, LEN).
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ldr r14, [sp, #96]
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ldr r12, [sp, #100]
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ldr r11, [sp, #104]
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orr r10, r14, r12
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// Use slow path if fewer than 64 bytes remain.
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cmp r11, #64
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blt .Lxor_slowpath\@
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// Use slow path if IN and/or OUT isn't 4-byte aligned. Needed even on
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// ARMv6+, since ldmia and stmia (used below) still require alignment.
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tst r10, #3
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bne .Lxor_slowpath\@
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// Fast path: XOR 64 bytes of aligned data.
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// Stack: x8-x9 x12-x15 x10-x11 orig_x0-orig_x15 OUT IN LEN
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// Registers: r0-r7 are x0-x7; r8-r11 are free; r12 is IN; r14 is OUT.
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// x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
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// x0-x3
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__ldrd r8, r9, sp, 32
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__ldrd r10, r11, sp, 40
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add X0, X0, r8
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add X1, X1, r9
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add X2, X2, r10
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add X3, X3, r11
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_le32_bswap_4x X0, X1, X2, X3, r8, r9, r10
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ldmia r12!, {r8-r11}
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eor X0, X0, r8
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eor X1, X1, r9
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eor X2, X2, r10
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eor X3, X3, r11
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stmia r14!, {X0-X3}
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// x4-x7
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__ldrd r8, r9, sp, 48
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__ldrd r10, r11, sp, 56
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add X4, r8, X4, ror #brot
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add X5, r9, X5, ror #brot
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ldmia r12!, {X0-X3}
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add X6, r10, X6, ror #brot
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add X7, r11, X7, ror #brot
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_le32_bswap_4x X4, X5, X6, X7, r8, r9, r10
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eor X4, X4, X0
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eor X5, X5, X1
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eor X6, X6, X2
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eor X7, X7, X3
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stmia r14!, {X4-X7}
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// x8-x15
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pop {r0-r7} // (x8-x9,x12-x15,x10-x11)
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__ldrd r8, r9, sp, 32
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__ldrd r10, r11, sp, 40
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add r0, r0, r8 // x8
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add r1, r1, r9 // x9
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add r6, r6, r10 // x10
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add r7, r7, r11 // x11
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_le32_bswap_4x r0, r1, r6, r7, r8, r9, r10
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ldmia r12!, {r8-r11}
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eor r0, r0, r8 // x8
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eor r1, r1, r9 // x9
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eor r6, r6, r10 // x10
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eor r7, r7, r11 // x11
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stmia r14!, {r0,r1,r6,r7}
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ldmia r12!, {r0,r1,r6,r7}
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__ldrd r8, r9, sp, 48
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__ldrd r10, r11, sp, 56
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add r2, r8, r2, ror #drot // x12
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add r3, r9, r3, ror #drot // x13
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add r4, r10, r4, ror #drot // x14
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add r5, r11, r5, ror #drot // x15
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_le32_bswap_4x r2, r3, r4, r5, r9, r10, r11
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ldr r9, [sp, #72] // load LEN
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eor r2, r2, r0 // x12
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eor r3, r3, r1 // x13
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eor r4, r4, r6 // x14
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eor r5, r5, r7 // x15
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subs r9, #64 // decrement and check LEN
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stmia r14!, {r2-r5}
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beq .Ldone\@
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.Lprepare_for_next_block\@:
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// Stack: x0-x15 OUT IN LEN
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// Increment block counter (x12)
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add r8, #1
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// Store updated (OUT, IN, LEN)
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str r14, [sp, #64]
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str r12, [sp, #68]
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str r9, [sp, #72]
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mov r14, sp
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// Store updated block counter (x12)
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str r8, [sp, #48]
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sub sp, #16
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// Reload state and do next block
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ldmia r14!, {r0-r11} // load x0-x11
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__strd r10, r11, sp, 8 // store x10-x11 before state
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ldmia r14, {r10-r12,r14} // load x12-x15
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b .Lnext_block\@
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.Lxor_slowpath\@:
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// Slow path: < 64 bytes remaining, or unaligned input or output buffer.
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// We handle it by storing the 64 bytes of keystream to the stack, then
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// XOR-ing the needed portion with the data.
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// Allocate keystream buffer
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sub sp, #64
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mov r14, sp
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// Stack: ks0-ks15 x8-x9 x12-x15 x10-x11 orig_x0-orig_x15 OUT IN LEN
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// Registers: r0-r7 are x0-x7; r8-r11 are free; r12 is IN; r14 is &ks0.
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// x4-x7 are rotated by 'brot'; x12-x15 are rotated by 'drot'.
