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+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * BLAKE2s digest algorithm, ARM scalar implementation
+ *
+ * Copyright 2020 Google LLC
+ *
+ * Author: Eric Biggers <ebiggers@google.com>
+ */
+
+#include <linux/linkage.h>
+
+ // Registers used to hold message words temporarily. There aren't
+ // enough ARM registers to hold the whole message block, so we have to
+ // load the words on-demand.
+ M_0 .req r12
+ M_1 .req r14
+
+// The BLAKE2s initialization vector
+.Lblake2s_IV:
+ .word 0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A
+ .word 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19
+
+.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
+
+// Execute a quarter-round of BLAKE2s by mixing two columns or two diagonals.
+// (a0, b0, c0, d0) and (a1, b1, c1, d1) give the registers containing the two
+// columns/diagonals. s0-s1 are the word offsets to the message words the first
+// column/diagonal needs, and likewise s2-s3 for the second column/diagonal.
+// M_0 and M_1 are free to use, and the message block can be found at sp + 32.
+//
+// Note that to save instructions, the rotations don't happen when the
+// pseudocode says they should, but rather they are delayed until the values are
+// used. See the comment above _blake2s_round().
+.macro _blake2s_quarterround a0, b0, c0, d0, a1, b1, c1, d1, s0, s1, s2, s3
+
+ ldr M_0, [sp, #32 + 4 * \s0]
+ ldr M_1, [sp, #32 + 4 * \s2]
+
+ // a += b + m[blake2s_sigma[r][2*i + 0]];
+ add \a0, \a0, \b0, ror #brot
+ add \a1, \a1, \b1, ror #brot
+ add \a0, \a0, M_0
+ add \a1, \a1, M_1
+
+ // d = ror32(d ^ a, 16);
+ eor \d0, \a0, \d0, ror #drot
+ eor \d1, \a1, \d1, ror #drot
+
+ // c += d;
+ add \c0, \c0, \d0, ror #16
+ add \c1, \c1, \d1, ror #16
+
+ // b = ror32(b ^ c, 12);
+ eor \b0, \c0, \b0, ror #brot
+ eor \b1, \c1, \b1, ror #brot
+
+ ldr M_0, [sp, #32 + 4 * \s1]
+ ldr M_1, [sp, #32 + 4 * \s3]
+
+ // a += b + m[blake2s_sigma[r][2*i + 1]];
+ add \a0, \a0, \b0, ror #12
+ add \a1, \a1, \b1, ror #12
+ add \a0, \a0, M_0
+ add \a1, \a1, M_1
+
+ // d = ror32(d ^ a, 8);
+ eor \d0, \a0, \d0, ror#16
+ eor \d1, \a1, \d1, ror#16
+
+ // c += d;
+ add \c0, \c0, \d0, ror#8
+ add \c1, \c1, \d1, ror#8
+
+ // b = ror32(b ^ c, 7);
+ eor \b0, \c0, \b0, ror#12
+ eor \b1, \c1, \b1, ror#12
+.endm
+
+// Execute one round of BLAKE2s by updating the state matrix v[0..15]. v[0..9]
+// are in r0..r9. The stack pointer points to 8 bytes of scratch space for
+// spilling v[8..9], then to v[9..15], then to the message block. r10-r12 and
+// r14 are free to use. The macro arguments s0-s15 give the order in which the
+// message words are used in this 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 BLAKE2s 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 (7, 8) after every round.
+.macro _blake2s_round s0, s1, s2, s3, s4, s5, s6, s7, \
+ s8, s9, s10, s11, s12, s13, s14, s15
+
+ // Mix first two columns:
+ // (v[0], v[4], v[8], v[12]) and (v[1], v[5], v[9], v[13]).
+ __ldrd r10, r11, sp, 16 // load v[12] and v[13]
+ _blake2s_quarterround r0, r4, r8, r10, r1, r5, r9, r11, \
+ \s0, \s1, \s2, \s3
+ __strd r8, r9, sp, 0
+ __strd r10, r11, sp, 16
+
+ // Mix second two columns:
+ // (v[2], v[6], v[10], v[14]) and (v[3], v[7], v[11], v[15]).
+ __ldrd r8, r9, sp, 8 // load v[10] and v[11]
+ __ldrd r10, r11, sp, 24 // load v[14] and v[15]
+ _blake2s_quarterround r2, r6, r8, r10, r3, r7, r9, r11, \
+ \s4, \s5, \s6, \s7
+ str r10, [sp, #24] // store v[14]
+ // v[10], v[11], and v[15] are used below, so no need to store them yet.
+
+ .set brot, 7
+ .set drot, 8
+
+ // Mix first two diagonals:
+ // (v[0], v[5], v[10], v[15]) and (v[1], v[6], v[11], v[12]).
+ ldr r10, [sp, #16] // load v[12]
+ _blake2s_quarterround r0, r5, r8, r11, r1, r6, r9, r10, \
+ \s8, \s9, \s10, \s11
+ __strd r8, r9, sp, 8
+ str r11, [sp, #28]
+ str r10, [sp, #16]
+
+ // Mix second two diagonals:
+ // (v[2], v[7], v[8], v[13]) and (v[3], v[4], v[9], v[14]).
