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Diffstat (limited to 'arch/arm/crypto/chacha-scalar-core.S')
-rw-r--r-- | arch/arm/crypto/chacha-scalar-core.S | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/arch/arm/crypto/chacha-scalar-core.S b/arch/arm/crypto/chacha-scalar-core.S new file mode 100644 index 0000000000..083fe1ab96 --- /dev/null +++ b/arch/arm/crypto/chacha-scalar-core.S @@ -0,0 +1,443 @@ +/* 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 + +.macro _le32_bswap_4x a, b, c, d, tmp +#ifdef __ARMEB__ + rev_l \a, \tmp + rev_l \b, \tmp + rev_l \c, \tmp + rev_l \d, \tmp +#endif +.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 + 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 + 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 + 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 + 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 + 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 + 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 + 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 + 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 chacha_doarm(u8 *dst, const u8 *src, unsigned int bytes, + * const u32 *state, int nrounds); + */ +ENTRY(chacha_doarm) + cmp r2, #0 // len == 0? + reteq lr + + ldr ip, [sp] + cmp ip, #12 + + push {r0-r2,r4-r11,lr} + + // Push state x0-x15 onto stack. + // Also store an extra copy of x10-x11 just before the state. + + add X12, r3, #48 + ldm X12, {X12,X13,X14,X15} + push {X12,X13,X14,X15} + sub sp, sp, #64 + + __ldrd X8_X10, X9_X11, r3, 40 + __strd X8_X10, X9_X11, sp, 8 + __strd X8_X10, X9_X11, sp, 56 + ldm r3, {X0-X9_X11} + __strd X0, X1, sp, 16 + __strd X2, X3, sp, 24 + __strd X4, X5, sp, 32 + __strd X6, X7, sp, 40 + __strd X8_X10, X9_X11, sp, 48 + + beq 1f + _chacha 20 + +0: add sp, #76 + pop {r4-r11, pc} + +1: _chacha 12 + b 0b +ENDPROC(chacha_doarm) + +/* + * void hchacha_block_arm(const u32 state[16], u32 out[8], int nrounds); + */ +ENTRY(hchacha_block_arm) + push {r1,r4-r11,lr} + + cmp r2, #12 // ChaCha12 ? + + 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 + + beq 1f + _chacha_permute 20 + + // Skip over (unused0-unused1, x10-x11) +0: 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} + +1: _chacha_permute 12 + b 0b +ENDPROC(hchacha_block_arm) |