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264 lines
6.8 KiB
264 lines
6.8 KiB
/*
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* Scalar AES core transform
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*
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* Copyright (C) 2017 Linaro Ltd.
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* Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/cache.h>
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.text
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.align 5
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rk .req r0
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rounds .req r1
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in .req r2
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out .req r3
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ttab .req ip
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t0 .req lr
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t1 .req r2
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t2 .req r3
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.macro __select, out, in, idx
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.if __LINUX_ARM_ARCH__ < 7
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and \out, \in, #0xff << (8 * \idx)
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.else
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ubfx \out, \in, #(8 * \idx), #8
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.endif
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.endm
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.macro __load, out, in, idx, sz, op
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.if __LINUX_ARM_ARCH__ < 7 && \idx > 0
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ldr\op \out, [ttab, \in, lsr #(8 * \idx) - \sz]
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.else
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ldr\op \out, [ttab, \in, lsl #\sz]
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.endif
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.endm
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.macro __hround, out0, out1, in0, in1, in2, in3, t3, t4, enc, sz, op, oldcpsr
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__select \out0, \in0, 0
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__select t0, \in1, 1
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__load \out0, \out0, 0, \sz, \op
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__load t0, t0, 1, \sz, \op
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.if \enc
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__select \out1, \in1, 0
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__select t1, \in2, 1
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.else
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__select \out1, \in3, 0
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__select t1, \in0, 1
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.endif
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__load \out1, \out1, 0, \sz, \op
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__select t2, \in2, 2
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__load t1, t1, 1, \sz, \op
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__load t2, t2, 2, \sz, \op
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eor \out0, \out0, t0, ror #24
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__select t0, \in3, 3
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.if \enc
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__select \t3, \in3, 2
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__select \t4, \in0, 3
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.else
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__select \t3, \in1, 2
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__select \t4, \in2, 3
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.endif
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__load \t3, \t3, 2, \sz, \op
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__load t0, t0, 3, \sz, \op
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__load \t4, \t4, 3, \sz, \op
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.ifnb \oldcpsr
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/*
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* This is the final round and we're done with all data-dependent table
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* lookups, so we can safely re-enable interrupts.
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*/
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restore_irqs \oldcpsr
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.endif
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eor \out1, \out1, t1, ror #24
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eor \out0, \out0, t2, ror #16
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ldm rk!, {t1, t2}
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eor \out1, \out1, \t3, ror #16
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eor \out0, \out0, t0, ror #8
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eor \out1, \out1, \t4, ror #8
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eor \out0, \out0, t1
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eor \out1, \out1, t2
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.endm
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.macro fround, out0, out1, out2, out3, in0, in1, in2, in3, sz=2, op, oldcpsr
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__hround \out0, \out1, \in0, \in1, \in2, \in3, \out2, \out3, 1, \sz, \op
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__hround \out2, \out3, \in2, \in3, \in0, \in1, \in1, \in2, 1, \sz, \op, \oldcpsr
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.endm
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.macro iround, out0, out1, out2, out3, in0, in1, in2, in3, sz=2, op, oldcpsr
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__hround \out0, \out1, \in0, \in3, \in2, \in1, \out2, \out3, 0, \sz, \op
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__hround \out2, \out3, \in2, \in1, \in0, \in3, \in1, \in0, 0, \sz, \op, \oldcpsr
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.endm
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.macro __rev, out, in
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.if __LINUX_ARM_ARCH__ < 6
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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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.else
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rev \out, \in
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.endif
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.endm
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.macro __adrl, out, sym, c
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.if __LINUX_ARM_ARCH__ < 7
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ldr\c \out, =\sym
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.else
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movw\c \out, #:lower16:\sym
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movt\c \out, #:upper16:\sym
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.endif
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.endm
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.macro do_crypt, round, ttab, ltab, bsz
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push {r3-r11, lr}
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// Load keys first, to reduce latency in case they're not cached yet.
