--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/*
+ * Copyright (C) 2016-2018 René van Dorst <opensource@vdorst.com>. All Rights Reserved.
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#define MASK_U32 0x3c
+#define CHACHA20_BLOCK_SIZE 64
+#define STACK_SIZE 32
+
+#define X0 $t0
+#define X1 $t1
+#define X2 $t2
+#define X3 $t3
+#define X4 $t4
+#define X5 $t5
+#define X6 $t6
+#define X7 $t7
+#define X8 $t8
+#define X9 $t9
+#define X10 $v1
+#define X11 $s6
+#define X12 $s5
+#define X13 $s4
+#define X14 $s3
+#define X15 $s2
+/* Use regs which are overwritten on exit for Tx so we don't leak clear data. */
+#define T0 $s1
+#define T1 $s0
+#define T(n) T ## n
+#define X(n) X ## n
+
+/* Input arguments */
+#define STATE $a0
+#define OUT $a1
+#define IN $a2
+#define BYTES $a3
+
+/* Output argument */
+/* NONCE[0] is kept in a register and not in memory.
+ * We don't want to touch original value in memory.
+ * Must be incremented every loop iteration.
+ */
+#define NONCE_0 $v0
+
+/* SAVED_X and SAVED_CA are set in the jump table.
+ * Use regs which are overwritten on exit else we don't leak clear data.
+ * They are used to handling the last bytes which are not multiple of 4.
+ */
+#define SAVED_X X15
+#define SAVED_CA $s7
+
+#define IS_UNALIGNED $s7
+
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define MSB 0
+#define LSB 3
+#define ROTx rotl
+#define ROTR(n) rotr n, 24
+#define CPU_TO_LE32(n) \
+ wsbh n; \
+ rotr n, 16;
+#else
+#define MSB 3
+#define LSB 0
+#define ROTx rotr
+#define CPU_TO_LE32(n)
+#define ROTR(n)
+#endif
+
+#define FOR_EACH_WORD(x) \
+ x( 0); \
+ x( 1); \
+ x( 2); \
+ x( 3); \
+ x( 4); \
+ x( 5); \
+ x( 6); \
+ x( 7); \
+ x( 8); \
+ x( 9); \
+ x(10); \
+ x(11); \
+ x(12); \
+ x(13); \
+ x(14); \
+ x(15);
+
+#define FOR_EACH_WORD_REV(x) \
+ x(15); \
+ x(14); \
+ x(13); \
+ x(12); \
+ x(11); \
+ x(10); \
+ x( 9); \
+ x( 8); \
+ x( 7); \
+ x( 6); \
+ x( 5); \
+ x( 4); \
+ x( 3); \
+ x( 2); \
+ x( 1); \
+ x( 0);
+
+#define PLUS_ONE_0 1
+#define PLUS_ONE_1 2
+#define PLUS_ONE_2 3
+#define PLUS_ONE_3 4
+#define PLUS_ONE_4 5
+#define PLUS_ONE_5 6
+#define PLUS_ONE_6 7
+#define PLUS_ONE_7 8
+#define PLUS_ONE_8 9
+#define PLUS_ONE_9 10
+#define PLUS_ONE_10 11
+#define PLUS_ONE_11 12
+#define PLUS_ONE_12 13
+#define PLUS_ONE_13 14
+#define PLUS_ONE_14 15
+#define PLUS_ONE_15 16
+#define PLUS_ONE(x) PLUS_ONE_ ## x
+#define _CONCAT3(a,b,c) a ## b ## c
+#define CONCAT3(a,b,c) _CONCAT3(a,b,c)
+
+#define STORE_UNALIGNED(x) \
+CONCAT3(.Lchacha20_mips_xor_unaligned_, PLUS_ONE(x), _b: ;) \
+ .if (x != 12); \
+ lw T0, (x*4)(STATE); \
+ .endif; \
+ lwl T1, (x*4)+MSB ## (IN); \
+ lwr T1, (x*4)+LSB ## (IN); \
+ .if (x == 12); \
+ addu X ## x, NONCE_0; \
+ .else; \
+ addu X ## x, T0; \
+ .endif; \
+ CPU_TO_LE32(X ## x); \
+ xor X ## x, T1; \
+ swl X ## x, (x*4)+MSB ## (OUT); \
+ swr X ## x, (x*4)+LSB ## (OUT);
+
+#define STORE_ALIGNED(x) \
+CONCAT3(.Lchacha20_mips_xor_aligned_, PLUS_ONE(x), _b: ;) \
+ .if (x != 12); \
+ lw T0, (x*4)(STATE); \
+ .endif; \
+ lw T1, (x*4) ## (IN); \
+ .if (x == 12); \
+ addu X ## x, NONCE_0; \
+ .else; \
+ addu X ## x, T0; \
+ .endif; \
+ CPU_TO_LE32(X ## x); \
+ xor X ## x, T1; \
+ sw X ## x, (x*4) ## (OUT);
+
+/* Jump table macro.