+ __ldrd r8, r9, sp, 0 // load v[8] and v[9]
+ __ldrd r10, r11, sp, 20 // load v[13] and v[14]
+ _blake2s_quarterround r2, r7, r8, r10, r3, r4, r9, r11, \
+ \s12, \s13, \s14, \s15
+ __strd r10, r11, sp, 20
+.endm
+
+//
+// void blake2s_compress_arch(struct blake2s_state *state,
+// const u8 *block, size_t nblocks, u32 inc);
+//
+// Only the first three fields of struct blake2s_state are used:
+// u32 h[8]; (inout)
+// u32 t[2]; (inout)
+// u32 f[2]; (in)
+//
+ .align 5
+ENTRY(blake2s_compress_arch)
+ push {r0-r2,r4-r11,lr} // keep this an even number
+
+.Lnext_block:
+ // r0 is 'state'
+ // r1 is 'block'
+ // r3 is 'inc'
+
+ // Load and increment the counter t[0..1].
+ __ldrd r10, r11, r0, 32
+ adds r10, r10, r3
+ adc r11, r11, #0
+ __strd r10, r11, r0, 32
+
+ // _blake2s_round is very short on registers, so copy the message block
+ // to the stack to save a register during the rounds. This also has the
+ // advantage that misalignment only needs to be dealt with in one place.
+ sub sp, sp, #64
+ mov r12, sp
+ tst r1, #3
+ bne .Lcopy_block_misaligned
+ ldmia r1!, {r2-r9}
+ stmia r12!, {r2-r9}
+ ldmia r1!, {r2-r9}
+ stmia r12, {r2-r9}
+.Lcopy_block_done:
+ str r1, [sp, #68] // Update message pointer
+
+ // Calculate v[8..15]. Push v[9..15] onto the stack, and leave space
+ // for spilling v[8..9]. Leave v[8..9] in r8-r9.
+ mov r14, r0 // r14 = state
+ adr r12, .Lblake2s_IV
+ ldmia r12!, {r8-r9} // load IV[0..1]
+ __ldrd r0, r1, r14, 40 // load f[0..1]
+ ldm r12, {r2-r7} // load IV[3..7]
+ eor r4, r4, r10 // v[12] = IV[4] ^ t[0]
+ eor r5, r5, r11 // v[13] = IV[5] ^ t[1]
+ eor r6, r6, r0 // v[14] = IV[6] ^ f[0]
+ eor r7, r7, r1 // v[15] = IV[7] ^ f[1]
+ push {r2-r7} // push v[9..15]
+ sub sp, sp, #8 // leave space for v[8..9]
+
+ // Load h[0..7] == v[0..7].
+ ldm r14, {r0-r7}
+
+ // Execute the rounds. Each round is provided the order in which it
+ // needs to use the message words.
+ .set brot, 0
+ .set drot, 0
+ _blake2s_round 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
+ _blake2s_round 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3
+ _blake2s_round 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4
+ _blake2s_round 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8
+ _blake2s_round 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13
+ _blake2s_round 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9
+ _blake2s_round 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11
+ _blake2s_round 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10
+ _blake2s_round 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5
+ _blake2s_round 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0
+
+ // Fold the final state matrix into the hash chaining value:
+ //
+ // for (i = 0; i < 8; i++)
+ // h[i] ^= v[i] ^ v[i + 8];
+ //
+ ldr r14, [sp, #96] // r14 = &h[0]
+ add sp, sp, #8 // v[8..9] are already loaded.
+ pop {r10-r11} // load v[10..11]
+ eor r0, r0, r8
+ eor r1, r1, r9
+ eor r2, r2, r10
+ eor r3, r3, r11
+ ldm r14, {r8-r11} // load h[0..3]
+ eor r0, r0, r8
+ eor r1, r1, r9
+ eor r2, r2, r10
+ eor r3, r3, r11
+ stmia r14!, {r0-r3} // store new h[0..3]
+ ldm r14, {r0-r3} // load old h[4..7]
+ pop {r8-r11} // load v[12..15]
+ eor r0, r0, r4, ror #brot
+ eor r1, r1, r5, ror #brot
+ eor r2, r2, r6, ror #brot
+ eor r3, r3, r7, ror #brot
+ eor r0, r0, r8, ror #drot
+ eor r1, r1, r9, ror #drot
+ eor r2, r2, r10, ror #drot
+ eor r3, r3, r11, ror #drot
+ add sp, sp, #64 // skip copy of message block
+ stm r14, {r0-r3} // store new h[4..7]
+
+ // Advance to the next block, if there is one. Note that if there are
+ // multiple blocks, then 'inc' (the counter increment amount) must be
+ // 64. So we can simply set it to 64 without re-loading it.
+ ldm sp, {r0, r1, r2} // load (state, block, nblocks)
+ mov r3, #64 // set 'inc'
+ subs r2, r2, #1 // nblocks--
+ str r2, [sp, #8]
+ bne .Lnext_block // nblocks != 0?
+
+ pop {r0-r2,r4-r11,pc}
+
+ // The next message block (pointed to by r1) isn't 4-byte aligned, so it
+ // can't be loaded using ldmia. Copy it to the stack buffer (pointed to
+ // by r12) using an alternative method. r2-r9 are free to use.
+.Lcopy_block_misaligned:
+ mov r2, #64
+1:
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ ldr r3, [r1], #4
+#else
+ ldrb r3, [r1, #0]
+ ldrb r4, [r1, #1]
+ ldrb r5, [r1, #2]
+ ldrb r6, [r1, #3]
+ add r1, r1, #4
+ orr r3, r3, r4, lsl #8
+ orr r3, r3, r5, lsl #16
+ orr r3, r3, r6, lsl #24
+#endif
+ subs r2, r2, #4
+ str r3, [r12], #4
+ bne 1b
+ b .Lcopy_block_done
+ENDPROC(blake2s_compress_arch)