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ldm rk!, {r8-r11}
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ldr r4, [in]
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ldr r5, [in, #4]
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ldr r6, [in, #8]
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ldr r7, [in, #12]
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#ifdef CONFIG_CPU_BIG_ENDIAN
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__rev r4, r4
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__rev r5, r5
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__rev r6, r6
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__rev r7, r7
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#endif
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eor r4, r4, r8
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eor r5, r5, r9
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eor r6, r6, r10
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eor r7, r7, r11
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__adrl ttab, \ttab
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/*
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* Disable interrupts and prefetch the 1024-byte 'ft' or 'it' table into
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* L1 cache, assuming cacheline size >= 32. This is a hardening measure
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* intended to make cache-timing attacks more difficult. They may not
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* be fully prevented, however; see the paper
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* https://cr.yp.to/antiforgery/cachetiming-20050414.pdf
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* ("Cache-timing attacks on AES") for a discussion of the many
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* difficulties involved in writing truly constant-time AES software.
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*/
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save_and_disable_irqs t0
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.set i, 0
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.rept 1024 / 128
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ldr r8, [ttab, #i + 0]
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ldr r9, [ttab, #i + 32]
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ldr r10, [ttab, #i + 64]
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ldr r11, [ttab, #i + 96]
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.set i, i + 128
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.endr
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push {t0} // oldcpsr
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tst rounds, #2
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bne 1f
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0: \round r8, r9, r10, r11, r4, r5, r6, r7
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\round r4, r5, r6, r7, r8, r9, r10, r11
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1: subs rounds, rounds, #4
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\round r8, r9, r10, r11, r4, r5, r6, r7
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bls 2f
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\round r4, r5, r6, r7, r8, r9, r10, r11
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b 0b
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2: .ifb \ltab
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add ttab, ttab, #1
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.else
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__adrl ttab, \ltab
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// Prefetch inverse S-box for final round; see explanation above
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.set i, 0
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.rept 256 / 64
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ldr t0, [ttab, #i + 0]
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ldr t1, [ttab, #i + 32]
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.set i, i + 64
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.endr
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.endif
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pop {rounds} // oldcpsr
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\round r4, r5, r6, r7, r8, r9, r10, r11, \bsz, b, rounds
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#ifdef CONFIG_CPU_BIG_ENDIAN
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__rev r4, r4
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__rev r5, r5
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__rev r6, r6
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__rev r7, r7
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#endif
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ldr out, [sp]
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str r4, [out]
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str r5, [out, #4]
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str r6, [out, #8]
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str r7, [out, #12]
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pop {r3-r11, pc}
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.align 3
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.ltorg
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.endm
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ENTRY(__aes_arm_encrypt)
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do_crypt fround, crypto_ft_tab,, 2
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ENDPROC(__aes_arm_encrypt)
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.align 5
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ENTRY(__aes_arm_decrypt)
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do_crypt iround, crypto_it_tab, __aes_arm_inverse_sbox, 0
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ENDPROC(__aes_arm_decrypt)
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.section ".rodata", "a"
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.align L1_CACHE_SHIFT
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.type __aes_arm_inverse_sbox, %object
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__aes_arm_inverse_sbox:
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.byte 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38
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.byte 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb
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.byte 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87
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.byte 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb
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.byte 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d
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.byte 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e
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.byte 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2
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.byte 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25
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.byte 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16
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.byte 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92
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.byte 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda
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.byte 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84
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.byte 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a
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.byte 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06
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.byte 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02
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.byte 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b
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.byte 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea
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.byte 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73
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.byte 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85
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.byte 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e
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.byte 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89
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.byte 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b
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.byte 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20
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.byte 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4
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.byte 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31
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.byte 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f
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.byte 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d
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.byte 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef
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.byte 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0
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.byte 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61
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.byte 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26
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.byte 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
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.size __aes_arm_inverse_sbox, . - __aes_arm_inverse_sbox
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