+ * Used for setup and handling the last bytes, which are not multiple of 4.
+ * X15 is free to store Xn
+ * Every jumptable entry must be equal in size.
+ */
+#define JMPTBL_ALIGNED(x) \
+.Lchacha20_mips_jmptbl_aligned_ ## x: ; \
+ .set noreorder; \
+ b .Lchacha20_mips_xor_aligned_ ## x ## _b; \
+ .if (x == 12); \
+ addu SAVED_X, X ## x, NONCE_0; \
+ .else; \
+ addu SAVED_X, X ## x, SAVED_CA; \
+ .endif; \
+ .set reorder
+
+#define JMPTBL_UNALIGNED(x) \
+.Lchacha20_mips_jmptbl_unaligned_ ## x: ; \
+ .set noreorder; \
+ b .Lchacha20_mips_xor_unaligned_ ## x ## _b; \
+ .if (x == 12); \
+ addu SAVED_X, X ## x, NONCE_0; \
+ .else; \
+ addu SAVED_X, X ## x, SAVED_CA; \
+ .endif; \
+ .set reorder
+
+#define AXR(A, B, C, D, K, L, M, N, V, W, Y, Z, S) \
+ addu X(A), X(K); \
+ addu X(B), X(L); \
+ addu X(C), X(M); \
+ addu X(D), X(N); \
+ xor X(V), X(A); \
+ xor X(W), X(B); \
+ xor X(Y), X(C); \
+ xor X(Z), X(D); \
+ rotl X(V), S; \
+ rotl X(W), S; \
+ rotl X(Y), S; \
+ rotl X(Z), S;
+
+.text
+.set reorder
+.set noat
+.globl chacha20_mips
+.ent chacha20_mips
+chacha20_mips:
+ .frame $sp, STACK_SIZE, $ra
+
+ addiu $sp, -STACK_SIZE
+
+ /* Return bytes = 0. */
+ beqz BYTES, .Lchacha20_mips_end
+
+ lw NONCE_0, 48(STATE)
+
+ /* Save s0-s7 */
+ sw $s0, 0($sp)
+ sw $s1, 4($sp)
+ sw $s2, 8($sp)
+ sw $s3, 12($sp)
+ sw $s4, 16($sp)
+ sw $s5, 20($sp)
+ sw $s6, 24($sp)
+ sw $s7, 28($sp)
+
+ /* Test IN or OUT is unaligned.
+ * IS_UNALIGNED = ( IN | OUT ) & 0x00000003
+ */
+ or IS_UNALIGNED, IN, OUT
+ andi IS_UNALIGNED, 0x3
+
+ /* Set number of rounds */
+ li $at, 20
+
+ b .Lchacha20_rounds_start
+
+.align 4
+.Loop_chacha20_rounds:
+ addiu IN, CHACHA20_BLOCK_SIZE
+ addiu OUT, CHACHA20_BLOCK_SIZE
+ addiu NONCE_0, 1
+
+.Lchacha20_rounds_start:
+ lw X0, 0(STATE)
+ lw X1, 4(STATE)
+ lw X2, 8(STATE)
+ lw X3, 12(STATE)
+
+ lw X4, 16(STATE)
+ lw X5, 20(STATE)
+ lw X6, 24(STATE)
+ lw X7, 28(STATE)
+ lw X8, 32(STATE)
+ lw X9, 36(STATE)
+ lw X10, 40(STATE)
+ lw X11, 44(STATE)
+
+ move X12, NONCE_0
+ lw X13, 52(STATE)
+ lw X14, 56(STATE)
+ lw X15, 60(STATE)
+
+.Loop_chacha20_xor_rounds:
+ addiu $at, -2
+ AXR( 0, 1, 2, 3, 4, 5, 6, 7, 12,13,14,15, 16);
+ AXR( 8, 9,10,11, 12,13,14,15, 4, 5, 6, 7, 12);
+ AXR( 0, 1, 2, 3, 4, 5, 6, 7, 12,13,14,15, 8);
+ AXR( 8, 9,10,11, 12,13,14,15, 4, 5, 6, 7, 7);
+ AXR( 0, 1, 2, 3, 5, 6, 7, 4, 15,12,13,14, 16);
+ AXR(10,11, 8, 9, 15,12,13,14, 5, 6, 7, 4, 12);
+ AXR( 0, 1, 2, 3, 5, 6, 7, 4, 15,12,13,14, 8);
+ AXR(10,11, 8, 9, 15,12,13,14, 5, 6, 7, 4, 7);
+ bnez $at, .Loop_chacha20_xor_rounds
+
+ addiu BYTES, -(CHACHA20_BLOCK_SIZE)
+
+ /* Is data src/dst unaligned? Jump */
+ bnez IS_UNALIGNED, .Loop_chacha20_unaligned
+
+ /* Set number rounds here to fill delayslot. */
+ li $at, 20
+
+ /* BYTES < 0, it has no full block. */
+ bltz BYTES, .Lchacha20_mips_no_full_block_aligned
+
+ FOR_EACH_WORD_REV(STORE_ALIGNED)
+
+ /* BYTES > 0? Loop again. */
+ bgtz BYTES, .Loop_chacha20_rounds
+
+ /* Place this here to fill delay slot */
+ addiu NONCE_0, 1