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// Save keystream for x0-x3
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__ldrd r8, r9, sp, 96
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__ldrd r10, r11, sp, 104
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add X0, X0, r8
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add X1, X1, r9
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add X2, X2, r10
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add X3, X3, r11
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_le32_bswap_4x X0, X1, X2, X3, r8, r9, r10
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stmia r14!, {X0-X3}
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// Save keystream for x4-x7
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__ldrd r8, r9, sp, 112
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__ldrd r10, r11, sp, 120
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add X4, r8, X4, ror #brot
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add X5, r9, X5, ror #brot
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add X6, r10, X6, ror #brot
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add X7, r11, X7, ror #brot
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_le32_bswap_4x X4, X5, X6, X7, r8, r9, r10
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add r8, sp, #64
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stmia r14!, {X4-X7}
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// Save keystream for x8-x15
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ldm r8, {r0-r7} // (x8-x9,x12-x15,x10-x11)
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__ldrd r8, r9, sp, 128
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__ldrd r10, r11, sp, 136
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add r0, r0, r8 // x8
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add r1, r1, r9 // x9
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add r6, r6, r10 // x10
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add r7, r7, r11 // x11
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_le32_bswap_4x r0, r1, r6, r7, r8, r9, r10
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stmia r14!, {r0,r1,r6,r7}
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__ldrd r8, r9, sp, 144
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__ldrd r10, r11, sp, 152
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add r2, r8, r2, ror #drot // x12
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add r3, r9, r3, ror #drot // x13
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add r4, r10, r4, ror #drot // x14
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add r5, r11, r5, ror #drot // x15
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_le32_bswap_4x r2, r3, r4, r5, r9, r10, r11
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stmia r14, {r2-r5}
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// Stack: ks0-ks15 unused0-unused7 x0-x15 OUT IN LEN
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// Registers: r8 is block counter, r12 is IN.
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ldr r9, [sp, #168] // LEN
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ldr r14, [sp, #160] // OUT
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cmp r9, #64
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mov r0, sp
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movle r1, r9
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movgt r1, #64
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// r1 is number of bytes to XOR, in range [1, 64]
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.if __LINUX_ARM_ARCH__ < 6
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orr r2, r12, r14
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tst r2, #3 // IN or OUT misaligned?
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bne .Lxor_next_byte\@
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.endif
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// XOR a word at a time
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.rept 16
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subs r1, #4
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blt .Lxor_words_done\@
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ldr r2, [r12], #4
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ldr r3, [r0], #4
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eor r2, r2, r3
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str r2, [r14], #4
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.endr
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b .Lxor_slowpath_done\@
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.Lxor_words_done\@:
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ands r1, r1, #3
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beq .Lxor_slowpath_done\@
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// XOR a byte at a time
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.Lxor_next_byte\@:
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ldrb r2, [r12], #1
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ldrb r3, [r0], #1
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eor r2, r2, r3
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strb r2, [r14], #1
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subs r1, #1
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bne .Lxor_next_byte\@
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.Lxor_slowpath_done\@:
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subs r9, #64
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add sp, #96
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bgt .Lprepare_for_next_block\@
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.Ldone\@:
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.endm // _chacha
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/*
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* void chacha_doarm(u8 *dst, const u8 *src, unsigned int bytes,
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* const u32 *state, int nrounds);
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*/
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ENTRY(chacha_doarm)
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cmp r2, #0 // len == 0?
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reteq lr
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ldr ip, [sp]
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cmp ip, #12
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push {r0-r2,r4-r11,lr}
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// Push state x0-x15 onto stack.
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// Also store an extra copy of x10-x11 just before the state.
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add X12, r3, #48
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ldm X12, {X12,X13,X14,X15}
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push {X12,X13,X14,X15}
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sub sp, sp, #64
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__ldrd X8_X10, X9_X11, r3, 40
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__strd X8_X10, X9_X11, sp, 8
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__strd X8_X10, X9_X11, sp, 56
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ldm r3, {X0-X9_X11}
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__strd X0, X1, sp, 16
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__strd X2, X3, sp, 24
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__strd X4, X5, sp, 32
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__strd X6, X7, sp, 40
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__strd X8_X10, X9_X11, sp, 48
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beq 1f
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_chacha 20
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0: add sp, #76
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pop {r4-r11, pc}
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1: _chacha 12
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b 0b
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ENDPROC(chacha_doarm)
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/*
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* void hchacha_block_arm(const u32 state[16], u32 out[8], int nrounds);
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*/
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ENTRY(hchacha_block_arm)
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push {r1,r4-r11,lr}
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cmp r2, #12 // ChaCha12 ?
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mov r14, r0
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ldmia r14!, {r0-r11} // load x0-x11
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push {r10-r11} // store x10-x11 to stack
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ldm r14, {r10-r12,r14} // load x12-x15
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sub sp, #8
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beq 1f
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_chacha_permute 20
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// Skip over (unused0-unused1, x10-x11)
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0: add sp, #16
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// Fix up rotations of x12-x15
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ror X12, X12, #drot
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ror X13, X13, #drot
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pop {r4} // load 'out'
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ror X14, X14, #drot
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ror X15, X15, #drot
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// Store (x0-x3,x12-x15) to 'out'
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stm r4, {X0,X1,X2,X3,X12,X13,X14,X15}
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pop {r4-r11,pc}
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1: _chacha_permute 12
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b 0b
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ENDPROC(hchacha_block_arm)
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