linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * SHA1 routine optimized to do word accesses rather than byte accesses,

 * and to avoid unnecessary copies into the context array.

 *

 * This was based on the git SHA1 implementation.

 */

​

#include <linux/kernel.h>

#include <linux/export.h>

#include <linux/bitops.h>

#include <linux/cryptohash.h>

#include <asm/unaligned.h>

​

/*

 * If you have 32 registers or more, the compiler can (and should)

 * try to change the array[] accesses into registers. However, on

 * machines with less than ~25 registers, that won't really work,

 * and at least gcc will make an unholy mess of it.

 *

 * So to avoid that mess which just slows things down, we force

 * the stores to memory to actually happen (we might be better off

 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as

 * suggested by Artur Skawina - that will also make gcc unable to

 * try to do the silly "optimize away loads" part because it won't

 * see what the value will be).

 *

 * Ben Herrenschmidt reports that on PPC, the C version comes close

 * to the optimized asm with this (ie on PPC you don't want that

 * 'volatile', since there are lots of registers).

 *

 * On ARM we get the best code generation by forcing a full memory barrier

 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and

 * the stack frame size simply explode and performance goes down the drain.

 */

​

#ifdef CONFIG_X86

  #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))

#elif defined(CONFIG_ARM)

  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)

#else

  #define setW(x, val) (W(x) = (val))

#endif

​

/* This "rolls" over the 512-bit array */

#define W(x) (array[(x)&15])

​

/*

 * Where do we get the source from? The first 16 iterations get it from

 * the input data, the next mix it from the 512-bit array.

 */

#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)

#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)

​

#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \

    __u32 TEMP = input(t); setW(t, TEMP); \

    E += TEMP + rol32(A,5) + (fn) + (constant); \

    B = ror32(B, 2); } while (0)

​

#define T_0_15(t, A, B, C, D, E)  SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )

#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )

#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )

#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )

#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )

​

/**

 * sha_transform - single block SHA1 transform

 *

 * @digest: 160 bit digest to update

 * @data:   512 bits of data to hash

 * @array:  16 words of workspace (see note)

 *

 * This function generates a SHA1 digest for a single 512-bit block.

 * Be warned, it does not handle padding and message digest, do not

 * confuse it with the full FIPS 180-1 digest algorithm for variable

 * length messages.

 *

 * Note: If the hash is security sensitive, the caller should be sure

 * to clear the workspace. This is left to the caller to avoid

 * unnecessary clears between chained hashing operations.

 */

void sha_transform(__u32 *digest, const char *data, __u32 *array)

{

    __u32 A, B, C, D, E;

​

    A = digest[0];

    B = digest[1];

    C = digest[2];

    D = digest[3];

    E = digest[4];

​

    /* Round 1 - iterations 0-16 take their input from 'data' */