+
+ /* BYTES < 0? Handle last bytes */
+ bltz BYTES, .Lchacha20_mips_xor_bytes
+
+.Lchacha20_mips_xor_done:
+ /* Restore used registers */
+ lw $s0, 0($sp)
+ lw $s1, 4($sp)
+ lw $s2, 8($sp)
+ lw $s3, 12($sp)
+ lw $s4, 16($sp)
+ lw $s5, 20($sp)
+ lw $s6, 24($sp)
+ lw $s7, 28($sp)
+
+ /* Write NONCE_0 back to right location in state */
+ sw NONCE_0, 48(STATE)
+
+.Lchacha20_mips_end:
+ addiu $sp, STACK_SIZE
+ jr $ra
+
+.Lchacha20_mips_no_full_block_aligned:
+ /* Restore the offset on BYTES */
+ addiu BYTES, CHACHA20_BLOCK_SIZE
+
+ /* Get number of full WORDS */
+ andi $at, BYTES, MASK_U32
+
+ /* Load upper half of jump table addr */
+ lui T0, %hi(.Lchacha20_mips_jmptbl_aligned_0)
+
+ /* Calculate lower half jump table offset */
+ ins T0, $at, 1, 6
+
+ /* Add offset to STATE */
+ addu T1, STATE, $at
+
+ /* Add lower half jump table addr */
+ addiu T0, %lo(.Lchacha20_mips_jmptbl_aligned_0)
+
+ /* Read value from STATE */
+ lw SAVED_CA, 0(T1)
+
+ /* Store remaining bytecounter as negative value */
+ subu BYTES, $at, BYTES
+
+ jr T0
+
+ /* Jump table */
+ FOR_EACH_WORD(JMPTBL_ALIGNED)
+
+
+.Loop_chacha20_unaligned:
+ /* Set number rounds here to fill delayslot. */
+ li $at, 20
+
+ /* BYTES > 0, it has no full block. */
+ bltz BYTES, .Lchacha20_mips_no_full_block_unaligned
+
+ FOR_EACH_WORD_REV(STORE_UNALIGNED)
+
+ /* BYTES > 0? Loop again. */
+ bgtz BYTES, .Loop_chacha20_rounds
+
+ /* Write NONCE_0 back to right location in state */
+ sw NONCE_0, 48(STATE)
+
+ .set noreorder
+ /* Fall through to byte handling */
+ bgez BYTES, .Lchacha20_mips_xor_done
+.Lchacha20_mips_xor_unaligned_0_b:
+.Lchacha20_mips_xor_aligned_0_b:
+ /* Place this here to fill delay slot */
+ addiu NONCE_0, 1
+ .set reorder
+
+.Lchacha20_mips_xor_bytes:
+ addu IN, $at
+ addu OUT, $at
+ /* First byte */
+ lbu T1, 0(IN)
+ addiu $at, BYTES, 1
+ CPU_TO_LE32(SAVED_X)
+ ROTR(SAVED_X)
+ xor T1, SAVED_X
+ sb T1, 0(OUT)
+ beqz $at, .Lchacha20_mips_xor_done
+ /* Second byte */
+ lbu T1, 1(IN)
+ addiu $at, BYTES, 2
+ ROTx SAVED_X, 8
+ xor T1, SAVED_X
+ sb T1, 1(OUT)
+ beqz $at, .Lchacha20_mips_xor_done
+ /* Third byte */
+ lbu T1, 2(IN)
+ ROTx SAVED_X, 8
+ xor T1, SAVED_X
+ sb T1, 2(OUT)
+ b .Lchacha20_mips_xor_done
+
+.Lchacha20_mips_no_full_block_unaligned:
+ /* Restore the offset on BYTES */
+ addiu BYTES, CHACHA20_BLOCK_SIZE
+
+ /* Get number of full WORDS */
+ andi $at, BYTES, MASK_U32
+
+ /* Load upper half of jump table addr */
+ lui T0, %hi(.Lchacha20_mips_jmptbl_unaligned_0)
+
+ /* Calculate lower half jump table offset */
+ ins T0, $at, 1, 6
+
+ /* Add offset to STATE */
+ addu T1, STATE, $at
+
+ /* Add lower half jump table addr */
+ addiu T0, %lo(.Lchacha20_mips_jmptbl_unaligned_0)
+
+ /* Read value from STATE */
+ lw SAVED_CA, 0(T1)
+
+ /* Store remaining bytecounter as negative value */
+ subu BYTES, $at, BYTES
+
+ jr T0
+
+ /* Jump table */
+ FOR_EACH_WORD(JMPTBL_UNALIGNED)
+.end chacha20_mips
+.set at
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